Gear transmission with undulating surface clutch and brake element connections

Abstract: An improved gear transmission (10) includes a one-way clutch (52) for connecting together selectively two drive elements to establish a plural torque flow path through the transmission (10) and the clutch (52) includes at least one inner race (528) and one outer race (52A), each of the races having concentric inner and outer race portions, the outer surface (112) of the outer race portion (528) defined by a first undulating surface, the inner surface (113) of a mating drive element defined by a second undulating surface in conjugate registration with the first undulating surface, the profiles of the first and second undulating surfaces (112,113) being controlled to provide a controlled clearance therebetween reducing shock loading at the interface of the inner and outer race portions through a gradual lock-up through a controlled wind-up of the mating members and reducing vibration in the gear elements.

Description: This invention relates to a gear transmission as described in the preamble of independent claims 1, 2 and 3. A conventional connection between a one-way clutch or brake element and another transmission element in a gear transmission includes conventional splines in which a plurality of parallel spline teeth is formed integrally with a race of the clutch or brake element and a plurality of spline tooth spaces is formed in a mating transmission element. Such spline connections are capable of transmitting heavy torques but they have inherent drawbacks, such as the relatively high manufacturing cost and the need for aligning the mating spline teeth for assembly. Furthermore, the backlash between the mating spline teeth that prevents the teeth from jamming together causes shock loading upon clutch or brake engagement and speed change, such as during shifting. This may cause damaging shock loading and/or vibration upstream and/or downstream in the torque flow path. One publication entitled "A Better Way To Make Shaft Connections" by David Ryffel, found in MACHINE DESIGN magazine dated August 11, 1988 at page 124, discusses the use of a polygonal profile in a torque transmitting connection for locking a shaft to a hub. The connection comprises polygonal lobes on a shaft which register with polygonal internal spaces on a hub. Another publication entitled "Locating Nodes On Radially Loaded Rings" by David Hustvedt and found in MACHINE DESIGN magazine dated April 10, 1986 discusses use of a differential bending equation to calculate node point locations on a circular ring subjected to equal, uniformly spaced radial loads. In UK-A-2149029 (which forms the basis for the preamble of the independent claims 1, 2 and 3) there is generally disclosed a gear transmission including a housing and adapted to transmit torque in one direction between a driving member and a driven member, the gear transmission comprising a ring gear element, a sun gear element, a plurality of planet pinions meshing with the ring gear element and the sun gear element, a carrier element journalling the planet pinions, the driving member being drivably connected to one of the elements, the driven member being connected to a second of the elements, and clutch and/or brake means respectively for connecting together selectively two of the elements or for anchoring selectively one of the elements to the housing thereby to establish plural torque flow paths through the gear transmission, the clutch and/or brake means comprising an inner race and an outer race, each of the races having concentric inner and outer race portions , the surface of one of the races having a first undulating surface, a mating surface of one of the elements defining a second undulating surface in conjugate registration with the first undulating surface. More particularly, the first and second undulating surfaces comprise, respectively, generally rectangular outer and inner splines in cooperating engagement but with substantial circumferential clearance therebetween so that the outer race is loosely fitted in the mating element, and a resilient member is interposed between a side wall surface of an inner spline of the mating element and an opposing side wall surface of the cooperating outer spline of the outer race to urge the outer race constantly in the locking direction of the clutch and/or brake means. The provision of the resilient member is to prevent impacts which would otherwise occur between the circumferentially loose fitting cooperating outer and inner splines when the clutch and/or brake means is reversed to change from rotation in the free direction to rotation in the locking direction. It is an object of the present invention to provide a gear transmission having an improved connection between a clutch and/or brake element and a mating transmission element. This object is accomplished, in accordance with the present invention as claimed in the independent claims 1, 2 and 3, in that the gear transmission is characterized by the profiles of the first and second undulating surfaces are shaped to provide a predetermined controlled