CA1100785A

CA1100785A - Clutch assemblies for use in planetary transmissions

Info

Publication number: CA1100785A
Application number: CA317,920A
Authority: CA
Inventors: Willis E. Windish
Original assignee: Caterpillar Tractor Co
Current assignee: Caterpillar Inc
Priority date: 1978-04-27
Filing date: 1978-12-14
Publication date: 1981-05-12
Also published as: JPS54142450A; GB2019964B; GB2019965B; FR2434312B1; SG53883G; JPS6357659B2; FR2434312A1; FR2431641A1; GB2019964A; MY8500022A; FR2431641B1; GB2019965A; HK73383A; BE875100A

Abstract

ABSTRACT OF THE DISCLOSURE
A reversible clutch plate including a generally circular, disc-like member having generally parallel, opposed friction surfaces, an opening in the center of the member, at least three, equally angularly spaced tangs extending radially outwardly from the periphery of the member, reaction member receiving apertures in each tang displaced from the center there-of in the circumferential direction, the reaction member re-ceiving apertures in each tang being equally angularly spaced, and a spring mounting formation on each tang displaced from the center thereof in the circumferential direction oppositely from the reaction member receiving apertures. Also disclosed is a clutch pack utilizing a plurality of the clutch plates and a planetary gear transmission employing such a clutch pack which eliminates precision machining in the fabrication thereof.

Description

1~0785 BACKGROUND OF THE INV NTI ON
This invention relates to reversible clutch plates, clutch pack assemblies, and a planetary transmission in which the clutch elements may be used.
A large variety of mechanisms utilized in machinery employ clutch plates and packs of such clutch plates. For example, heavy-duty clutches may utilize such plates and packs thereof as may heavy duty disc brakes. Similarly, planetary gear mechanisms as, for example, transmissions, where large torques are involved, may use such clutch packs for braking ~;
; the ring gears of one or more planetary gear assemblies. ~ -In many such mechanisms, particularly transmissions where plural clutch packs are used, one for each planetary gear assembly, the stationary plates of each clutch pack have been secured between housing parts in any o a variety of ways and, in the usual case, dowels have been employed to locate the housing parts with respect to each other in order to achieve proper orientation of the various components. Such dowels require precision machining in order to achieve precise alignment and, as a consequence, fabrication of such mechanisms is con-siderably more expensive than would be the case if precision machining could be minimized or eliminated altogether.
Moreover, the stationary clutch plates in a given pack will not all be identical. In the typical case, where the pack

2~ is compressed by a fluid operated piston, a stationary plate will immediately abut the piston so as to avoid relative rotation between the two. In order to provide for retraction of the piston when the same is not subject to fluid under pressure, a retraction spring will be engaged with that stationary plate to apply therethrough a retracting force to the piston. The `-" 11~078S
retraction spring will typically be opcrativc axially of the pack with the consequence that the remaining stationary plates in the pack must be relieved in some fashion to accommodate the retraction springs.
As a consequcnce, both in~entory and manuacturing problems arise in that two different types of stationary clutch plates must be maintaincd on hand and, of course, be manufactured differently.
SUMMARY OF THE INVENTION
According to the present invention, there is provided in a planetary gear mechanism including input and output shafts; at least one planetary gear assembly interconnecting the shafts and including a sun gear, a planet gear meshed with the sun gear and mounted by a carrier and a ring gear meshed with the planet gear; at least two housing parts at .
least partially enclosing the planetary gear assemblyi a friction assembly including a piston, a first friction plate engageable by the piston and secured against rotation relative to the housing parts, a second friction plate aligned with ~, 20 and engageable by the first friction plate and mounted on said one of the ring gear and the carrier against relati~e ` rotation with respect thereto; a plurality of t;e bolts assembling said housing parts, and coil springs urging said first plate towards said piston and away from said second plate; the improvement comprising a plurality of aligned bores in said housing parts radially outwardly of the planetary gear assembly and a plurality of pins, each said pin loosely received in corresponding ones of said aligned bores in said housing parts and extending through said first plate, said bores being of larger size than the corresponding pin so that each said pin floats in its bores enabling the . ~ ~

