CA1100425A

CA1100425A - Self-contained belleville spring-type wet clutch

Info

Publication number: CA1100425A
Application number: CA316,952A
Authority: CA
Inventors: Edward F. Labuda; Ting M. Wang
Original assignee: Borg Warner Corp
Current assignee: Borg Warner Corp
Priority date: 1977-12-14
Filing date: 1978-11-27
Publication date: 1981-05-05
Also published as: FR2412001A1; GB2010422A; SE7812465L; AU4211678A; IT1101560B; DE2858077A1; AU527166B2; IT7830799A0; BR7808153A; DE2854051A1; AR219144A1; GB2010422B; JPS5489149A; ES475924A1; DE2854051C2; SE443423B; DE2858077C2; FR2412001B1

Abstract

SELF-CONTAINED BELLEVILLE SPRING-TYPE WET CLUTCH

Abstract:
A self-contained wet clutch assembly (10) of the Belleville spring type having a two-piece cover (A,B) mated to a clutch member (C) and sealed together as a unit, with the sealed clutch assembly ( A,B, C) operatively connected to and driven through a drive plate (12) on the engine crankshaft, thus eliminating the conventional flywheel for the clutch assembly.
The clutch assembly (10) includes a concentric cylinder (73) and piston (61) to actuate the clutch release bearing (62), a radial-type driven member retarding brake (81) inserted into the bearing carrier for the clutch release bearing, and turbulizer vanes (42) in the wet clutch housing to increase oil splash and enhance the cooling effect of the oil and to retard the clutch member.

Description

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The present invention relates to a self contained wet clutch assembly and is of ~he type adapted to be mounted on a transmission input shaft.
Dissipation of heat from friction linings of clutch plates has long been a problem during operation of the clutch to engage or disengage the manual transmission from a vehicle engine. Fluid has been introduced wi~hin the clutch assembly to be forced between the friction linings and the pressure plate and fl~wheel as a solution to the problem, but this solution is complicated by the centrifugal force developed on the fluid whil~ the clutch is rotating tending to sling the fluid radially outwardly of the plates. Even where the fluid has been successfulin the cooling of the friction linings, a further problem o~ leakage of the cooling fluid from the clutch assembly is encountered because most wet clutches are adapted to the engine flywheel to make up the containment package. The present invention effectively solves the leakage problem in providing a truly self-contained wet clutch assembly.
According to ~he present invention there is provided a sel~-contained wet clutch assembly adapted to be mounted on a transmission input shaft, the assembl~ having a front cover assembly, a rear cover assembly, a clutch plate assembly, and a concentric ~lave cylinder assembly. The front cover assembly includes a front co~er having an outer peripheral flange and the rear cover assembly includes a rear cover having outer and inner peripheral flanges extending in opposite directions. The outer peripheral flanges of the front and rear covers conform telescopically and are seal welded together. The clutch pla~e assembly is loca-ted within the sealed front and rear covers and ws~l o , - . : : -, : . ; . . . - :
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, ~Q~L2~i is operatively connected onto -the transmission shaft. The slave cylinder assembly is rigidly moun-ted on a transmission housing receiving the transmission input shaft, and includes a bearing and an oil seal receiving the inner flange of the rear cover to provide a completely sealed assembly.
In a specific embodiment of the invention there is provided a plurality of circumferentially spaced inertia weights which are mounted on the front cover ancl are adapted to be secured on a radial flange of an engine ou-tput shaft providing the driving torque for the assembly.
The present invention thus comprehends the provision of a self-contained wet clutch assembly that mates the wet ~`
clutch driven member to a cover wherein the assembly is suitably sealed together as a unit. The sealed assembly may be mounted on and operatively connected to the engine crankshaft through the series oE mounting bosses or inertia we.ights on the cover secured to a drive plate mounted on the cran~shaft. This arrangement eliminates the necessity o a fl~heel on the crankshafi. Without the flywheel, the sealed unit obviates 2~ the oil leakage problem of prior wet clutches.
A specific embodiment of the present invention also comprehends the provision of a self~contained sealed wet clutch assembly having a release or throw-out bearing to engage the spring fingers of the Belleville spring within the sealed assembly, wherein the bearing carrier takes the form of a con-centric hydraulic piston in a hydraulic cylinder mounted to the transmission face~ The piston .in the cylinder is actuated ....
through a master cyllnder that is hydraulically connected thereto and is actuated through the clutch pedal by the vehicle operator.
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A specific embodiment oE the present invention further comprehends the provision of a ratarding brake adapted to engage the driven shaft when the clutch assembly .is disenga~ed through actuation of the release bearing carrier by the vehicle operator.
The retarding brake is of the radial type and is housed in the stationary cylinder portion carrying the actuating piston for the release bearing. The retarding brake comprises a pair of diametrically opposed bra~ing elements that are normally biased away from the driven shaft and, upon movement o~ the piston and release beaxing to disengage the clutch, the braking elements are cammed into engagemen~ with the shaft.
A specific embodiment of the present inven~ion may also comprehend the provision of turbulizer vanes on the interior surface of the clutch housing to .increase oil splash and enhance movement of the oil between the clutch plate and the pressure plate and housing for cooling of the elements. The increase of oil splash also reacts with protruding diverters on the . periphery of the clutch plate and retards the clutch plate or driven member.
20 The present invention further comprehends the provision of a self-contained wet clutch that is adaptable to a single clutch plate or a multi-plate clutch construction.
Further objects are to provide a construction oE
maximum simplicity, efficiency, economy and ease of assembly and operation, and such further objects, ' A ~ WS/' 3 -2a-- .. ~ - . .. .

