Field
[001] This application relates to diaphragm clutches and provides a pressure plate with a reversible fulcrum ring.
Background
[002] The life of a clutch driven disk assembly (DDA) depends mainly on the friction lining life. Due to the design space and interface constraints, the thickness of the driven disk assembly cannot be increased liberally. Nor can the clutch comprise bulky adjustment mechanisms. But, it is desirable to use all of the friction lining life, to avoid waste. To use all of the friction lining life, other clutches have comprised threaded adjustment mechanisms, opposed ratcheting cams, or spring-based adjusters in an attempt to account for wear-down of the friction lining.
SUMMARY
[003] The disclosed fulcrum ring increases the thickness of the pressure plate, bringing more life to the driven disk assembly without affecting the design space and interface constraints. The methods and devices disclosed herein overcome the above disadvantages and improves the art by way of a pressure plate comprising a stepped groove comprising a first seat wider than a second seat, the second seat at a greater depth in to the pressure plate than the first seat. A fulcrum ring can be flipped between a first position and a second position. The fulcrum ring comprises a stepped profile complementary to the stepped groove. The stepped profile comprises an obverse profile comprising a convex pivot portion and a reverse profile comprising a second convex pivot portion. When the fulcrum ring is in the first position, the obverse profile projects from the first seat and the reverse profile is in the second seat. When the fulcrum ring is flipped over to the second position, the reverse profile of the fulcrum ring projects out of the stepped groove, the second seat in the groove is empty, and the obverse profile projects in to the first seat.
[004] The pressure plate and fulcrum ring can be used in a diaphragm clutch comprising an actuator and a diaphragm biased against the actuator and against the fulcrum ring. The diaphragm clutch can further comprise one or more driven disk assemblies comprising a friction lining.
[005] A method of servicing a clutch can comprise determining that a friction lining of a driven disk assembly has worn down. The fulcrum ring can be removed from the pressure plate. The fulcrum ring can be flipped over from the first position to the second position
[006] Additional objects and advantages will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the disclosure. The objects and advantages will also be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[007] Figure 1A & 1B are exploded views of alternative clutches comprising a diaphragm, a pressure plate, and a driven disc assembly.
[008] Figure 2 is a perspective view of a pressure plate
[009] Figures 3A-4B are cross-section views of a pressure plate and fulcrum ring.
[010] Figures 5-7 are examples of clutch installations.
DETAILED DESCRIPTION
[011] Reference will now be made in detail to the examples which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. Directional references such as, “bottom,” “left” and “right” are for ease of reference to the figures. In use, the installation direction may be centered differently to result in, for example, the “bottom” facing left or right.
[012] A diaphragm clutch can comprise one or more driven disk assemblies. Discs 200, 400 of the driven disk assemblies can comprise paddles with friction material 215, 415. Additional friction material 216, 416 can be mounted on the reverse sides of the discs 200, 400. The friction material can be mounted on pucks 130 secured via fasteners 120, as shown in Figure 1A. The friction material can be a ceramic or organic material. Alternative arrangements can comprise more or less paddles or can comprise full-disc, or ring-shaped, friction material 418 mounted on a cushion assembly, as shown in Figure 1B. A damping assembly 417, 330 can comprise damping springs and other mechanisms.
[013] An intermediate plate 450 can have one side 451 facing one driven disc assembly 401 and a second side 452 facing the other driven disc assembly 201. Guide fingers 420 can be included for including guide posts or drive straps, among others. When using only a single driven disc assembly or single friction disc as in Figures 5 &7, the intermediate plate 450 can be omitted. But, as shown in Figure 1B, it is possible to include drive straps 641. A fastener 642, such as a screw or rivet, can secure one or a stack of drive strap 641 to mounting feature 620. Another fastener 643, such as a screw or rivet, can secure the drive strap to a corresponding mounting feature 520 on cover 500.
[014] A cover 500 can be mounted to a flywheel of an engine. An actuator 900 can be mounted to the cover and can be actuated by a linkage 901. The linkage 901 can connect to a user interface with a clutch pedal or to computer or other control. The actuator 900 can interface with a diaphragm 800. The diaphragm can comprise an elastic plate and fingers or other slots formed to provide a spring force when the diaphragm is mounted. The diaphragm 800 can span between a bracket or other mounting 905 on the actuator 900 to the pressure plate 600. Diaphragm 800 can also touch or bias against an additional surface, such as against an internal surface of the cover 500 or against another part such as fitting rings 804, 806.