11~)07~5 use of large tolerances, said coil springs being disposed on corresponding ones of said pins in abutment with said --first plate and one of said housing parts.
DESCRIPTION OF THE DRAWINGS
Fig. 1 is a fragmentary, sectional view of a planetary gear transmission made according to an embodiment of the invention; ~ ;
Fig. 2 is a further fragmentary view of the transmission;
Fig. 3 is a sectional view taken approximately along the line 3-3 of Fig. 2 illustrating a single clutch plate; and Fig. ~ is a sectional v;ew taken approximately along the line 4-4 in Fig. 2 illustrating a plurality of clutch plates in alignment with each other.
DESCRIPTION OF THE PREFERRED EM~ODIMENT
. . .
An exemplary embodiment of the invention is illustrated in the various figures of drawing and will be described herein in connection with a planetary gear trans-- 20 mission. It is to be understood, however, that certain aspects of the invention can be employed in mechanisms other than planetary gear transmissions. It is also to be under- -stood that the following description of the planetary gear assemblies within the transmission will be described only broadly for the purpose of acquainting one with one environ-ment of intended use, the precise nature of the planetary gear assemblies in the transmission, the gear ratios, and their interaction forming no part of the present invention.

11~)(~785 With referellce to Fig. 1, t}ie transmission includes rotatable input sha:Et 10 which may be driven by an engine ~ia a torque converter or the like, neither one of which is shown. The output of the transmission is taken from gear teet}l lZ on a quillshaft 14 disposed in concentric relation to the input shaft 10.
Splined to the input shaft 10, is a sun gear 16 having two sets of gear teeth 18 and 20. The teeth 18 are in mesh with a plurality of planet gears 22 ~only one of which is shown) journalled on a rotatable carrier 24 which is journalled to a housing part 26 by bearings 28.

11~(J7~5 A ring gear 30 is meshed with the planet gears 22 and is journalled for rotation within the assemblage by bearings 32 via a carrier 34 for planet gears 36 (only one of which is shown) meshed with the gear teeth 20. A ring gear 40 is meshed with the planet gears 36.
A third set of planet geaLs including plural planets - 42 (only one of which is shown) includes a carrier 44 therefor which is connected to the carrier 34. The planet gears 42 are meshed with a sun gear 46 on the quillshaft 14 and a ring gear 48.
A carrier 50 for a fourth planetary gear assembly is :
connected to the ring ge~r 4~ and mounts a plurality of planet gears 52 (only one of which is shown~ which engage a sun gear 54 splined to the quill shaft 14 and a ring gear 56.
The ring gear 56 is selectively connectible to the quillshaft 14 via a rotating, piston operated, rotatable clutch assembly, generally designated 58, of conventional construction.
The housing part 26 includes an annular chamber . receiving an annular piston which is operative to drive a stationary clutch plate 62 in the axial direction to compress a clutch pack including additional stationary plates 62 and interleaved rotatable plates 64 against a housing part 66. The housing part 66 is held against rotation by being sandwiched between the housing part 26,as best seen in the upper right-hand part of Fig. 1, and a housing part 68. The rotatable clutch plates 64 are splined to the carrier 24, with the consequence that when the piston 60 is extended, the carrier 24 will be braked to halt the rotation thereof.
The housing part 68 includes an annular chamber receiving an annular piston 70 which is abutted by a stationary : - 6 -1~a)(~785 clutch plate 72 identical to the clutch plate 62 and which is operable to compress a clutch pack including additional stationary clutch plates 72 and interleaved rotatable clutch plates 74.
The pack is compressed against the housing part 66.
The rotatable clutch plates 74 are splined to the ring gear 40 of the second planetary gear assembly and when the piston 70 is extended, at some point in time, the ring gear 40 will ~e braked to a halt. As is well known, controls are pro-vided so that the pistons 60 and 70 are never simultaneously preSsurized.
The housing part 68 includes an additional annular chamber receiving an annular piston 80 which is abutted by a stationary clutch plate 82 which is identical to the clutch plates 62 and 72. The clutch plate 82 can compress a further clutch pack including additional stationary clutch plates 82 and interleaved rotatable clutch plates 84 against a housing part 86. The housing part 86 is held stationary by being sand-wiched between the housing part 68 and a housing part ~8, as best seen in the upper center of Fig. 1. The rotatable clutch plates ~4 are splined to the carrier 50 of the third planetary gear assembly and thus, when compressed against the plates 82, will halt rotation of the same.
The housing part 88 includes an annular chamber re-ceiving an annular piston 90 which abuts a stationary clutch plate 92. The stationary clutch plate 92 can compress a clutch pack including an additional stationary clutch plate 92 and interleaved rotatable clutch plates 94 against the housing part 86. The clutch plates 92 are identical to the clutch plates 62, 72 and 82. When the piston 90 is extended to compress the pack, including the plates 92 and 94, the ring gear 56 for the 1~)078S ~ ~

