Note: Descriptions are shown in the official language in which they were submitted.
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"UNDERGROUND EXCAVATOR n
BACKGROUND OF THE INVENTION
This invention relates to an underground
excavator for excavating an underground in boring tunnels,
sloped shaft and so on through the underground.
The underground excavator of the kind referred
to can be effectively employed in boring the tunnel,
sloped shaft, underground pipe-ways for buried pipes and
so on, by once positioning the excavator in a vertical
shaft bored down into the underground and propelling the
excavator into the ground in, for example, horizontal
direction.
DESCRIPTION OF RELATED ART
In forming the tunnel or the pipe-way for buried
pipes, in general, there has been adopted a method in
which the vertical shaft is formed to a depth at which the
tunnel is to be disposed or the pipes are to be buried,
and then the excavator is propelled into the ground from
this vertical shaft horizontally, but there has been a
problem that, in an event when a propelling force cannot
be supplied in smooth manner, tunnelling course is caused
to be deviated.
In U.S. Patent No. 5,032,039 to Mituwa, for
example, there has been suggested an excavator having a
chamber defined in front portion for collecting excavated
earth, a rotary shaft disposed as passed through the
chamber, an excavating cutter having many tunnel-face
cutting bits on front side part of the rotary shaft, and a
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cutter driver comprising a cutter driving motor and a
reduction gear for providing a power to the excavating
cutter and a propelling force to the excavator.
With the above known excavator, however, there
have been such problems as in the followings:
A. In the case of excavators for large bore
tunnels, the cutter driving motors and reduction gears
have been required to be provided, so that the cutter
driver has been made on a large scale, and costs of
equipment are increased.
B. While a pinion and main gear are employed for
providing a required torque to the cutter section, these
pinion and main gear require high working precision, so
that many hours are required for the manufacturing, and a
~5 long term is required eventually for manufacturing a
shield machine of the excavator so as to render required
duration until the completion of the tunnel to be
remarkably prolonged.
C. Required number of parts for constituting the
cutter driver is increased, a delivery time has to be
extended, and the driver is expensive.
D. It is required to keep a gear case fully
charged with a lubricating oil so that, in the case of the
excavator for the large bore tunnel, a tremendous amount
of the lubricating oil is required, so as to render the
running costs to be high.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention
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is to provide an underground excavator capable of
overcoming the foregoing problems, while remarkably
simplifying the structure of the cutter drive section, and
rendering the cutter section to be rotatively driven with
a drive means of a simpler structure without requiring any
parts of high working precision nor lubricant oil.
According to the present invention, the above
object is realized by means of an underground excavator
wherein a rotary driver of a cutter section is provided at
a rear end portion with a crank, a coupling board is
rotatably mounted to outer periphery of the rear end
portion of the crank, and a plurality of hydraulic jacks
are coupled to the coupling board as mutually spaced in
circumferential direction of the board, the rotary driver
1~ being rotatively driven by means of the plurality of
hydraulic jacks to be thereby provided with an excavation
force.
Other objects and advantages of the present
invention shall become clear as the description of the
invention advances as detailed with reference to
embodiments of the invention shown in accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a schematic vertical, longitudinal
section of underground excavator in an embodiment
according to the present invention;
FIG. 2 is a cross section taken along line
III-III in FIG. 1 of the excavator;
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FIG. 3 is a fragmentary magnified view of a part
encircled by a single dot chain line in FIG. 2;
FIG. 4 is a diagram showing with characteristic
curves the operation of the excavator in FIG. l;
FIG. 5 is a schematic longitudinal section of
another embodiment of the excavator according to the
present inventlon;
FIG. 6 is a cross section taken along line VI-VI
in FIG. 5 of the excavator;
FIG. 7 is a fragmentary magnified view of a part
similar to FIG. 3 of the excavator of FIG. 5;
FIG. 8 is a schematic longitudinal section of
the excavator in another embodiment according to the
present invention;
FIG. 9 is a cross section similar to FIG. 6 of
the excavator shown in FIG. 8;
FIG. 10 is a schematic longitudinal section of
the excavator in another embodiment according to the
present invention;
FIG. 11 is a cross section taken along line
XI-XI in FIG. 10 of the excavator;
FIG. 12 is a schematic longitudinal section of
the excavator in another embodiment according to the
present invention;
FIG. 13 is a cross section taken along line
XIII-XIII in FIG. 12 of the excavator;
FIG. 14 is another cross section of the
excavator in FIG. 12i
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FIG. 15 shows another embodiment of the
invention in a schematic longitudinal section; and
FIG. 16 is a cross section of the embodiment of
FIG. 15.
