U.S. patent application number 09/770307 was filed with the patent office on 2001-10-04 for apparatus for setting selection gate positions for change speed in automatic gear transmission.
Invention is credited to Kamiya, Mitsutoshi.
Application Number | 20010025535 09/770307 |
Document ID | / |
Family ID | 18545774 |
Filed Date | 2001-10-04 |
United States Patent
Application |
20010025535 |
Kind Code |
A1 |
Kamiya, Mitsutoshi |
October 4, 2001 |
Apparatus for setting selection gate positions for change speed in
automatic gear transmission
Abstract
For setting selection gate positions for change speed in a
gear-shift mechanism of an automatic gear transmission, a first
actuator is activated to rotate a shift-and-select lever for
shifting one of shift heads engaged therewith in its neutral
position to a low or high speed side in a shift direction, and a
second actuator is activated to effect movement of the
shift-and-select lever in a select direction perpendicular to the
shift direction in a condition where the shift head was shifted to
the low or high speed side. The second actuator is deactivated when
the movement of the shift-and-select lever in the select direction
was restricted by engagement with the shift head shifted to the low
or high speed side. When the second actuator was deactivated, an
output value of a selection-stroke sensor for detecting operation
of the second actuator is read out for setting a selection gate
position of the shift head shifted to the low or high speed side
based thereon.
Inventors: |
Kamiya, Mitsutoshi;
(Kariya-shi, JP) |
Correspondence
Address: |
Platon N. Mandros
BURNS, DOANE, SWECKER & MATHIS, L.L.P.
P.O. Box 1404
Alexandria
VA
22313-1404
US
|
Family ID: |
18545774 |
Appl. No.: |
09/770307 |
Filed: |
January 29, 2001 |
Current U.S.
Class: |
74/335 |
Current CPC
Class: |
F16H 63/20 20130101;
F16H 63/36 20130101; Y10T 74/19251 20150115; F16H 59/70 20130101;
F16H 61/2807 20130101 |
Class at
Publication: |
74/335 |
International
Class: |
F16H 059/04; F16H
063/20 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 27, 2000 |
JP |
2000-18999 |
Claims
What is claimed is:
1. An apparatus for setting selection gate positions for change
speed in a gear-shift mechanism of an automatic gear transmission
including a changeover shaft mounted within a housing of the gear
transmission for both axial and rotary movements to be axially
shifted from a neutral position to a forward or reverse position in
a select direction and to be rotated at its shifted position in
shifting operation, a shift-and-select lever fixed to an
intermediate portion of the changeover shaft for axial and rotary
movements therewith, an interlock member rotatably mounted in place
on the changeover shaft and having a pair of interlock arms located
at the opposite sides of the shift-and-select lever, detent means
for restricting rotary movement of the interlock member and for
permitting axial movement of the interlock member, a plurality of
fork shafts mounted in parallel within the housing for axial
movement in a shift direction perpendicular to the select
direction, a plurality of shift forks mounted on the fork shafts to
be selectively engaged with each sleeve of a plurality of
changeover mechanisms for selectively establishing a plurality of
change-speed gear trains in the gear transmission, a plurality of
shift heads mounted on the fork shafts to be selectively engaged
with the shift-and-select lever at their neutral positions, a first
actuator operatively connected to the changeover shaft for
effecting rotary movement of the changeover shaft when activated
under control of an electronic controller, a shift-stroke sensor
for detecting operation of the first actuator, a second actuator
operatively connected to the changeover shaft for effecting axial
movement of the changeover shaft in the select direction when
activated under control of the electronic controller, and a
selection-stroke sensor for detecting operation of the second
actuator, wherein the electronic controller comprises a program
memory storing instructions for activating the first actuator such
that the shift-and-select lever is rotated to shift one of the
shift heads engaged therewith in its neutral position to a low or
high speed side in the shift direction, for activating the second
actuator to effect movement of the shift-and-select lever with the
changeover shaft in the select direction in a condition where the
shift head was shifted to the low or high speed side, for
deactivating the second actuator when the movement of the
shift-and-select lever in the select direction was restricted by
engagement with the shift head shifted to the low or high speed
side, for reading out an output value of the selection-stroke
sensor when the second actuator was deactivated, and for setting a
selection gate position of the shift head shifted to the low or
high speed side on a basis of the output value of the
selection-stroke sensor.
2. An apparatus for setting selection gate positions for change
speed in a gear-shift mechanism as claimed in claim 1, wherein the
program memory of the electronic controller is arranged to store
instructions for activating the second actuator to effect movement
of the interlock member with the changeover shaft in the selection
direction in a condition where the shift head was shifted to the
low or high speed side, for deactivating the second actuator when
the movement of the interlock member in the select direction was
restricted by engagement with the shift head shifted to the low or
high speed side.