[015] The pressure plate 600 can comprise a diaphragm side 603 and a pressure side 602. The pressure side 602 can press upon the clutch components to press the friction material and actuate the clutch, as by pushing the friction material against a flywheel so as to couple the torque output from an engine to a transmission. While a vehicle context is shown and described, the teachings herein can be applied to other clutch packs and clutched assemblies.
[016] The diaphragm side 603 can comprise features tailored to the application, such as holes, rims, mounting features 620, etc. A center hole of the pressure plate can be tailored for coupling to or around, and reciprocating along, a center shaft or hub, such as an input shaft for a transmission. As illustrated, a neck 605 is included to adjust the over-all height of the pressure plate 600. The stepped groove 6000 is shown included in the optional neck 605.
[017] The pressure plate 600 is modified by adding a stepped groove 6000 at the location of the fulcrum ring 700. The neck 605 can comprise a hole 790 for receiving a set screw or other removable fastener 791. The removable fastener 791 can press upon a portion of the fulcrum ring, such as upon reverse profile 7002 at second outer wall 713, or upon obverse profile 7001 at first outer wall 717, to hold the fulcrum ring 700 in place with respect to the pressure plate 600. Alternatively, a hole 795 can be included in the fulcrum ring 700 to receive the removable fastener 791. The hole 795 can be piloted through portions of both obverse profile 7001 and reverse profile 7002.
[018] The fulcrum ring 700 is designed with a stepped profile to match the stepped groove. The profile of the fulcrum ring 700 seats the fulcrum ring in a first seat S1 and in a second seat S2 in the groove so that the first seat S1 in the groove accepts a portion of first step profile (obverse profile 7001) on the fulcrum ring 700 and so that a second seat S2 in the groove accepts a second step profile (reverse profile 7002) of the fulcrum ring. A projecting portion of the obverse profile 7001 projects out of the first seat S1.
[019] During a service interval, for example, after the driven disc assembly has worn away a certain percentage, for example 50%, the fulcrum ring 700 is removed, flipped over, and reinserted. So, a method of servicing a clutch can comprise determining that a friction lining of a driven disk assembly has worn down, removing a fulcrum ring from a pressure plate, flipping the fulcrum ring over, and reinserting the fulcrum ring in the pressure plate so that the fulcrum ring flips from a first position to a second position. A portion of the reverse profile 7002 of the fulcrum ring now projects out of the stepped groove 6000. The second seat S2 in the groove is empty. The first seat in the groove accepts the projecting portion of the obverse profile 7001. The height H2 of the reverse profile is selected so that the actuator 900, for example, a bearing housing 903, will return to its home position thereby giving more life to the driven disk assembly.
[020] The pressure plate can comprise a plate 604 comprising a stepped groove 6000, the stepped groove comprising a first seat S1 and a second seat S2. The first seat S1 comprises a width WG1, and the second seat S2 comprises a second width WG2. The first seat is wider than the second seat. The second seat is beneath the first seat, so the second seat S2 is recessed in to the pressure plate further than the first seat. So, the second seat S2 is at a depth D2 greater than the depth D1 of the first seat S1. The first seat S1 can comprise bottom walls 621, 624 and side walls 615, 617. The second seat S3 can comprise side walls 611, 613 and bottom wall 607. The bottom walls and side walls can be at 90 degree angles or they can be slanted to taper the first seat S1 and second seat S2. The depth D2 of second seat S2 can be chosen so that reverse profile 7001 does not abut bottom wall 607, or so that reverse profile 7001 has minimal contact with bottom wall 607.
[021] The fulcrum ring 700 can comprise a stepped profile complementary to the stepped groove 6000. It, too, can comprise a tapered or regular shape. The fulcrum ring 700 aligns so that there is minimal to no play between the fulcrum ring and pressure plate. So, when the fulcrum ring is in the first position, portions of first outer walls 715, 717 can abut side walls 615, 617, ledges 721, 723 can abut bottom walls 621, 623, and second outer walls 711, 713 can abut side walls 611, 613. Head 701 projects out from the first seat S1. When the fulcrum ring 700 is in the second position, the second outer walls 711, 713 and tail 703 project out from the first seat S1, while the head 701 faces the bottom walls 621, 623 and portions of first outer walls 715, 717 adjoin side walls 615, 617. Second seat S2 is empty. Contact between first outer walls 715, 717 and side walls 615, 617 can be minimal, or contact can be planar and flush with one another, depending upon the tapered or regular shapes chosen.
