Automatic speed-change apparatus for a gear transmission

The object is to provide a small-sized speed-change apparatus for performing the automatic gear shifting of the conventional gear transmission. In the speed-change apparatus 1, the select mechanism comprises a select motor 6 controllable for forward and backward rotation, gears 7, 8 for transmitting the rotation, a select-shift shaft 11 to be rotated forward and backward through said gears 7, 8 and connected with the select-shift rod 5 of the gear transmission M; and the shift mechanism comprises a piston 12 for moving the select-shift shaft 11 in the axial direction, hydraulic chambers 13, 14 accommodating the piston 12 and a shift-operating hydraulic-pressure generator for supplying the hydraulic oil through hydraulic tubes into the hydraulic chambers 13, 14.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an automatic speed-change apparatus for a 
gear transmission. 
2. Description of the Prior Art 
In the prior art, there has been developed an apparatus in which the 
mechanism for a manual gear transmission is used as it is and the speed 
change operation is automated through a hydraulic apparatus by a computer 
control. However, it requires three cylinders for clutching, shifting and 
selecting, and a number of solenoid valves to actuate these cylinders, so 
that it has such problems as complicated structure, large size and high 
cost. 
Also, a speed-change apparatus in which motors are used as actuators to 
select or shift the gear transmission has been disclosed in JP publication 
Toku-ko-sho 61-51497, for example. However, this apparatus requires 
certain numbers of motors depending on the numbers of the select lines, 
and because of using a plurality of motors or solenoids, it results in a 
complicated structure and large size apparatus and further in high cost. 
SUMMARY OF THE INVENTION 
Accordingly, the present invention has been developed in order to solve the 
above problems in the prior art, and an object of the invention is to 
provide an automatic speed-change apparatus which is formed in a small 
size and can be disposed in a narrow space. 
Another object of the present invention is to provide an automatic 
speed-change apparatus which is supplied with hydraulic fluid from a 
hydraulic pressure generator properly arranged at a position separated 
from itself. 
The preceeding objects are accomplished in an automatic speed-change 
apparatus for a gear transmission having a select-shift rod extended out 
thereof; said automatic speed-change apparatus connected with said 
select-shift rod for performing automatic shift operation of said gear 
transmission by converting driving force of motors into the rotational and 
the axial movement of said select-shift rod to transmit the movement to 
the shift fork of the transmission; said automatic speed-change apparatus 
provided with a select mechanism for performing the select operation and a 
shift mechanism for performing the shift operation; said select mechanism 
comprising a select motor controllable for forward and backward rotation, 
gears for transmitting the rotation, a select-shift shaft to be rotated 
forward and backward through said gears and connected with said 
select-shift rod; and said shift mechanism comprising a piston for moving 
said select-shift shaft in the axial direction, a hydraulic chamber 
accommodating said piston, and a shift-operating hydraulic-pressure 
generator for supplying the hydraulic oil through hydraulic tubes into 
said hydraulic chamber.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
With reference to the accompanying drawings, a preferred embodiment of the 
present invention will be described hereinafter. 
FIG.1 is a schematic arrangement of an automatic speed-change apparatus 1 
for automatically performing the speed change of a conventional gear 
transmission M installed below a floor F of a cockpit R in an automobile 
and a shift-operating haydralic pressure generator 2 for supplying 
hydraulic fluid to the apparatus 1. The automatic speed-change apparatus 1 
is connected directly with a select-shift rod 5 extended out of the gear 
transmission M and disposed in the narrow lower part of the space. The 
shift-operating hydraulic pressure generator 2 is disposed in the 
comparatively wide upper part of the space. The automatic speed-change 
apparatus 1 and the shift-operating hydraulic pressure generator 2 are 
communicated with each other by a first hydraulic tube 3 and a second 
hydraulic tube 4. 
That is to say, since the automatic speed-change apparatus 1 of the 
invention can be formed of small size, it can be compactly disposed in a 
narrow space in a lower part of an automobile. On the other hand, the 
shift-operating hydraulic pressure generator 2 of comparatively large size 
is disposed in comparatively broad space in an upper part of the 
automobile. They are communicated with each other by the hydraulic tubes 
3, 4 which are possible to make free layout of tubing, and installed 
compactly as a whole below the floor F. 
Incidentally, in the gear transmission M, by rotating the extended 
select-shift rod 5 on its axis, a shifting line is selected within the 
gear transmission M, as shown in a diagram of the select operation of 
FIG.5. As shown in FIG.5, by rotating the select-shift rod clockwise on 
its axis, the low or the second speed position can be selected, and also 
by rotating it counterclockwise, the fifth speed position can be selected, 
and by putting it on the center shifting line, the third or the fourth 
speed position can be selected. 
