BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded view of a friction clutch assembly having a dual reaction plate and friction plate with a friction interface according to the invention;
FIG. 2A is a fragmentary side view of a portion of a reaction plate between adjacent friction plates, each forming a friction interface with the reaction plate according to one embodiment of the invention;
FIG. 2B is a fragmentary top view of a portion of the reaction plate according to the invention;
FIG. 3A is a fragmentary perspective view of a reaction plate having a blind hole according to a second embodiment of the invention;
FIG. 3B is a fragmentary perspective view of a portion of a reaction plate having an alternately oriented blind hole according to the second embodiment of the invention;
FIG. 3C is a fragmentary perspective view of a portion of a reaction plate having a selectively pluggable inner orifice according to a third embodiment of the invention;
FIG. 4A is an exploded view of a friction clutch assembly having unitary friction/reaction plates according to a fourth embodiment of the invention; and
FIG. 4B is a fragmentary side view of a portion of pair of unitary friction/plates forming a friction interface therebetween according to the fourth embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawings wherein like reference numbers correspond to like or similar components throughout the several figures, there is shown in FIG. 1 an exploded view of a clutch plate assembly 10 having a friction plate 14 and a reaction plate 18, and a friction interface 65 therebetween. For simplicity, only one friction plate 14 is shown, however those skilled in the art will recognize that clutch plate assembly 10 may consist of any number of alternately arranged friction plates 14 and reaction plates 18, depending on the specific clutch application. Friction plate 14 has a core plate 36 having a first and second main surface 28, 29, respectively, the core plate 36 preferably constructed of a suitable grade of stainless steel and having a plurality of inwardly-extending splines 24 configured to mate or interlock with alternating grooves of an adjoining clutch hub (not shown).
Preferably, first and second main surfaces 28, 29 each have a layer of friction material 20A, 20B, respectively, which is bonded or otherwise attached to surfaces 28, 29 of the core plate 36, although friction material such as 20A, 20B may also be bonded directly to a unitary friction/reaction plate (not shown). The friction material 20A, 20B is preferably ring-shaped and sized to cover the primary surface 28, 29 of the core plate 36 to which the friction material is bonded, and further includes a plurality of surface fluid channels 16 that separate the friction material layer 20A, 20B into substantially equal patches or segments for directing pressurized fluid 15 between the outer diameter 38 and the inner diameter 13 of the core plate 36, or between the inner diameter 13 and the outer diameter 38, depending on the design of the clutch assembly 10. While the friction material 20A, 20B as shown in FIG. 1 have fluid channels 16 as shown, other styles or designs of friction material may also be used within the scope of the invention, including, for example, smooth or grooveless material, or a series of surface channels or grooves that are pressed partially through the thickness of the friction material 20A, 20B.
Friction plate 14 is configured to press against and synchronize with the speed of the mating reaction plate 18 when a controllable source of hydraulic pressure, preferably a positive displacement transmission pump 11, actuates or engages an apply mechanism such as clutch-apply piston (not shown) to selectively compress the alternating friction plates 14 and reaction plates 18 that make up the clutch assembly 10. As plates 14, 18 become interlocked due to the friction forces imparted by the layer of friction material 20B, the clutch plate assembly is thereby engaged, and the mating plates 14, 18 are permitted to rotate in unison.
Reaction plate 18 is a preferably circular metallic ring of a suitable grade of stainless steel having an outer and inner diameter 22, 12, respectively, and includes a plurality of outwardly extending splines 32 configured to mate or interlock with a plurality of grooves positioned on the inside surface of a mating clutch drum (not shown). The reaction plate 18 has a first main surface 37 and a reverse or second main surface 39 (see FIG. 2A), with main surfaces 37, 39 being at least as wide as the width of friction material 20A, 20B to allow for maximum frictional contact area between mating plates such as plates 14 and 18. The reaction plate 18 also has outer and inner lateral or side surfaces 48, 58, respectively, each having a width/height sufficient to provide the reaction plate 18 with adequate bending and surface strength without adding excessive weight for a given clutch application, and with sufficient thickness to accommodate the drilling of fluid passages therein as described hereinbelow.
