GB2079208A

GB2079208A - Improved Rivetting Structure for a Torque Converter

Info

Publication number: GB2079208A
Application number: GB8120481A
Authority: GB
Original assignee: Nissan Motor Co Ltd
Current assignee: Nissan Motor Co Ltd
Priority date: 1980-07-03
Filing date: 1981-07-02
Publication date: 1982-01-20
Also published as: FR2495708A1; DE3125995A1; GB2079208B; JPS5717343A

Abstract

Rivets (19) serve to connect a turbine runner shell (7a) to the turbine hub (12) of a torque converter (4) and simultaneously serve as connectors, spacers and part of a lost-motion connection in a lock-up clutch damper mechanism. To protect the press- formed turbine runner shell (7a) from deformation during rivet head (19d) formation, a hard annular rivet head motion shield (27) is interposed between the head (19d) of each of the rivets (19) and the turbine runner shell (7a). To prevent bending of the rivet shanks which form part of the lost motion connection, a flange (19e) is provided on each rivet which flange abuts a side plate (18) of the damper mechanism to disperse the force applied thereto upon the rivet shanks abutting the edges of apertures (7b) in the lock-up clutch hub which apertures define part of the lost motion connection. <IMAGE>

Description

SPECIFICATION Improved Rivetting Structure for a Torque Converter or the Like The present invention relates generally to a rivetting arrangement and more particularly to an improved rivetting arrangement suitable for use in arrangements such as a torque converter having a lock-up clutch.

Rivetting is frequently used to interconnect two or more components together due to the inherent simplicity and reliability of the rivets. However, where one of the elements connected by the rivet is made of a relatively soft or malleable metal it is apt to be deformed upon a headless end of the rivet being "cold headed" or otherwise worked to form a securing head, especially if this relatively soft member is immediately adjacent the head formed, This deformation tends to reduce the structural strength of the member in the vicinity of the aperture through which the rivet shank is disposed leading to a problem that, when the members interconnected by the rivet are used to transmit torque, the weakened zone of the member is apt to be further deformed leading to loosening or breakage of the rivet connection.

This problem has been particularly prevalent in an automotive torque converter wherein a shell member of the torque converter is connected to a hub member or the like thereof through a plurality of rivets. This shell member, usually a turbine runner of the torque converter, is preferably made by stamping in order to reduce production costs and is accordingly required to be adequately malleable. Hence, the turbine runner, an important element of the torque converter is apt to become loose from, buckled or even partially disconnected from the hub member to which it is fastened after prolonged use.Further, in the case where the torque converter is provided with a lock-up clutch of the type wherein the same rivets which secure the shell member of the torque converter to the hub thereof, are simultaneously used as connecting means, spacers and part of a lost motion connection in a damper mechanism of the lock-up clutch, the rivets are apt to be bent or snapped off by the sudden applications of torque on the damper mechanism which occur during lock-up and release of the lock-up clutch.

The present invention features a rivetting arrangement wherein a relatively hard protective or shielding member is interposed between the member to be connected by the rivet and the rivet head, so that upon formation of the rivet head, any unwanted deformation of the member or members interconnected by the rivet is completely eliminated. The invention further features a rivet which is suitable for use as part of a lost motion connection in a lock-up clutch damper mechanism and which has a relatively large diameter flange thereon for dispersing the force suddenly applied to the rivet to a structural member of the damper mechanism abutting thereagainst and therefore reducing the tendancy for the rivet to bend.

In the accompanying drawings:- Fig. 1 is sectional elevation of a torque converter having a lock-up clutch which is connected to the torque converter through a plurality of rivets; Fig. 2 is a front elevation of a damper of the lock-up clutch shown in Fig. 1; Fig. 3 is an enlarged sectional view showing the deformation which is apt to occur during the rivet head formation; and Fig. 4 is a sectional view similar to that of Fig.

