Friction gear transmission systems or components – Friction transmission or element – Particular friction surface
Reexamination Certificate
2001-10-19
2003-09-23
Fenstermacher, David (Department: 3682)
Friction gear transmission systems or components
Friction transmission or element
Particular friction surface
C476S072000, C384S912000
Reexamination Certificate
active
06623400
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a toroidal-type continuously variable transmission which is used, for example, as an automatic transmission for a vehicle and, in particular, to such toroidal-type continuously variable transmission which is enhanced in the durability of its component parts such as disks and power rollers.
2. Description of the Related Art
Conventionally, as a toroidal-type continuously variable transmission, there is known a toroidal-type continuously variable transmission having such a structure as shown in FIG.
1
.
Within a housing (not shown), specifically, on an input shaft
3
rotatably supported in the interior of the housing, there are disposed an input side disk
1
and an output side disk
2
in such a manner that they are concentric with and opposed to each other. The input shaft
3
is penetrated through the axial core portion of a toroidal transmission part including the input side disk
1
and output side disk
2
. A loading cam
4
is disposed on one end of the input shaft
3
. This loading cam
4
is structured such that it can transmit the power (rotational force) of the input shaft
3
to the input side disk
1
through a cam roller
5
. Referring in more detail to the structures of the input side and output side disks
1
and
2
, they respectively include inner surfaces formed as concave surfaces each having an arc-shaped section, have substantially the same shape, and are disposed concentric with each other with their respective inner surfaces opposed to each other. These mutually opposed surfaces are respectively formed as toroidal surfaces such that they cooperate together in forming a substantially semicircular shape, when the present toroidal-type continuously variable transmission is viewed as a section in the axial direction thereof.
Within a toroidal cavity defined by the toroidal surfaces of the input side and output side disks
1
and
2
, there are disposed a pair of power roller bearings
6
and
7
which are respectively thrust rolling bearings, in such a manner that they are in contact with the input side and output side disks
1
and
2
. By the way, the power roller bearing
6
is composed of a power roller
6
a
(which corresponds to an inner race forming the power roller bearing
6
) which can roll on the toroidal surfaces of the input side and output side disks
1
and
2
, an outer race
6
b
, and a plurality of rolling bodies (steel balls)
6
c
. On the other hand, the power roller bearing
7
is composed of a power roller
7
a
(which corresponds to an inner race forming the power roller bearing
7
) which can roll on the toroidal surfaces of the input side and output side disks
1
and
2
, an outer race
7
b,
and a plurality of rolling bodies (steel balls)
7
c;
and, the power roller bearing
7
is used to support a thrust load that is applied to the power roller.
That is, the power roller
6
a
also plays the role of an inner race which is a component of the power roller bearing
6
, while the power roller
7
a
also plays the role of an inner race which is a component of the power roller bearing
7
. In the present structure, the power roller
6
a
is pivotally and rotatably mounted through a pivot shaft
8
, the outer race
6
b
and the plurality of rolling bodies
6
c
on a trunnion
10
swinging about a pivot shaft
9
disposed at a position which is perpendicular to an axial line of the input shaft
3
and does not intersect the axial line thereof (hereinafter, this physical relationship is referred as “a torsional position”). And, at the same time, the power roller
6
a
includes a peripheral surface formed as a spherical-shaped convex surface, and is inclinedly supported about displacement shafts
0
, which are respectively supported on their associated trunnions and serve as the centers of the toroidal surfaces of the input side and output side disks
1
and
2
. On the other hand, the power roller
7
a
is pivotally and rotatably mounted through a pivot shaft
9
, the outer race
7
b
and the plurality of rolling bodies (steel balls)
7
c
on a trunnion
11
swinging about a pivot shaft
9
disposed at the torsional position with respect to the input shaft
3
; and, at the same time, the power roller
7
a
is inclinedly supported about displacement shafts
0
, which respectively serve as the centers of the toroidal surfaces of the input side and output side disks
1
and
2
. And, these power rollers
6
a
and
7
a
transmit the power of the input shaft
3
to the input side and output side disks
1
and
2
.
By the way, the input side and output side disks
1
and
2
are independent from the input shaft
3
with needle rollers
12
between them (that is, they are held in such a state where they are not directly influenced by the power of the input shaft
3
). On the output disk
2
, there is disposed an output shaft
14
which is arranged in parallel to the input shaft
3
and is also rotatably supported on the housing (not shown) through angular bearings
13
. In the present toroidal-type continuously variable transmission
20
, the power of the input shaft
3
is transmitted to the loading cam
4
. And, in case where the loading cam
4
is rotated due to such power transmission to the loading cam
4
, power caused by the rotation of the loading cam
4
is transmitted through the cam roller
5
to the input side disk
1
, so that the input side disk
1
can be rotated. Further, power generated due to the rotation of the input side disk
1
is transmitted through the power rollers
6
a
and
7
a
to the output side disk
2
. As a result of this, the output side disk
2
can be rotated integrally with the output shaft
14
.
In transmission, the trunnions
10
and
11
are respectively moved by a slight distance in the directions of the displacement shafts
0
. That is, the axial-direction movements of the trunnions
10
and
11
shift slightly the intersection between the rotary shafts of the power rollers
6
a
,
7
a
and the axes of the input side and output side disks
1
and
2
. This intersection shift loses balance between the rotational peripheral speed of the power rollers
6
a
,
7
a
and the rotational peripheral speed of the input side disk
1
; and, due to the component of the rotation driving force of the input side disk
1
, the power rollers
6
a
,
7
a
are caused to roll inclinedly around the displacement shafts
0
. Therefore, the power rollers
6
a
,
7
a
are allowed to roll inclinedly on the curved surfaces of the input side and output side disks
1
and
2
. As a result of this, the speed ratio is changed: that is, deceleration or acceleration is carried out.
As a toroidal-type continuously variable transmission having the above structure, for example, there is known a conventional toroidal-type continuously variable transmission which is disclosed in JP-B-2-49411U. And, as the input side disk, output side disk and power roller bearings of the above type, as set forth in [NASA Technical note NASA ATN D-8362], there are conventionally known input side disk, output side disk and power roller bearing which use AISI52100 (JIS SUJ2, corresponding to high-carbon chromium bearing steel); and, as disclosed in JP-A-9-79336, there are known disks and bearings in which SCM420, that is, steel for mechanical structural purposes containing Cr is carbonitrided.
In the above-mentioned conventional toroidal-type continuously variable transmission, when it is driven, there are generated high contact pressures respectively between the input side disk and power roller bearings, between the output side disk and power roller bearings, and between the power roller inner and outer races and rolling bodies. These high contact pressures are combined with lubricating oil (traction oil) existing between the input side and output side disks and power roller bearings, and between the power roller raceway surfaces and rolling bodies to lower the fatigue lives of the contact surfaces. Therefore, for the purpose of enhancing the rolling fatigue life u
Murakami Yasuo
Yoshikawa Tomonobu
Fenstermacher David
NSK Ltd.
Sughrue & Mion, PLLC
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