Rotary shafts – gudgeons – housings – and flexible couplings for ro – Torque transmitted via flexible element – Coil spring
Reexamination Certificate
1999-06-14
2001-08-28
Browne, Lynne H. (Department: 3629)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Torque transmitted via flexible element
Coil spring
C192S003290, C192S212000, C464S066100
Reexamination Certificate
active
06280333
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention concerns hydrokinetic coupling appliances, notably for motor vehicles, equipped with a locking clutch, usually referred to as a “lock-up” clutch, for mechanically making their turbine wheel and their impeller wheel integral with respect to rotation, as described for example in the document FR-A-2 726 620.
DESCRIPTION OF RELATED ART
In this document, the hydrokinetic coupling appliance has, inside a sealed casing, filled with oil, a torque converter having a turbine wheel and an impeller wheel, and a lock-up clutch.
The casing has a first half-shell provided with an axially fixed transverse wall by means of which it is connected to the driving shaft. The turbine wheel is connected to an internally fluted hub for rotatably connecting it to a driven shaft.
The first half-shell, and therefore the casing, forms the input element of the hydrokinetic coupling appliance which is rotary in operation, whilst the hub forms the output element of the said appliance.
Being a case of an application for a motor vehicle, the driving shaft consists of the crankshaft of the vehicle engine, whilst the driven shaft consists of the input shaft of the transmission box.
The lock-up clutch has at least one friction lining which, fixed with respect to rotation to the turbine wheel and hub, either directly, or indirectly by means of a torsion damper, is disposed axially between on the one hand the said transverse wall fixed with respect to the impeller wheel and on the other hand a piston which is mounted so as to be able to move axially with respect to the transverse wall forming a counter-piston.
This piston is rotatably connected to the transverse wall, usually by elastic tongues substantially elongated tangentially to a circumference of the whole.
These tongues are mounted inside a variable-volume control chamber delimited on the one hand radially externally by the friction lining and radially internally by a cylindrically shaped centring device adjacent to the transverse wall and on the other hand axially by the piston and transverse wall.
The centring device consists of a ring which has at its centre a blind hole and passages for connecting the control chamber to the blind hole in communication with the driven shaft provided with a feed channel.
The ring is interposed axially between the hub and the transverse wall.
This ring forms a guide surface for the piston and is fixed by welding or force fitting, or crimping, to the transverse wall.
As a result the arrangement is axially bulky.
The object of the present invention is to mitigate this drawback, in a simple and economical fashion.
SUMMARY OF THE INVENTION
According to the invention, a lock-up clutch of the type indicated above is characterised in that, the hub having an internally fluted socket, for connecting the hub with the driven shaft with respect to rotation, the said socket enters inside the blind hole in the centring device, in that the hub has, parallel to its socket and radially beyond it, an axially oriented annular rim whose external periphery constitutes a guide surface for the piston, and in that a sealing joint acts between the said rim and the piston.
By virtue of the invention the axial bulk is reduced and a sealing joint is saved.
In fact, it would have been possible to create the guide surface on the centring device, hereinafter referred to as the ring, but in this case it would have been necessary to provide one joint at the guide surface and another joint at the hub in order to prevent oil passing between the hub and ring when the lock-up clutch is engaged.
Here, with a single joint there is a perfect seal, both when the lock-up clutch is engaged and when it is disengaged.
According to another characteristic, an annular recess being formed between the rim and the socket, the ring enters inside the groove.
Thus the hub and ring fit into each other, so that the axial bulk is reduced.
The hub guide surface is roughly axially aligned with the external periphery of the ring. An axially oriented bearing is housed in the recess and acts between the internal periphery of the ring and the external periphery of the socket for centring the hub. In one embodiment, the bearing is fixed to the ring. An axial clearance exists between the ring and the internal periphery of the hub rim.
An axial stop is mounted in the recess, between the base of the recess and the rear end of the ring.
This arrangement facilitates a rotation movement of the hub with respect to the ring.
The piston has, at its internal periphery, a ferrule directed axially in the direction of the hub.
An axial clearance exists between the free end of the rim of the hub and the ring.
Thus friction between the ring and hub is minimised, which makes it possible to obtain correct functioning, the hub being in contact with the ring at the axial stop and bearing.
The hub has a groove serving to house another axial stop for minimising friction between the free end of the ferrule of the piston and the hub.
The ring thus forms a centring device for the hub and, at the same time, allows feeding of the control chamber delimited by the piston and the transverse wall, the said ring having, in a known fashion, passages for the chamber to communicate with the inside of the ring (the blind hole thereof) fed with fluid by means of the driven shaft.
The hub socket can come as close as possible to the passages adjacent to the transverse wall.
Thus the socket can have great axial length, which enables the hub to slide well along the driven shaft.
The hub has a shield at its rear end furthest away from the transverse wall.
The hub rim issues from this shield, which closes off the recess inside which the ring enters.
The rim is shorter axially than the socket in order to allow the ring to feed, via its passages, the said control chamber.
The shield can have, at its external periphery, a countersink for fixing the turbine wheel and output element of the torsion damper associated with the lock-up clutch.
The hub thus has the shape of an annular comb with three annular teeth of different axial length, one tooth delimiting the countersink, the other forming the rim and the last the socket.
All this makes it possible to reduce to the maximum extent the axial bulk at the centre of the hydrokinetic appliance whilst having a good seal and good supply to the control chamber.
It will be appreciated that the ring is simply machined so as to be able to enter the recess.
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Browne Lynne H.
Dunwoody Aaron M
Liniak Berenato Longacre & White
Valeo
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