3. An apparatus for setting selection gate positions for change
speed in a gear-shift mechanism as claimed in claim 1, wherein the
first and second actuators each are in the form of a hydraulic
actuator.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an automatic gear
transmission and more particularly to an apparatus for setting
selection gate positions for change speed in a gear-shift mechanism
of the automatic gear transmission.
[0003] 2. Discussion of the Prior Art
[0004] In a conventional gear-shift mechanism of an automatic gear
transmission including a changeover shaft mounted within a housing
of the gear transmission for both axial and rotary movements to be
axially shifted from a neutral position to a forward or reverse
position in a select direction and to be rotated at its shifted
position in shifting operation, a shift-and-select lever fixed to
an intermediate portion of the changeover shaft for axial and
rotary movements therewith, an interlock member rotatably mounted
in place on the changeover shaft and having a pair of interlock
arms located at the opposite sides of the shift-and-select lever,
detent means for restricting rotary movement of the interlock
member and for permitting axial movement of the interlock member, a
plurality of fork shafts mounted in parallel within the housing for
axial movement in a shift direction perpendicular to the select
direction, a plurality of shift forks mounted on the fork shafts to
be selectively engaged with each sleeve of a plurality of
changeover mechanisms for selectively establishing a plurality of
change-speed gear trains in the gear transmission, a plurality of
shift heads mounted on the fork shafts to be selectively engaged
with the shift-and-select lever at their neutral positions, the
shift-and-select lever is selectively engaged with one of the shift
heads at a selection gate position and moved to a low or high speed
side during which the other shift heads are retained in their
neutral positions by engagement with the interlock arms. If the
selection gate position was deviated from a proper position for
engagement with the selected shift head, the shift-and-select lever
would be brought into frictional contact with the other shift head
adjacent thereto during movement to the low or high speed side or
would not be moved due to contact with the other shift head.
SUMMARY OF THE INVENTION
[0005] It is, therefore, a primary object of the present invention
to provide an apparatus for accurately setting selection gate
positions for change speed in the gear-shift mechanism without
causing any problems described above.
[0006] According to the present invention, the object is
accomplished by providing an apparatus for setting selection gate
positions for change speed in a gear-shift mechanism of an
automatic gear transmission including a changeover shaft mounted
within a housing of the gear transmission for both axial and rotary
movements to be axially shifted from a neutral position to a
forward or reverse position in a select direction and to be rotated
at its shifted position in shifting operation, a shift-and-select
lever fixed to an intermediate portion of the changeover shaft for
axial and rotary movements therewith, an interlock member rotatably
mounted in place on the changeover shaft and having a pair of
interlock arms located at the opposite sides of the
shift-and-select lever, detent means for restricting rotary
movement of the interlock member and for permitting axial movement
of the interlock member, a plurality of fork shafts mounted in
parallel within the housing for axial movement in a shift direction
perpendicular to the select direction, a plurality of shift forks
mounted on the fork shafts to be selectively engaged with each
sleeve of a plurality of changeover mechanisms for selectively
establishing a plurality of change-speed gear trains in the gear
transmission, a plurality of shift heads mounted on the fork shafts
to be selectively engaged with the shift-and-select lever at their
neutral positions, a first actuator operatively connected to the
changeover shaft for effecting rotary movement of the changeover
shaft when activated under control of an electronic controller, a
shift-stroke sensor for detecting operation of the first actuator,
a second actuator operatively connected to the changeover shaft for
effecting axial movement of the changeover shaft in the select
direction when activated under control of the electronic
controller, and a selection-stroke sensor for detecting operation
of the second actuator, wherein the electronic controller comprises
a program memory storing instructions for activating the first
actuator such that the shift-and-select lever is rotated to shift
one of the shift heads engaged therewith in its neutral position to
a low or high speed side in the shift direction, for activating the
second actuator to effect movement of the shift-and-select lever
with the changeover shaft in the select direction in a condition
where the shift head was shifted to the low or high speed side, for
deactivating the second actuator when the movement of the
shift-and-select lever in the select direction was restricted by
engagement with the shift head shifted to the low or high speed
side, for reading out an output value of the selection-stroke
sensor when the second actuator was deactivated, and for setting a
selection gate position of the shift head shifted to the low or
high speed side on a basis of the output value of the
selection-stroke sensor.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Other objects, features and advantages of the present
invention will be more readily appreciated from the following
detailed description of preferred embodiments thereof when taken
together with the accompanying drawings, in which:
[0008] FIG. 1 is a block diagram showing the whole components of an
automatic gear transmission in accordance with the present
invention;
[0009] FIG. 2 illustrates a shift-pattern of a gear-shift mechanism
in the gear transmission;
[0010] FIG. 3 is a schematic illustration of a group of switches
associated with a shift lever in the gear-shift mechanism;
[0011] FIG. 4 is a skeleton view illustrating change-speed gear
trains in the gear transmission;
[0012] FIG. 5 is a vertical sectional view of the gear-shift
mechanism;
[0013] FIG. 6 is a sectional view taken along line 6-6 in FIG.