After a shifting line in the transmission is selected as described above, 
by moving the select-shift rod 5 in the axial direction, the shift fork in 
the transmission is subsequently moved, and the innner gear is shifted in 
the required low or second position, for example, as shown in a diagram of 
the shift pattern of FIG.6. Thus, the speed-change operation can be 
completed. 
The automatic speed-change apparatus 1 is directly conneceted with the 
select-shift rod 5 extended out of this gear transmission M. Within the 
apparatus 1 is provided a select-shift shaft 11 coaxially connected with 
the select-shift rod 5, as shown in FIG.1 and FIG.2. Also, there is 
provided a select motor 6 that is controllable for forward and backward 
rotation and has a select drive gear 7 fixedly provided on the motor 
shaft. This select drive gear 7 is rotatable through a bearing provided on 
the housing H. On the outer portion of the select drive gear 7 projected 
out of the bearing is provided a select sensor 15 coaxially with the gear 
7. This select sensor 15 is adapted to detect an angle of rotation of the 
select motor 6. With the select drive gear 7 is meshed a select driven 
gear 8 which is integrally provided on a cylindrical member 9 and formed 
in a sectorial shape. The cylindrical member 9 is disposed over the 
periphery of the select-shift shaft 11. In a spline 9a axially formed on 
the inner periphery of the cylindrical member 9 is inserted a slide key 10 
fixed on the outer periphery of the select-shift shaft 11. Consequently, 
the select-shift shaft 11 is axially movable to the cylindrical member 9 
and the rotation of the cylindrical member 9 is transmitted through the 
slide key 10 to the select-shift shaft 11. 
The left end of the select-shift shaft 11, as shown in FIG.2, is connected 
with the select-shift rod 5 of the gear transmission M and the other end 
is extended to the right and connected with a piston 12 disposed in a 
cylinder formed in the housing H. By the piston 12 the interior of the 
cylinder is divided into a first hydraulic chamber 13 and a second 
hydraulic chamber 14, and in the respective chambers are formed operating 
oil gateways 13a, 14a respectively. 
In such a constitution, when the select motor 6 is operated, the select 
drive gear 7, select driven gear 8 and cylindrical member 9 are rotated 
and accordingly the select-shift shaft 11 is rotated on the axis. Thereby, 
the select-shift rod 5 is rotated to select a line of the shift fork 
within the gear transmission N as described above. 
Next, when the operating oil is supplied from the shift-operating 
hydraulic-pressure generator 2 through the hydraulic tubes 3, 4 to any one 
of the first hydraulic chamber 13 and second hydraulic chamber 14, the 
piston 12 is moved in the axial direction, and accordingly the 
select-shift shaft 11 is axially moved to cause the select-shift rod 5 
move in the axial direction. Thereby, the shift fork in the gear 
transmission M is subsequently moved to perform gear shifting. 
Thus, the automatic speed-change apparatus 1 of this invention has a 
compact combination of a select mechanism comprising gears 7, 8 to be 
rotated by a select motor 6 and a select-shift shaft 11 to be rotated 
through the gears 7, 8; and a shift mechanism comprising a piston 12 
provided in hydraulic chambers 13, 14 and the select-shift shaft 11 to be 
axially moved by the piston 12. Consequently, the whole of the apparatus 
can be formed in an extremely small-sized and compact form and disposed 
compactly even in a narrow space. Incidentally, with the operating oil 
gateway 13a is connected the first hydraulic tube 3 and with the operating 
oil gateway 14a is connected the second hydraulic tube 4. 
On the other hand, the shift-operating hydraulic-pressure generator 2 for 
supplying shift-operating oil into the first hydraulic chamber 13 and 
second hydraulic chamber 14 is formed in a structure as shown in the 
sectional view of FIG. 3. The hydraulic-pressure generator 2 is provided 
with a shift motor 20 rotatable forward and backward, and in the ho using 
H is provided a shift drive gear 21 fixed to the shaft of the motor 20. 
With the drive gear 21 is meshed a shift driven gear 22, which is fixed to 
an intermediate shaft 23. To the intermediate shaft 23 is further fixed a 
long shift gear 24 extending in the axial direction. With the long shift 
gear 24 is meshed a shift gear 25, to which is fixed a female screw 26 and 
a slider 27 extending in the axial direction. With the female screw 26 is 
meshed a male screw 28 fixedly fitted on the periphery of a shift shaft 
29. 