clearance therebetween, thereby providing a gradual lock-up through a ramping or wedging lock-up between the undulating surfaces thus reducing shock loading at the interface of the inner and outer race portions and torsional vibration in the gear elements. In a preferred embodiment of the present invention, each of the first and second undulating surfaces is defined by a plurality of regularly spaced crests and troughs which establish the respective profile. Advantages of a gear transmission constructed in accordance with the present invention are that it eliminates on on/off locking engagement of splined connections and the associate shock loading without the necessity of employing additioning resilient means for cushioning such shock loading; its improved connection is less costly than conventional spline connections; and its improved connection is easier to assemble because the need to align spline teeth has been eliminated and is less costly than a spline connection. In order that the present invention may be well understood there will now be described an embodiment thereof, given by way of example, reference being made to the accompanying drawings, in which: Brief Description Of The Drawings Figure 1 is a cross-section of a gear transmission according to one embodiment of the invention showing in the assembled condition, the clutches, brakes and gear units; Figure 2 is a diagram of the same multiple speed gear transmission showing the components that operate to produce each of the various speeds; Figure 3 is a front view of a one-way clutch or brake element of the same gear transmission illustrating concentric inner and outer race portions with undulating surfaces in conjugate registration; and Figure 4 is a sectional view of the one-way clutch and brake element of Figure 3 illustrating the controlled clearance between the registering inner and outer races. Referring first to Figures 1 and 2 of the drawings, there is shown a gear transmission (10) adapted to transmit torque in one direction between a driving member 13 and a driven member 14. A main transmission housing 12 encloses simple planetary gear units 16, 18 and 20. An input shaft (driving member) 13 is connected to carrier 21 of first planetary gearset 16, which includes sun gear 22, a set of planetary pinions 24 rotatably supported on carrier 21 and ring gear 26. Sun gear 22 is drivably connected to a member 30 that is common to a coast clutch 32 and an overdrive brake 34. Ring gear 26 is drivably fixed to a drum portion 28 connected to intermediate shaft 36. Overdrive brake 34 includes a set of clutch discs fixed to housing 12, a load block 38 fixed to housing 12, a set of clutch discs drivably connected to the outer surface of clutch member 30 and interposed between the discs affixed to the housing, a clutch piston 40 displaceable hydraulically against the clutch disc assembly and hydraulic cylinder 42 containing piston 40. A Belleville spring 44 returns piston 40 to the inactive position when hydraulic pressure is removed from cylinder 42. Coast clutch 32 includes a set of clutch discs drivably connected to the inner surface of clutch member 30, a load block connected to the inner surface of clutch member 30, a second set of clutch discs drivably fixed to ring gear 26, piston 46 actuated hydraulically to engage the coast clutch disc sets, a hydraulic cylinder 48 within which piston 46 moves, and a Belleville spring 50 to return piston 46 to the disengaged position when hydraulic pressure is removed from cylinder 48. A first one-way clutch 52 has its outer race 52A formed with an undulating profiled outer surface 112, as illustrated in Figures 3 and 4. It is drivably connected and in conjugate registration with a corresponding profiled inner surface 113 of ring gear 26. Clutch 52 has an inner race 52B drivably connected by a spline to cylinder 48 and to sun gear 22, and a driving member located in the annulus between the inner and outer races for producing a one-way clutch 54 is located between intermediate brake 56 and direct clutch 58. One-way clutch 54 includes an outer race that carries a set of brake discs for the intermediate brake 56, an inner race drivably fixed to drum 60, and a driving member located in the annular region between the inner and outer races for producing a one-way drive connection therebetween. The outer race of one-way clutch 54 has an undulating profile and the inner surface of intermediate brake 56 has a corresponding undulating profile as illustrated in Figures 3 and 4, for conjugate registration as hereinafter more fully described. Intermediate brake 56 includes a second set of brake discs fixed to housing 12, a load block fixed to the housing, a piston 61 actuated hydraulically to force the brake disc sets into drivable relationship against the load block, hydraulic cylinder 43 within which piston 61 moves and a Belleville spring. Drum 60 is stopped and held against the transmission casing through the action of an intermediate brake band 62 actuated via a conventional manner by a hydraulic transmission servo, not shown. Direct clutch 58 operates to produce a drive