5;
[0014] FIG. 7 is a sectional view taken along a fork-shaft for
1.sup.st-2.sup.nd speeds and a fork-shaft for reverse drive in the
gear transmission;
[0015] FIG. 8 is a flow chart of a program executed for setting a
selection gate position;
[0016] FIG. 9 is a flow chart of a first part of a modification of
the program shown in FIG. 8; and
[0017] FIG. 10 is a flow chart of a second part of the modification
of the program.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0018] FIG. 1 of the drawings, there is schematically illustrated
the whole components of an automatic gear transmission in
accordance with the present invention. In FIG. 1, the reference
numeral 1 designates a switch portion for detecting a change-speed
gear train selected by operation of a manual shift lever 2 and for
applying an electric signal indicative of the selected gear train
to an electronic controller 3 in the form of a microcomputer for
control of the gear transmission. The shift lever 2 is supported in
place to be shifted by a driver in a shift-pattern shown in FIG. 2.
The reference numeral 4 designates the gear transmission with
change-speed gear trains of forward six steps and a reverse step
which are changed over by means of a gear-shift mechanism 5.
[0019] As shown in FIG. 3, the shift lever 2 is mounted on a
housing 10 of the gear transmission. The reference numerals 11-17
designate a group of switches mounted within the gear transmission
housing 10 and opposed to a lower end of the shift lever 2. The
switches 11-17 are connected to the electronic controller 3. When
the shift lever 2 is selectively shifted to 1.sup.st to 6.sup.th
speed positions of the shift pattern shown in FIG. 2, the switches
11-16 are selectively turned on by engagement with the lower end of
the shift lever 2. When the shift lever 2 is shifted to a reverse
position Rev of the shift pattern, the switch 17 is turned on by
engagement with the lower end of the shift lever 2. Thus, when the
shift lever 2 is shifted in accordance with the driving condition
of the vehicle, a selected gear train is detected by on-operation
of either one of the switches 11-17, and an electric signal
indicative of the selected gear train is applied to the electronic
controller 3.
[0020] As shown in FIG. 4, the gear transmission 4 includes a
changeover mechanism 20 in which a sleeve 22 is coupled with a hub
member 21 fixed to an output shaft B for reciprocal movement in an
axial direction. First and second speed gears 23, 24 are rotatably
mounted on the output shaft B at opposite sides of the hub member
21 and positioned in place for transmitting a drive power from an
input shaft A to the output shaft B. When shifted to a right-hand
first speed position, the sleeve 22 is brought into engagement with
a clutch gear 26 fixed to the first speed gear 23 through a
synchronizer (not shown) to establish a first speed gear train.
When shifted to a left-hand second speed position, the sleeve 22 is
brought into engagement with a clutch gear 27 fixed the second
speed gear 24 through a synchronizer (not shown) to establish a
second speed gear train. When retained in neutral position, the
sleeve 22 is disengaged from the clutch gears 26 and 27 to
disconnect the first and second speed gears 23 and 24 from the
output shaft B. Each sleeve of changeover mechanisms 30 and 31 is
mounted on the output shaft B in the same manner as in the
changeover mechanism 20 to selectively establish a third or fourth
speed gear train and to selectively establish a fifth or sixth
speed gear train. Similarly, a sleeve of a changeover mechanism 32
is mounted on the output shaft B to establish a reverse gear
train.
[0021] When the sleeve of the changeover mechanism 30 for third and
fourth speed gears is shifted to a left-hand fourth speed position,
the sleeve is brought into engagement with a clutch gear 33 fixed
to the input shaft A to establish a direct drive connection between
the input and output shafts A and B. A gear train 34 is arranged to
provide drive connection between the input shaft A and a counter
shaft C. Except for the fourth speed, the rotation of input shaft A
is transmitted to the output shaft B through the gear train 34,
counter shaft C and the corresponding changeover mechanism.
