Abstract:
The invention comprehends friction plates, typically fabricated of metal, having friction material that is disposed in multiple concentric bands disposed in interrupted or discontinuous segments or a combination of both. In a first embodiment, the friction material is arranged in two concentric bands on each face, an inner band having a smaller radial width and an outer band having a larger radial width. In a second embodiment, the inner band is replaced with a plurality of discontinuous sections or segments wherein their circumferential separation is greater than their circumferential length. A third embodiment is similar to the second embodiment except that the inner, discontinuous segments have a circumferential length greater than their circumferential separation.

Description:
FIELD 
       [0001]    The present disclosure relates to friction plates for clutches and more particularly to friction plates for friction clutches having interrupted or discontinuous patterns of friction material on the faces of the clutch plates. 
       BACKGROUND 
       [0002]    The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art. 
         [0003]    Friction clutch assemblies are extraordinarily common components of mechanical power transmission devices. Wherever a rotating, torque supplying member must be coupled to an initially non-rotating member a friction clutch will generally be utilized. The friction clutch typically includes one or more plates rotationally coupled to a first member having friction material on both faces which are interleaved with plates such as reaction plates which are rotationally coupled to a second member and which lack such material. The interleaved plates are compressed by a linear actuator and, when compressed, torque is transmitted through the device. 
         [0004]    In the prior art, the friction material on the clutch plates takes the form of two bands of equal inside and outside diameters that are secured to opposite faces of the clutch plate, typically by an adhesive. The bands may be fabricated of clutch paper or of a more specialized material that provides certain, desirable frictional characteristics. While simple and inexpensive, this friction material configuration is accompanied by certain shortcomings. First of all, a continuous band of material may interfere with radial flow of cooling and lubricating fluid in a wet clutch. Second of all, because the outside edge of the band of friction material is generally adjacent to the outside edge of the clutch plate, uneven pressure and loading on the plates of the clutch may result. Such uneven loading can result in both reduced torque capacity and service life. 
         [0005]    The present invention is directed to improving torque capacity and service life by addressing this problem. 
       SUMMARY 
       [0006]    The present invention provides a friction plate having interrupted or discontinuous bands of friction material on its faces. The invention comprehends friction plates, typically fabricated of metal, having friction material that is disposed in concentric bands disposed in interrupted or discontinuous segments or a combination of both. In a first embodiment, the friction material is arranged in two concentric bands on each face, an inner band having a smaller radial width radially spaced from an outer band having a larger radial width. In a second embodiment, the inner band is replaced with a plurality of discontinuous sections or segments wherein their circumferential separation is greater than their circumferential length. A third embodiment is similar to the second embodiment except that the inner, discontinuous segments have a circumferential length greater than their circumferential separation. Friction plates having either inner, female splines or outer, male splines as well as a friction clutch assembly incorporating friction plates incorporating the present invention are also disclosed. Friction plates embodying the present invention provide improved lubrication circulation in wet clutches and thus improved heat dissipation as well as enhanced operation. 
         [0007]    Thus it is an aspect of the present invention to provide a friction plate having interrupted or non-continuous bands of friction material on its faces. 
         [0008]    It is a further aspect of the present invention to provide a friction plate having multiple, radially spaced apart bands of friction material on its faces. 
         [0009]    It is a still further aspect of the present invention to provide a friction plate having circumferentially interrupted or spaced apart segments or section of friction material on its faces. 
         [0010]    It is a still further aspect of the present invention to provide a friction plate having a combination of multiple spaced apart bands and discontinuous segments of friction material on its faces. 
         [0011]    It is a still further aspect of the present invention to provide a friction clutch assembly incorporating friction plates having interrupted or non-continuous bands of friction material on their faces. 