While the present invention shall now be
described with reference to the respective embodiments
shown in the drawings, it should be appreciated that the
intention is not to limit the invention only to these
embodiments shown but rather to include all alterations,
modifications and equivalent arrangements possible in the
scope of appended claims.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIGS. 1-4, there is shown an
embodiment of the underground excavator according to the
present invention, in which a shield machine 11 of the
underground excavator 10 is provided with a shield machine
body 12, a bulkhead 13, a cutter section 14, a cutter
drive section 15 and a screw conveyor 16 as means for
discharging excavated earth, and shield propelling jacks
17. To a rear end of the shield machine body 12, a tail
seal 18 is provided. To inner wall on a machine chamber
side of the shield machine body 12, brackets l9a-19c are
mounted for mounting thereto hydraulic jacks as mutually
spaced by 120~ in circumferential direction.
The cutter section 14 is constituted by an axial
rotary driver 20, cutter spokes 21 radially extended from
the driver 20, and cutter bits 22 provided on front side
faces of the spokes 21. The rotary driver 20 is rotatably
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supported through a bearing 23 in the center of the
blukhead 13. This rotary driver 20 way be constituted by
any of such known members as a center shaft, intermediate
shaft, outer-peripheral support shaft and the like. In
the present case, the cutter spokes 21 are integrally
mounted to a front side end part of the rotary driver 20,
and a larger number of the bits 22 are fixed to the front
side of the spokes 21.
The cutter drive section 15 comprises a crank 24
provided to a rear end of the rotary driver 20, a coupling
board 26 mounted to a later descrived crank pin 25 of the
crank 24, and a plurality, for example, three of hydraulic
jacks 27a-27c, in combination with a hydraulic pressure
generator and sequence controller (which are not shown).
The crank 24 comprises the axial rotary driver 20 as a
crank shaft, and a crank arm 28 provided integral with the
crank shaft at an end and having at the other end the
crank pin 25. With respect to the rotary driver 20 as the
crank shaft, the crank arm 28 is disposed to be deviated
by an eccentricity of "e".
The coupling board 26 is disposed rotatably on
outer periphery of the crank pin 25, and is provided with
brackets 29a-29c at intervals of 120~ in circumferential
direction of the periphery. This coupling board 26 is
held by a stopper 31 interposed between the board 26 and a
swivel 30, so as to be prevented from escaping and to be
held always in a constant posture with respect to the
crank pin 25.
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The hydraulic jacks 27a-27c carry respectively
each of piston rods 32a-32c for hydraulic expansion and
contraction, and are disposed in the interior of the
shield machine body 12 substantially at intervals of 120~
in the circumferential direction, while the piston rods
32a-32c are connected with pins 33 to the brackets 29a-29c
mounted on the coupling board 26 to be rotatably coupled
thereto. The hydraulic jacks 27a-27c themselves are
connected with pins 34a-34c to the brackets l9a-19c
mounted on the inner wall of the shield machine body 12,
to be rotatably held thereto.
The hydraulic pressure generator is provided as
has been known with a hydraulic pump or valve means
including a changeover valve (not shown), and is arranged
for supplying a hydraulic pressure to push-side or
pull-side ports of the hydraulic jacks 32a-32c with the
changeover valve operated in accordance with commands of
the sequence control circuit of an optimum arrangement,
and also for supplying the hydraulic pressure to the
shield propelling propelling jacks 17.
The sequence control circuit is so arranged to
control the direction of the hydraulic pressure supplied
to the hydraulic jacks 27a-27c, so that the piston rods
32a-32c will respectively expand or contract in accordance
with a predetermined operational sequence to have the
crank 24 rotated through the coupling board 26 in a
predetermined direction. The swivel 30 is provided to
rear end of the crank pin 25.
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A pouring means of an additive agent to tunnel
face being excavated is formed by a pouring hose 35
connected to the swivel 30, a pouring path 36 formed
through respective bodies of the crank pin 25, crank arm
28 and rotary driver 20 and a pouring port 37 opened at
tunnel-face side end of the rotary driver 20 and
communicating with the pouring path 36.