[0022] As shown in FIGS. 5 to 7, the gear-shift mechanism 5
includes a fork shaft 40 for 1.sup.st-2.sup.nd speeds, a fork shaft
41 for 3.sup.rd-4.sup.th speeds, a fork shaft 42 for
5.sup.th-6.sup.th speeds and a fork shaft 43 for reverse drive
which are mounted in parallel to each other within an upper portion
44 of the transmission housing 10. As shown in FIG. 6, a shift fork
45 for 1.sup.st-2.sup.nd speed is fixed to the fork shaft 40 and
maintained in engagement with an annular groove formed on the
sleeve 22 of the changeover mechanism 20 to selectively shift the
sleeve 22 to the first speed, neutral and second speed portions. As
shown in FIG. 7, the fork shaft 40 is formed with recesses 51-53
which are selectively engaged with a detent ball 49 loaded by a
coil spring 50 when the fork shaft 40 is selectively shifted to the
first speed, neutral and second speed positions. Similarly, shift
forks 46 and 47 for 3.sup.rd-4.sup.th speeds and for
5.sup.th-6.sup.th speeds are respectively fixed to the fork shaft
41 and 42 and maintained in engagement with each annular groove
formed on the sleeves of the changeover mechanisms 30 and 31 to
selectively shift the sleeves to the third speed, neutral and
fourth speed positions and to fifth speed, neutral and sixth speed
positions. The fork shafts 41 and 42 are retained in their shifted
positions by means of a detent mechanism (not shown) as in the fork
shaft 40. As shown in FIG. 7, a shift fork 48 for reverse drive is
fixed to the fork shaft 43 and slidably supported by the fork shaft
40 for 1.sup.st-2.sup.nd speeds. The shift fork 48 is engaged with
an annular groove formed on the sleeve of the changeover mechanism
32. The fork shaft 43 is retained in its shifted position by means
of a detect mechanism 54.
[0023] Shift heads 55-58 are fixed to the fork shafts 40-43
respectively at the opposite side of the fork shafts. The shift
heads 55-58 are formed with recessed portions 59-62 respectively
which are selectively brought into engagement with a
shift-and-select lever 66. When all the fork shafts 40-43 are
retained in their neutral positions, the recessed portions 59-62 of
shift heads 55-58 are aligned in a select direction perpendicular
to the fork shafts 40-43.
[0024] A changeover shaft 65 is mounted within the upper portion 44
of the gear transmission housing 10 for both axial and rotary
movements and is placed in the select direction. The
shift-and-select lever 66 and a lever 67 for reverse drive are
fixed to the changeover shaft 65 and located at the backside of the
shift forks 45-48. A drive arm 68 is fixed at one end thereof to a
rear end of the changeover shaft 65 and connected at the other end
thereof to a drive shaft 69 arranged in parallel with the
changeover shaft 65. A drive fork 70 is maintained in engagement
with the drive shaft 69 and is moved by a hydraulic actuator 71 to
effect rotary movement of the changeover shaft 65. When the
changeover shaft 65 is rotated by the drive fork 70, an arm 73 of
the shift-and-select lever 66 and the lever 67 for reverse drive
are moved in a shift direction parallel with the fork shafts 40-43
to be selectively retained at their low-speed, neutral and
high-speed positions. Fluid chambers 71a, 71b of the hydraulic
actuator 71 are connected to a hydraulic pump P through a linear
solenoid changeover valve 101 and a regulator valve 102. Thus, a
shift-drive mechanism is composed of the changeover shaft 65, drive
arm 68, drive shaft 69, drive fork 70 and hydraulic actuator 71 for
shifting the arm 73 of shift-and-select lever 66 in the shift
direction. A shift-stroke sensor 72 is provided as a shift-stroke
detection means to detect a displaced position of the piston of
hydraulic actuator 71 and to detect a shifted position of the arm
73 of shift-and-select lever 66. An output of the shift-stroke
sensor 72 is applied as a feedback signal to the electronic
controller 3 through an A-D converter (not shown).
[0025] A hydraulic actuator 75 is connected to the rear end of
changeover shaft 65 to move the arm 73 of shift-and-select lever 66
in the select direction. Fluid chambers 75a, 75b of hydraulic
actuator 75 are connected to the hydraulic pump P through a linear
solenoid changeover valve 103 and a regulator valve 104. In a
condition where all the fork shafts 40-43 are retained in their
neutral positions, the recessed portions 59-62 of shift heads 55-58
are aligned in the select direction to permit the movement of the
arm 73 of shift-and-select lever 66 in the select direction. In
such a condition, the changeover shaft 65 is moved rightward by
activation of the hydraulic actuator 75 to bring the arm 73 of
shift-and-select lever 66 selectively into engagement with any one
of the recessed portions 59, 60 and 61 of shift heads 55-57 located
at gate-positions for 1.sup.st-2.sup.nd, 3.sup.rd-4.sup.th and
5.sup.th-6.sup.th speeds. When the changeover shaft 65 is further
moved rightward by activation of the hydraulic actuator 75, the
lever 67 for reverse drive is brought into engagement with the
recessed portion 62 of shift head 58 located at a gate-position for
reverse drive. Thus, a select-drive mechanism is composed of the
changeover shaft 65 and hydraulic actuator 75 for moving the arm 73
of shift-and-select lever 66 in the select direction. A
selection-stroke sensor 76 is provided as a selection-stroke
detection means to detect a displaced position of the piston of
hydraulic actuator 75 and to detect a shifted position of the arm
73 of shift-and-select lever 66. An output of the selection-stroke
sensor 76 is applied as a feedback signal to the electronic
controller 3 through an A-D converter (not shown).