         [0012]    Further aspects, advantages and areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0013]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
           [0014]      FIG. 1  is a plan view of a first embodiment of a clutch plate for a friction clutch assembly having two radially spaced apart and continuous bands or annuli of friction material; 
           [0015]      FIG. 2  is a fragmentary, sectional view of the first embodiment of a clutch plate for a friction clutch assembly taken along line  2 - 2  of  FIG. 1 ; 
           [0016]      FIG. 3  is a plan view of a second embodiment of a clutch plate for a friction clutch assembly having an outer continuous band or annulus of friction material and an inner discontinuous or segmented band or annulus of friction material with smaller segments and larger spaces; 
           [0017]      FIG. 4  is a fragmentary, sectional view of the second embodiment of a clutch plate for a friction clutch assembly taken along line  4 - 4  of  FIG. 3 ; 
           [0018]      FIG. 5  is a plan view of a third embodiment of a clutch plate for a friction clutch assembly having an outer continuous band or annulus of friction material and an inner discontinuous or segmented band or annulus of friction material with larger segments and smaller spaces; 
           [0019]      FIG. 6  is a fragmentary, sectional view of the third embodiment of a clutch plate for a friction clutch assembly taken along line  6 - 6  of  FIG. 5 ; and 
           [0020]      FIG. 7  is a full, sectional view of a friction clutch pack assembly having friction clutch plates incorporating to the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
         [0022]    With reference to  FIGS. 1 and 2 , a first embodiment of a friction clutch plate incorporating the present invention is illustrated and generally designated by the reference number  10 . The friction clutch plate  10  includes a flat metal disc or plate  12  which defines a large center opening  14  and a plurality of male splines or teeth  16  disposed and evenly circumferentially spaced about its periphery. The plurality of male splines or teeth  16  engage and drive (or are driven by) complementarily configured female spines or teeth in a clutch housing described below with reference to  FIG. 7 . The friction clutch plate also defines flat or planar opposed front and back sides, faces or surfaces  18 A and  18 B. 
         [0023]    An identical pattern or arrangement of friction material is disposed on both front and back surfaces  18 A and  18 B and thus only the complete front surface  18 A is illustrated and will be described, it being understood that the back side, surface or face  18 B is identical to the front side, surface or face  18 A. On the front face  18 A of the friction plate  10  resides a continuous first or outer band or annulus of friction material  20  having an outer circumferential edge  22  disposed just radially inside and adjacent the minor diameter of the splines or teeth  16  on the periphery of the friction plate  10 . Similarly, just inside and adjacent the inner edge  24  of the friction plate  10  resides a continuous second or inner band or annulus of friction material  26 . The friction material utilized here and in the other disclosed embodiments may be either what is commonly referred to as friction paper or may be one of numerous other conventional or proprietary materials commonly utilized in friction clutch assemblies which is secured to the front and back surfaces  18 A and  18 B of the disc or plate  12  by an adhesive. 
         [0024]    The width of the first band or annulus of friction material  20  is preferably approximately twice as wide as the width of the second band or annulus of friction material  26 . A circular space or region  28  radially separates the inner and outer bands  20  and  26  of friction material. Preferably, the width of the circular space or region  28  between the bands  20  and  26  of friction material is approximately as wide as the width of the second, inner band  26  of friction material. As noted above, the inner and outer diameters of the bands  20  and  26  are the same width and spacing on each face  18 A and  18 B so that axial forces applied to the friction material  20  and  26  do not distort, i.e., warp, the friction plate  10 . 
         [0025]    Referring now to  FIGS. 3 and 4 , a second embodiment of a friction clutch plate incorporating the present invention is illustrated and generally designated by the reference number  40 . Once again, the second embodiment friction clutch plate  40  includes a flat or planar metal disc  42  which defines a large center opening  44  and a plurality of male splines or teeth  46  disposed and evenly circumferentially spaced about its periphery. The plurality of male splines or teeth  46  engage and drive (or are driven by) complementarily configured female spines or teeth in a clutch housing described below with reference to  FIG. 7 . The friction clutch plate also defines planar opposed front and back sides, faces or surfaces  48 A and  48 B. 
