WO1981001731A1

WO1981001731A1 - Torsional vibration damper assembly

Info

Publication number: WO1981001731A1
Application number: PCT/US1979/001086
Authority: WO
Inventors: W Windish
Original assignee: W Windish
Priority date: 1979-12-13
Filing date: 1979-12-13
Publication date: 1981-06-25

Abstract

A torsional vibration damping assembly adapted to be interposed between an engine flywheel (10) and a transmission (12). The vibration damping assembly comprises a plurality of plates (14, 16, 18) with friction material (30) interposed therebetween along with springs (28). The springs (28) are located radially inwardly with respect to the plates (14, 16, 18) forming the damping assembly while the friction material (30) is located radially outwardly thereof.

Description

Torsional Vibration Damper Assembly

Technical Field

This invention relates to a torsional vibration damper assembly such as is typically interposed between the fly wheel of an engine and a transmission or torque converter- Background Art

The prior art of possible relevance includes the following United States letters patents: 2,359,180 issued September 26, 1944 to Williams; 3,266,271 issued August 16, 1966 to Stromberg; and 3,628,353 issued December 21, 1971 to Armstrong.

Torsional vibration dampening assemblies are frequently interposed between the flywheel of an engine and a transmission for isolating and damping torsional vibrations occurring in the drive line formed thereby. A number of structures are commercially available and they typically include one or more of the features of construction illustrated in the various embodiments of the above identified Stromberg patent.

In the usual case, springs such as shown by Stromberg interconnect two or more spaced damping plates and tend to isolate drive line shock. However, because the springs also will return to the system torsional energy applied to them, it is also necessary to provide damping. This is typicaly achieved by utilizing fric¬ tion material at the interfaces of the plates.

Heretofore, the prior art has generally located the springs at positions relatively radially outwardly of the axis of rotation of the assemblies with the friction material being located at -a relatively radially inward position. As a consequence, the friction produced at the friction material upon relative movement between the plate acts over a relatively short moment arm. Damping action is thereby limited by the length of the damping arm.

At the same time, most such constructions employ an axial, splined sleeve of considerable length for connection to the transmission in the drive line with which the assembly is to be used. Because the as¬ sembly must also be secured to the flywheel, during as¬ sembly of the drive line, considerable care must be ex- ercised in aligning the input shaft of the transmission with the splined sleeve before the two may be assembled together. When this assembly operation is attempted in confined quarters, considerable difficulty in achieving the alignment that is requisite to assembly may be en- countered.

In addition, in many such assemblies, various components are held in assembled relation by threaded bolts which also serve limit relative movement between the plates. Usually, the bolts are supported only at one end with the consequence 'that bending forces are more difficult to resist. And because the bolts are threaded, they cannot withstand the same bending force as an unthreaded member of the same outer diameter.

Disclosure of the Invention The present invention is directed to over¬ coming one or more of the problems as set forth above.

According to one aspect of the invention, there is provided a vibration damping assembly composed of a plurality of plates with friction material interposed therebetween along with the usual springs. According to the invention, the same is sandwiched between a fly¬ wheel and an annular flange with the latter being secured to the flywheel. Unthreaded reaction pins are supported by both the flange and the flywheel, that is, the pins are supported at both ends, to thereby resist bending forces and thereby provide a long-lived assembly.

O P

AΛ — According to another aspect of the invention, the springs are located radially inwardly with respect to the plates forming the damping assembly while the friction material is located radially outwardly thereof. Consequently, the moment arm over which friction acts to damp vibration in the drive line is increased pro¬ viding enhanced damping..

According to still another facet of the inven¬ tion, the plates making up the vibration damping assem- bly include aligned central apertures with the central aperture of the central plate in the assembly being of smaller size that the apertures in the adjacent plates and provided with radially inwardly directed spline teeth having an axial length no greater than the thickness of the plate. Consequently, a coup.ling having an ex¬ ternal spline can be connected to the central plate and be canted through substantial angles with respect thereto to facilitate alignment with the input shaft of a transmission, torque converter, or the like.