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s advantages and capabilities as will later more ully appear and are inherently possessed thereby.
One way of carrying out the invention is described in det~l below with reference to drawings which illustrate only one specific embodiment, in wh:ich:-Figure 1 is a vertical cross sectional view througha self-contained wet clutch of the ~resent invention with a master cylinder and clutch pedal being shown diagram-matically.
Figure 2 is an enlarged vertical cross sectional view through the release bearing9 carrier and actuating piston with the clutch in disengaged position.
Figure 3 is a vertical cross sectional view taken on the line 3-3 of Figure 1.
Figure 4 is a vertical cross sectional view taken on the line 4-4 of Figure 1.
Figure 5 is a vertical cross sectional view taken on the line 5-5 of Figure 1.
Figure 6 is a partial vertical cross sectional view similar to Figure l but._sh"o,wing a.m,ulti-plate clutch assembly.
Referring more particularly to the disclosure in the drawings wherein are shown illustrative embodiments of the present invention, Figure l discloses a self-contained clutch assembly 10 that is suitably sealed and eliminates the necessity for a flywheel as is conventionally found mounted on an engine crankshaf~ ll. A drive plate 12 is substituted for the flywheel and is secured to the crank-shaft by bolts 13. The drive plate has an outer peri-pheral flange 14 with a starter gear 15 suitably securedthereto, such as by welding. A bell housing 16 encompasses the clutch assembly 10 and is adapted to be secured to the engine or the vehicle and to the transmission housing.