connection between drum 60 and clutch member 64. The direct clutch includes a first set of clutch discs splined to the inner surface of drum 60 and a second set of clutch discs connected to clutch member 64 which are interposed between successive members of the first clutch disc set. A piston 66 moves within a hydraulic cylinder to force the clutch disc sets into drivable connection against the load block that is carried on the inner surface of the drum 60. Piston 66 moves within the hydraulic cylinder defined by drum 60 and is restored to its disengaged position through operation of coil compression springs 68. Forward clutch 70 operates to produce a driving connection between clutch member 64 and the ring gear 72 of the second planetary gearset 18. This gearset includes a sun gear 74, a set of planetary pinions 76 in continual meshing engagement with sun gear 74 and ring gear 72, the latter being rotatably supported on a carrier 78 which is drivably connected by spline 80 to the tail shaft (driven member) 14. Forward clutch 70 includes a first set of clutch discs drivably connected to the inner surface of clutch member 64 and a second set of clutch discs, each interposed with discs of the first set, drivably connected to the outer surface of ring gear 72. Piston 82 is hydraulically actuated for movement within the cylinder defined by clutch member 64 to force the clutch discs into a drivable connection. Belleville spring 84 returns piston 82 to the disengaged position when hydraulic pressure is removed from the clutch cylinder. The third planetary gear gearset 84 includes sun gear 86 formed integrally with sun gear 74, ring gear 88 connected by spline 90 to tailshaft 14, a set of planet pinions 92 rotatably supported on carrier 94, which is drivably connected to a first set of brake discs of the low-and-reverse brake 96. A second set of brake discs of brake 96 is fixed to transmission casing 12. Each disc of the second set is interposed between successive discs of the first disc set of brake 96. Brake piston 98 is actuated hydraulically when cylinder 100 is pressurized to force the piston against the first and second brake disc sets and to produce a drivable connection therebetween against the effect of the return spring 102. Spring 102 forces piston 98 to the brake disengaged position when cylinder 100 is vented. Load block 104, fixed to the transmission casing provides a reaction for the force applied by piston 138 to the disc brake sets. A third one-way clutch 106 includes an outer race having an undulating profile in conjugate registration with a correspondingly undulating profiled inner surface of carrier 94, illustrated in Figures 3 and 4, an inner race 110 bolted to the transmission casing 12, and a driving member located in the annular region between the inner and outer races to produce a one-way drive connection between carrier 94 and the casing. Figures 3 and 4 illustrate one of the three one-way clutches 52, for purposes of illustration. As herein described, clutch 52 includes concentric inner 52B and outer 52A race portions concentrically connected to ring gear 26. The outer surface 112 of outer race 52A has an undulating profile defined by a plurality of crests and troughs. The inner surface 113 of ring gear 26 has a corresponding undulating profile defined by a like plurality of crests and troughs. The profiles of the outer race outer surface 112 and ring gear inner surface 113 register in conjugate registration. The undulating profile is designed to provide a controlled clearance between the surfaces which provides a gradual lock-up of the surfaces through a wedging or ramping lock-up of the surfaces as rotational forces are communicated through the transmission 10. The gradual lock-up, through controlled wind-up, eliminates shock loading and reduces torsional vibration in the gear elements upstream and downstream in the transmission. The same principle is used in clutch 54 and brake 106 connections. Although the connection hereinabove described is the outer race of a one-way clutch-transmission element connection, the connection can be utilized to connect the inner race of a one-way clutch to a mating transmission element. The profile of the crests and troughs is tailored to the application dynamics such as the deflected shape that mating circular surfaces seek when they are radially loaded to enhance and stabilize the one-way response of the clutches 52, 54 and brake 106. The wind-up through ramping lock-up eliminates the on/off locking engagement of splined connections and the associated shock loading upstream and downstream on transmission components as rotational forces are transmitted. The undulating surfaces 112,113 can be coated with a composite coating of a material such as an elastomeric plastic of synthetic rubber energizing material, or a thermoplastic engineering plastic composite material, either filled or unfilled with various reinforcing materials or fibers to dampen shock loading and further reduce vibration. Alternatively, or in combination, plugs of the shock dampening material can be impregnated into the undulating surfaces 112,113.

