Friction gear transmission systems or components – Friction gear includes idler engaging facing concave surfaces – Toroidal
Reexamination Certificate
1999-10-15
2003-02-18
Joyce, William C (Department: 3682)
Friction gear transmission systems or components
Friction gear includes idler engaging facing concave surfaces
Toroidal
C476S040000, C384S623000
Reexamination Certificate
active
06520888
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a loading cam apparatus incorporated in a toroidal type continuously variable transmission used as a transmission for an automobile, for example.
Toroidal type continuously variable transmission of a double cavity type used as a transmission for an automobile, for example, is configured as shown in FIG.
14
. As shown in the figure, the toroidal type continuously variable transmission is provided with an input shaft
1
coupled to a driving source such as an engine or the like. The input shaft
1
is provided with a loading cam apparatus
2
so that the driving force is transmitted to a variator
3
through the loading cam apparatus
2
. The variator
3
is provided with a driving force transmission shaft
4
which rotates and is interlocked with the loading cam apparatus
2
and the driving force transmission shaft
4
is provided with a pair of input disks
5
a
,
5
b
disposed so as to oppose each other. A pair of output disks
6
a
,
6
b
are coaxially disposed between the pair of the input disks
5
a
and
5
b
in a loosely fitted state with respect to the driving force transmission shaft
4
so that the output disks
6
a
and
6
b
rotate synchronously.
A plurality of power rollers
7
are provided between the input disks
5
a
,
5
b
and the output disks
6
a
,
6
b
so that the rollers roll in contact with the disks swangably. The output disks
6
a
,
6
b
are interlocked to each other through a loosely fitting shaft
8
which is loosely fitted to the driving force transmission shaft
4
.
The variator
3
is arranged in a manner that the rotation driving force transmitted to the driving force transmission shaft
4
is further transmitted to the loosely fitting shaft
8
through the input disks
5
a
,
5
b
, the power rollers
7
and the output disks
6
a
,
6
b
, wherein a speed ratio, that is, a value obtained by dividing the rotation speed of the output disks
6
a
,
6
b
by the rotation speed of the input disks
5
a
,
5
b
is determined by the swing angle of the power rollers
7
. In other words, the speed ratio is determined by a tilt angle of the displacement shafts rotatably supporting the ends of the power rollers
7
.
To be more concrete, when the power rollers
7
lie along the level or horizontal direction in parallel to the driving force transmission shaft, the transmission is in a neutral state with the speed ratio of 1. When the output disks
6
a
,
6
b
sides of the power rollers
7
incline to the direction away from the driving force transmission shaft
4
, the speed ratio decreases in accordance with the inclined angle. In contrast, when the output disks
6
a
,
6
b
sides of the power rollers
7
incline toward the driving force transmission shaft
4
, the speed ratio increases in accordance with the inclined angle. A first gear
9
is fitted into the loosely fitting shaft
8
and further engages with a second gear
11
provided at a counter shaft
10
.
The loading cam apparatus
2
is arranged to include a first cam surface
13
formed to have concave and convex portions thereon along a circumferential direction of one side surface of a loading cam
12
which engages with the input shaft
1
and rotates together with the input shaft
1
, a second cam surface
14
formed to have concave and convex portions thereon along a circumferential direction of the rear surface of the input disk
5
a
, and a plurality of rollers
16
serving as rolling elements which are sandwiched between the first cam surface
13
and the second cam surface
14
in a state being held by a retainer
15
so as to be freely rolled.
As shown in
FIGS. 13A and 13B
, the retainer
15
is formed by a metal plate of a circular annular shape and integrally provided with a plurality of, for example, four convex portions
18
at the outer peripheral portions thereof along the circumferential direction thereof with a constant interval therebetween. A pocket
17
for holding the roller
16
is provided at each of the convex portions
18
. Each of the pockets
17
is formed in a rectangular shape and the width and length allowances or tolerances thereof are preferably to be a space sufficient not for restricting the roller
16
. That is, since the roller is restricted when the space is small, the space between the roller and the pocket is preferably in a range of about 0.05 to 0.5 mm. The symmetrical degree, positional degree and angular allowance of the four pockets
17
are required to be managed strictly to some extent in a view point of adjusting the phase between the cam surfaces and the pockets.
The retainer
15
of the loading cam apparatus
2
is manufactured by the cutting process and the pockets
17
are subjected to the induction hardening process. However, since the yield of the material of the retainer is not good and the cutting process takes a long time, the cost of the loading cam apparatus becomes expensive.
Further, since the induction hardening process is performed by abutting a coil to the convex portion
18
, if the coil is not set suitably, the coil may touch the convex portion and so there arises a problem that the convex portion may be cracked or broken when the external force is applied to the touched portion.
In the case of performing the induction hardening process, the inner diameter portion as well as the four pockets
17
are required to be subjected to the hardening process. Furthermore, in the case of performing the induction hardening process, it is difficult to perform the hardening process at the pockets in particular since recesses are formed at the four corner portions of each of the pockets
17
. Thus, since each of the pockets receives the centrifugal force of the roller
16
at the outer side thereof while receiving a large face pressure at the side walls, the stress applied to the four corner portions thereof becomes large, so that the hardness of the four corner portions having been subjected to the hardening process is low and so there arises a problem that the breakage occurs from the corner portions.
Each of the pockets
17
is usually formed in a manner that each of the four corner portions is designed to have the single radius R of less than 1 mm, so that the stress is likely concentrated at the corner portions. Further, since the coupling portion between the corner portion and the linear portion of the pocket is formed to be sharp, a burr or flash is likely generated at the coupling portion and so there arises a problem that the roller is likely restricted by the coupling portion at the time of assembling.
SUMMARY OF THE INVENTION
Accordingly, the present invention has been performed in order to obviate the aforesaid problems of the prior art.
An object of the present invention is to provide a retainer for a loading cam apparatus which is low in a carbon concentration and can be fabricated easily by the pressing process and so cost thereof can be reduced.
Another object of the present invention is to provide a loading cam apparatus wherein a space is partially formed between the boss portion of a loading cam and the retainer so that lubricating oil flows through the space on the cam surface of an input disk thereby to improve the lubrication property.
A further object of the present invention is to provide a loading cam apparatus wherein each of the four corner portions of a pocket is arranged to form a recess of arc shape and a coupling portion between the corner portion and a linear portion of the pocket is formed to have an obtuse angle thereby to avoid the concentration of stress at the corner portions, and a burr is scarcely generated at the time of stamping out the pocket by the pressing process.
A still further object of the present invention is to provide a loading cam apparatus wherein a step portion is formed between the boss portion of a loading cam and the retainer so as to partially form a space therebetween so that the contact area between the boss portion and the retainer is made smaller thereby to smoothly slide the retainer.
In order to attain the aforesaid object,
Fujinami Makoto
Goto Nobuo
Itoh Hiroyuki
Kato Hiroshi
Okubo Kiyoshi
Joyce William C
NSK Ltd.
Sughrue & Mion, PLLC
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