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4;2~i The clutch assembly 10 includes a rear cover assembly A and a front cover assembly B. The rear cover assembly A comprises a rear cover 17 having an outer for~ardly extending annular flange 18 and an inner rearwardly extending annular flange 19 defining a central opening 21 for a transmission input shat 22. .A plurality of rivets 23 are secured in the cover 17 to support a Belleville or diaphragm type spring 24 and annular fulcrum wires 25, 25, with an annular ring 26 s~.cured to the inner ends of the rivets 23. A pressure plate 27 has a rearwardly extending annular fulcrum surface 28 engaging the spring 24 and a plurality of radial lugs 29. A plurality of drive straps 31 are secured at their ends to the lugs 29 and at their opposite ends to the cover 17 by rivets 32 so as to provide a driving connection between the pressure plate 27 and the cover 17. The drive straps 31 are also deformed 90 as to act as retractor springs for the pressure plate when the clutch is disengaged. A blower 33 is spot welded to the exterior surface of the cover 17 for cooling purposes, and a fluid fill plug 34 is located in the cover 17.
The front cover assembly B includes a front cover 35 having an outer rearwardly extending annular flange 36 and an inner pilot bushing 37 for pilo~ing the inner end of the transmission input shaft 22. A plurality of : segmental inertia weights 38 (Figures 1 and 5) are welded to the cover 35 and are provided with threaded openings 39.to receive bolts 41 securing the drive plate 12 to the front cover assembly B. Turbulizer vanes 42 are secured, as by spot welding, to the interior surface of the flange 36 to aid in fluid distribution. The rear cover assembly ~ A and the front cover assembly B are mated together with : the flanges 18 and 36 nested and seal welded at 43 to form a completely self-contained unit to contain the cooling fluid.

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Housed in the sealed cover assembly is a driven member assembly C comprising an internally splined hub 44 receiving an exteriorly splined port:ion 45 of the shaft 22, the hub having an integral radial 1ange 46. A
clutch plate 47 and a spring retainer plate 48 sandwich the flange 46 and are secured together by shouldered rivets 49 and piloted on the hub by eompression sprlngs 51 received in pockets defined by al:igned openings in the flange 46 and plates 47 and 48. The flange 46 has circumferentially spaced notches 52 receiving the rivets 49 to limit the relative rotation between the flange and the plates allowed by the compression springs. The clutch plate 47 has oppositely disposed friction material surfaces 53, 53 positioned adjacent the outer periphery of the plate so as to engage an annular friction surface 54 ormed in the cover 35 and the friction surface 55 of the pressure plate 27.
A slave cylinder assembly D is provided at the rear end of the clutch assembly and includes a hollow ram-type cylinder housing 56 having a radial flange 57 at the rear end secured by bolts 58 to the bell housing 16. The housing provide~ a central passage 59 receiving the transmission input shaft 22 and an annular chamber 60 receiving a reciprocable bearing carrier 61 with a clutch throw-out bearing 62 press-mounted on the fo~ard end and ~ an enlarged piston 63 forming the rear end of the carrier.
A lip-type seal 64 is provided in an annular groove 65 on the exterior surface of the piston, and an 0-ring type seal 66 is provided in an annular groove 67 on the internal diameter of the piston, with the seals slidingly engaging the chamber walls. Also, a snap ring 68 is provided in an annular groove 69 in the wall of the chamber 60 to limit ~he forward travel of the piston; the piston having an annular flange 71 at its rear end adapted .

to abut ~he rear end of the chamber to limit rearward travel and provide a substantial area of the piston face 72 exposed to actuating hydraulic fluid.
The cylinder housing includes an outer wall 73 counterbored at 74 to receive a bearing 75, such as a bronze bushing, and having an enlarged counterbore 76 to receive an oil seal 77 pressed thereinto. The inner flange 19 of the rPar cover 17 is sealingly received within the oil seal 77 and rotatably received in the bearing 75 so that the rear covPr assembly A, front cover assembly B and driven member assembly C can rotate relative to the stationary slave cylinder assembly D. A
hydraulic fitting 78 is positioned in the housing 56 to communicate with the rear end of the chamber 60 and to connect the chamber with a master cylinder 79 removed from the clutch assembly.
A transmission input shaft retarder 81 is provided in the housing passage 59 to retard or brake rotation of the transmission input shaft 22 when the clutch is ; 20 disengaged. The retarder comprises a pair of arcuate metallic shoes 82, 82 on diametrically opposite sides of the shaft 22 with bonded friction linings 83, 83 on the inner curved suraces of the shoes facing the shaft.
Each shoe has a central projection 84 rec2ived in a slot 85 in the inner wall 86 of the housing 56 with a curved ~-upper surface 87 extending into the chamber 60. A central groove 88 in each shoe receives a spring clip 89 to hold the shoes in place and act as a retractor spring at the time of clutch re-engagement. The interior wall of the bearing carrier 61 is provided with an annular groove 90 receiving the curved end surfaces 87, 87 of the projections 84, 84; the rear end of the groove being provided with a c~mming ramp ~1 acting to urge the shoes 82, 82 inwardly to contac~ the shaft 22 as will be later described.