Reaction plate 18 is further provided with a plurality of primary fluid passages 42 extending radially inward through the reaction plate 18 from outer lateral surface 48 to inner lateral surface 58, preferably perpendicularly with respect to the lateral surfaces 48, 58 as shown in FIG. 1 and substantially parallel to the main surfaces 37, 39. Each of primary fluid passages 42 are in fluid communication with a source 11 of pressurized fluid 15 which is configured to deliver the fluid 15 through one of the outer or inner orifices 34, 50 of primary fluid passage 42, depending on the application. Orifices 34, 50, along with primary fluid channels 42, are preferably circular or cylindrical in shape so as to minimize the effects of fluid friction and are preferably positioned approximately midway up lateral surfaces 48, 58 and approximately halfway between main surfaces 37, 39 of reaction plate 18, and approximately midway between each of the outer splines 32, so as to minimize the amount of material that must be removed from the reaction plate 18 during forming or drilling of the primary fluid passages 42. However, those skilled in the art will recognize that the location of the outer orifices 34 may be positioned in alternate locations along or around the outer lateral surface 48. For example, each of outer orifices 34 may be positioned on a respective spline face 33 of an outer spline 32 to thereby increase the area of potential fluid/metal contact for an enhanced fluid cooling effect.
Turning to FIG. 2A, which is a side view of a portion of the clutch plate assembly 10, a reaction plate 18 is disposed between a pair of friction plates 14A, 14B, forming or defining a pair of boundary or friction interfaces 65A, 65B between the friction plates 14A, 14B and the reaction plate 18, respectively. Outer orifice 34 admits a flow of pressurized fluid 15 from outer lateral surface 48 into the reaction plate 18, as previously explained herewithin. For delivery of fluid 15 directly to the friction interfaces 65A, 65B for the cooling of main surfaces 37, 39, the reaction plate 18 is further provided with a preferably circular or cylindrical secondary fluid passage 62 having a pair of circular or cylindrical first and second orifices 40 and 70, respectively, each in fluid communication with primary fluid passage 42 through the secondary fluid passage 62.
In the preferred embodiment, first and second orifices 40, 70 are each positioned on main surfaces 37, 39, respectively, at opposite ends of secondary fluid passage 62 and open to the friction interfaces 65A, 65B between reaction plate 18 and friction plates 14A, 14B, respectively. First orifice 40 is positioned on the main surface 37 of reaction plate 18 directly above primary fluid passage 42 and approximately midway between the respective outer and inner diameters 22, 12 of the reaction plate 18, and second orifice 70 is positioned on the second primary surface 39 directly below primary fluid passage 42. While FIG. 1 shows just one first and second orifice 40, 70, those skilled in the art will recognize that additional orifices substantially identical to first and second orifices 40, 70 may be added as needed depending on the size/width of the reaction plate and/or desired cooling/lubricating requirements of a given clutch plate assembly design.
During a transient high temperature, low relative velocity condition, i.e. the low speed conditions most likely to cause shudder or vibration due to slippage, the secondary fluid passage 62 takes advantage of the relatively low viscosity of the fluid 15 under high temperature conditions to draw the fluid from primary fluid passage 42 directly to the low local pressure region created in proximity to the first and second orifices 34, 70. Without requiring a reduction in contact surface area of the friction material 20A, 20B, shudder or vibration at low relative rotational speed is thereby reduced in part by delivering the fluid 15 directly to the friction interfaces 65A, 65B as needed. When the clutch assembly 10 is rotating in unison at relatively high rates of speed, the low pressure region formed in proximity to first and second orifices 40, 70, respectively, between the disparately rotating plates 14, 18 disappears, and the various plates of the clutch assembly 10 are pressed together, thereby substantially blocking the flow of fluid 15 through the orifices 40, 70. In this manner, loss of excess fluid 15 into the friction interfaces 65A, 65B helps to preserve fluid and prevent flooding of the friction interfaces 65A, 65B, thus minimizing the hydroplaning effect between friction plates 14A, 14B and reaction plate 18. Those skilled in the art will recognize that when clutch assembly 10 is disengaged, fluid 15 will continue to be fed at line pressure through the orifices 40, 70, which will provide a hydraulic force at the friction interfaces 65A, 65B sufficient to separate the various adjacent plates, such as friction plates 14 and reaction plate 18 and reducing or minimizing the spin losses or drag therebetween.
