Rotary shafts – gudgeons – housings – and flexible couplings for ro – Torque transmitted via flexible element – Coil spring
Reexamination Certificate
1999-05-27
2002-06-25
Browne, Lynne H. (Department: 3629)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Torque transmitted via flexible element
Coil spring
C192S213200
Reexamination Certificate
active
06409605
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to hubs for torsion damping devices comprising a predamper, especially for motor vehicles
It also relates to torsion damping devices equipped with the said hub, described for example in the document FR-A-2 693 778 (U.S. Pat. No. 5,601,173) to which reference may be made for further details.
2. Description of the Related Art
As is known (
FIGS. 1
to
3
), such a hub
3
constitutes the output element of the torsion damping device. The hub
3
is surrounded by two guide rings
1
,
2
which are disposed on either side of a damper plate
4
, which also surrounds the hub
3
but with circumferential loose coupling means
60
interposed, the latter comprising a denture, that is to say alternate teeth and recesses, which are conventionally of trapezoidal form and which are formed at the outer periphery of the hub
3
, together with a denture consisting of alternate teeth and recesses, which are conventionally of trapezoidal form and are formed at the inner periphery of the damper plate
4
. The teeth of the damper plate
4
penetrate, with a clearance, into the recesses of the hub
3
and vice versa. The hub
3
is splined internally for coupling it in rotation with a first shaft.
The guide rings
1
,
2
are joined together through spacers
8
which extend with a circumferential clearance through notches
7
formed at the outer periphery of the damper plate
4
. The spacers
8
may take another form, and may consist of axial lugs projecting from one of the guide rings and fixed to the other guide ring, for example by seaming.
The guide rings
1
,
2
are fixed to the input element
16
of the said damping device. This input element
16
is fixed for example to a reaction plate which is mounted on a second shaft, for rotation with the latter, either directly or, in this example indirectly through friction liners
31
,
32
which are divided into pads
41
,
42
fixed by rivets
47
on blades
17
which extend outwardly the input element
16
which is in the form of a disc. The liners
31
,
32
may of course be of endless form. In the case of an application to a motor vehicle, the first shaft is typically the input shaft of the gearbox and the second shaft the crankshaft of the engine, the liners
31
,
32
being arranged to be gripped releasably between the pressure and reaction plates of a clutch. For this reason the hub must be able to slide axially along the first shaft.
The torsion damping device in this example comprises an input element
16
which is coupled elastically to the output element
3
(i.e. the hub) through a main damper including guide rings
1
,
2
and the damper plate
4
, together with a predamper which includes the damper plate
4
and the hub
3
(i.e. the output element).
Circumferentially acting resilient means
5
,
9
, which in this example consist of coil springs, together with axially acting friction means
20
, are interposed operatively between the guide rings
1
,
2
and the hub
3
.
The springs
5
are mounted in windows (not given a reference numeral in
FIG. 1
) which are formed in facing relationship with each other in the rings
1
,
2
and the damper plate
4
.
These springs
5
are part of the main damper and are stiffer than the springs
9
which are part of the predamper. These springs
9
are mounted in open slots
91
,
92
formed in facing relationship, respectively, at the inner periphery of the damper plate
4
and at the outer periphery of the hub
3
.
The slots, which are of generally swallowtail form, and the springs
9
bear on the circumferential edges of the slots through interposed inserts
90
, the dorsal face of which is of dihedral form in order to cooperate with the said edges, defining a point when the damper plate
4
and the hub
3
are in the rest state. The front faces of the inserts
90
, which are preferably of plastics material in order to reduce noise, carry retaining and centring spigots each of which is engaged in a spring
9
of the predamper.
The friction means
20
comprise a resilient ring
56
, which in this example is a corrugated ring, which bears on the guide ring
2
and on an application ring
55
in contact with the damper plate
4
, so as to grip a friction ring
57
by reaction between the damper plate
4
and the disc
16
which is backed on the damper plate
1
. The rings
55
to
57
are part of the main damper and act during relative rotating movement between the damper plate
4
and the guide rings
1
,
2
. This movement is only produced when the damper plate
4
comes into engagement with the hub
3
after the circumferential clearance of the loose coupling means
60
has been taken up, because the springs
5
are stiffer than the springs
9
of the predamper. Shocks therefore occur as the clearance in the loose coupling means
60
is being taken up.
The application ring
55
and the friction ring
57
are coupled in rotation respectively to the guide ring
2
and the guide ring
1
. For this purpose, each of the rings
1
,
2
, which in this example are identical, has holes
54
through which there pass lugs
58
and spigots
59
which project respectively from the application ring
55
and the friction ring
57
, so as to obtain the said coupling in rotation. Each spigot
59
does of course extend through an aperture in the disc
16
.
A centring bearing
51
is interposed between the outer periphery of the hub
3
and the inner periphery of the guide ring
1
. A resilient ring
61
, which in this example is a Belleville ring, a friction ring
52
and a metallic insert ring
53
are interposed between the outer periphery of the hub
3
and the inner periphery of the guide ring
2
.
The bearing
51
and the ring
52
have an L-shaped cross section and include thickened portions, each of which is engaged in the known way in a notch formed in the inner periphery of the guide ring
1
,
2
concerned, so as to couple the bearing
51
and the ring
52
respectively in rotation with the guide ring
1
and the guide ring
2
.
The components
51
to
53
and
61
are located radially inwardly of the rings
55
to
57
of the main damper. These components
51
to
53
and
61
act permanently during relative motion between the input element
16
and the output element
3
. The spring
61
has a lower stiffness than the spring
56
. The spring
61
has a stiffness such that it does not overcome the action of the low stiffness springs
9
.
The notches housing the springs
9
interrupt the dentures of the loose coupling means
60
with their circumferential clearance. The hub
3
has at its outer periphery a shouldered flange in which the denture of the hub
3
is formed.
The torsion damping device operates in the following way during relative movement between the input element
16
and the output element
3
:
in a first step, since the springs
5
are stiffer than the springs
9
, the predamper operates by itself so as to absorb the vibrations in the slow running mode of the engine, so that the springs
9
are compressed with relative movement firstly of the damper plate
4
with respect to the hub
3
, and secondly of the bearing
51
and the ring
52
with respect to the hub
3
; this movement is continued until the teeth of the damper plate
4
come into engagement with the teeth of the hub
3
;
in a second step, the damper plate
4
is coupled to the hub
3
for rotation together because the clearance in the loose coupling means
60
has been taken up, and relative movement occurs between the guide rings
1
,
2
, the damper plate
4
against the action exerted by the springs
5
and the rings
55
to
57
; this movement is continued until the spacers
8
come into abutment against the edges of the slots
7
, or until interlocking occurs between the turns of the stepped action springs
5
which in this example are disposed in pairs in the windows of the damper plate
4
and guide rings
1
,
2
.
When the friction liners
31
,
32
are released, the hub
3
slides axially along the splines of the driven shaft by virt
Browne Lynne H.
Liniak Berenato Longacre & White
Thompson Kenn
Valeo
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