         [0026]    An identical pattern or arrangement of friction material is disposed on both front and back surfaces  48 A and  48 B and thus only the complete front surface  48 A is illustrated and will be described, it being understood that the back side, surface or face  48 B is identical with regard to both spacing and arrangement of the friction material to the front side, surface or face  48 A. On the front face  48 A of the friction plate  40  resides a continuous first or outer band or annulus of friction material  50  having an outer circumferential edge  52  disposed just inside and adjacent the minor diameter of the splines or teeth  46  on the periphery of the friction plate  40 . Similarly, just inside and adjacent the inner edge  54  of the friction plate  40  resides an interrupted or discontinuous second or inner band or annulus of friction material comprising a plurality of equally circumferentially spaced apart arcuate segments or sections  56 . 
         [0027]    The width of the first band or annulus of friction material  50  is preferably approximately twice as wide as the width of the arcuate segments or sections of friction material  56 . While six segments or sections  56  each extending over approximately 10° are illustrated in  FIG. 3 , it will be appreciated that fewer segments or sections  56  such as three, four, or five or more segments or sections  56  such as eight, ten or twelve may be utilized and fall within the scope of the present invention. Similarly, each of the segments or sections  56  may extend over an angle greater than 10°, especially if fewer than six sections or segments  56  are utilized; the engineering criteria being that the angular spaces between the segments or sections  56  are significantly greater than the angular length of the segments or sections  56 . For example, and as stated, the segments or sections  56  extend over approximately 10° whereas the angular spaces between them extend over approximately 50°. 
         [0028]    The segments or sections  56  are spaced radially inwardly from the first continuous band or annulus of friction material  50 . Preferably, the width of the radial spaces  58  between the band or annulus  50  of friction material and the segments or sections  56  of friction material is approximately as wide as the width of the segments or sections  56 . As noted above, the width, and inner and outer diameters of the first continuous band  50  of friction material and the number, width, inner and outer diameters and placement of the discontinuous segments or sections  56  are the same on each face  48 A and  48 B so that axial forces applied to the friction material  50  and  56  do not distort, i.e., warp, the friction plate  40 . 
         [0029]    Referring now to  FIGS. 5 and 6 , a third embodiment of a friction clutch plate incorporating the present invention is illustrated and generally designated by the reference number  60 . Once again, the third embodiment friction clutch plate  60  includes a flat or planar metal disc  62  which defines a large center opening  64  and a plurality of male splines or teeth  66  disposed and evenly circumferentially spaced about its periphery. The plurality of male splines or teeth  66  engage and drive (or are driven by) complementarily configured female spines or teeth in a clutch housing described below with reference to  FIG. 7 . The friction clutch plate also defines planar opposed front and back sides, faces or surfaces  68 A and  68 B. 
         [0030]    An identical pattern or arrangement of friction material is disposed on both front and back surfaces  68 A and  68 B and thus only the complete front surface  68 A is illustrated and will be described, it being understood that the back side, surface or face  68 B is identical with regard to both spacing and arrangement of the friction material to the front side, surface or face  68 A. On the front face  68 A of the friction plate  60  resides a continuous first or outer band or annulus of friction material  70  having an outer circumferential edge  72  disposed just inside and adjacent the minor diameter of the splines or teeth  66  on the periphery of the friction plate  70 . Similarly, just inside and adjacent the inner edge  74  of the friction plate  70  resides an interrupted or discontinuous second or inner band or annulus of friction material comprising a plurality of equally circumferentially spaced apart arcuate segments or sections  76 . 
         [0031]    The width of the first band or annulus of friction material  70  is preferably approximately twice as wide as the radial width of the arcuate segments or sections  76  of friction material. While five segments or sections  76  each extending over approximately 40° are illustrated in  FIG. 5 , it will be appreciated that fewer segments or sections  76  such as three or four, or more segments or sections  76  such as six, eight or ten may be utilized and fall within the scope of the present invention. Similarly, each of the segments or sections  76  may extend over a greater angle than 40°, especially if a smaller number than five sections or segments  76  are utilized; the engineering criteria being that the angular spaces between the segments are smaller than the angular length of the segments or sections  76 . For example, and as stated, the segments or sections  76  extend over approximately 40° whereas the angular spaces between them extend over approximately 30°. 