In a second embodiment shown in FIG. 3A, a blind primary fluid passage 142 is shown extending or penetrating from the outer lateral surface 48 to a closed or blind end 72 of primary fluid passage 142 which is short of the inner diameter 12 of reaction plate 18. As configured, fluid 15 may enter the outer orifice 34, pass through primary fluid passage 142, and exit first and second orifices 40, 70 as previously explained herewithin. However, due to the blind end 72 of primary fluid passage 142, the fluid 15 is blocked or prevented from passing all the way through to the inner diameter 12. Fluid 15 is conserved in this manner while still being drawn by the local low pressure zone between plates 14A, 14B and 18 through secondary fluid passages 62 to reach the friction interface 65A, 65B (see FIG. 2A). Alternately, as shown in FIG. 3B, in situations or configurations in which flow of the fluid 15 initiates from the inner lateral surface 58 of internal diameter 12, an alternate primary fluid passage 242 may extend or penetrate from the inner diameter 12 to a closed or blind end 74 of primary fluid passage 242. The blind end 74 is short of the outer diameter 22 of reaction plate 18. Both blind ends 72 and 74 are preferably positioned approximately ¾ of the distance between the inner diameter 12 and outer diameter 22 of reaction plate 18 to allow for some additional core cooling of reaction plate 18, although other distances are also within the scope of the invention.
In a third embodiment as shown in FIG. 3C, primary fluid passage 42 extends all the way through reaction plate 18 from inner diameter 12 to outer diameter 22, and is capped or otherwise blocked, preferably by a plug 67 that is inserted into the inner orifice 50, thus blocking fluid 15 from flowing all the way through reaction plate 18. This embodiment facilitates a drilling or boring process initiating from within the inner diameter 12 of the reaction plate 18, as may be required to produce the embodiment of FIG. 3B, particularly in situations in which the reaction plate 18 is relatively small in diameter. Preferably, the plug 67 is constructed of suitable material such as stainless steel when the plus is to be inserted into inner orifice 50 and secured with epoxy or other adhesive material (not shown) with sufficient strength and materials properties to retain the plug 67 within the inner orifice 50 in the presence of fluid 15 for the operational lifetime of the reaction plate 18.
While a multi-plate design is preferred, a fourth embodiment includes unitary friction/reaction plates 110A, 110B as shown in FIG. 4, which are stacked without a separate core plate 36 (see FIG. 1). Friction material 26 is bonded or attached directly to one surface 137A, 137B of each unitary plate 110A, 110B, respectively, with each unitary plate 110A, 110B having respective alternating internally and externally projecting splines 124, 132. Unitary plate 110A has an internal orifice 150A and an external orifice 134A disposed at either end of at least one primary fluid passage 342, each of which is intersected by a secondary fluid passage 162 having a single orifice 170. Likewise, unitary plate 110B has an internal orifice 150B and an external orifice 134B disposed at either end of at least one primary fluid passage 342, with primary fluid passages 342 being substantially identical to passage 42 as previously described hereinabove (see FIG. 1). In this fourth embodiment, as shown in partial side view in FIG. 4B, only one friction interface 65C will be formed relative to each pair of unitary plates 110A, 110B, and accordingly, only a single orifice 170 would be required opening thereto from each of primary fluid passages 342, although multiple secondary passages 162 and orifices 170 may be added as needed to deliver more fluid 15 to the friction interface 65C as required. Orifices 134A and 150A, and primary fluid passage 342 may also be configured using blind or plugged holes as previously described herewithin as the application or clutch design requires.
While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.
Patent Application
20080073171
