Endless belt power transmission systems or components – Pulley with belt-receiving groove formed by drive faces on... – Load responsive
Reexamination Certificate
2001-12-20
2003-12-30
Charles, Marcus (Department: 3682)
Endless belt power transmission systems or components
Pulley with belt-receiving groove formed by drive faces on...
Load responsive
C474S017000, C474S018000, C474S028000, C474S072000, C474S019000, C474S021000, C475S211000, C475S209000, C475S045000, C475S046000, C475S048000
Reexamination Certificate
active
06669588
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a continuously variable, conical disk transmission with an integrated torque sensor. More particularly, the present invention relates to a continuously variable, conical disk transmission with an integrated torque sensor for controlling the contact pressure between the conical disks and an endless, torque-transmitting member that passes between two pairs of conical disks.
2. Description of the Related Art
A transmission of the type herein disclosed is described in German Patent Publication DE 199 519 50 A1 and will be explained in greater detail below with the help of
FIG. 4
, which shows a longitudinal section through parts of the transmission and shows its hydraulic control.
An input shaft
6
, which is connected with an internal combustion engine by way of a starting clutch, for example, drives a hydraulic pump
8
. The pump can be connected through a spool valve
10
with either a return
12
or, alternatively, with a conduit
14
that can be connected to an adjusting chamber, further described below, for adjusting a conical disk
4
. A pressure relief valve
15
is arranged between the pump
8
and the spool valve
10
. Pump
8
is connected by another line
16
to a pressure chamber that is further described below and that determines the contact pressure with which the conical disks
2
and
4
contact a loop member
18
that can be in the form of a chain. An adjustable conical disk of another pair of conical disks (not shown) has a corresponding pressure chamber that is also supplied with pressure through conduit
16
.
The basic function of such a conical disk transmission mechanism, shown in the upper half of
FIG. 4
at maximum conical disk spacing and in the lower half at minimum conical disk spacing, is known and will therefore not be described herein.
A generally conical seal support
20
is rigidly connected with the free end of a hollow shaft
5
that is integrally formed with the non-adjustable conical disk
2
, and terminates in a cylindrical region
22
. A fixed annular element
25
that is tightly connected with conical disk
4
is movable on a radially-outwardly-facing surface of seal support
20
, between which an annular seal
24
is arranged. An annular sleeve
28
of conical disk
4
is sealingly guided on a radially-inwardly-facing cylindrical surface
26
of seal support
20
, between which an annular seal is arranged.
Arms
32
(for example, three arms) that are distributed in a circumferential direction and that are rigidly connected to a sensing piston
34
, extend through openings
30
or pockets in the conical region of seal support
20
. At its radial inner end, sensing piston
34
, which is generally cup-shaped, is axially movable on the outer periphery of hollow shaft
5
. A cylindrical region extends from the radially-extending base of sensing piston
34
, the outer surface of which is movably guided, and tightly engages a radially-inwardly facing surface of an annular ring
36
of seal carrier
20
, between which an annular seal is arranged. The right front surface of annular ring
36
, as viewed in
FIG. 4
, is formed as an approximately radially extending cam surface
38
that has a curved peripheral surface, opposite from which is positioned a further, approximately radially-extending cam surface
40
that has a curved peripheral surface, and that is carried on a curved extension
41
of the free end of sensing piston
34
.
Cam surfaces
38
and
40
receive between them balls
42
that serve as rolling bodies and that determine the axial position of sensing piston
34
.
For guiding balls
42
, a concave guide surface
46
is formed on the outer side of an annular extension
44
on movable conical disk
4
, that corresponds to a similarly concave and generally obliquely-extending guide surface
48
that is angled at its end, and that is formed on a sheet metal element
50
that is rigidly connected with conical disk
4
.
Arms
32
, which are formed as sheet metal parts, extend into an annular element
33
at their radially-outwardly-directed ends, and that is formed with a slide tooth system that meshes with a corresponding slide tooth system on a sleeve. The sleeve mates with the gears of an intermediate transmission assembly
54
that, in turn, is in meshing engagement with the rotationally driven drive shaft
6
. Depending upon the operation of one of two clutches
55
, the direction of rotation of conical disks
2
and
4
changes.
Two pressure chambers are formed between seal carrier
20
and conical disk
4
—a radially inner contact pressure chamber
56
and a radially outer adjustment chamber
58
. Adjustment chamber
58
is supplied with hydraulic medium from conduit
14
by way of bores formed in seal carrier
20
and a blind bore in drive shaft
6
. Contact pressure chamber
56
is supplied with hydraulic medium pressure through an axial blind bore
60
in drive shaft
6
and radial bores. A radial bore serving as a return opening
62
, is supplied with the pressure within contact pressure chamber
56
from within the annular ring
36
, and is more or less widely pre-closed by sensing piston
34
, and opens into a further axial blind bore in drive shaft
6
.
The function of the torque sensor that is constituted by balls
42
, annular ring
36
, and sensing piston
34
, all arranged together within contact pressure chamber
56
, is as follows:
If only a weak torque is provided by drive shaft
6
and if sensing piston
34
is correspondingly loaded with only a weak torque by arms
32
, the piston is found to be in its leftmost position, as viewed in
FIG. 4
, whereby the radial bore serving as a return opening
62
is substantially unblocked by sensing piston
34
, so that the pressure in contact pressure chamber
56
is low.
If the torque increases, sensing piston
34
has the tendency to twist relative to conical disk
4
or relative to sheet metal component
50
, whereby the sensing piston will shift toward the right due to the influence of balls
42
as they roll on the cam surfaces, thereby increasingly closing return opening
62
, so that the pressure in contact pressure chamber
56
increases. In that way, the contact pressure of conical disks
2
and
4
against loop member
18
depends upon the torque.
At constant torque, by appropriate admission of hydraulic medium into adjustment chamber
58
there results an adjustment of conical disk
4
to the right (toward lower speed ratios or the speed of the conical disk transmission; loop member
18
thereby travels toward the outside), and thus balls
42
are shifted radially inwardly by guide surfaces
46
and
48
. Because of the radially changing slope of cam surfaces
38
and
40
in the direction of the periphery, the pressure in contact pressure chamber
56
decreases.
From the above it is apparent that the contact pressure that acts on loop member
18
between conical disks
2
and
4
depends not only on the torque applied through the intermediate gear set
54
, but also on the distance between the conical disks, and thereon depends the speed ratio of the transmission. That is adjusted in terms of a contact pressure that is sufficient for the given operating conditions but as low as possible, and that ensures a slip-free run of loop member
18
between conical disks
2
and
4
, whereby the energy consumption is reduced and the life span is increased.
A characteristic of the above-described transmission consists in that balls
42
influence the prevailing pressure in the contact pressure chamber, corresponding to the speed of the transmission, and thereby the centrifugal force that acts on them, because they attempt to move radially outwardly along guide surfaces
46
and
48
as the rotational speed increases, and thereby exert an additional adjusting force on cam surface
40
of sensing piston
34
. That results in an undesired speed dependence of the contact pressure. Furthermore, the movement of the balls along the guide surfaces is accompanied with distinct friction, which, depe
Charles Marcus
LuK Lamellen und Kupplungsbau Beteiligungs KG
Mangels Alfred J.
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