1 but showing the provision of both a shielding member and a large diameter force dispersing flange according to the present invention.

Before turning to the preferred embodiment it is deemed advantageous to firstly consider a prior arrangement in which the rivet connection tends to deteriorate.

Fig. 1 shows an example of a torque converter in which rivets are used to act as spacers, connect various elements of the lock-up clutch and define part of a lost-motion connection which is an essential feature of the lock-up clutch damper mechanism. In this figure an engine crankshaft 1 is fixedly connected to a drive plate 2 formed with a ring gear 3 at the periphery thereof. A torque converter 4 includes a converter housing 5, a pump impeller 6, a turbine runner 7, a stator or reaction member 8, a pump drive shaft 9, a hollow stationary sleeve 10, a torque converter output shaft 11 and a turbine hub 12, assembled in a well known manner. The arrangement further includes a lock-up clutch piston 13 on which a clutch facing 14 is disposed and which is slidably disposed on the turbine hub 12.A clutch damper mechanism 1 5 operatively interconnects the turbine hub 12 and the lock-up clutch piston 13.

The damper mechanism includes a clutch hub 1 6 on which front and rear side plates 1 7 and 1 8 are rotatably supported. The clutch hub 1 6 is formed with a series of equidistantly spaced circular apertures 1 6a and a series of peripheral apertures 1 6b. As best seen in Fig. 2, the peripheral apertures 1 6b receive therein a series of connection flanges 21 which are fixedly connected to the lock-up clutch piston 1 3. The clutch hub 1 6 is further formed with rectangular apertures 1 6c in which coil springs 20 are disposed. Each of the front and rear side plates 1 7 and 1 8 are also formed with rectangular windows 1 7a and 188 which are smaller in width than the apertures 1 6c.Disposed spacedly through the circular apertures and fixedly interconnecting the front and rear side plates 1 7 and 18, the turbine hub 12 and the outer shell 7a of the turbine runner are stepped rivets 19. Each of the rivets 19 is formed with a larger diameter portion 1 9a which is disposed in the circular apertures 1 6a.

As best seen in Fig. 2 the arrangement is such that the clutch hub 16 may rotate through an angle "a" in one rotational direction and through an angle "p" in the other rotational direction, before coming into contact with the rivets 1 9.

During this rotation the springs 20 are compressed between the clutch hub and the side plates to absorb shock produced upon the engagement of the clutch facings 14 with the converter housing 5 which is induced in this case by creating a pressure differential across the clutch piston 13 via selectively draining the lock up chamber 30.

To supplement the disclosure of the arrangement shown in Figs. 1 and 2 the present application incorporates by reference the disclosure of United States Patent Specification 4,266,641 issued on May 12,1981 in the name of Sunohara.

In order to facilitate economical mass production of the hereinbefore disclosed arrangement it is preferable to be able to stamp the turbine runner shell 7a and thereafter rivet same to the turbine hub 12 via the same rivets which simultaneously secure the clutch hub 16 and side plate arrangement to the turbine hub 1 2.

Now, as the front side plate 1 7 is flat and not required to be stamped into any particular shape, it may be formed of a relatively hard metal which is resistant to any deformation upon the rivet heads 1 9c being formed. However, on the other hand the turbine runner shell must be sufficiently deformable so as to allow ready press forming which renders same susceptible to deformation upon the formation of the rivet heads 1 9d.

Fig. 3 shows a possible deformation apt to occur upon the cold forming (or the like) of the rivet heads 19d. As shown in this figure, the sheet metal of which the turbine runner shell is formed is deformed so as to have a thinned out region about the periphery of the aperture 7b through which the rivet was inserted prior to the formation of the rivet head. This thinned out portion has a relatively sharp edge 7c which is subject to an abnormally high surface pressure and is unable to offer sufficient resistance to load applied to the I rivet when rotational energy is transmitted from the turbine runner 7 to the turbine hub 12.