         [0032]    The segments or sections  76  are spaced radially inwardly from the first continuous band or annulus of friction material  70 . Preferably, the width of annular spaces  78  between the continuous band or annulus of friction material  70  and the segments or sections  76  of friction material is at least as wide as the width of the segments or sections  76 . As noted above, the width and inner and outer diameters of the continuous band  70  and the number, width, inner and outer diameters and placement of the discontinuous segments or sections  76  are the same on each face  68 A and  68 B of the friction plate  60  so that axial forces applied to the friction material  70  and segments or sections  76  of friction material do not distort, i.e., warp, the friction plate  70 . 
         [0033]    Referring now to  FIG. 7 , it should be understood that a friction clutch pack assembly may include either friction plates  20 ,  40  and  60 , as illustrated and described above, having external or male splines or teeth  16 ,  46  and  66  which couple them to a clutch housing interleaved with reaction plates having internal or female splines or teeth which couple them to a clutch hub, or vice versa, that is, friction plates having internal splines or teeth which couple them to a hub interleaved with reaction plates having external splines or teeth which couple them to a housing. It should be understood that both friction clutch plate configurations are within the scope of the present invention. 
         [0034]    A typical and exemplary friction pack clutch assembly having the latter configuration and incorporating the present invention is illustrated and generally designated by the reference number  100 . The friction pack clutch assembly  100  includes an input hub  102  which is connected to and driven by a source of torque such as a shaft, quill, or clutch or brake component of a transmission, transfer case, differential of other torque carrying member of, for example, a motor vehicle powertrain (not illustrated). The input hub  102  includes axially extending male splines or teeth  104  which are complementary to and engage female splines or teeth  106  on a plurality of first or friction plates  108 . The plurality of first or friction plates  108  each includes friction material  110  disposed on both faces which may be arranged according to any of the three embodiments of the present invention  20 ,  40  and  60  described directly above. The plurality of first or friction plates  108  are interleaved with a plurality of second or reaction plates  112 . The reaction plates  112  are preferably fabricated of steel or aluminum and include a plurality of male splines or teeth  114  disposed about their peripheries which engage and drive complementarily configured axially extending female splines or teeth  116  on a clutch housing  120 . 
         [0035]    The clutch housing  120  may be either rotatable or stationary. On a first end of the interleaved friction clutch plates  108  and reaction plates  112 , the clutch housing  120  includes an inwardly extending circular web or stop  122  and an adjacent annular backing plate  124  against which the interleaved plates  108  and  112  are compressed. On a second or opposite end of the interleaved plates  108  and  112  is an apply plate  126  which is acted upon by a piston  128  of a hydraulic, electric or pneumatic operator or actuator  130 . Axial force from the operator or actuator  130  is applied across the apply plate  126 , compressing the interleaved plates  108  and  112  against the backing plate  124  thereby transmitting torque through the friction pack clutch assembly  100 . 
         [0036]    Although the term “input hub” has been utilized above and the description, for reasons of clarity and simplicity, has assumed that when the clutch is engaged, torque is transmitted from the input hub  102  to the clutch housing  120 , it should be appreciated that (a) not only torque may be as readily transmitted from the housing  120  of the friction pack clutch assembly  100  to the hub  102  ( b ) but also the assembly  100  may readily function as a brake when, as noted above, the clutch housing  120  is stationary. 
         [0037]    It will be appreciated that friction clutch plates  20 ,  40  and  60  according to the present invention provide improved lubrication flow from the inner diameter of the clutch plates to their outer diameter by virtue of the radial and circumferential spacing of the bands and segments of friction material on the faces or surfaces of the plates. By providing improved lubrication flow, first of all, heat dissipation is improved and, second of all, the repeatability and proportionality of clutch engaging force versus torque transfer and thus the control of delivered torque is also improved. 
         [0038]    The description of the invention is merely exemplary in nature and variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.