[0026] A detent mechanism 85 for retaining the shift-and-select
lever 66 in its neutral position includes a detent ball 87 in
engagement with an axial groove 86 formed on the backside of
shift-and-select lever 66 in the select direction, a holder 88
slidably mounted within the upper portion 44 of the gear
transmission housing 10 for retaining the detent ball 87 in
engagement with the axial groove 86, and a coil spring 89 provided
to bias the detent ball 87 toward the backside of shift-and-select
lever 66 through the holder 88. An interlock member 90 is formed to
enclose the shift-and-select lever 66 and is mounted in place on
the changeover shaft 65 to selectively restrict shift movement of
the shift heads 55-57. The interlock member 90 is integrally formed
at the lower portion thereof with a pair of interlock arms 92 which
are located at the opposite sides of the arum 73 of
shift-and-select lever 66 to be brought into engagement with the
shift heads 55-57. The interlock member 90 is formed at the upper
portion thereof with an axial hole 93 in which the holder 88 of
detent mechanism 85 extends to restrict rotary movement of the
interlock member 90 and to permit axial movement of the interlock
member 90 in the select direction.
[0027] Assuming that the shift lever 22 has been shifted to the
fifth speed position, the switch 15 is turned on by engagement with
the lower end of shift lever 22. When applied with an output signal
from the switch 15, the electronic controller 3 activates a driving
circuit 110 to control the linear solenoid valve 103 in such a
manner that the hydraulic actuator 75 is operated to move the
changeover shaft 65 rightward in the select direction thereby to
bring the arm 73 of shift-and-select lever 66 into engagement with
the recessed portion 61 of shift head 57. In this instance, the
shifted position of the arm 73 of shift-and-select lever 66 is
detected by the selection-stroke sensor 76, and a signal indicative
of the detected position is applied as a feedback signal to the
electronic controller 3 through the A-D converter. Thus, the arm 73
of shift-and-select lever 66 is accurately engaged with the
recessed portion 61 of shift head 57 at the selected gate. When the
arm 73 of shift-and-select lever 66 is engaged with the recessed
portion 61 of shift head 57, the driving circuit 110 is activated
under control of the electronic controller 3 to control the linear
solenoid valve 101 in such a manner that the hydraulic actuator 71
is operated to rotate the changeover shaft 65 thereby to shift the
arm 73 of shift-and-select lever 66 to the low speed side. Thus,
the shift head 57, fork shaft 42 and shift fork 47 are moved to
shift the sleeve of the changeover mechanism 31 to the fifth speed
position.
[0028] To accurately shift the arm 73 of shift-and-select lever 66
to each selection gate for 1.sup.st-2.sup.nd, 3.sup.rd-4.sup.th and
5.sup.th-6.sup.th speeds and to accurately shift the lever 67 for
reverse drive to a reverse drive gate, it is required to memorize
each selection gate position detected by the select-stroke sensor
76 when the ann 73 of shift-and-select lever 66 and the lever 67
for reverse drive have been accurately positioned for the
change-speeds and reverse drive during an assembly process of the
automatic gear transmission. In this embodiment, each selection
gate position for the change-speeds and reverse drive is set by
execution of a program shown by a flow chart in FIG. 8 as described
hereinafter.
[0029] In general, the automatic gear transmission is assembled in
such a manner that the fork shafts 40-43 are retained in their
neutral positions to align all the recessed portions 59-62 of shift
heads 55-57 in the select direction and that the shift-and-select
lever 66 is retained in its neutral position to maintain the lever
67 for reverse drive in engagement with an internal wall of the
upper portion of transmission housing 10. In such a condition, the
arm 73 of shift-and-select lever 66 is engaged with the recessed
portion 59 of shift head 55 fixed to the fork shaft 40 for
1.sup.st-2.sup.nd speeds and coarsely positioned at a selection
gate position for 1.sup.st-2.sup.nd speeds.
