Machine element or mechanism – Gearing – Interchangeably locked
Reexamination Certificate
2000-04-12
2001-08-21
Estremsky, Sherry (Department: 3681)
Machine element or mechanism
Gearing
Interchangeably locked
Reexamination Certificate
active
06276224
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a shift Control Apparatus for a speed change apparatus (transmission), especially for a synchromesh type transmission.
2. Related Art
In a synchromesh-type transmission, as shown in
FIG. 5
, sleeves
17
and
18
which constitute a part of a cynchro mechanisms
15
and
16
are pressed to one of free-rotate gear groups of a 2nd-shift gear
11
, a 3rd-shift gear
12
and a 4th-shift gear
13
(a 1st-shift gear and the like are not shown) mounted onto an output shaft
30
disposed coaxial with an input shaft
10
, thereby rotating the free-rotate gear together with the output shaft
30
. On a counter shaft
40
disposed parallel to the output shaft
30
, gears
41
,
42
and
43
are mounted to mesh with the above gears
11
,
12
and
13
respectively.
The above synchromesh transmission is mainly comprised of clutch hubs
21
and
22
, sleeves
17
and
18
, second speed to fourth speed gear pieces
23
to
25
, three synchronize rings
27
to
29
. In detail, the clutch hubs
21
and
22
are spline-engaged with the input shaft
10
to be rotated together therewith, and the sleeves
17
and
18
are engaged with an outer peripheral surface of the clutch hubs
21
and
22
via splines
17
a
and
18
a
to be shifted axially but not to be rotated circumferantially relative thereto. Each of the second-speed gear piece
23
, the third-speed gear piece
24
and the fourth-speed gear piece
25
is spline-engaged with a boss portion protruded from a side face of the free-rotate gear and having on an outer periphery thereof a dog teeth
23
a
,
24
a
and
25
a
. The synchronize rings (hereinafter, briefly called “ring”)
27
,
28
and
29
for second-speed, the third shft and the fourth shift are disposed respectively between a cone surface of the gear pieces
23
,
24
or
25
and splines
17
a
and
18
a
on the inner peripheral surfaces of the sleeves
17
and
18
.
Between the clutch hub
21
and the sleeve
17
, and between the clutch hub
22
and the sleeve
18
, shift keys (not shown) are respectively mounted by engaging with axial grooves formed by cutting some parts on the outer periphery of the clutch hubs
21
and
22
and nipped by inner peripheral surfaces of the sleeve
17
and
18
. The shift gear has radial protrusions which engage with recesses formed on the inner peripheral surface of the sleeve
17
or
18
positioned at the neutral position, and disengage from the sleeve
17
and
18
positioned other than the neutral position.
Shift forks
31
and
32
engage with the sleeves
17
and
18
, respectively. One of the shift forks
31
and
32
is engaged by a select member (not shown) selectively moved by a select operation of an operate (manual) lever in a select direction, then the selected sleeve
17
or
18
is moved (shifted) by a shift operation of the operate lever in a shift (Y) direction.
A speed-change process of the above synchromesh-type transmission will be explained with reference to
FIG. 6
which shows a shift/select pattern of the operate lever,
FIG. 7
which shows a stroke position of the sleeves
17
and
18
, and
FIG. 8
which shows an operate pressure of an actuator which actuates the sleeves.
In the synchromesh-type transmission, as shown in
FIG. 5
, the select member is engaged with the shift fork
31
in the 2nd-speed condition prior to the speed-change, and the sleeve
17
of the synchro mechanism
15
is shifted leftwardly. To the contrary, the sleeve
18
of the synchro mechanism
16
is positioned in the nuetral position. For speed-changing from a 2nd shift to a 3rd shift, as shown in
FIG. 6
, the operate lever is shifted from a 2nd shift position to a nuetral position N, then selected from a position corresponding to a 1st shift and 2nd shift to a position corresponding to a 3rd shift and a 4th shift, and then shifted from the neutral position N to a 3rd shift position.