fourth planetary gear assembly will be braked. Again, suitable controls are provided so as to prevent simultaneous pressurization of the pistons 80 and 90.
Those skilled in the art will readily appreciate that the input shaft and the output quillshaft 14 can be selectively coupled through the various planetary gear assemblies and/or the movable clutch 58 to provide a large variety of gear ratios~
According to the invention, a unique structure is pro-vided for causing the pistons 60, 70, 80 or 90 to retract when they are not subjected to fluid under pressure. In particular, at equally angularly spaced locations, in the prefer~ed embodiment three such locations spaced at 120 are provided, the various housing parts are provided with bores which may align. As seen in Fig. 1, the housing part 26 is provided with such a bore at 100, the housing 66 at 102, the housing part 68 at 104, the housing part 86 at 106 and the housing part 88 at 108. The bores 102 and 106 are larger than the bores 100, 104 and 108 and, in the aligned ones of the bores 100-108, there is loosely received a floating, elongated pin 110. The pin 110 extends through holes, to be described, in each of the stationary clutch plates 62, 72, 82 and 92 in abutment with the corresponding pistons 60, 70, 80 and 90. The pin 110 does not, however, extend through the remaining stationary plates 62, 72, 82 and 92, as will be seen.
A compression coil spring 112 is disposed about the pin 110 so as to extend through the bore 102 and abut the stationary plates 62 and 72 in abutment with the pistons 60 and 70. A similar compression coil spring 114 extends through the bore 106 to abut the stationary clutch plates 82 and 92 in abutment with the pistons 80 and 90. As a consequence of this 11~)078S
construction, those stationary plates 62, 72, 82 and 92 in direct abutment with the pistons 60, 70, 80 and 90 are spring biased by the associated spring 112 or 114 in such a way as to cause the associated piston to be moved to its retracted position. Thus, when pressurized fluid is not applied against one of the pistons, it will be moved to a retracted position to release compression on the associated clutch pack. This con-struction assures proper retraction of the pistons and the release of compression in all clutch packs when desired and because the bores are of ~reater diameter than the pin 110, allowing the latter to float, large tolerances may be employed eliminating the need for precision machined bores and their associated dowels.
Circumferentially spaced from the bores 100-108 and at equally angularly spaced locations about the centerline of the shaft 10, are a plurality of additional bores, in the exemplary embodiment, six in number. The housing part 26 in~
cludes such a bore at 116, the housing part 66, a bore 118, the housing part 68, a bore 120, the housing part 86, a bore 20 122, and the housing part 88, a bore 124. Corresponding ones of the bores 116-124 are aligned for receipt of a corresponding number of tie bolts 126.
As best seen in Fig. 2, the tie bolts 126 have hex heads 128 at one end and a threaded end 130 oppositely thereof 25 threadably received in a threaded part 132 of the bore 116 in the housing part 26. The tie bolts act to hold the components ; in assembled relation, as is well known.
In addition, the tie bolts 126 serve as reaction members for all of the stationary clutch plates 62, 72, 82 and 92, 30 including the plates 62, 72, 82, 92 in direct abutment with the pistons 60, 70, 80 and 90.