Accordingly one or more of the apertures 7b are apt to be undesirably enlarged which leads to loosening of the rivets and/or the sharp edges are apt to cut into the rivet shanks 1 9b leading to a possible removal of one or more of the rivet heads.

This drawback of course greatly hinders ready mass production of the torque converter in which the highly advantageous multi-function rivets are used, as excessive care must be taken upon the formation of the rivet head 1 9d.

Fig. 4 shows a preferred embodiment of the invention. In order to prevent the previously mentioned deformation of the turbine runner shell 7a, an annular shield member 27 is disposed about the shank of the rivet 19 prior to the formation of the rivet head 1 9d. This shield is made of a particularly hard metal such as carbon tool steel (SK 5) or carbon steel (S 60 C) which is harder than the metal used in the rivet, viz., a soft steel such as (S 20 C).

Thus, with the provision of the shield 27 upon formation of the rivet head 1 9dthe surface pressure applied to the zone surrounding the apertures 7b is dispersed through the shield 27 preventing any deformation.

In order to increase the resistance of the rivets against bending under sudden applications of torque on the damper mechanism of which they form a vital part, each of the rivets is provided with a relatively large diameter flange 19e. This flange, as shown abuts the rear side plate 1 8 so that upon the large diameter portion 1 9a of the rivet shank coming into contact with the edge of the circular aperture 1 6a in which it is located, the sudden force applied to the rivet is in part dispersed through the flange 1 9e to the rear side plate 1 8. Bending and/or breakage of the rivet is accordingly resisted promoting the longevity of the damper mechanism.

Thus in summary, the present invention features the use of rivets which prior to having the heads thereof formed resemble a stepped dowel pin having a large diameter portion and a relatively large diameter flange. In the preferred embodiment the flange is formed integrally on the rivet but may be a separate washer-like member disposed on the shank of the rivet to abut one end of the large diameter portion 1 9a if so desired.

Further, the rivet may be set in a suitable jig with the clutch hub 16, front and rear side plates 17 and 18, turbine hub 12, and turbine runner shell 7a and shield 27, and both of the rivet heads 1 9c and 1 formed simultaneously so as to reduce the number of operations required for the production of the torque converter unit.

Alternately the heads may be formed in individual steps if this is deemed more advantageous.

Production of course is facilitated through the use of this type of flanged multifunction rivet wherein it functions as a spacer, connector and part of a lost motion connection, the shields and the press formed turbine runner shell.

Claims

1. in a rivetting arrangement the combination of: a driving member; a driven member; a plurality of rivets fixedly interconnecting said driving member and said driven member; and a plurality of shields each disposed between a head of one of said plurality of rivets and one of said driving and driven members.

2. A combination as claimed in claim 1, wherein said driving and driven members are both adapted to rotate about the same axis of rotation.

3. A combination as claimed in claim 2, further comprising a second driven member rotatable about said axis of rotation, said second driven member being connected to said first driven member through a lost-motion connection which takes the form of a plurality of apertures formed in said second driven member through each of which extends a shank of one of said plurality of rivets.

4. A combination as claimed in claim 3, further comprising: first and second side plates disposed on either side of said second driven member, said first and second side plates being fixedly connected by, and held at, a predetermined distance by said plurality of rivets, said first and second side plates being adapted to retain springs therebetween which resist movement of said rivets toward the edges of said apertures; and a flange formed on each of said plurality or rivets which abuts said second side plate to disperse force applied to said rivet upon abutment with said edge of the aperture through which it is disposed to said second side plate.

5. A combination as claimed in claim 4, wherein said arrangement is applied to a torque converter having with a lock-up clutch, and wherein said first driven member is a turbine runner of said torque converter, said first driven member is a turbine hub, and said second driven member is a clutch hub of a damper mechanism of said lock-up clutch.

6. A torque converter substantially as described with reference to, and as illustrated in, Fig. 4 of the accompanying drawings.