Machine element or mechanism – Control lever and linkage systems – Multiple controlled elements
Reexamination Certificate
2000-08-22
2002-06-04
Herrmann, Allan D. (Department: 3682)
Machine element or mechanism
Control lever and linkage systems
Multiple controlled elements
C074S473120, C074S473180, C074S473270
Reexamination Certificate
active
06397698
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a controlling device for a transmission, and more particular it relates to improvement of the controlling device for a manual transmission in which a predetermined speed-changing gear is selected by driving an operating mechanism with an actuator based on operation of a shifting lever and so on.
2. Related Background Art
A speed-changing mechanism (referred to as a “transmission” hereinafter) changes the ratio between the number of engine rotations and the number of wheel rotations to suitably transmit an output of the engine to the wheels corresponding to a running condition of the vehicle. A manual transmission performing speed-change based on the driver's manual operating is one example of such transmission. The manual transmission generally includes a gear portion selecting one of plural pairs of the speed-changing gears, an operating mechanism for operating the gear portion, and a controlling device for controlling the operating mechanism, although it includes minor differences depending on the type of transmission.
For example, the gear portion of five forward shifts and one backward shift type includes first to fifth speed-changing gears and a backward gear. The operating mechanism of the synchromesh-type includes first to third sleeves, and first to third paired synchronizer rings (referred to as “ring” hereinafter).
The controlling device includes, as shown in
FIGS. 8
to
10
, first, second and third fork shafts
71
,
72
and
73
respectively supported by a transmission casing
80
, a selecting member
78
to be engaged with one of three fork shafts, a shift actuator
81
for driving the fork shafts
71
to
73
, a selecting actuator
76
for driving the selecting member
78
, and a shifting lever
75
handled by a driver (in another type, a shifting switch (for example. button) is switched). Each of the fork shafts
71
,
72
and
73
has at a lower portion of a tip end a fork (only
72
a
is shown) engaging with the fork engaging portion of the sleeve, and has an upper portion of the tip end a head portion
71
b
,
72
b
or
73
b
engaged by a fever portion
78
b
of the selecting member
78
. At the rear part of the first, second and third fork shafts
71
,
72
and
73
. first, second and third locking mechanisms
86
,
87
and
88
to be explained later are provided.
The fork shafts
71
to
73
and the selecting member
78
have been conventionally driven directly by the shifting lever
75
. However, a hydraulic driving device or an electric motor controlled by a ECU etc. has been recently interposed between the fork shafts
71
to
73
, and the selecting member
78
and the shifting lever
75
. In this case, the shifting lever
75
functions as a shift commanding member to command the driver's intention for the speed-changing to the ECU. So, it can be comprised of switch member such as a button, instead of the shifting lever
75
shown in FIG.
8
.
For example, an oil hydraulic actuator is used as the hydraulic driving device. As shown in
FIGS. 9 and 10
, a selecting rod
78
extending from a cylinder
77
of a selecting actuator
76
has a piston portion
78
a
at a rear end thereof, and is advanced/retraced by a pressured oil supplied to a cylinder
77
at both sides of the piston portion
78
a
. The selecting rod
78
has, at a tip end thereof, a lever portion
78
b
to be engaged with the head portion
71
b
,
72
b
or
73
b
. A shifting rod
83
extends in a crossing manner with a selecting rod
78
from a cylinder
82
of a shifting actuator
81
disposed to cross the selecting actuator
76
. It has a piston portion
83
a
at a rear end, and has an engaging portion
83
b
engaging with the selecting rod
78
at the tip end.
With advancement/retraction of the selecting rod
77
by the selecting actuator
76
based on command of the ECU, the lever portion
78
b
of the selecting member
78
engages with one of the head portions
71
b
,
72
b
and
73
b
of the fork shafts
71
,
72
or
73
. Then, the selecting actuator
76
and one of the first to third fork shaft
71
to
73
engaged by the selecting member
78
are shifted integrally by the shifting actuator
81
based on the operating of the shifting lever
75
. Thus, one of the first, second and third sleeves is shifted axially to select one of the speed-changing gears.
A first, second and third locking mechanism
86
,
87
and
88
are provided for the first, second and third fork shafts
71
,
72
and
73
respectively. These locking mechanisms
86
to
88
lock the fork shafts
71
to
73
and the sleeves at shifted positions thereof corresponding to shifting of the shift, locking them at the neutral position thereof corresponding to operation of the shifting lever
75
. The locking mechanisms
86
to
88
are comprised of, as shown in
FIGS. 9 and 10
, three sets of semi-spherical hall holes
86
a
1
,
86
a
2
and
86
a
3
,
87
a
1
,
87
a
2
and
87
a
3
, and
88
a
1
,
88
a
2
and
88
a
3
respectively formed at rear end of the fork shafts
71
,
72
and
73
; three halls
86
b
,
87
b
and
88
b
respectively pressed into the hall holes of each fork shaft: and three springs
86
c
,
87
c
and
88
c
respectively biasing the ball toward the corresponding ball holes.
The operating mechanism (the sleeves, the rings) are held at a leftward or a rightward position by moving the piston portion
83
a
near to the stroke ends of the shift actuator
81
via the fork shafts
71
to
73
. For, example, when the sleeve etc. have been moved to the leftward position or the rightward position, the ball
87
b
is pressed into the ball hole
87
a
3
or
87
a
1
to hold the fork shaft
72
or the sleeve at the meshed position.
To the contrary, holding the sleeve etc. which have been shift-drawn out from the speed changing gear at the neutral position is not easy. For holding the sleeve etc. at the neutral position, they need to be positioned at a predetermined axial position or in extremely narrow allowable ranges located at both sides thereof. The sleeve etc. are held at the neutral position via the fork shafts
71
to
73
by holding the piston portion
83
a
at the axially neutral portion in the cylinder
82
. However, the piston portion
83
a
can be hardly held at the neutral position even by regulating supply/discharge of the pressured oil. Thus, stopped position of the sleeve etc. may offset delicately in the axial direction of the cylinder
82
.
For example, assume the piston portion
83
a
is offset in the cylinder
82
slightly leftward from the neutral position in the shift drawing-out of the second sleeve. In this case, the central ball groove
87
a
2
of the second locking mechanism
87
offsets slightly leftward from the position opposing the ball
87
b
. As a result, the ball
87
b
being drawn out from the ball hole
87
a
3
or
87
a
1
abuts a right edge of the ball hole
87
a
2
to apply a rightward biasing force F
1
to the fork shaft
72
. However, a sliding resistance F
2
applied from the cylinder
82
to the piston portion
83
a
is larger than the biasing force F
1
. For this reason, the fork shaft
72
can not move rightward, stopping at a position offset slightly leftward from the neutral position. Thus, the locking mechanism
87
does not function to hold the fork shaft
72
and the sleeve at the neutral position. If vibration is applied to the transmission in this condition, the sleeve etc. are pressed to the speed-changing gears to be damaged and deteriorated.
When the central ball hole
87
a
2
of the second locking mechanism
87
is shifted slightly rightward from the position opposing to the ball
87
b
, the above mentioned members move in the direction reverse to the above direction. The above mentioned circumstances are similar for the first and third fork shafts
71
and
73
.
Also, the engaging portion
83
b
of the shifting rod
83
engaging with the selecting rod
78
, an engaging portion between head portions
72
b
etc. and the lever portion
78
b
of the selecting member
78
, a
Kamiya Mitsutoshi
Miyazaki Takeshige
Aisin AI Co., Ltd.
Burns Doane , Swecker, Mathis LLP
Herrmann Allan D.
LandOfFree
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