Brief Description of Drawings

Fig. 1 is a fragmentary, end view of a vibra¬ tion damping assembly made according to the invention; and

Fig. 2 is an enlarged sectional view taken approximately along the line 2-2 in Fig. 1 and addition¬ ally illustrating in phantom, components of a drive train with which the damping assembly is to be used.

Best Mode for Carrying Out the Invention

An exemplary embodiment of a vibration damping assembly made according to the invention is illustrated in the drawings and with reference thereto is adapted to the interposed between a flywheel 10 of an engine and the input end 12 of a transmission having a transmission shaft (not shown) . The damping assembly consists of three plates 14, 16 and 18 although a greater number could be

__0A.PI ^• used if desired. The plates 14, 16 and 18 are generally circular in configuration and each is provided with a central aperture 20, 22 and 24 respectively. As can be seen in Fig. 2, the apertures 20 and 24 in the plates 14 and 18 have substantially the same diameter and both are considerably larger than the aperture 22 in the plate 16. Moreover, the aperture 22 includes radially inwardly directed spline teeth 25 for purposes to be seen.

In a relatively radially inward position on the plates 14, 16 and 18, all are provided with a plurality of aligned apertures 26 which receives spring assemblies 28 which may be of conventional construction. It will be observed that the springs 28 engage each of the plates 14 16 and 18 for the usual purpose. Radially outwardly of the apertures 26 and the springs 28, friction material 30 is interposed about the periphery of the plates at their interfaces. The friction material 30 may be bonded to the plate 16 if desired. Axially extending bores 32 on the^' flywheel 10 receive compression springs 34 which bear against the plate 14 to bias the same against the plate 16 which in turn is biased against the plate 18.

About the periphery of each of the plates 14, 16 and 18, there are provided a plurality of aligned radially outwardly opening slots 36 with the slots 36 in the plate 16 being somewhat elongated to permit relative movement between the plates to allow compres¬ sion of the springs 28. Axially extending reaction pins 38 extend through the slots 36 and, as seen in Fig. 2, each such pin 38 has one end received in a bore 40 in the flywheel 10 and an opposite end re¬ ceived in a bore 42 formed in an annular flange 44 secure to the flywheel 10 by a series of bolts 46 (only one of which is shown) . As a consequence, the pack defined by the plates (14,16 and 18) is sandwiched between the flange 44 and the flywheel 10. Relative movement, to a

UR OKPΓ limited degree, between the plates 14, 16, and 18 can occur by reason of the fact that the slots 36 are formed to be somewhat larger than the pins 38 as shown in Fig. 1. The sides of the slots 36 do, however, limit relative movement between the plates 14, 16 and 18 as is well known. Because the plates 14_. and 18 are in direct contact with driving components, the flywheel 10 and the flange 44, respectively, they constitute the driving plates in the assembly. The central plate 16 constitutes a driven plate being driven by friction provided by the friction material 30, forces generated in the springs 28 and/or abutment with the reaction pins 38 when maximum spring deflection has occurred. The plate 16, is therefore, the one to be coupled to the input shaft of the transmission or the like. To facilitate such coupling, there is provided a coupling 50 having a sleeve-like body 52 provided with an internal spline 54 which may receive a mating external spline on the input shaft (not shown) of the. transmission. One end of the body 52 is provided with a peripheral, radially out- wardly directed web 56 which terminates ina peripheral, ex¬ ternal spline 58 which is engaged with the spline teeth 25 on the plate 16. The spline 58 is also spaced from the bounds of the apertures 20 and 24 and the plates 14 and 18. It will be observed that the internal spline de- fined by the spline teeth 24 have an axial length equal to the thickness of the plate 16. For purposes to be seen, this axial length should be substantially no greater than the thickness of the plate 16. Industrial Applicability During installation, alignment of the transmission with the damping assembly is easily achieved. The short axial length of the spline 25 allows the coup¬ ling 50 to be canted at substantial angles with respect to the rotational axis of the drive line. There is, therefore, no need to bring the input shaft of the trans¬ mission into precise axial alignment with the rotational axis of the flywheel and then axially advance the shaft i to a spline coupling as is the case with prior art structures. This type of prior art assembly technique requires a great deal of space. Rather, one may pivot the coupling 50 to a substantial angle with respect to the rotational axis of the flywheel and insert the trans mission input shaft into the spline 54. The transmissio may then be pivoted, in a far lesser space, into the required axial alignment. Consequently, the assembly of the present invention reduces spacial requirements re- quired for assembly and thereby minimizes the time re¬ quired for assembly in many instances.

