Machine element or mechanism – Gearing – Interchangeably locked
Reexamination Certificate
2002-06-28
2004-09-07
Ho, Ha (Department: 3681)
Machine element or mechanism
Gearing
Interchangeably locked
C074S333000, C074S344000, C192S053360
Reexamination Certificate
active
06786107
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a constant-mesh transmission, such as a gear-type transmission mounted on a vehicle.
2. Description of Background Art
As a transmission of this type, for example, a constant-mesh transmission disclosed in Japanese Patent Publication No. Hei-2-39660, is known. A transmission
01
has, as shown in
FIGS. 9 and 10
, a transmission gear
03
formed integrally with a main shaft
02
, and a transmission gear
05
which meshes with the gear
03
and is rotably provided for a counter shaft
04
. In the transmission gear
05
, a recess
07
is formed having a bottom in which a plurality of nails
06
are formed at intervals in the circumferential direction. A synchronizer ring
08
constructing a synchronizing mechanism in teamwork with the recess
07
is assembled in the recess
07
so as to be relative to the transmission gear
05
. In the synchronizer ring
08
, a plurality of openings
09
are formed at intervals in the circumferential direction, and an arm
010
having a chamfer
011
is formed between two neighboring openings
09
. In a transmission gear
013
(slider) provided for the counter shaft
04
so as to be slidable in the axial direction and moved by a shift fork
012
, nails
014
are formed at intervals in the circumferential direction, which can be inserted into the openings
09
.
As shown in FIG.
10
(A), at the time of changing speed, the transmission gear
013
moved by the shift fork
012
moves the synchronizer ring
08
via a synchronizer spring
015
from a speed change start position, thereby allowing a tapered face
016
of the synchronizer ring
08
to come into contact with a tapered face
017
of the second gear
05
, and thus generating a frictional torque. This causes a chamfer
018
of the nail
014
and the chamfer
011
of the arm
010
to come into contact with each other. When the transmission gear
013
further presses the synchronizer ring
08
, the transmission gears
013
and
05
are synchronized with each other via the synchronizer, ring
08
, with a high frictional torque generated on both the tapered faces
016
and
017
.
As shown in FIG.
10
(B), after completion of synchronization of both of the gears
013
and
05
, the transmission gear
013
is further moved in the axial direction, the nails
014
mesh with the nails
06
formed on the bottom of the recess
07
, and the speed changing operation is completed.
In the conventional technique, the nails
014
of the transmission gear
013
as a slider moves in the axial direction. First, nails
014
come into contact with the chamfers
011
of the arms
010
with respect to the arms
010
and nails
06
positioned in a straight line in the axial direction and are inserted into the openings
09
. Subsequently, nails
014
mesh with the nails
06
of the transmission gear
05
. Therefore, a movement stroke LO in the axial direction of the transmission gear
013
from the speed change start position to the speed change completion position is long. This is one of the factors causing an increase in the size in the axial direction of the transmission
01
. In the case of shortening the movement stroke LO, the width in the axial direction of the arm
010
having the chamfer
011
is narrowed, so that it becomes difficult to assure sufficient rigidity of the arms
010
of the synchronizer ring
08
pressed in the axial direction by the nails
014
.
SUMMARY AND OBJECTS OF THE INVENTION
It is an object of the present invention to realize minimization in the axial direction of a constant-mesh transmission having a synchronizing mechanism and to achieve high rigidity of a synchronization spline formed in a synchronizer ring. Another object of the invention is to prevent an increase in size of the radial direction of a synchronizing mechanism.
The invention is directed to a constant-mesh transmission comprising a first gear provided for a first rotary shaft as to rotate integrally with the first rotary shaft, a second gear which meshes with the first gear and is rotatably provided for a second rotary shaft, and a synchronizing mechanism. The synchronizing mechanism includes a shifter provided for the second rotary shaft so as to rotate integrally with the second rotary shaft and to be movable in the axial direction, ring-shaped recess formed in the first gear, and a synchronizer ring disposed in the recess so as to be rotatable relative to the second gear and pressed by the shifter at the time of changing speed to move in the axial direction so as to come into frictional engagement with the first gear, thereby achieving synchronization between the shifter and the first gear.
In turn, the shifter include a first connection spline formed in a circumferential wall face of the recess and a first synchronization spline formed in a circumferential face of the synchronizer ring occupying a position where they at least partly overlap with each other in the axial direction. The shifter also includes a second connection spline which can mesh with the first connection spline and a second synchronization spline which presses the first synchronization spline in the axial direction to make the synchronizer ring and the first gear come into frictional engagement with each other, and can mesh with the first synchronization spline. At the time of changing speed, the first and second synchronization splines mesh with each other, after which the first and second connection splines mesh with each other.
According to the present invention, at the time of changing speed, the second synchronization spline of the shifter presses the first synchronization spline of the synchronizer ring, the synchronizer ring is moved in the axial direction and comes into frictional engagement with the first gear, thereby achieving synchronization between the shifter and the first gear. After completion of the synchronization, the first and second synchronization splines mesh with each other, and then the first and second connection splines mesh with each other, whereby the speed changing operation is completed.
As a result, the following effect is produced: Specifically, the first connection spline and the first synchronization spline have an overlap portion where they overlap with each other at least partly in the axial direction. Consequently, the movement distance of the shifter until completion of the sped changing operation is minimized, since the synchronizer ring is moved in the axial direction by the shifter, and the synchronizer ring and the first gear come into frictional engagement with each other to achieve synchronization between the shifter and the first gear. Then, after completion of the synchronization, the first and second synchronization splines mesh with each other. Finally, the first and second connection splines mesh with each other. With the configuration of the present invention, the movement stroke becomes shorter than with conventional configurations. It becomes possible to reduce the width in the axial direction of the first gear in which the recess is formed and dispose the first gear and the shifter so as to be closer to each other in the axial direction. Thus, the size of the transmission can be reduced in the axial direction.
Moreover, the first synchronization spline pressed by the second synchronization spline occupies a position where it overlaps with the first connection spline at least partly in the axial direction. As compared with the case where the first synchronization spline and the first connection spline are positioned without being overlapped in the axial direction, the width in the axial direction of he first synchronization spline can be increased and the rigidity of the first synchronization n spline against the pressing force acting from the second synchronization spline can be increased. This can be accomplished without increasing the width in the axial direction of the recess in which the synchronizer ring is disposed, and without increasing the width in the axial direction of the first gear in which the re
Matsumoto Shinya
Nakamura Kazuhiko
Tsukada Yoshiaki
Ho Ha
Honda Giken Kogyo Kabushiki Kaisha
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