Claims: A gear transmission (10) adapted to transmit torque in one direction between a driving member (13) and a driven member (14), said transmission comprising: a ring gear element (26;88) a sun gear element (22;86) a plurality of planet pinions (24;92) meshing with said ring gear element (26,88) and sun gear element (22;86) a carrier element (21;94) adapted to journal said pinions (24;92); said driving member (13) being drivably connected to one (21,86) of said elements (21,22,24,26; 86,88,92,94), said driven member (14) being connected to a second (26,88) of said elements; and clutch (52) and brake (106) means for connecting together selectively, two of said elements and for anchoring selectively one of said elements to establish plural torque flow paths through said transmission (10), said clutch (52) and brake (106) means comprising at least one inner race (52B) and one outer race (52A), each of said races (52A,52B) having concentric inner and outer race portions, the inner surface of said inner race or the outer surface of said outer race having a first undulating surface (112), the mating surface (113) of one of said elements having a second undulating surface (113) in conjugate registration with said first undulating surface (112), characterised in that the profiles of said first and second undulating surfaces are shaped to provide a predetermined controlled clearance therebetween, such that they provide a gradual lock-up through a ramping or wedging lock-up of said undulating surfaces, thereby reducing shock loading at the interface of said inner and outer race portions and torsional vibration in said gear elements. A gear transmission (10) adapted to transmit torque in one direction between a driving member (13) and a driven member (14), said transmission comprising: a ring gear element (26); a sun gear element (22); a plurality of planet pinions (24) meshing with said ring gear element (26) and sun gear element (22); a carrier element (21) adapted to journal said pinions (24); said driving member (13) being drivably connected to one of said elements, said driven member (14) being connected to a second of said elements; a one-way clutch (52) for connecting together selectively, two of said elements to establish plural torque flow paths through said transmission (10), said clutch comprising at least one inner race (52B) and one outer race (52A), each of said races having concentric inner and outer race portions, the outer surface of said outer race having a first undulating surface (112), the inner surface (113) of a mating element having a second undulating surface in conjugate registration with said first undulating surface, characterised in that the profiles of said first and second undulating surfaces are shaped to provide a predetermined controlled clearance therebetween, such that they provide a gradual lock-up through a ramping or wedging lock-up of said undulating surfaces, thereby reducing shock loading at the interface of said inner and outer race portions and torsional vibration in said gear elements. A gear transmission (10) adapted to transmit torque in one direction between a driving member (13) and a driven member (14), said transmission comprising: a ring gear element (26); a sun gear element (22); a plurality of planet pinions (24) meshing with said ring gear element (26) and sun gear element (22); a carrier element (21) adapted to journal said pinions (24); said driving member (13) being drivably connected to one of said elements, said driven member (14) being connected to a second of said elements; and a brake assembly (106) for anchoring selectively one of said elements to establish plural torque flow paths through said transmission (10), said brake assembly (106) comprising at least one inner race (52B) and one outer race (52A), each of said races having concentric inner and outer race portions, the outer surface of said outer race having a first undulating surface (112), a mating surface having a second undulating surface (113) in conjugate registration with said first undulating surface, characterised in that the profiles of said first and second undulating surfaces are shaped to provide a predetermined controlled clearance therebetween, such that they provide a gradual lock-up through a ramping or wedging lock-up of said undulating surfaces, thereby reducing shock loading at the interface of said inner and outer race portions and torsional vibration in said gear elements. A gear transmission (10) as claimed in any of the preceding claims, wherein said undulating surfaces (112,113) are defined by a plurality of regularly spaced crests and troughs which establish said profile. A gear transmission (10) as claimed in any of the preceding claims, wherein said undulating surfaces (112,113) further include a composite coating of a material to dampen shock loading and vibration. A gear transmission (10) as claimed in claim 5, wherein said material is an elastomeric plastic of synthetic rubber energizing material, or a thermoplastic engineering plastic composite material, either filled or unfilled with various reinforcing materials or fibres. A gear transmission (10) as claimed in any of the preceding claims, wherein said undulating surfaces (112,113) further includes a plug of a shock absorbing material to dampen shock loading and vibration. A gear transmission (10) as claimed in claim 7, wherein said shock absorbing material is an elastomeric plastic of synthetic rubber energizing material, or a thermoplastic engineering plastic composite material, either filled or unfilled with various reinforcing materials or fibers.

Inventors: MALECHA GREGORY J, MALECHA, GREGORY J.
Applicants: BORG WARNER AUTOMOTIVE, BORG-WARNER AUTOMOTIVE TRANSMISSION AND ENGINE COMPONENTS CORPORATION
Application year: 1992
Main classification: F16H3
IPC codes: F16H63, F16D41, F16H57, F16H3