11~07~3~

In particular, each of the plates 62, 72, 82 and 92 is provided with a plurality of apertures 134 through which corresponding ones of the tie bolts 126 extend.
In a highly preferred embodiment, the tie bolts 126 at least are surface hardened to a greater hardness than that of the clutch plates 62, 72, 82 and 92 in the vicinity of the apertures 134. This assures that wear due to torque reaction upon engagement of the various clutch packs is confined to the clutch plate and will not occur in the surface of the tie bolts 126 abutted by the clutch plates.
Fig. 3 illustrates a single clutch plate which may be used as any one of the clutch plates 62, 72, 82 and 92. While the illustration of Fig. 3 is specifically concerned with the plate 92 in abutment with the piston 90, for reasons that follow, it will be appreciated that its construction is typical.
The clutch plate 92 in Fig. 3 is formed of a generally circular disc-like member 140 having opposed friction surfaces 142 and 144 (Fig. 2) which are parallel to each other. The member 140 includes a central, circular opening 146 as well as a plurality of substantially equally angularly spaced tangs 148, 150, 152, 154, 156 and 158 extending radially outwardly from the periphery o~ the member 140. According to the invention, the number of the tangs 148-158 will be equal to n and, preferably, but not always, n is an even integer, i.e., 2, 4, 6, 8, etc.
As illustrated in Fig~ 3, every second tang has at least one dimension greater than that of the remaining tangs~ As seen in Fig. 3, the tangs 150, 154 and 158 have a greater width than the tangs 148, 152 and 156, that is, the greater dimension extends circumferentially of the disc 140~ According to the invention, every Xth tang has such a greater dimension~

Preferably, but not always, X will be an integer of 2 or more.
When X is an integer of 2 or more, the quantity n is equal to an integer of 2 or more Each of the tangs 148-158 includes a tie bolt receiving aperture 134 and it will be observed from Fig. 3 that the apertures 134 are equally angularly spaced. Moreover, they are equally radially spaced from the center of the disc 140 and preferably are radially elongated as, for example~ by being formed as two intersecting, nonconcentric bores 160 and 162.
Because of the radial elongation of the apertures 134, they may shift somewhat to self-align the center of rotation of their associated clutch pack, again, eliminating the need for precision machining.
It will also be observed that the apertures 134 in the tan~s 150, 154 and 158 are displaced to one side of the center of such tangs.
Displaced to the side of the center of the larger -tangs 150, 154 and 158, oppositely from the apertures 134, are holes 164. The holes 164, when used, receive the pins 110 and the immediately surrounding area of each tang 150, 154 and 158, when the holes 164 receive the pins 110, will be abutted by one of the springs 112 or 114.
In a highly preferred embodiment, there will be at least three of the larger tangs provided. Where the larger tangs have their larger dimension extending in the circum-ferential direction, the smaller tangs 148, 152 and 156 may be dispensed with in favor of the large tangs entirely. Generally, however, there will be at least three of the large tangs and at least three of the small tangs to ensure adequate guidance for the stationary plates as well as to prevent the existence ~ 11 -of cocking forces which might cause the plates to bind on the tie bolts 126. Of course, utilizing smaller tangs, such as is shown in Fig. 3 for the tangs 148, 152 and 156, minimizes material costs and therefore is preferable.
As a result of the foregoing construction, a reversible clutch plate is formed. Such a plate can be used in any one of the stationary clutch plate positions illustrated and is not restricted to use as a clutch plate abu~ting one of the pistons. Fig. 4 illustrates how such plates are oriented with respect to each other in the pack to achieve this function.
The forwardmost clutch plate illustrated in Fig. 4 is the clutch plate 82 in abutment with the piston 80 and, it will be seen that even though the piston 80 acts oppositely of the piston 90, the forwardmost clutch plate 82 is disposed identically to the clutch plate 92 abu~ting ~he piston 90. The coil springs 114 are illustrated in dotted lines surrounding the pins 110 and, ; as will be appreciated from Fig. 1, are in abutment with the rear side of the forwardmost plate 82.
Also shown in Fig. 4 is a clutch plate 82 not in direct abutment with the piston 80 and such a clutch plate is given the designation 82R in Fig. 4. The plate 82R is identical to the plate 82 but has been rotated about a diameter thereof through 180, i.e., flipped. It is also rotated about its center such that the apertures 134 in the plate 82 and the apertures 134 in the plate 82R are aligned to receive the tie bolts126. This results in a pack configuration wherein the rear side of the larger tangs 150, 154 and 158 o the forwardmost plate 82 have parts directly facing a remote housing part,such as the housing part 86 (Fig. 2~ so that the springs 114 may abut the same without interference or contact with any of the tangs on the rearwardmost plate 82R.