In a space between the bulkhead 13 and the
cutter spokes 21, a chamber 38 is formed as surrounded by
a hood provided on front side of the shield machine body
12, for accommodating therein the excavated earth. The
screw conveyor 16 is disposed within the shield machine
body 12, and a forward end of the conveyor 16 is opened to
the chamber 38 through the bulkhead 13. The shield
propelling ~acks 17 are disposed at a plurality of
positions on the inner wall of the shield machine body 12
at predetermined intervals in the circumferentia'
direction, as mounted to the shield machine body 12
through brackets 39.
The operation of the shield machine 10 in the
embodiment arranged as has been described shall now be
described in the followings.
Now, in an initial state, as shown in FIG. 2, it
is assumed here that the crank pin 25 and coupling board
26 are positioned at their top dead center, at which state
the piston rod 32a of the hydraulic jack 27a topmost
positioned is in the most contracted state, while the
piston rod 32b of the next positioned hydraulic jack 27b
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in the rotating direction X of the crank 2 is in a
slightly contracted state, and the piston rod 32c of the
last positioned jack 27c in the direction X is in a
slightly expanded state, as shown in FIG. 4.
From this state, the rotary driver 20 of the
cutter section 14 is to be rotated once in the rotating
direction X shown in FIG. 4. In this case, the sequence
control circuit causes, with the changeover valve
operated, the hydraulic pressure supplied to the jack 27a
in a direction of gradually expanding the piston rod 32a
from 0~ to 180~ rotation and, then, in a direction of
gradually contracting the piston rod 32a from 180~ to 360~
rotation, as shown in FIG. 4. At the same time, the
hydraulic pressure is supplied to the next hydraulic jack
27b in a direction of gradually contracting the piston rod
32b from 0~ to 120~ rotation, then, in a direction of
gradually expanding the piston rod 32b from 120~ to 300~
and, then, in the direction of gradually contracting again
the pistc,n rod 32b from 300 to 360~ rotation. Also at
the same time, the hydraulic pressure is supplied to the
last hydraulic jack 27c in the direction of gradually
expanding the piston rod 32c from 0~ to 60~ rotation,
then, in the direction of gradually contracting the piston
rod 32c from 60~ to 240~ rotation and, then, in the
direction of gradually expanding again the piston rod 32c
from 240~ to 360~ rotation.
As has been described above, the crank pin 25 is
pushed in the direction X in FIG. 2 through the coupling
- 10 -
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board 26 by the cooperation of the piston rods 32a-32c, by
means of the control of the hydraulic pressure supplied to
the hydraulic jacks 27a-27c so that the rotary driver 20
is rotatively driven, with the eccentricity "e" between
the rotary driver 20 forming the crank shaft and crank pin
25 made as the rotary radius.
Repeating the above rotary stroke, the rotary
driver 20 is continuously rotated, the cutter section 14
is thereby rotated while advancing the shield machine 11
by means of the shield propelling jacks 17, to have the
cutter section 14 propelled towards the tunnel face ground
G, and the bits 22 excavate the ground G. As occasion
demands, the additive agent is poured through the pouring
means to the excavated earth, the cutter spokes 21 kneads
the earth, and a mixture as kneaded of the excavated earth
and additive agent is urged into the chamber 38.
The shield machine 11 is propelled by means of
the shield propelling jacks 17 with a repulsive force
provided by tunnel-wall reinforcing segments 40 assembled
in a manner known for the sheild tunnelling system, the
excavated ground is thereby pressurized, and the tunnel
face is prevented from being collapsed. While maintaining
earth pressure in the chamber 38 at a predetermined level,
the excavated earth is discharged out of the chamber 38 by
means of the screw conveyor 16. After excavation of the
ground G for a predetermined extent, a further set of the
segments 40 is assembled immediately behind the shield
machine 11, the excavation work is performed repeatedly,
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and the tunnel is bored underground.
According to the shield machine 11 as the
underground excavator of the foregoing embodiment, the
cutter section 14 can be rotated by controlling the
expansion and contraction of the hydraulic jacks 27a-27c
for the rotative driving in accordance with their
operation in the predetermined sequence, so that the
structure of the cutter drive section 15 can be remarkably
simplified. Further, the cutter section 14 can be
rotatively driven without employing such parts requiring
high working precision nor such lubricant oil as ones
required for lubricating the pinion and gears.
