192 clutches and power-stop control – Clutches – Axially engaging
Reexamination Certificate
2001-09-10
2004-03-09
Siconolfi, Robert A. (Department: 3683)
192 clutches and power-stop control
Clutches
Axially engaging
C267S047000, C267S036100, C267S160000
Reexamination Certificate
active
06702082
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains to a leaf spring arrangement, especially for attaching the pressure plate of a pressure plate assembly to a housing, comprising a plurality of adjacent leaf spring elements, where each leaf spring element has a first attachment area for establishing a connection to a first element, preferably the pressure plate, a second attachment area for establishing a connection to a second element, preferably the housing, and a connecting area extending between the first attachment area and the second attachment area.
2. Description of the Related Art
A pressure plate assembly in which a plurality of leaf spring arrangements is used is known from DE 198 48 582 and illustrated schematically in FIG.
1
. This pressure plate assembly
10
comprises a housing arrangement
12
, which can be fixed to a flywheel arrangement in a manner known in and of itself to form a friction clutch. A pressure plate
14
is mounted in the housing arrangement
12
. The housing arrangement
12
and the pressure plate
14
are connected to each other by a plurality of leaf spring arrangements
16
arranged in a row around the circumference in such a way that the pressure plate
14
is able to move with respect to the housing arrangement
12
, namely, in the same direction as that in which a rotational axis A extends, to enable the clutch to engage and disengage, but is completely unable to rotate around the rotational axis A relative to the housing
12
or is at most able to rotate within only a relatively small angular range. Both the housing
12
and the pressure plate
14
have sections
18
,
20
, to which the leaf spring arrangements
16
can be attached; in the case of the pressure plate
14
, for example, these sections can be formed by radially outward-projecting attachment arms. In the case of the housing
12
, they can take the form of several recessed areas, created during the process by which the housing was shaped.
It is known that leaf spring arrangements comprising a plurality of adjacent leaf spring elements
22
, similar to those shown in
FIG. 2
by way of example, can be used. These leaf spring elements
22
have a first attachment area
24
and a second attachment area
26
. A hole
28
,
30
, through which a fastening bolt can be inserted, is provided in each of the attachment areas
24
,
26
. These fastening bolts then establish the connection to the associated attachment sections
18
,
20
.
A connecting area
32
extends between the two attachment areas
24
,
26
. It can be seen in
FIG. 2
that the two attachment areas
24
,
26
extend at an angle with respect to the connecting area
32
. The attachment areas
24
,
26
are essentially parallel to each other and thus bent away from the connecting area
32
in opposite directions. It can also be seen in
FIG. 2
that the two attachment areas
24
,
26
have the same length, starting from the point where they join with the connecting area
32
. When a leaf spring arrangement or a leaf spring package consisting of a plurality of these types of leaf spring elements
22
, as shown in
FIG. 2
, is assembled, the problem arises that, because the first and second attachment areas
24
,
26
are all of the same length, the holes
28
,
30
in the adjacent attachment areas
24
,
26
are slightly offset from each other when these leaf spring elements
22
are laid directly on top of one another, which makes it difficult to insert the fastening bolt all the way through these holes
28
,
30
. After the fastening bolts have been inserted through these holes
28
,
30
, furthermore, the leaf spring elements are held under tension even when no outside load is being exerted on them. This tension increases significantly under load, because the leaf spring elements then have the tendency to come into even closer contact with each other; that is, they are pressed with greater force against each other. Thus more intense frictional interactions occur in the surface areas which are in contact with each other, which brings with it the danger that at least some of the leaf spring elements of a stack of this type will experience premature fatigue or breakage.
The problem just described occurs primarily in the types of pressure plate assemblies in which a self-reinforcing contact interaction occurs between the pressure plate and the friction surfaces of the clutch disk. This self-reinforcing effect can be achieved, for example, by increasing the angle by which the attachment areas
24
,
26
shown in
FIG. 2
are bent with respect to the connecting area
32
. In the extreme case, this angle can reach a value in the range of 45°.
SUMMARY OF THE INVENTION
It is the object of the present invention to provide a leaf spring arrangement which, while providing the necessary elasticity or spring action, is easier to install and offers a prolonged service life.
In accordance with a first aspect of the present invention, this object is achieved by a leaf spring arrangement, especially for attaching the pressure plate of a pressure plate assembly to a housing, comprising a plurality of adjacent leaf spring elements, where each leaf spring element has a first attachment area for establishing a connection to a first element, preferably the pressure plate, a second attachment area for establishing the connection to a second element, preferably the housing, and a connecting area extending between the first attachment area and the second attachment area. It is also provided that at least certain areas of the minimum of two leaf spring elements between the first attachment area and the second attachment area are spaced apart.
By providing at least two leaf spring elements with at least certain areas where they do not rest against each other, free space or escape room is created, into which the various leaf spring elements can move without coming into contact with each other or pressing against each other with considerable force when they are deformed. The stress effects described above can therefore be avoided both in the presence and in the absence of load.
An especially advantageous embodiment provides that the minimum of two leaf spring elements contact each other only in the areas of their first and second attachment areas.
Preventing the two leaf spring elements from contacting each other at least along a portion of their length can be achieved, for example, by bending the first attachment area and/or the second attachment area of the minimum of two leaf spring elements at an angle to the connecting area between them, by making the first attachment area of one of the minimum of two leaf spring elements longer than the first attachment area of the other of the minimum of two leaf spring elements, and/or by making the second attachment area of one of the minimum of two leaf spring elements shorter than the second attachment area of the other of the minimum of two leaf spring elements.
Especially when a relatively large number of leaf spring elements is to be provided, it is advantageous for at least one additional leaf spring element to be installed between the minimum of two leaf spring elements and for the first attachment area and the second attachment area of the minimum of one additional leaf spring element to be essentially of equal length. At least certain areas of this minimum of one additional leaf spring element are then a certain distance away from the adjacent leaf spring element.
According to another advantageous aspect of the present invention, it can be provided that the minimum of two leaf spring elements are essentially of the same design, where the first attachment area of the first of the minimum of two leaf spring elements is essentially equal in length to the second attachment area of the other of the minimum of two leaf spring elements, and where the second attachment area of the first of the minimum of two leaf spring elements is equal in length to the first attachment area of the other of the minimum of two leaf spring elements.
In an alternative design of the prese
Bach Hartmut
Carlson Cora
Dau Andreas
Dörfler Matthias
Esly Günther
Cohen & Pontani, Lieberman & Pavane
Mannesmann Sachs AG
Siconolfi Robert A.
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