`7~5 It will accordingly be appreciated that a reversible clutch plate made according to the invention can be utilized at any position in a clutch pack wllereat a stationary clutch plate is required. As a result, the requirement for two, dissimilar, S types of stationary plates and a single clutch pack frequently required by the prior art is eliminated. Inventory expenses are thereby reduced as are manufacturing costs, since only one plate, as opposed to two, need to be manufactured and stocked.
This feature of the invention can be employed in a variety of mechanisms, as mentioned previously, and is particularly useful in connection with the mechanism such as illustrated in Figs. 1 and 2 made according to the invention wherein precision machining is eliminated.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a planetary gear mechanism including input and output shafts;
at least one planetary gear assembly interconnecting the shafts and including a sun gear, a planet gear meshed with the sun gear and mounted by a carrier and a ring gear meshed with the planet gear;
at least two housing parts at least partially enclosing the planetary gear assembly;
a friction assembly including a piston, a first friction plate engageable by the piston and secured against rotation relative to the housing parts, a second friction plate aligned with and engageable by the first friction plate and mounted on said one of the ring gear and the carrier against relative rotation with respect thereto;
a plurality of tie bolts assembling said housing parts, and coil springs urging said first plate towards said piston and away from said second plate;
the improvement comprising a plurality of aligned bores in said housing parts radially outwardly of the planetary gear assembly and a plurality of pins, each said pin loosely received in corresponding ones of said aligned bores in said housing parts and extending through said first plate, said bores being of larger size than the correspond-ing pin so that each said pin floats in its bores enabling the use of large tolerances, said coil springs being dis-posed on corresponding ones of said pins in abutment with said first plate and one of said housing parts.

2. A gear mechanism according to claim 1, wherein there are a plurality of the planetary gear assemblies and the number of the housing parts exceeds the number of the planetary gear assemblies, and each of the pins links several of the housing parts and mounts a plurality of the coil springs.

3. A planetary gear mechanism according to claim 1, wherein there are a plurality of the planetary gear assemblies and each of the pins is common to at least some of the planetary gear assemblies and mounts the coil springs for the planetary gear assemblies to which it is common.

4. A planetary gear mechanism according to claim 1, wherein the first friction plate comprises a generally circular, disc-like member having an opening in its center; a plurality of equally angularly spaced tangs extending radially outwardly from the periphery of the member; equally angularly spaced tie bolt receiving apertures one in each tang dis-placed from the center thereof in the circumferential direction;
and, on each of at least three angularly spaced ones of the tangs and displaced from the center thereof in the circumferen-tial direction oppositely from the tie bolts receiving aper-ture, a spring engaging formation including an opening for reception of the corresponding spring mounting pin.

5. A planetary gear mechanism according to claim 4, wherein the second friction plate is interposed between the first friction plate and a third friction plate which is con-structed identically to the first friction plate and is also secured against rotation relative to the housing parts, one of the first and third friction plates being reversed with res-pect to the other such that the tie bolt receiving apertures in these plates are axially aligned with one another while the spring engaging formations on one of these plates are out of axial alignment with the tangs on the other of these plates.

6. A planetary gear mechanism according to claim 1, wherein the first friction plate comprises a generally cir-cular, disc-like member having an opening in its center; n substantially equally angularly spaced tangs extending radial-ly outwardly from the periphery of the member, where "n"
is an even integer; every Xth tang having at least one dimension greater than that of the remaining tangs, wherein "X" is an integer of 2 or more and wherein ? is equal to an integer of 2 or more; a plurality of equally angularly and radially spaced tie bolts receiving apertures, one in each tang; and, on the part of each Xth tang having the greater dimension, a spring engaging formation including an opening for reception of the corresponding spring mounting pin.

7. A planetary gear mechanism according to claim 6, wherein n is equal to at least 6, and ? is equal to at least 3.

8. A planetary gear mechanism according to claim 6 or claim 7, wherein the greater dimension extends in the circumferential direction.

9. A planetary gear mechanism according to claim 6 or 7, wherein the second friction plate is interposed between the first friction plate and a third friction plate which is constructed identically to the first friction plate and is also secured against rotation relative to the housing parts, the first and third friction plates being so relatively angularly oriented that the tie bolt receiving apertures in these plates are axially aligned with one another while the spring engaging formations on one of these plates are out of axial alignment with the tangs on the other of these plates.

10. A planetary gear mechanism according to any one of claims 4 to 6, wherein the tie bolts have a greater surface hardness than the tangs whereby wear due to torque reaction will occur in the tangs rather than in the tie bolts.

11. A planetary gear assembly according to any one of claims 4 to 6, wherein the tie bolt receiving apertures are radially elongate.