Machine element or mechanism – Gearing – Interchangeably locked
Reexamination Certificate
2000-01-03
2001-05-08
Wright, Dirk (Department: 3681)
Machine element or mechanism
Gearing
Interchangeably locked
Reexamination Certificate
active
06227063
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an automatically operated speed-changing apparatus (transmission) of an automobile and an industrial vehicle. In particular, it relates to the automatically operated speed-changing apparatus in which an operating mechanism to change a gear speed changing mechanism for speed-changing is automatically operated by a hydraulically or electrically operated actuator, and a controlling method therefor.
2. Related Art
In a transmission of an automobile, there is an automatically operated transmission in which a speed-changing operation for changing combination of gears of a gear train is automatically carried out by an actuator of a hydraulic type or an electrical type, based on a driver's manual handling.
FIG. 4
shows one example of such automatically operated transmission which is comprised of a gear speed-changing mechanism
2
, an operating mechanism for setting a predetermined speed-changing ratio by changing combination of meshing gears i.e. transmitting condition of the gear speed-changing mechanism
2
, actuators
4
and
5
for hydraulically or electrically driving the operating mechanism
3
, and a controlling means
6
for controlling the actuators
4
and
5
, all of which are disposed in a speed-changing case
1
. The controlling means
6
controls the actuators
4
and
5
based on a signal generated by handling of a manually operated shift member
7
such as a switch or lever. The controlling means
6
is constructed by a hydraulically controlled device when the actuators
4
and
5
are of hydraulically-operated type, while it is constructed by a ECU (Electrically Controlled Unit) when the actuators
4
and
5
are electrical motors.
The automatically operated transmission shown in
FIG. 4
is for a manually operated transmission (manual transmission), so the gear speed-changing mechanism
2
is comprised of constantly meshed type gear train mounted on an input shaft, a counter shaft and an output shaft (driven shaft), and transmitting condition or combination of the gears thereof is changed by the operating mechanism
3
to set (shift) a predetermined speed-changing ratio.
The operating mechanism
3
is comprised of a synchromesh mechanism in which a relative braking is generated by a coned friction surface thereof, and a shift fork engaged with a sleeve of the synchromesh mechanism. The synchromesh mechanism is, as shown in
FIG. 5
, provided with the sleeve
8
which has inner peripheral splines
8
a
meshing with outer peripheral splines of a clutch hub (not shown), a synchronizer ring
9
of cone-shape and is pushed in an axial direction of X by the sleeve
8
, and a key
10
fitted on an inner peripheral surface of the sleeve
8
centrifugally and pushes an end surface of the synchronizer ring
9
in the axial direction X in an initial period (this is called as “shift put-in area”) of the shifting operation of the sleeve
8
. The key
10
is positioned on the inner peripheral surface of the sleeve
8
to be rotated at a position offset toward one side of a groove of an outer peripheral tooth
9
b
of the synchronizer ring
9
. Therefore, when the sleeve
8
is shifted in the axial direction x by the shift fork
12
, as shown in
FIG. 6
, the sleeve
8
and the synchronizer ring
9
are opposed in a phase where a chamfered surface
8
b
of the inner peripheral splines
8
a and a chamfered surface
9
a
of the outer peripheral teeth
9
b
are offset in a circumferential direction.
That is, in the synchromesh mechanism, when the sleeve
8
positioned at the neutral position is shifted by the shift fork
12
in the axial direction X so that the key
10
presses the end surface of the synchronizer ring
9
in the axial direction X (shift push-in area), as shown in
FIG. 6
, the chamfered surface
8
b
of the sleeve
8
and the chamfered surface
9
a
of the synchronizer ring
9
regulate the inner peripheral splines
8
a
of the sleeve
8
and the outer peripheral gears
9
b
of the synchronizer ring
9
in a state where they are offset with each other by width of the key
10
(synchronize area). Thus, the sleeve
8
further shifts in the axial direction X to press the chamfered surface
9
a
of the synchronizer ring
9
by the chamfered surface
8
b
thereof, so that the inner peripheral splines
8
a
of the sleeve
8
put into the adjacent grooves of the outer peripheral teeth
9
b
of the synchronizer ring
9
. This period is called as “push-apart area”, and the push-apart completes when the number of rotations of a gear
11
coincides with that of the synchronizer ring
9
due to direct pushing by the sleeve
8
to the synchronizer ring
9
. In state where the push-apart is completed, since the synchronizer ring
9
can be freely rotated, the sleeve
8
is shifted in the axial direction x by the shift fork
12
driven by the actuators
4
and
5
, so that the inner peripheral splines
8
a
of the sleeve
8
put into the adjacent grooves of outer teeth lla of the gear
11
(this period is called as “piece mesh area”), to complete the speed-changing.
The actuators
4
and
5
apply an axial load to a shift fork
12
of the operating mechanism
3
, and a hydraulic cylinder or hydraulic motor is used as the hydraulic type actuator, while an electric motor is used as the electric type actuator. When the gear speed changing mechanism
2
is operated via the operating mechanism
3
by the actuators
4
and
5
of the hydraulic or electric type, the actuators
4
and
5
should assume position to press the sleeve
8
for maintaining the gear speed-changing mechanism
2
in a state where a predetermined speed-changing ratio is set. However, the axial load applied to the actuators
4
and
5
to press the sleeve
8
axially is relieved at the time when the shifting operation of the operating mechanism
3
including the sleeve
8
is completed, and the sleeve
8
is then retained at the present position by a ball-lock mechanism in the transmission.
However, if shock is applied to the vehicle due to sudden acceleration or deceleration of running speed, running on a rough (convex/concave) surface, or running over a step, load in a reverse direction to the force applied by the ball locking mechanism is applied to the sleeve
8
of the operating mechanism
3
which has reached to the shift completing position to retract the sleeve
8
to the piece-mesh area, the push-apart area or the synchronizing area to thereby cause “a shift-fall”. In the shift fallen state, the gear speed-changing mechanism
2
becomes a neutral state where a gear rotating together with the output shaft freely rotates relative to the output shaft, so that the driver feels uneasiness due to unintentional running of the vehicle.
For restoring or returning the neutral state of the gear speed-changing mechanism
2
to the original shifted state automatically, the shift-fall of the synchromesh mechanism may possibly be detected by a stroke sensor disposed in the actuators
4
and
5
corresponding to the shift push-in area of the synchromesh mechanism, and the actuators
4
and
5
are operated again, based on the output of the actuators
4
and
5
for driving the operating mechanism
3
. However, if the synchromesh mechanism is always driven again to the shift completing position based on detection of the synchromesh mechanism at the shift push-in area via the synchronizing area, the push-apart area and piece-mesh area, the driver is left in the unintentional running state for a long time.
SUMMARY OF THE INVENTION
The present invention is made in view of the above mentioned circumstances, and intends to provide an automatically operated transmission and a controlling method therefor, which can avoid occurrence of the neutral state of the gear speed changing mechanism due to the shift-fall of the operating mechanism, and can restore the shift-fall, if occurred, shortly and securely.
In order to achieve the above purpose, an inventor of the present invention has studied in many view points and found that the operating mechani
Kodera Nobuyuki
Ohmori Makoto
Aisin Ai Co., Ltd.
Burns Doane , Swecker, Mathis LLP
Wright Dirk
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