Friction gear transmission systems or components – Friction gear includes idler engaging facing concave surfaces – Toroidal
Reexamination Certificate
2001-10-22
2003-06-03
Fenstermacher, David (Department: 3682)
Friction gear transmission systems or components
Friction gear includes idler engaging facing concave surfaces
Toroidal
C476S010000
Reexamination Certificate
active
06572509
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a toroidal-type continuously variable transmission that is used, for example, as a transmission mechanism of a vehicle.
Conventionally, as a transmission mechanism of a vehicle, there has been developed and used practically a toroidal-type continuously variable transmission.
Now,
FIG. 6
shows the structure of a half-toroidal-type continuously variable transmission of a double cavity type. This toroidal-type continuously variable transmission comprises, within a housing
1
, a first input disk
2
a
and a first output disk
3
a
respectively forming a first cavity la as well as a second input disk
2
b
and a second output disk
3
b
respectively forming a second cavity
1
b.
A pair of power rollers
5
is interposed between the first input and output disks
2
a
and
3
a.
The outer peripheral surfaces of the power rollers
5
are respectively contacted with the traction surfaces
4
of the respective disks
2
a,
3
a.
Between the second input and output disks
2
b,
3
b
as well, there are interposed a pair of power rollers
5
, while the outer peripheral surfaces of these power rollers
5
are also respectively contacted with the traction surfaces
4
of the respective disks
2
b,
3
b.
These power rollers
5
are rotatably mounted on their respective trunnions
7
by power roller bearings
6
. The respective trunnions
7
can be swung about their associated trunnion shafts
8
.
The traction surfaces
4
of the respective disks
2
a,
2
b,
3
a,
3
b
are each formed as a concave-shaped surface which can be obtained by rotating an arc, the center of which is the trunnion shaft
8
, about an axis extending at right angles to the trunnion shaft
8
.
The first input disk
2
a
is mounted on an input shaft
10
in such a manner that it can be moved in the axial direction of the input shaft
10
with respect to the input shaft
10
while it is prevented against rotation by a ball spline
11
.
The second input disk
2
b
is mounted on the input shaft
10
by a loading nut in such a manner that it is prevented against rotation by an involute spline
12
. Therefore, the input disks
2
a,
2
b
can be rotated integrally with the input shaft
10
. This input shaft
10
can be driven or rotated by a drive source such as an engine.
The output disks
3
a,
3
b
are interposed between the input disks
2
a
and
2
b.
The first output disk
3
a
is disposed opposed to the first input disk
2
a,
while the second output disk
3
b
is disposed opposed to the second input disk
2
b.
These output disks
3
a,
3
b
are respectively supported on the input shaft
10
through bearings
13
,
14
in such a manner that they can be rotated with respect to the input shaft
10
. And, the output disks
3
a,
3
b
are connected to each other by a connecting member
15
and can be rotated in synchronization with each other. On the connecting member
15
, there is disposed an output gear
16
.
On the back surface side of the first input disk
2
a,
there is disposed a hydraulic loading mechanism
20
of an oil pressure type. The loading mechanism
20
includes a hydraulic cylinder
21
that is mounted on the input shaft
10
in such a manner that it is opposed to the back surface of the input disk
2
a.
The peripheral wall
21
a
of the hydraulic cylinder
21
is fitted with the outer periphery of the input disk
2
a
in a liquid-tight manner through a seal member
22
in such a manner that it can be slid in the axial direction thereof. Between the hydraulic cylinder
21
and input disk
2
a,
there is formed a hydraulic chamber
25
having a closed structure.
The hydraulic cylinder
21
includes a fit cylinder
26
that is disposed in the center portion of the hydraulic cylinder
21
integrally therewith, while the input shaft
10
is fitted into the fit cylinder
26
. And, there is formed an oil supply passage
27
which extends from an inner hole
10
a
formed in the input shaft
10
to the hydraulic chamber
25
within the hydraulic cylinder
21
. That is, by means of the oil supply passage
27
, oil can be pressure fed into the hydraulic chamber
25
through a control valve
29
from a hydraulic pump
28
serving as an oil supply member.
In addition, within the hydraulic chamber
25
, there is disposed a countersunk spring
30
serving as pre-load applying means. When the countersunk spring
30
is viewed from the side surface thereof, it has a flat trapezoid shape. When it is viewed from the plane surface thereof, it has a circular ring shape.
This countersunk spring
30
is fitted with the outer periphery of the fit cylinder
26
of the hydraulic cylinder
21
and is interposed between the back surface of the input disk
2
a
and the inner surface of the hydraulic cylinder
21
with the plate section thereof inclined such that the inner peripheral edge thereof can be contacted with the back surface of the input disk
2
a
and the outer peripheral edge thereof can be contacted with the inner surface of the hydraulic cylinder
21
. By the way, the countersunk spring
30
may also be disposed in such a manner that the inner peripheral edge thereof can be contacted with the back surface of the hydraulic cylinder
21
and the outer peripheral edge thereof can be contacted with the back surface of the input disk
2
a.
Due to the elastic force of the countersunk spring
30
, there is applied such a preload that allows the respective disks
2
a,
2
b,
3
a,
3
b
and their respective power rollers
5
to be elastically contacted with each other.
And, when the input shaft
10
and input disks
2
a,
2
b
are rotated in linking with a drive source such as an engine, oil is supplied from the hydraulic pump
28
into the hydraulic chamber
25
through the control valve
29
. Due to the oil pressure of the thus supplied oil, the first input disk
2
a
is pushed toward the first output disk
3
a.
Since a reaction force which the hydraulic cylinder
21
receives is applied to the input shaft
10
, the second input disk
2
b
is pushed toward the second output disk
3
b.
The rotation power of the input disks
2
a,
2
b
is transmitted through the power rollers
5
to the output disks
3
a,
3
b
and, in linking with the output disks
3
a,
3
b,
the output gear
16
is rotated.
To change the rotation speed ratio between the input shaft
10
and output gear
16
, the respective power rollers
5
may be swung about their associated trunnion shafts
8
. The swinging movements of the power rollers
5
change the contact positions between the peripheral surfaces of the power rollers
5
and the traction surfaces
4
of the disks
2
a,
2
b,
3
a,
3
b,
thereby changing the rotation speed ratio between the input disks
2
a,
2
b
and output disks
3
a,
3
b,
that is, the rotation speed ratio between the input shaft
10
and output gear
16
.
In order to enhance the power transmission efficiency of a transmission, it is important to secure a sufficient contact-pressure between the disks
2
a,
2
b,
3
a,
3
b
and power rollers
5
. In the present transmission, such contact pressure is secured by the oil pressure within the hydraulic chamber
25
as well as by the elastic force of the countersunk spring
30
within the hydraulic chamber
25
.
The structure, in which, as described above, the countersunk spring
30
is incorporated into the hydraulic chamber
25
and the contact pressure between the disks
2
a,
2
b,
3
a,
3
b
and power rollers
5
is secured by the oil pressure and the elastic force of the countersunk spring
30
, is long known; for example, such structure is disclosed in U.S. Pat. No. 3,823,613.
In case where the countersunk spring
30
is incorporated in the hydraulic chamber
25
, there is an advantage that the wear resistance of the countersunk spring
30
is enhanced, but there arises a problem that the presence of the countersunk spring
30
obstructs the flow of the oil within the hydraulic chamber
25
.
That is, the circular-ring-shaped countersunk spring
30
is disposed within the hydraulic chamber
25
in the following m
Kato Hiroshi
Kobayashi Norihisa
Fenstermacher David
NSK Ltd.
Sughrue & Mion, PLLC
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