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- ~Q6~`425 The master c~linder 79 comprises a housing 92 for a reciprocable piston 93 having a seal 94, and a push rod 95 secured to the piston and extending from the cylinder to be pivo~ally mounted at the free end on a push-type pedal 96 to be actuated by the vehicle operator. The cylinder 79, ccnnecting conduit 97 and chamber 60 behind the piston 63 are filled with hydrau,lic fluid; the cylinder housing 56 having a bleeder valve 98 acting to purge the hydraulic system of entrapped air.
As more clearly seen in Figure 4, ~he clutch plate 47 is provided with several diagonally extending slots 99 partially dividing the plate into a plurality of circum-ferentially spaced segments 101, the slots 99 extending from the outer periphery 102 of the plate to an inner peripheral portion thereof. Associated with the slots are fluid diverters or scoops 103 at the outer edge of each segment 101; each diverter being integral with the plate and having an outer peripheral edge 104 with the forward or leading portion formed as a finger lOS in overlapping relation to the slot 99 immediately ahead of the segment. The inner edge 106 of the finger is a curved fluid scooping surface generally parallel with the curved edge 107 of the adjacent trailing portion of the segment thereahead. At the trailing edge of each scoop 103 is a pocket 108 defined by a rearwardl~ and slightly outwardly extending finger 109 having a concave edge llI
joining the ~inger to the plate periphery.
It should be understood that the terms "leading" and "trailing" used with reference ~o the fluid diverters refer to the direction of relative rotation between the cover assembly A and B and the driven clutch plate 47. The clutch plate 47 is rotating in the same direction as the cover assembly, however, until full clutch engagement, the plate 47 rotates slower than the cover assembly; thus having a direction of reIative rotation opposite to the . ~ .
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~ ' ' ' arrow X of Figure 4. The friction pads 53 on ~he clutch plate segments 101 each has a waf1e grid formed thereon by intersecting grooves 112 and 113.
With the vehicle engine running, the clutch assembly 10 is normally engaged ~hrough the load imparted by the Belleville spring 24 against -the fulcrum surface 28 of the pressure plate 27 to urge the pressure plate against the clutch plate 47 and the friction surface 5h of the front cover 35 so that the driven member assembly C rotates with the sealed rear cover assembly A and front ccver assembly B
to rotate the transmission input shaft 22. The positioning of the parts of the clutch assembly with the clutch engaged is shown in Figure l. The inner ends of the spring fingers 114 of the spring 24 are in constant engagement with the clutch throw-out bearing 62.
To release the driven member C from the pressure plate 27 and the front cover 35 for the purpose of shifting gears, the operator depresses the clutch pedal 96 to force fluid from the cylinder 79 by means of the piston 93 into the annular chamber 60 behind the piston 63, thus imparting hydraulic force against the piston face 72 to shif~ the bearing carrier 61 forwardly to the position shown in Figure 2. The throw-out bearing 62 moves against the fingers 114 of the Bellevil~e spring 24 to unload the pressurP plate 27, with the drive straps 31 acting to retract the pressure plate.
At the same time, the camming ræmp 91 is moved relative to the retarder 81 and engage the curved surfaces 87, 87 to urge the shoes 82, 82 and riction linings 83, 83 radially inward against the force of the spring 89 to engage the rotating shaft 22. The engagement between the shoes and ^
the shaft acts to retard rotation thereof and, as -the housing assembly A and B is decreasing in rotation due to the closed throttle of the engine, the fluid tends to - . . . . .