[022] Obverse profile 7001 can comprise a head 701 which can be a convex pivot portion. Reverse profile 7002 can comprise a tail 703 which can be a second convex pivot portion. Head and tail can be flat or can be provided with curvature. When curved, the convex portions can provide a fulcrum point for the diaphragm 800, and a smooth rocking of the diaphragm thereon during actuator motion.
[023] The first seat S1 and the second seat S2 can be concentric, and the obverse profile 7001 and reverse profile 7002 can likewise be concentric. The obverse profile 7001 and reverse profile 7002 are shown centered with respect to one another, but it is permissible to offset them from each other creating a staggered profile.
[024] The obverse portion 7001 can comprise a first step height H1 chosen to align the actuator 900 and diaphragm 800 with respect to the friction material. A second step height H2 can likewise be chosen for the reverse portion 7002. The first step height H1 can be less than the second step height H2 when the obverse portion 7001 faces the diaphragm 800 and the clutch is new. The friction material of the clutch has not yet worn down, and so the pressure plate is closer to the actuator 900. The second step height H2 can be larger than the first step height H1 so that when the fulcrum ring is flipped over, the wear-down distance of the friction material is accounted for in the second step height H2. The pressure side 602 of the pressure plate 600 may be farther away from the actuator 900, but the angle between the actuator 900 and the diaphragm 800 returns to the like-new position, or at least to a re-calibrated position that can take in to account actuator or diaphragm fatigue or wear. So, when the actuator 900 is in a first position with respect to the pressure plate 600, the first step height H1 of the obverse profile 7001 is such that the actuator 900 is a first distance from the pressure plate 600. When the fulcrum ring 700 is in the second position, the second step height H2 of the reverse profile 7002 is such that the actuator 900 is a second distance from the pressure plate 600.
[025] Figure 5 summarizes the wear-through travel issue with respect to a pull-type clutch. The diaphragm 800 is shown in its unworn position in solid lines, and the obverse profile 7001 abuts the diaphragm 800. However, as the friction material 415, 416 on disc 400 wears out, the diaphragm moves to a wear-through position 804 shown in phantom lines. Flipping the fulcrum ring 700 moves the diaphragm 800 to a more suitable position for the worn friction material 415, 416.
[026] A push-type clutch is shown in Figure 7 with the reverse profile 7002 projecting from the pressure plate 600. An alternative and simplified friction disc 400 is shown. The cover 500 can include a mounting feature 502 for receiving a cover fastener 503. The diaphragm 800 can be mounted to cover 500 via one or more spring fastener 508.
[027] Figure 6 shows another type of clutch where the pressure plate 600 is mechanically coupled to opposed ramp sections, or cams 504, 506. The cams can be spring-loaded to self-adjust the clamp load as the friction material wears down. But, including the fulcrum ring 700 provides another possibility to prolong clutch life and use as much friction material as possible during clutch lifetime. This reduces waste and permits continued use of actuators such as zerked bearing 907.
[028] Other implementations will be apparent to those skilled in the art from consideration of the specification and practice of the examples disclosed herein.

We claim:
1. A diaphragm clutch comprising:
an actuator;
a pressure plate comprising a stepped groove, the stepped groove comprising a first seat and a second seat, the first seat wider than the second seat, the second seat at a greater depth in to the pressure plate than the first seat;
a fulcrum ring comprising a stepped profile complementary to the stepped groove, and when the fulcrum ring is in a first position, the stepped profile comprises an obverse profile projecting from the first seat and a reverse profile in the second seat; and
a diaphragm biased against the actuator and against the fulcrum ring.
2. The diaphragm clutch of claim 1, wherein the fulcrum ring is removable from the pressure plate so that the fulcrum ring can be flipped over to a second position.