When the operate lever is shifted from the 2nd shift position to the neutral position N at the time T1 in
FIG. 7
, an operate force directed rightwardly in
FIG. 5
is applied to the sleeve
17
via the select member and shift fork
31
, so that the sleeve
17
slides over the gear piece
23
of the 2nd-shift gear
11
without recieving resistance to reach the neutral position N at the time T2. This time period (T
1
-T
2
) is called a “shift draw-out area”).
After the shift draw-out of the sleeve
17
, the operate lever is operated in the select direction so that the select member is disengaged from the shift lever
31
and is engaged with the shift lever
32
during a time period (T
2
-T
3
) of FIG.
7
. The shift fork
32
, by a successive shift operation of the operate lever, starts to shift the sleeve
18
of the synchro mechanism
16
rightwardly in
FIG. 5
at a time T
3
. As a result, the shift key, by cooperating with the sleeve
18
, presses an end surface of the ring
28
. A time period (T
3
-T
4
) when the shift key presses the end surface of the ring
28
is called a “shift push-in (index) area”.
As apparent from
FIG. 7
, the sleeve
17
shifts by a constant speed in the shift draw-out area (T
1
-T
2
), and the sleeve
18
shifts by a constant speed in the shift push-in area (T
3
-T
4
) but is stopped in the select area (T
2
-T
3
).
At a time T
4
when the shift key does not follow the shift of the sleeve
18
, a chamfer of the spline
18
a
of the sleeve
18
starts to engage with outer teeth
28
a
of the ring
28
. A stroke position of the sleeve
18
corresponding to the time T
4
is called a “synchronize start point (balk point)” where the sleeve
18
is stopped irrespective the force applied thereto. In the stroke position S of the balk point T
4
, the sleeve
18
presses the ring
28
against the gear piece
24
and waits time T
5
when the gear piece
24
synchronizes with the sleeve
18
and the ring
28
of low-speed rotation. This time period (T
4
-T
5
) is called a “synchronize area” where the sleeve
18
is stopped.
When the gear piece
24
synchronize with the sleeve
18
and the ring
28
, a rotation friction torque between the ring
28
and the gear piece
24
is removed, so that sleeve
18
as the shifting thereof pushes apart the ring
28
and meshes with the dog teeth
24
a
of the gear piece
24
. At this time, the rotate speed of the gear piece
24
and the 3rd-shift gear
12
is decreased to a value smaller than that upon the synchronization with the sleeve
18
due to drag torque thereof. For this reason, upon a re-synchronizing when the sleeve
18
meshes with the dog teeth
24
a
of the gear piece
24
, the load applied from the gear piece
24
and the 3rd-shift gear
13
to the sleeve
18
varies suddenly. This stroke position of the sleeve
18
is called “two-shift input point”.
The sleeve
18
, after having pushed apart the gear piece
24
by overcoming the load at the two-shift input point, receives a stop force from an end surface of the 3rd-shift gear
12
to stop at a stroke position corresponding to a time T6. This time period (T
5
-T
6
) is called “push-apart area” in which the sleeve
18
shifts in a constant speed. Thereafter, the sleeve
18
is maintained at the 3rd-shift position by a predetermined lock mechanism which engages with the shift fork
32
and the operate lever.
The shifting of the sleeves
17
and
18
of the synchro-mechanisms
15
and
16
based on the shift operation of the shift lever is automatically operated by a hydraulic or electric actuator controlled by a controller. One of the transmission which includes such automatic operation is shown in WO97/05410, for example. In this prior art, as shown in
FIG. 8
, a control means including the controller, adjusts an operate pressure of the actuator based on a vehicle condition or a speed-change process.
In detail, the control means sets an operate pressure in a max. value P
max
in the shift draw-out area (T
1
-T
2
) of the sleeve
17
and the shift push-in area (T
3
-T
4
) of the sleeve
18
to shift the sleeves
17
and
18
by a large drive force and in a high sp
Ito Yoshiki
Ueda Yukio
Aisin Ai Co., Ltd
Burns Doane , Swecker, Mathis LLP
Estremsky Sherry
Pang Roger
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