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continue at a high velocity due to its inertia, thus impinging on the turbulizer vanes 42 and forcing the fluid into the path of the fingers 109 of the diverters 103 (as seen in Figure 4) to aid in retardat:ion of the clutch plate 47 and driven member assembly C. The fluid acting on the vanes 42 and the diverters 103 aids :in heat dissipation and lubrication of the clutch wi~h a portion of the fluid being forced ~hrough the slots 99 and the Lining grooves 112, 113 toward the center of the unit.
Another purpose of the turbulizer vanes 42 is to act as a reserve means of diverting fluid onto the driven member 47 in the event that the dynamic oil level falls below the required level, thereby rendering the driven member diverters 103 inopera~ive.
Once the gears are shifted, the operator gradually releases the pedal 96 and the spring 24 through the fingers 114 acts to urge the bearing 62 and bearing carrier 61 rearwardly to force the fluid back into the cylinder 79.
Initial movement of the carrier 61 releases the shaft retarder shoes 82, 82 from the camming ramp 91 for re-traction by the spring 89, and the spring 24 fulcrums about the wire 25 to urge the pressure plate 27 against the clutch plate 47 and the front cover 35. As the ~riction surfaces begin to engage and the throttle causes rotation of the cover assembly A and B, the fluid is moved in the cover assembly ~aster than rotation of the clutch plate and a portion of the fluid is scooped up by the diverters 103 to ente~ the slots 99 and travel toward the center of the unit and then urged outward through the grooves 112, 113 by centrifugal force to cool and lubricate the assembly. When the clutch is fully engaged, the scooping o~ the fluid ceases as there is no relative rotation be-tween the cover assembly A and B and the clu~ch driven assembly C.
Figure 6 discloses an alternate embodiment of self-contained wet clutch utilizing a multi-plate driven mem~er, and parts identical to those o~ the previously described ~,, . .. ' , .' ' , - .. .
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assembly will have the same reference numeral with a script a. In this embodiment, the clutch assembly lOa includes a rear cover 17a with an outer flange 18a and an inner flange 19a, shouldered rivets 23a supporting the fulcrum wires 25a and support ring 26a for the Belleville spring 24a, and the blower 33a secured to the outer rear surface of the cover.
A front cover 35a has an outer flang~e 36a telescopingly receiving the flange 18a, segmental inertia weights 38a welded to the cover 35a and an inner pilot bushing 37a receiving the inner end of the transmission input shaft 22a. A drive plate 12a secured to the engine crankshaft (not shown~ is secured to the segmental weights 38a by bolts 41a. The ~langes 18a and 36a are seal welded at 43a.
The driven member assembly includes a pair of clutch members 115 and 116, each clutch member having a hub 44a on the splined portion 45a of the transmission input shaft 22a with an integral radial ~lange 46a. Each hub flange is sandwiched between a clutch plate 47a, 117 and spring retainer plates 48a, 48a, and compression springs 51a are received in aligned windows for a vibration damper. Each clutch plate has clutch friction pads 53a similar to those shown in Figure 4. The clutch plate 47a is adapted to engage the fxiction surface 54a of the front cover 35a while the clutch plate 117 has an offset ll8 so as to contact the friction surface 55a of the pressure plate 27a.
~ An intermediate pressure plate 119 is interposed between the clutch plates 47a, 117 to frictionally engage the friction pads~53a of each; the intermediate plate being connected to the pressure plate 27a by drive straps 121 secured to each member by rivets 122.
The concentric hydraulic slave cylinder includes a housing 56a or a bearing carrier 61a in a chamber 60a supporting a clutch ~hrow-out bearing 62a. Shaf~ retarder shoes 82a are mounted in the housing to cooperate with the :. . - , , . ,. : :