The shift shaft 29 is fixed at the left end to the housing H and provided 
on the periphery at the right end with a slide key 30. On the periphery of 
this slid key 30 is provided a sleeve 31 slidably in the axial direction. 
The left end of the sleeve 31 is connected with the right end of the 
slider 27 through an slider bearing 32 interposed. The slider 27 is 
rotatably disposed onto the housing H through a bearing 38. The sleeve 31 
is axially movably disposed on the housing H through a bearing 39. 
With the right end of the sleeve 31 is connected a piston rod 33 extending 
in the right direction, to the end of which is fixed a piston 34. This 
piston 34 is disposed in a cylinder 35 formed in the housing H. The 
interior of the cylinder 35 is divided into a first hydraulic chamber 36 
an d a second hydraulic chamber 37 by the piston 34. In the respective 
hydraulic chambers 36, 37 are provided operating oil gateways 36a, 37a 
respectively. The operating oil gateway 36a is connected with the first 
hydraulic tube 3 and the operating oil gateway 37a is connected with the 
second hydraulic tube 4. 
On the periphery of the shift gear 25 is disposed a slide piece 40, as 
shown in the exploded perspective view of FIG.4, extending over both side 
surfaces of the shift gear 25. This slide piece 40 is axially movably 
mounted on a guide bracket 41 of which one end is fixed to the housing; 
the inside of U-shaped slot 41a of the guide bracket 41 is inserted in 
guide grooves 40a formed in the slide piece 40. The right surface of this 
slide piece 40, shown in the drawing, is brought into contact with a 
contact member 42a extending from a stroke sensor 42. Consequently, this 
stroke sensor 42 is adapted to detect the amount of axial movement of the 
shift gear 25 through the slide piece 40. 
In such a sift-operating hydraulic-pressure generator 2, by operating the 
shift motor 20 the long shift gear 24 is rotated through the shift drive 
gear 21 and shift driven gear 22, and accordingly the shift gear 25 is 
rotated. Since the female screw 26 fixed to this shift gear 25 is meshed 
with the male screw 28, the shift gear 25 is axially moved along the male 
screw 28. Thereby, the slider 27 is axially moved rotating. Since the 
rotating force of the slider 27 is cut by the slider bearing 32, the 
rotating force is not transmitted to the sleeve 31, which is moved only in 
the axial direction. Consequently, the piston rod 33 is axially moved and 
by the axial movement of the piston 34 any one of the first and the second 
hydraulic chamber 36, 37 is compressed, so that the hydraulic oil is 
supplied outside under pressure. As a result, the pressurized operating 
oil is supplied into the first hydraulic chamber 13 or the second 
hydraulic chamber 14 of the automatic speed-change apparatus 1 and the 
sift operation of the apparatus 1 is performed by the hydraulic oil. 
That is, when the select operation is performed, the shift motor 20 is in 
the rest condition and only the select motor 6 is operated to perform the 
select operation. Thereafter, the select motor 6 is stopped, and by 
operating the shift motor 20 the shift operation is performed. 
Although in this embodiment the stroke sensor 42 is adapted to detect the 
axial movement of the shift gear 25, it is possible that the stroke sensor 
42 is arranged so as to detect the amount of axial movement of any one of 
the slider 27, sleelve 31, piston rod 33 or the select shift shaft 11. 
As described above, the shift-operating hydraulic-pressure generator 2 of 
this invention is disposed in a place distant from the automatic 
speed-change apparatus 1 and can automatically perform the select and the 
shift operation of the gear transmission M through the hydraulic tubes 3, 
4 communicating the generator 2 with the apparatus 1. 
Besides, instead of the sift-operating hydraulic-pressure generator 2, it 
is also possible to use a hydraulic pump in order to supply hydraulic oil 
into the first and the second hydraulic chamber 13, 14 of the automatic 
speed-change apparatus 1. This hydraulic pump may be constituted to be 
operated by an engine or an electric motor, and further may be adapted to 
supply the operating oil into the first or the second hydraulic chamber 
13, 14 of the automatic speed-change apparatus 1 by switching of a control 
valve. Also in this case, through a hydraulic tubing the supply of 
hydraulic oil can be performed from the hydraulic pump into the hydraulic 
chambers 13, 14 of the automatic speed-change apparatus 1, so that the 
apparatus 1 is constituted in a small size and disposed in a compact 
arrangement.