Referring next to FIGS. 5 to 7, there is shown
another embodiment of the present invention, in which a
crank-type suppc,rt shaft 42 having an eccentric shaft 41
is rotatably mounted to, for example, rear (interior) side
face of the bulkhead 13, by means of a bearing 44 disposed
in a bearing cover 43 secured to the bulkhead 13, as shown
in particular in FIG. 7. This support shaft 42 is
provided at an optional position chosen not to be obstacle
to installation of other constituting members of the
shield machine 11.
More specifically, as shown in FIGS. 5 and 6, an
elongated coupling board 45 having two coupling ends is
mounted at one coupling end to the rear end outer
periphery of the foregoing crank pin 25 of the crank 24,
and brackets 46a-46c are provided to the outer periphery
of the one coupling end of the elongated coupling board 45
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at mutual intervals substantially by 120~ in the
circumferential direction and, to these brackets 46a-46c,
the piston rods 32a-32c of the hydraulic jacks 27a-27c are
coupled through pins 47. The support shaft 42 is coupled
to the other coupling end of the elongated coupling board
45, and this coupling board 45 is held always at a
constant posture with respect to the crank pin 25. Thus
the coupling board 45 is provided across the crank pin 25
and the support shaft 42.
To the support shaft 42, as shown in FIGS. 6 and
7, a further hydraulic jack 48 is coupled as a rotation
assisting means, and an outer end of this hydraulic jack
48 is connected to a further bracket 49 mounted to the
shield machine body 12 by means of a pin 50. An inner end
of a piston rod 51 inserted in the hydraulic jack 48 is
pin-coupled to a bracket 52 provided to outer periphery of
the coupling board 45 rotatably provided to outer
periphery of the eccentric shaft 41. Shown further in
FIG. 7 is a stopper 52' for preventing the coupling board
45 from escaping out of the eccentric shaft 41, as secured
to rear end of the shaft 41 behind the board 45.
According to this embodiment, the crank type
support shaft 42 is rotated by the hydraulic jack 48
through the coupling board 45, to assist the rotation of
the crank 24 by means of the hydraulic jacks 27a-27c
through this support shaft 42 and coupling board 45 and,
at same time, to prevent inverse rotation of the crank, so
that the rotary driver 20 can be rotated in smooth manner.
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Other constituents and their functions of this embodiment
are the same as those in the foregoing embodiment of FIGS.
1-4.
In another embodiment shown in FIGS. 8 and 9,
the elongated coupling board 45 is coupled at its central
coupling part to the rear end of the crank 24 behind the
rotary driver 20 and at both outer end coupling parts
rotatably to outer peripheries of the eccentric shafts 41
of the crank type support shafts 42 provided to the rear
side face of the bulkhead 13 on both sides of the rotary
driver 20. In the present embodiment, thus, the rear end
of the crank 20 is supported by both side support shafts
42 and coupling board 45 extending across theses support
shafts 42, without any provision of such rotation
assisting means as in the above embodiment, so that the
crank 20 can be rotated stably in a fixed direction.
Other constituents and their functions are the same as
those in the foregoing embodiment of FIGS. 1-4.
In another embodiment shown in FIGS. 10 and 11,
next, the crank 24 is rotatively driven by four hydraulic
jacks comprising two of the hydraulic jacks 27a and 27b
coupled to the coupling board 26 rotatably mounted to the
outer periphery of the crank pin 25 and two further
hydraulic jacks 27c and 27d coupled rotatably to an
extended end 26" of the coupling board 26, the extended
end 26" being provided rotatably to outer periphery of
eccentric shaft of a crank type support shaft 42.
That is, as shown in FIG. 10, one side of the
- 14 -
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coupling board 26 provided to the outer periphery of the
crank pin 25 is formed higher, and the extended coupling
end 26" of the coupling board 26 provided to the outer
periphery of the eccentric shaft of the support shaft 42
is coupled through an arm-shaped coupling part to the
higher formed memeber 27', as shown in FIG. 11. Due to
this, the coupling board 26 provided to the crank pin 25
and the extended coupling end 26" of the coupling board 26
and provided to the support shaft 42 are disposed as
mutually deviated in the axial direction of the crank pin
25, that is, in elongated direction of the shield machine
body 12, as seen clearly in FIG. 10, so that the two
hydraulic jacks 27a and 27b as well as other two hydraulic
jacks 27c and 27d will not mutually interfere.
The first two hydraulic jacks 27a and 27b are
connected with pins 54 to the corresponding brackets l9a
and l9b mounted to the shield machine body 12. The piston
rods 32a and 32b carried by the hydraulic jacks 27a and
27b are connected with pins 33 to the brackets 29a and 29b
provided to the coupling board 26.