[0030] During the assembly process of the automatic gear
transmission described above, the program for setting the selection
gate positions is initialized at step 111. In this instance, the
linear solenoid valves 101, 103 are deactivated to maintain the
hydraulic actuators 71 and 75 respectively in an unloaded
condition, and the regulator valves 102 and 104 are set at a low
pressure suitable for setting each selection gate position. Thus,
the number of the selection gate position is memorized as N=1 in a
memory of the electronic controller 3, and an output value of the
stroke-sensor 72 is read out by the electronic controller 3 at step
112 for setting a neutral position SiC of the arm 73 of
shift-and-select lever 66 in the shift direction.
[0031] At step 113, the electronic controller 3 issues an
instruction signal for shifting the arm 73 of shift-and-select
lever 66 to a low speed side in the shift direction at a low speed,
and the driving circuit 110 activates the linear solenoid valve 101
under control of the electronic controller 3 so that the fluid
chamber 71a of hydraulic actuator 71 is supplied with fluid under
pressure from the pump P to shift the arm 73 of shift-and-select
lever 66 to the low speed side. At the following step 114, the
electronic controller 3 issues an instruction signal for shifting
the arm 73 of shift-and-select lever 66 rightward (to a high speed
side) in FIG. 5 in the select direction at a low speed, and the
driving circuit 110 activates the linear solenoid valve 103 under
control of the electronic controller 3 so that the fluid chamber
75a of hydraulic actuator 75 is supplied with fluid under pressure
from the pump P to shift the arm 73 of shift-and-select lever 66
rightward. As the arm 73 of shift-and-select lever 66 at an initial
condition is slightly displaced leftward from the proper selection
gate position for 1.sup.st-2.sup.nd speeds, the right-hand
interlock arm 92 is placed in the recessed portion 59 of shift head
55. In such a condition, the movement of the arm 73 of
shift-and-select lever 66 in the shift direction is blocked by the
right-hand interlock arm 92 when the arm 73 of shift-and-select
lever 66 is shifted to the low speed side. When the arm 73 of
shift-and-select lever 66 is moved rightward with the interlock
member 90 in the select direction, the right-hand interlock arm 92
is disengaged from the recessed portion 59 of shift head 55, and
the arm 73 of shift-and-select lever 66 is shifted to the low speed
side.
[0032] When the arm 73 of shift-and-select lever 66 is further
moved rightward by operation of the hydraulic actuator 75, the
rightward movement of left-hand interlock arm 92 is restricted by
engagement with the shift head 55 for 1.sup.st-2.sup.nd speeds
shifted to the low speed side. The shift of the arm 73 of
shift-and-select lever 66 to the low speed side is read out by the
electronic controller 3 based on the output value of stroke sensor
72 and determined at step 115 by the fact that a low speed position
SiL added with a space between the neutral position and the low
speed position becomes the neutral position SiC previously
memorized. The shift of the arm 73 of shift-and-select lever 66 may
be determined by the fact that the output value of stroke-sensor 72
does not change despite of lapse of a predetermined time .DELTA.t.
The fact that the rightward movement of left-hand interlock arm 92
in the select direction was restricted by engagement with the shift
head 55 is determined by the fact that the output value of
stroke-sensor 76 does not change despite of lapse of the
predetermined time .DELTA.t.
[0033] When the shift of the arm 73 of shift-and-select lever 66 to
the low speed side is confirmed, the linear solenoid valve 101 is
deactivated under control of the electronic controller 3 at step
117, and the hydraulic actuator 71 is unloaded. When the engagement
of the left-hand interlock arm 92 with the shift head 55 is
confirmed, the linear solenoid valve 103 is deactivated under
control of the electronic controller 3 at step 118, and the
hydraulic actuator 75 is unloaded to release resilient deformation
of the interlock member 91, shift head 55 and fork shaft 40. In
such a condition, an output value Sel of stroke sensor 76 is
memorized in the memory of electronic controller 3 at step 119.
Thus, a difference .DELTA.e between the position of the interlock
arm 92 in engagement with the shift head 55 and the selection gate
position for 1.sup.st-2.sup.nd speeds is subtracted from the output
value Sel of stroke-sensor 76, and a resultant value Sel-.DELTA.e
of the subtraction is memorized as the selection gate position for
1.sup.st-2.sup.nd speeds in the memory of electronic controller 3
at step 120. At step 121, the linear solenoid valve 101 is
activated under control of the electronic controller 3 to supply
fluid under pressure into the fluid chamber 71b of hydraulic
actuator 71 thereby to return the arm 73 of shift-and-select lever
66 to the neutral position. The return of shift-and-select lever 66
to the neutral position is confirmed by the fact that the output
value of stroke-sensor 72 becomes SiC.
