Friction gear transmission systems or components – Friction gear includes idler engaging facing concave surfaces – Toroidal
Reexamination Certificate
2002-07-15
2004-09-28
Joyce, William C. (Department: 3682)
Friction gear transmission systems or components
Friction gear includes idler engaging facing concave surfaces
Toroidal
C476S042000, C403S327000, C403S376000
Reexamination Certificate
active
06796923
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a toroidal-type continuously variable transmission which can be used as a transmission for a car.
Now,
FIG. 4
shows a conventional toroidal-type continuously variable transmission which can be used as a transmission for a car. This is a toroidal-type continuously variable transmission of a so-called double cavity type which has a structure designed for high torque. This conventional toroidal-type continuously variable, transmission is structured such that two input side disks
2
,
2
and two output side disks
3
,
3
are mounted on the outer periphery of an input shaft
1
. Also, an output gear
4
is rotatably supported on the outer periphery of the middle portion of the input shaft
1
. The two output side disks
3
and
3
are respectively connected by spline engagement to cylindrical-shaped flange portions
4
a
and
4
a
formed in the central portion of the output gear
4
.
By the way, the input shaft
1
can be driven or rotated by a drive shaft
22
through a pressing device
12
of a loading cam type interposed between the input side disk
2
situated on the left side in
FIG. 3 and a
cam plate
7
. Also, the output gear
4
is supported within a housing
14
through a partition wall
13
which is composed of two members connected together, whereby the output gear
4
can be rotated about the axis O of the input shaft
1
but is prevented from shifting in the axis O direction.
The output side disks
3
and
3
are supported in such a manner that they can be rotated about the axis O of the input shaft
1
by their respective needle roller bearings
5
and
5
interposed between the input shaft
1
and output side disks
3
,
3
. On the other hand, the input side disks
2
and
2
are supported on the two end portions of the input shaft
1
through their respective ball splines
6
and
6
in such a manner that they can be rotated together with the input shaft
1
. Also, as shown in
FIG. 7
as well, power rollers
11
are rotatably held by and between the inner surfaces (concave surfaces)
2
a
,
2
a
of the respective input side disks
2
,
2
and the inner surfaces (concave surfaces)
3
a,
3
a
of the respective output side disks
3
,
3
.
Between the input side disk
2
situated on the left side in FIG.
4
and cam plate
7
, there is interposed a first countersunk plate spring
8
; and, between the input side disk
2
situated on the right side in FIG.
4
and loading nut
9
, there is interposed a second countersunk plate spring
10
. These countersunk plate springs
8
and
10
apply pressing forces to the mutual contact portions between the concave surfaces
2
a,
2
a,
3
a,
3
a
of the respective disks
2
,
2
,
3
,
3
and the peripheral surfaces
11
a,
11
a
(see
FIG. 7
) of the power rollers
11
,
11
.
Therefore, in the continuously variable transmission having the above structure, in case where a rotational force is input into the input shaft
1
from the drive shaft
22
, the two input side disks
2
and
2
are rotated integrally with the input shaft
1
, and the rotational movements of the input side disks
2
and
2
are transmitted by the power rollers
11
and
11
to the output side disks
3
and
3
at a given transmission ratio. Also, the rotational movements of the output side disks
3
and
3
are transmitted from the output gear
4
to an output shaft
17
through a transmission gear
15
and a transmission shaft
16
.
By the way, in the thus structured continuously variable transmission, generally, in order to prevent the needle roller bearing
5
, which supports the output disk
3
rotatably, from shifting in the axis O direction of the input shaft
1
and thus slipping out of its given position, there is disposed slippage preventive means for preventing the slippage of the needle roller bearing
5
.
Here,
FIG. 5
shows a conventional example of such needle roller bearing
5
slippage preventive means (see JP-A-11-166605). As shown in
FIG. 5
, the slippage preventive means is composed of a retaining ring (slippage preventive member)
18
; and, specifically, the retaining ring
18
has a substantially rectangular section shape and is fitted into and secured to a ring-shaped securing groove
3
b
formed in the inner peripheral surface of the output side disk
3
(that is, the peripheral surface of a stepped-penetration hole
30
formed in the output side disk
3
). That is, the retaining ring
18
prevents the needle roller bearing
5
from shifting in the axis O direction (that is, from slipping off the output side disk
3
).
Also, as shown in
FIG. 6
, the ball spline
6
supporting the input side disk
2
includes a first ball spline groove
31
(see
FIG. 4
) formed in the outer peripheral surface of the input shaft
1
, a second ball spline groove
32
formed in the inner peripheral surface of the input side disk
2
(the peripheral surface of a penetration hole
43
formed in the input side disk
2
), and a plurality of balls
33
rollably interposed between the first and second ball spline grooves
31
and
32
. And, in order to prevent the balls
33
from slipping in the axial direction of the input shaft
1
, there is disposed slippage preventive means which is used to prevent the balls
33
against slippage.
Such slippage preventive means, for example, as shown in
FIG. 6
, is composed of a retaining ring (slippage preventive member)
35
having a circular-shaped section which is fitted into and secured to a ring-shaped securing groove
2
b
formed in the inner peripheral surface of the input side disk
2
; that is, the retaining ring
35
prevents the balls from shifting in the axis O direction of the input shaft
1
(namely, from slipping out of the input side disk
2
).
By the way, as can be seen from
FIG. 5
, the conventional retaining ring
18
is structured such that its section has a substantially rectangular shape and, therefore, the securing groove
3
b,
to which the retaining ring
18
is to be secured, is also structured such that its section has a substantially rectangular shape. That is, when observing the securing groove
3
b
through its section shown in
FIG. 5
(
b
), the securing groove
3
b
includes a bottom surface (groove bottom) p and two side surfaces q, q which extend from the bottom surface p toward the penetration hole
30
of the output side disk
3
; and, the bottom surface p is formed linear (straight) and, at the same time, the bottom surface p and two side surfaces q, q are connected to each other through their respective arc-shaped surfaces the sections of which respectively have a small radius of curvature.
Also, as can be understood from
FIG. 6
, in the case of the conventional retaining ring
35
, its section has a circular shape and, therefore, the securing groove
2
b
for securing the retaining ring
35
thereto is also structured such that its section has a circular shape. That is, when observing the securing groove
2
b
through its section shown in FIG.
6
(
b
), the bottom surface r and two side surfaces s, s of the securing groove
2
b
are continuously connected together as a surface the section of which has an arc-like shape.
However, as shown in FIG.
5
(
b
), in case where the two corners R
1
, R
1
of the groove bottom of the securing groove
3
b,
that is, the two connecting portions R
1
, R
1
between the bottom surface p and two side surfaces q, q are respectively formed as a surface the section of which has an arc shape with a small radius of curvature, when, as shown in
FIG. 7
, in order to increase a transmission ratio, the power roller
11
is shifted and a force in the arrow mark F direction is thereby applied to the securing groove
3
b,
stresses are concentrated on the groove bottom of the securing groove
3
b,
especially, on the corner portions (connecting portions) R
1
, R
1
. Therefore, there is a fear that, when transmitting high torque, the yield strength of the output side disk
3
can be short.
On the other hand, as shown in FIG.
6
(
b
), in case where the bottom surface r and two side surfa
Goto Nobuo
Nishii Hiroki
Joyce William C.
NSK Ltd.
Sughrue & Mion, PLLC
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