The use of unthreaded reaction pins such as the pins 38 which are supported at both ends by the flywheel 10 and the flange 44, respectively, reduces bending forces applied thereto when one or more of the plates has a side of its slots 36 in contact therewith. The fact that the pins 38 are unthreaded increases their strength while dual end support provides increased support against bending. Finally, the location of the friction material

30 at locations radially outwardly of the spring assem¬ blies 28 increases, by substantial amount, the moment arm over which frictional forces may operate to provide enhanced damping.

OMF

Claims

1. Avibrationdamping assembly adapted to be interposed between an engine flywheel (10) and a trans¬ mission (12) or the like comprising: at least three plates (14,16,18) in side by side relation; friction material (30) at the interface of said plates; aligned holes (26) in said plates; spring assemblies (28) in said holes and en- gaging each of said plates; means (34) biasing said plates and said fric¬ tion material into a pack; means (38,44,46) holding* said pack in assem¬ bled relation and limiting relative movement of said plates; and aligned central apertures (20,22,24) in said plates, the central plate (16) in said pack having its central aperture (22) smaller than the central aperture of the adjacent plates and provided with radially in- wardly directed splines (24) having an axial length sub¬ stantially no greater than the thickness of said central plate.

2. The vibration damping assembly of claim 1 in combination with a coupling (50) having a sleeve (52) like body having an internal spline (54) , a radially out¬ wardly directed web (56) adjacent one end of the sleeve, and external, radially outwardly directed spline (58) , about the radially outer periphery of the web in engage¬ ment with the spline on said central plate and spaced from the central apertures (20,24) on said adjacent plates.

3. A vibration damping assembly adapted to be interposed between an engine flywheel^' (10) and a trans- mission (12) or the like comprising: at least three plates (14,16,18) in side by sid relation; friction material (30) at the interfaces of sai plates at radially outer locations thereon; aligned holes (26) in said plates at radially inner locations thereon; spring assemblies (28) in said holes and en¬ gaging each of said plates; means biasing (32) said plates and said .frictio material into a pack; means (38,44,46) holding said pack in assembled relation and limiting relative movement of said plates; aligned central apertures (20,22,24) in said plates; and means (24) in at least one central aperture for coupling said assembly to a shaft.

4. The vibration damping assembly of claim 3 in combination with a flywheel (10, said pack being abut ted against one side of said flywheel iri axial alignment therewith, said holding and limiting means including an annular flange (44) secured to said flywheel and sand¬ wiching said pack thereagainst and a plurality of un¬ threaded reaction pins (38) extending thru enlarged, a- ligned slots (36) in said plates and having opposed ends received in aligned bores (40,42) in said flywheel and said flange.

5. A vibration damping assembly adapted to be interposed between an engine flywheel (10) and a trans- mission (12) or the like comprising: at least three plates (14,16,18) in side by side relation;

O PI friction material (30) at the interfaces of said plates at radially outer locations thereon; aligned holes (26) in said plates at radially inner locations thereon; spring assemblies (28) in said holes and en¬ gaging each of said plates; means (34) biasing said plates and said fric¬ tion material into a pack; means (38,44,46) holding said pack in assembled relation and limiting relative movement of said plates; and aligned central apertures (20,22,24) in said plates, the central plate (16) in said pack having its central aperture (22) smaller than the central aperture (20,24) of the adjacent plates and* provided with radially inwardly directed splines (25) having an axial length substantially no greater than the thickness of s.aid cen¬ tral plates.