[0034] For positioning the arm 73 of shift-and-select lever 66 in
the selection gate position for 3.sup.rd-4.sup.th speeds, the
electronic controller 3 issues at step 122 an instruction signal
for moving the arm 73 of shift-and-select lever 66 rightward in a
distance E-.DELTA.e defined by a difference between a distance E
spaced from the selection gate position and the difference .DELTA.e
described above. When applied with the instruction signal, the
linear solenoid valve 103 is activated under control of the
controller 3 to supply fluid under pressure into the fluid chamber
75a of hydraulic actuator 75 thereby to move the arm 73 of
shift-and-select lever 66 rightward. When the rightward movement of
shift-and-select lever 66 in the distance E-.DELTA.e is confirmed
by the output value of stroke-sensor 76, the linear solenoid valve
103 is deactivated under control of the electronic controller 3. In
this instance, the controller 3 determines whether the number of
the memorized selection gate position is defined as N=4 or not. As
the answer is "No", the content of the memory is set as N=2.
Subsequently, the electronic controller 3 repeats the execution of
processing at step 113-124 for setting each selection gate position
for 3.sup.rd-4.sup.th speeds, 5.sup.th-6.sup.th speeds and reverse
drive in the same manner as described above. When the selection
gate position for reverse drive has been set, the number of the
selection gate position memorized in the memory is defined as N=4,
and the execution of the program for setting the selection gate
positions is finished.
[0035] Hereinafter, a modification of the program for setting the
selection gate positions will be described with reference to flow
charts shown in FIGS. 9 and 10. Assuming that the engagement of the
left-hand interlock arm 92 with the shift head 55 has been
confirmed at step 116, the linear solenoid valve 103 is deactivated
at step 118 under control of the electronic controller 3. In this
instance, the controller 3 reads out an output value Sel.sub.LH of
stroke-sensor 76 at step 130 and issues at step 131 an instruction
signal for moving the arm 73 of shift-and-select lever 66 leftward
in FIG. 5 in the select direction at a low speed. In response to
the instruction signal, the driving circuit 110 activates the
linear solenoid valve 103 under control of the controller 3 to
supply fluid under pressure into the fluid chamber 75b of hydraulic
actuator 75 for moving the arm 73 of shift-and-select lever 66
leftward. When the arm 73 of shift-and-select lever 66 is moved
leftward, movement of right-hand interlock arm 92 in the select
direction is restricted by engagement with the shift head 55 for
1.sup.st-2.sup.nd speeds shifted to the low speed side. The fact
that the movement of shift-and-select lever 66 in the select
direction has been restricted is determined at step 132 by the fact
that the output value of stroke-sensor 76 does not change despite
of lapse of the predetermined time. When the engagement of
right-hand interlock arm 92 with the shift head 55 is confirmed,
the linear solenoid valve 103 is deactivated under control of the
electronic controller 3, and the hydraulic actuator 75 is unloaded
at step 133 to release resilient deformation of the interlock
member 91, shift head 55 and fork shaft 40. In such a condition,
the output value Sel.sub.LL of stroke-sensor 76 is memorized in the
memory of controller 3 at step 134. Thus, an average value
Sel.sub.L of the output values Sel.sub.LH and Sel.sub.LL is
calculated as a first gate position at the low speed side at step
135.
[0036] At step 136, the electronic controller 3 issues an
instruction signal for shifting the arm 73 of shift-and-select
lever 66 to a high speed side in the shift direction at a low
speed. In response to the instruction signal, the driving circuit
110 activates the linear solenoid valve 101 under control of the
controller 3 to supply fluid under pressure into the fluid chamber
71b of hydraulic actuator 71 thereby to shift the shift-and-select
lever 66 to the high speed side. The shift of the arm 73 of shift
-and-select lever 66 to the high speed side is read out by the
electronic controller 3 based on an output value of stroke sensor
72 and determined at step 137 by the fact that a high speed
position SiH added with a space between the neutral position and
the high speed position becomes the neutral position SiC previously
memorized. The shift of the arm 73 of shift-and-select lever 61 may
be determined by the fact that the output value of stroke-sensor 72
does not change despite of lapse of the predetermined time
.DELTA.t.
