Machine element or mechanism – Gearing – Interchangeably locked
Reexamination Certificate
2001-10-31
2003-12-02
Estremsky, Sherry (Department: 3681)
Machine element or mechanism
Gearing
Interchangeably locked
C074S473100, C477S097000
Reexamination Certificate
active
06655227
ABSTRACT:
This application is based on and claims priority under 35 U.S.C. §I19 with respect to Japanese Patent Application No. 2000-333061 filed on Oct. 31, 2000, the entire content of which is incorporated herein by reference.
FIELD OF THE INVENTION
This invention generally relates to a control device for a synchromesh-type transmission for a vehicle. More particularly, the present invention pertains to a control device for a vehicle synchromesh-type transmission in which a neutral position of an inner lever is detected based upon rotation of a shift and select shaft transmitted to a fork shaft.
BACKGROUND OF THE INVENTION
Vehicles such as passenger cars and busses are generally driven by a driving power source such as a gasoline engine or an electric motor. The vehicles include a transmission for performing an optimal running condition in response to road conditions. A shift stage of the transmission is selected or canceled for generating the desired driving torque or speed.
The manual transmission (MT), which is one known type of the above-described transmissions, includes a counter shaft, a main shaft, a plurality of counter gears mounted on the counter shaft, a plurality of idle gears idly mounted on the main shaft and always in meshing engagement with the counter gears, sleeves fixed to a plurality of shift fork shafts, and a synchromesh mechanism for integrally engaging the sleeves with the main shaft. The shift operational force of a shift lever produced by a driver is transmitted to any one of the shift fork shafts via a transmitting member such as a cable to move the selected shift fork shaft. That is, a sleeve corresponding to the selected shift fork shaft is moved according to the shift operational force.
Somewhat recent developments have led to automated manual transmissions which are structurally based on the manual transmission (MT) and are provided with an actuator such as a hydraulic pressure cylinder for moving the shift fork shafts. By virtue of the actuator provided for the automated manual transmission, the operational force inputted by the driver may not be required as much as the manual transmission. The automated manual transmission is provided, for example, with a shift and select shaft axially moved for a select operation and rotated for a shift operation. The axial and rotational movements of the shift and select shaft are transmitted to any one of the shift fork shafts via an inner lever and a shift head.
Referring to
FIGS. 5 and 6
, an inner lever
50
is formed as a cylindrical portion
51
and an extending portion
52
. The inner lever
50
is axially movable with a shift and select shaft
53
and is integrally rotatable with the shift and select shaft
53
in a circumferential direction. An interlock plate
55
is accommodated on the shift and select shaft
53
to close or enclose both edges of the cylindrical portion
51
. The interlock plate
55
is provided with a pair of pawl portions
56
,
57
surrounding both sides of the inner lever
50
. The interlock plate
55
is axially movable with the shift and select shaft
53
, but is not rotatable due to a lock ball mechanism
70
which is described later.
When the shift and select shaft
53
is axially moved upon the select operation, the inner lever
50
and the interlock plate
55
are integrally moved with the shift and select shaft
53
in the same direction. Further, the inner lever
50
is engaged with a shift head
61
of a shift fork shaft
60
for the third and fourth shift stages. Each of the pawl portions
56
,
57
is engaged with respective shift heads
64
,
67
of the shift fork shafts
63
,
66
.
When the shift and select shaft
53
is rotated in a direction upon the shift operation, the inner lever
50
is integrally rotated with the shift and select shaft
53
. The shift fork shaft
60
is moved in a direction in response to rotational movement of the inner lever
50
. Thus, one of the sleeves (not shown) is engaged with the corresponding idle gear (not shown) via a shift fork
59
. Accordingly, the inner lever
50
is moved from the neutral position to a shift stage position. The inner lever
50
is then operated to be returned to the neutral position from the shift stage position corresponding to a rotational movement of the shift and select shaft
53
in the other direction, whereby the shift fork shaft
60
is rotated in the other direction. Accordingly, the sleeve and the idle gear is disengaged, wherein the inner lever
50
is returned to the neutral position from the shift-stage position.
As shown in
FIG. 6
, the lock ball mechanism
70
is accommodated adjacent to the inner lever
50
and the interlock plate
55
. The lock ball mechanism
70
is provided with a movable member
72
movably disposed in a casing
71
. A ball
73
is disposed in the tip end of the movable member
72
. A ball groove
74
is defined at the upper surface of the inner lever
50
. A through hole
76
, which is shown in
FIG. 5
, is defined at an upper portion of the interlock plate
55
. The ball
73
supported at the lower edge of the movable member
72
is biased in a direction to be engaged with the ball groove
74
by a spring
78
.
The lock ball mechanism
70
is engaged with the inner lever
50
for guiding the shift fork shafts
60
,
63
,
66
to the neutral position. As used herein, the “neutral position” represents or refers to the situation in which the inner lever
50
is not engaged with any of the shift heads
61
,
64
,
67
, and the sleeves are not in meshing engagement with the idle gears for preventing the shift fork shafts
60
,
63
,
66
from being moved. The moving amount of the shift fork shaft
60
is determined corresponding to the rotational amount of the shift and select shaft
53
, i.e., the rotational amount of the inner lever
50
based upon the neutral position of the inner lever
50
. Therefore, it is of significant importance to correctly detect the neutral position of the inner lever
50
.
When a shift operation is performed, for example from a second shift stage to a third shift stage by a transmission provided with a shift pattern as shown in
FIG. 7
, a sleeve is disengaged from an idle gear for the second shift stage and is engaged with an idle gear for the third shift stage. In the case of the disclosed manual transmission, the above-described shift operation has been performed by virtue of a manual shift operation of the shift lever by the driver. The pushing force of the ball
73
, assisted by the spring
78
, to the ball groove
74
is larger than the resistance force of the shift mechanism. Therefore, the inner lever
50
is located at the neutral position by the lock ball mechanism
70
immediately before the sleeve is engaged with the idle gear and immediately after the sleeve is disengaged from the idle gear. Meanwhile, according to the automated manual transmission, the rotational movement of the shift and select shaft
53
driven by the actuator may be stopped when the ball
73
is not disposed in the ball groove
74
correctly and then the shift operation is performed. The pushing force of the ball
73
to the ball groove
74
is smaller than a slidable resistance force of the actuator. Therefore, under the above-described condition, the pushing force of the ball
73
is not sufficient for rotating the shift and select shaft
53
to the neutral position. Therefore, the inner lever
50
may not be moved to the neutral position. Under the above condition, if the shift lever is switched from a lower shift stage position to a middle shift stage position by the driver, the inner lever
50
is moved and comes in contact with a shift head for the third shift stage or a fourth shift stage. When the inner lever
50
has not been moved sufficiently and the shift lever is subsequently operated, the inner lever
50
may come in contact with the shift heads for the first and third shift stages or with the shift heads for the second and fourth shift stages. This is called a “double engagement”.
To overcome the above-described drawback of the disclosed synchromesh-ty
Aoyama Yoshiyuki
Choshi Ryuji
Ichikawa Yoshihiro
Kamiya Mitsutoshi
Miyazaki Takeshige
Aisin AI Co., Ltd.
Burns Doane , Swecker, Mathis LLP
Estremsky Sherry
Lewis Tisha D.
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