The second two hydraulic jacks 27c and 27d are
connected with pins 34 to the brackets l9c and l9d to the
shield machine body 12, while the piston rods 32c and 32d
carried by these hydraulic jacks 27c and 27d are connected
with pins 54' to brackets 53c and 53d provided to the
coupling board 26. In disposing the respective jacks
27a-27d, they are mounted at equal intervals, but may even
be disposed in some other way in relationship to other
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constituents inside the machine body 12.
Now, in the present embodiment, the arrangement
is so made that the rotary driver 20 will be rotatively
driven by expanding and contracting the four hydraulic
jacks 27a-27d in accordance with a predetermined operation
sequence, to have the crank 24 and supporting shaft 42
rotated in synchronism in the same direction. The second
two hydraulic jacks 27c and 27d also have such auxiliary
function as a smooth rotation of the crank 24 through the
supporting shaft 42. Other constituents and their
functions are substantially the same as those in the
foregoing embodiments.
In FIGS. 12 to 14, there is shown another
embodiment of the present invention, in which the
excavator comprises a plurality of rotary cutter shafts
rotatably passed through the bulkhead, first crank units
provided respectively to front side part of each of the
rotary cutter shafts, the cutter section born at its
shafts by front side parts of the first crank units,
second crank units provided respectively to rear side part
of each of the rotary cutter shafts, and a plurality of
the hydraulic jacks respectively coupled to the second
crank units for transmitting thereto the expanding and
contracting operation in a predetermined sequence to cause
their crank motion and to rotate the rotary cutter shafts,
whereby the cutter section is caused through the first
crank unlts to perform a parallel crank motion for
excavating the underground.
- 16 -
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More specifically, the underground excavator 10
in the present embodiment is provided with the first crank
units 61a-61d and the second crank units 62a-62d, for
driving the cutter section 14.
The cutter section 14 may be provided, in
addition to the cutter bits 22 provided many on acting
face of the section, with a plurality of kneading wings
22a on rear face. As will be clear from FIG. 13, the
first crank units 61a-61d respectively comprise the rotary
cutter shafts 64a-64d are disposed as mutually spaced by
90~ in the circumferential direction. Further, the first
crank units 61a-61d supported through bearings 63a-63d by
the bulkhead 13, the crank arms 65a-65d provided to front
end parts of the respective rotary cutter shafts 64a-64d,
and cutter support pillars 66a-66d provided as the crank
shafts to front parts of the respective crank arms 65a-65d
as deviated by the eccentricity e' with respect to the
rotary cutter shafts 64a-64d, and the cutter section 14 is
supported rotatably by crank pins in common of the cutter
support pillars 66a-66d.
The second crank units 62a-62d respectively
comprise the crank arms 62a-62d provided to the rear end
parts of the rotary cutter shafts 64a-64d, and crank pins
67a-67d provided to the rear end parts of the crank arms
62a-62d as deviated by the eccentricity e" with respect to
the rotary cutter shafts 64a-64d. The coupling board 45
is provided with bearings 68a-68d and a central aperture
41. The bearings 68a-68d supports the crank pins 67a-67d
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of the second crank units 62a-62d, and the central
aperture 41 allows the additive agent pouring means,
hydraulic hoses, sensor wires and so on to be passed
therethrough.
The hydraulic jacks 27a-27d are carrying the
piston rods 32a-32d, for expansion and contraction at
inward ends of the jacks, and are connected with pins at
outward ends to the inner wall of the shield machine body
12 of the excavator through mounting parts 70a-70d, while
the inward ends are coupled to the second crank units
62a-62d. That is, inward exposed ends of the piston rods
32a-32d are pin-connected to the coupling board 45.
Further, the hydraulic jacks 27a-27d are respectively
provided with push-side and pull-side ports, the push-side
ports of which are connected through hydraulic hoses
71a-71d to the sequence control circuit, and the pull-side
ports of which are connected through hydraulic hoses
72a-72d to the same sequence control circuit. The
hydraulic pressure generator comprises a hydraulic pump or
valve unit, and is arranged for supplying the hydraulic
pressure to the respective hydraulic jacks 27a-27d through
the push-side and pull-side hoses 71a-71d and 72a-72d and
the push-side and pull-side ports of the respective jacks,
and also for supplying the hydraulic pressure to the
shield propelling jacks 17.