3. The diaphragm clutch of claim 2, wherein, when the fulcrum ring is flipped over to the second position, the reverse profile of the fulcrum ring projects out of the stepped groove, the reverse profile is biased against the diaphragm, the second seat in the groove is empty, and the obverse profile projects in to the first seat.
4. The diaphragm clutch of claim 2 or 3, wherein, when the actuator is in the first position with respect to the pressure plate, the height of the obverse profile is such that the actuator is a first distance from the pressure plate, but when the fulcrum ring is in the second position, the height of the reverse profile is such that the actuator is a second distance from the pressure plate.
5. The diaphragm clutch of claim 4, wherein the second distance is greater than the first distance.
6. The diaphragm clutch of any one of claims 1-5, wherein the obverse profile comprises a convex pivot portion.
7. The diaphragm clutch of any one of claims 1-5, wherein the reverse profile comprises a second convex pivot portion.

8. A pressure plate, comprising:
a plate comprising a stepped groove, the stepped groove comprising a first seat and a second seat, the first seat wider than the second seat, the second seat at a greater depth in to the pressure plate than the first seat; and
a fulcrum ring comprising a stepped profile complementary to the stepped groove, the stepped profile comprising an obverse profile comprising a convex pivot portion and a reverse profile comprising a second convex pivot portion,
wherein, when the fulcrum ring is in a first position, the stepped profile comprises an obverse profile projecting from the first seat and a reverse profile in the second seat, and
wherein, when the fulcrum ring is flipped over to a second position, the reverse profile of the fulcrum ring projects out of the stepped groove, the second seat in the groove is empty, and the obverse profile projects in to the first seat.
9. The pressure plate of claim 8, wherein the first seat and the second seat are concentric.
10. The pressure plate of claim 8, wherein the pressure plate further comprises:
a hole in alignment with the stepped groove; and
a removable fastener in the hole, the removable fastener in contact with the fulcrum ring.
11. A diaphragm clutch, comprising:
an actuator;
a driven disk assembly comprising a friction lining;
a pressure plate between the driven disk assembly and the actuator, the pressure plate comprising a stepped groove, the stepped groove comprising a first seat and a second seat, where the first seat comprises a first seat width and a first seat depth, where the second seat comprises a second seat width and a second seat depth, where the second seat width is less than the first seat width, and where the second seat is positioned deeper in the stepped groove than the first seat;
a fulcrum ring comprising a stepped profile, the stepped profile comprising an obverse profile and a reverse profile, where the obverse profile comprises a first step width and a first step height, where the reverse profile comprises a second step width and a second step height, where the second step width is less than the first step width, where the reverse profile is configured to seat in the second seat while the obverse portion projects from the first seat when the fulcrum ring is in a first position, where the obverse profile is configured to seat in the first seat while the reverse portion projects from the first seat when the fulcrum ring is in a second position, where the fulcrum ring is removable from the stepped groove and replaceable to switch between the first position and the second position; and
a diaphragm biased between the actuator and the fulcrum ring.
12. The diaphragm clutch of claim 11, wherein the first step height is less than the second step height.
13. The diaphragm clutch of claim 11 or 12, wherein the first seat depth is less than the second seat depth.
14. The diaphragm clutch of claim 11, wherein the obverse profile is concentric with the reverse profile.
15. A method of servicing a clutch, comprising:
determining that a friction lining of a driven disk assembly has worn down;
removing a fulcrum ring from a pressure plate, the pressure plate being between the driven disk assembly and a diaphragm of the clutch, the pressure plate comprising a stepped groove, the stepped groove comprising a first seat and a second seat, where the first seat comprises a first seat width and a first seat depth, where the second seat comprises a second seat width and a second seat depth, where the second seat width is less than the first seat width, and where the second seat is positioned deeper in the stepped groove than the first seat;
flipping the fulcrum ring over; and
reinserting the fulcrum ring in the pressure plate so that the fulcrum ring flips from a first position to a second position, where the fulcrum ring comprises a stepped profile, the stepped profile comprising an obverse profile and a reverse profile, where the obverse profile comprises a first step width and a first step height, where the reverse profile comprises a second step width and a second step height, where the second step width is less than the first step width, where the reverse profile is configured to seat in the second seat when the fulcrum ring is in the first position, and where the obverse profile is configured to seat in the first seat while the reverse profile projects out of the stepped groove when the fulcrum ring is in the second position.