[0037] When the shift of the arm 73 of shift-and-select lever 66 to
the high speed side is confirmed, the linear solenoid valve 101 is
deactivated under control of the electronic controller 3, and the
hydraulic actuator 71 is unloaded at step 138. Subsequently, the
electronic controller 3 issues at step 139 an instruction signal
for moving the arm 73 of shift-and-select lever 66 rightward in
FIG. 5 in the select direction at a low speed. In response to the
instruction signal, the driving circuit 110 activates the linear
solenoid valve 103 to supply fluid under pressure into the fluid
chamber 75a of hydraulic actuator 75 thereby to move the arm 73 of
shift-and-select lever 66 rightward. In this instance, the
rightward movement of shift-and-select lever 66 is restricted by
engagement with the shift head 55 for 1.sup.st-2.sup.nd speeds
shifted to the high speed side. The restriction of rightward
movement of shift-and-select lever 66 is determined at step 140 by
the fact that the output value of stroke-sensor 76 does not change
despite of lapse of the predetermined time .DELTA.t. When the
engagement of the left-hand interlock arm 92 with the shift head 55
is confirmed, the linear solenoid valve 103 is deactivated under
control of the controller 3, and the hydraulic actuator 75 is
deactivated at step 141. In such a condition, the output value Sell
of stroke-sensor 76 is memorized in the memory of electronic
controller 3 at step 142.
[0038] At the following step 143, the electronic controller 3
issues an instruction signal for moving the arm 73 of
shift-and-select lever 66 leftward in FIG. 5 in the select
direction at a low speed. In response to the instruction signal,
the driving circuit 110 activates the linear solenoid valve 103 to
supply fluid under pressure into the fluid chambe 75b of hydraulic
actuator 75 thereby to shift the arm 73 of shift-and-select lever
66 leftward. In this instance, the leftward movement of right-hand
interlock arm 92 is restricted by engagement with the shift head 55
for 1.sup.st-2.sup.nd speeds shifted to the high speed side. The
restriction of leftward movement of right-hand interlock arm 92 is
determined at step 144 by the fact that the output value of
stroke-sensor 76 does not change despite of lapse of the
predetermined time .DELTA.t. When the engagement of right-hand
interlock arm 92 with the shift head 55 is confirmed, the linear
solenoid valve 103 is deactivated under control of the electronic
controller 3, and the hydraulic actuator 75 is unloaded at step
145. In such a condition, an output value Sel.sub.HL of stroke
sensor 76 is memorized in the memory of controller 3 at step 146,
and an average value Sel.sub.H of the output values Sel.sub.HH and
Sel.sub.HL is calculated as a first gate position at the high speed
side at step 147. Thus, an average value Sel of the value SeL
indicative of the first gate position at the low speed side and the
value SelH indicative of the first gate position at the high speed
side is memorized as the selection gate position for
1.sup.st-2.sup.nd speeds in the memory of controller 3 at step
148.
[0039] At the following step 149, the linear solenoid valve 101 is
activated under control of the electronic controller 3 to supply
fluid under pressure into the fluid chamber 71a of hydraulic
actuator 71 thereby to shift the arm 73 of shift-and-select lever
66 to the neutral position until the output value of stroke-sensor
72 becomes the value indicative of the neutral position SiC.
Subsequently, the electronic controller 3 issues at step 150 an
instruction signal for positioning the arm 73 of shift-and-select
lever 66 in the selection gate position for 3.sup.rd-4.sup.th
speeds. When applied with the instruction signal, the driving
circuit 110 activates the linear solenoid valve 103 to supply fluid
under pressure into the fluid chamber 75a of hydraulic actuator 75
thereby to shift the arm 73 of shift-and-select lever 66 rightward.
When the arm 73 of shift-and-select lever 66 is shifted rightward
in a distance E spaced from the adjacent selection gate position in
the select direction, the linear solenoid valve 103 is deactivated
under control of the controller 3, and the hydraulic actuator 71 is
unloaded. Thus, the electronic controller 3 determines at step 151
whether the number of the memorized selection gate position is
defined as N=4 or not. As the answer is "No", the content of the
memory is set as N=2. Subsequently, the electronic controller 3
repeats the execution of processing at step 113-152 for setting
each selection gate position for 3.sup.rd-4.sup.th speeds,
5.sup.th-6.sup.th speeds and reverse drive in the same manner as
described above. When the selection gate position for reverse drive
has been set, the number of the selection gate position memorized
in the memory is defined as N=4, and the execution of the program
for setting the selection gate positions is finished.
[0040] Since in the modification, the movement ends of the arm 73
of shift-and-select lever 66 to the high and low speed sides at
each selection gate position for change speed are detected for
setting a center of the movement ends as the selection gate
position, accurate setting of the selection gate position can be
effected. In the modification, the selection gate positions at the
low and high speed sides are calculated for setting an average
value of them as each selection gate position. This is useful for
setting each selection gate position properly at the low and high
speed sides.
* * * * *