: ' ' , ' ' ' ' ' -'' ' ' ' ,' ' ' ' . ~ , ' 13L~425 camming ramp 91a to engage the input shaft 22a when the clutch is disengaged. A bushing 75a and an oil seal 77a are pressed in the housing 56a to rotatably support the inner flange l9a of the rotating cover assembly. This clutch arrangement operates in substantially the same manner as previously described for the embodiment of Figures 1 through 5.

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Claims

?E EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS;

1. A self-contained wet clutch assembly adapted to be mounted on a transmission input shaft, comprising a front cover assembly, a rear cover assembly, a clutch plate assembly, and a concentric slave cylinder assembly, said front cover assembly including a front cover having an outer peripheral flange, said rear cover assembly including a rear cover having outer and inner peripheral flanges extending in opposite directions, said outer peripheral flanges of the front and rear covers conformably telescoping and seal welded together, said clutch plate assembly being located within the sealed front and rear covers and operatively connected onto said transmission shaft, said slave cylinder assembly rigidly mounted on a transmission housing receiving said transmission input shaft and including a bearing and an oil seal receiving the inner flange of the rear cover to provide a completely sealed assembly.

2. A self-contained wet clutch assembly as set forth in Claim 1, in which a plurality of circumferentially spaced inertia weights are mounted on said front cover and adapted to be secured on a radial flange of an engine output shaft providing the driving torque for the assembly.

3. A wet clutch assembly as set forth in Claim 1, in which said rear cover assembly includes an annular pressure plate and a diaphragm type spring fulcrumed on the rear cover to urge the pressure plate toward the clutch plate assembly.

4. A wet clutch assembly as set forth in Claim 3, including a blower secured to the exterior surface of said rear cover.

5. A wet clutch assembly as set forth in Claim 1, including a plurality of turbulizer vanes secured to the interior surface of the outer peripheral flange of said front cover which acts to increase oil splash and to retard rotation of the clutch plate assembly.

6. A self-contained wet clutch assembly as set forth in Claim 1, in which said slave cylinder assembly includes a housing having an annular chamber concentric with said transmission shaft, an annular bearing carrier received in said chamber and adapted to be hydraulically actuated, a concentric piston formed on the end of the bearing carrier opposite the clutch release bearing and conformably received in said chamber, having a concentric annular flange projecting axially from the rear end of the piston to contact the rear end of the chamber and provide a spacing to allow the rear face of the piston to be exposed to hydraulic fluid, a clutch release bearing mounted on the inner end of said bearing carrier, and a diaphragm-type spring mounted to fulcrum on said rear cover and engaged by said release bearing.

7. A wet clutch assembly as set forth in Claim 6, in which said housing is radially spaced from said transmission shaft, and a pair of diametrically oppositely disposed shaft retarders are located in the space between the housing and the shaft and adapted to be actuated upon movement of said bearing carrier to disengage the clutch.

8. A wet clutch assembly as set forth in Claim 7, in which each shaft retarder comprises an arcuate shoe having a radial projection, said housing having a slot receiving said projection, and said bearing carrier having a longitudinally extending annular camming groove receiving said projection.

9. A wet clutch assembly as set forth in Claim 8, including a spring clip acting as a retractor spring, each retarder shoe having a groove in the interior surface receiving said retractor spring.

10. A wet clutch assembly as set forth in Claim 8, in which the internal curved surface of each shoe has a friction lining to engage said transmission input shaft.

11. A wet clutch assembly as set forth in Claim 8, in which said annular groove is of a constant depth with an inclined camming portion at one end.

12. A wet clutch assembly as set forth in Claim 6, including a stop ring in said chamber adapted to engage said piston so as to limit axial movement of said bearing carrier.

13. A self-contained wet clutch assembly as set forth in Claim 1, in which a pair of clutch plates are mounted on said transmission input shaft, and an intermediate pressure plate is interposed between said clutch plates and operatively connected to a primary pressure plate for rotation therewith.