Turning – Lathe for wheel or axle
Reexamination Certificate
2003-04-30
2004-05-18
Fridie, Jr., Willmon (Department: 3722)
Turning
Lathe for wheel or axle
C082S128000, C476S072000, C476S073000
Reexamination Certificate
active
06736036
ABSTRACT:
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The present invention relates to a continuously variable transmission (CVT) for traction drives which is used to transmit rotation from an input side to an output side while continuously varying the speed by traction drive in a power transmission device of an automobile, industrial machinery and so forth, and more particularly, to a rotary assembly for traction drives which includes a rolling element having a traction contact surface which exhibits excellent traction characteristics as surface properties.
Various researches have been conducted on CVTs because of their excellent motive power transmission properties and absence of high-speed shock. In particular, researches have been conducted on systems (traction drive systems: rolling systems) that transmit motive power between traction contact surfaces by means of traction oil for the purpose of transmitting large motive power.
Traction drive systems which transmit motive power between traction contact surfaces by means of traction oil have a mechanism applicable to high-power engines. As shown, for example, in
FIG. 1
, the basic structure of rotary assembly
1
for traction drive type CVTs. Rotary assembly
1
includes two metal rolling elements, namely, two disks (input disk
3
circumferentially fixed on input shaft
2
and output disk
5
circumferentially fixed on output shaft
4
), and power roller
6
interposed between the rolling elements and contacted therewith through a traction oil. Power roller
6
has a tiltable roller shaft such that power roller
6
is inclined relative to input and output disks
3
and
5
when the roller shaft tilts. Owing to the inclination of power roller
6
, the contact between power roller
6
and input and output disks
3
and
5
shifts. This changes the ratio of the torque radius of input disk
3
to that of output disk
5
to thereby continuously change the transmission ratio. A half toroidal type CVT is one of traction drive CVTs.
FIG. 42
illustrates a toroidal type CVT which includes input shaft
101
and output shaft
102
coaxial with input shaft
101
and rotatable relative thereto. An engine torque is supplied via fluid coupling
103
to input shaft
101
. Forward and reverse input gears
104
and
105
are disposed on input shaft
101
so as to make a unitary rotation therewith. Two input disks
106
and
107
are drivingly connected with each other through hollow shaft
112
extending parallel to input shaft
101
. Two output disks
108
and
109
are arranged in an opposed relation to input disks
106
and
107
and connected with each other via shaft
111
extending inside hollow shaft
112
. Drive plate
110
is disposed between input disks
106
and
107
and drivingly connected therewith by loading cams
114
and
115
. Gear
113
integrally formed with drive plate
110
is engageable with forward input gear
104
. Two power rollers
116
are disposed between opposed input and output disks
106
and
108
and in friction contact with traction contact surfaces
106
a
and
108
a
thereof. Two power rollers
117
are disposed between opposed input and output disks
107
and
109
and in friction contact with traction contact surfaces
107
a
and
109
a
thereof. Power rollers
116
and
117
are rotatable about axes
116
a
and
117
a
thereof to transmit the torque from input disks
106
and
107
to output disks
108
and
109
, respectively. Power rollers
116
and
117
are also adapted to offset or swing in directions of axes
116
b
and
117
b
extending perpendicular to axes
116
a
and
117
a
, respectively. Forward/reverse change mechanism
123
is disposed on final drive shaft
119
disposed coaxially with input shaft
101
. Gear
120
rotatably supported on final drive shaft
119
is engageable with reverse input gear
105
. Forward/reverse change mechanism
123
includes forward clutch
121
connecting final drive shaft
119
with output disk
109
and reverse clutch
122
connecting final drive shaft
119
with gear
120
. Final drive shaft
119
is also connected with output shaft
102
via chain transmission mechanism
124
. Such a toroidal type CVT is disclosed in Japanese Patent Application First Publication No. 62-251559.
SUMMARY OF THE INVENTION
The rolling elements, namely, input disk
3
, output disk
5
, power roller
6
, of rotary assembly
1
shown in
FIG. 1
, are required to have excellent traction characteristics and high rolling fatigue life characteristics under high temperature and high bearing pressure. In addition, in consideration of the future burden on the environment, it is necessary that vehicle weight be reduced to achieve further improvement of fuel economy. In order to accomplish this, the unit size must be reduced, and in the case of units of the same size, it is necessary to increase the motive power that can be transmitted.
In consideration of the problems of the prior art described above, the object of the present invention is to provide a traction drive rotary assembly capable of transmitting large motive power and having excellent traction characteristics.
According to one aspect of the present invention, there is provided a rotary assembly for traction drives, comprising:
a plurality of rolling elements having a rotation axis and traction contact surfaces around the rotation axis and associating with each other to transmit a motive power between the rolling elements via a traction oil film formed between the traction contact surfaces;
at least one of said traction contact surfaces having a microstructure with irregularities which sizes are larger than a thickness of the traction oil film.
According to a further aspect of the present invention, there is provided a rotary assembly for traction drives comprising a plurality of rolling elements having a rotation axis and traction contact surfaces around the rotation axis and associating with each other to transmit a motive power between the rolling elements via a traction oil film formed between the traction contact surfaces, at least one of said traction contact surfaces having a microstructure with irregularities which sizes are larger than a thickness of the traction oil film, wherein the traction contact surface is formed by a process, the process comprising:
subjecting a surface of the rolling element to shot peening to form recesses and projections therein; and
subsequent to the shot peening, machining the projections by either one of lapping, mirror polishing, super finishing, cutting and grinding to form the top-flat lands and thus produce the traction contact surface.
According to a still further aspect of the present invention, there is provided a rotary assembly for traction drives comprising a plurality of rolling elements having a rotation axis and traction contact surfaces around the rotation axis and associating with each other to transmit a motive power between the rolling elements via a traction oil film formed between the traction contact surfaces, at least one of said traction contact surfaces having a microstructure with irregularities which sizes are larger than a thickness of the traction oil film, the microstructure being represented by an unfiltered primary profile curve including alternately arranged recesses and top-flat lands, wherein the traction contact surface is produced by a process, the process comprising:
forming recesses each having a depth of 10 &mgr;m or less at equal intervals in a surface of the rolling element to form alternate arrangement of the recesses and projections between the recesses; and
subsequent to the forming, machining the projections such that a height difference between a top of each top-flat land and a bottom of each recess is within a range of 0.5-2.5 &mgr;m, to produce the traction contact surface.
According to a still further aspect of the present invention, there is provided a rotary assembly for traction drives comprising a plurality of rolling elements having a rotation axis and traction contact surfaces around the rotation axis and associating with each other to t
Chiba Nobutaka
Kano Makoto
Nanbu Toshikazu
Omata Masahiro
Oota Minoru
Foley & Lardner LLP
Fridie Jr. Willmon
Nissan Motor Co,. Ltd.
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