The sequence control circuit is arranged for
controlling the changeover of the direction of the
hydraulic pressure supplied to the respective hydraulic
- 18 -
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jacks 27a-27d, expanding or contracting the respective
piston rods 32a-32d according to the predetermined
sequence, so as to rotate the coupling board 45 in a
predetermined direction and to thereby rotate the
respective rotary cutter shafts 64a-64d through the second
crank units 62a-62d. The screw conveyor 16 is disposed in
the interior of the shield machine body 12 with the inlet
port opened in the front chamber 38 of the body 12, and
discharges the excavated earth to a rear position in the
tunnel while maintaining a predetermined pressure inside
the chamber 38 with the excavated earth so as to prevent
any collapse from occurring at the tunnel face.
Other constituents and their functions are the
same as those in the foregoing embodiments, and
substantially the same elements as those in the foregoing
embodiments are shown in FIGS. 12-14 with the same
reference symbols.
The operation of the foregoing underground
excavator 11 shall now be described. Now, in the initial
state, it is assumed that, as seen best in FIG. 13, the
cutter section 14 is placed at its upper position, that
is, at a top dead center, and the crank pins 67a-67d of
the second crank units 62a-62d as well as the coupling
board 45 are also positioned at the top dead center. In
this state, as is clear from 14, the piston rod 32a of the
top-positioned hydraulic jack 27a is in the most
contracted state, the piston rod 32b of the laterally
positioned hydraulic jack 27b is slightly upward tilted
- 19 -
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with respect to horizontal direction and in slightly
contracted state, the piston rod 32c of the bottom
positioned hydraulic jack 27c is in the most upward
expanded state, and the piston rod 32d of the other
laterally positioned hydraulic jack 27d is slightly upward
tilted with respect to the horizontal direction and in
slightly contracted state.
From this initial state, the hydraulic pressure
generated by the hydraulic pressure generator is supplied
through the sequence control circuit to the push-side port
in the hydraulic jack 27a, to the pull-side port in the
jack 27b, to the pull-side port also in the jack 27c, and
to the push-side port in the jack 27d, so that the piston
rod 32a of the hydraulic jack 27a will be slightly
expanded from the contracted state, the rod 32b of the
jack 27b will be further contracted from the slightly
contracted state, the rod 32c of the jack 27c will be
slightly contracted from the most upward expanded state,
and the rod 32d will be slightly expanded further from the
slightly expanded state.
With this control, the coupling board 45 is
rotated by 90~ in clockwise direction of an arrow in FIG.
14, the second crank units 62a-62d attain the crank
rotation through the rotation of the coupling board 45,
the rotary cutter shafts 64a-64d are rotated through such
rotation of the second crank units 62a-62d, the first
crank units 61a-61d are caused to perform the parallel
crank motion through the rotary cutter shafts 64a-64d, and
- 20 -
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the cutter section 14 is rotated in the same direction by
90~ with the parallel crank motion of the first crank
units 6la-6ld.
After such 90~ rotation as in the above of the
cutter section 14, the sequence control circuit operates
the changeover valve and continues to supply the hydraulic
pressure to the push-side port in the hydraulic jack 27a,
to the push-side port in the jack 27b, to the pull-side
port in the jack 27c, and to the pull-side port in the
jack 27d, so that the piston rod 32a will be further
expanded from the slightly expanded state, the rod 32b
will be slightly expanded from the contracted state, the
rod 32c will be contracted from the slightly contracted
state, and the rod 32d will be slightly contracted from
the expanded state, whereby the coupling board 45 is
caused to rotate to 180~ position in the clockwise
direction from the 90~ position in FIG. 14, the rotary
cutter shafts 64a-64d are rotated through the second crank
units 62a-62d, similarly to the forgoing operation, and
the cutter section 14 is rotated in the same direction to
the 180~ position from the 90~ position through the
parallel crank motion of the first crank units 61a-61d.
After the 180~ rotation of the cutter section
14, the sequence control circuit operates the changeover
valve and now supplies the hydraulic pressure to the
pull-side port in the hydraulic jack 27a, still to the
push-side port in the jack 27b, to the push-side port in
the jack 27c, and still to the pull-side port in the jack
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27d, respectively, so that the piston rod 32a of the jack
27a will be slightly contracted from the expanded state,
the rod 32b will be further expanded from the slightly
expanded state, the rod 32c will be slightly expanded from
the contracted state, and the rod 32d will be further
contracted from the slightly contracted state, whereby the
coupling board 45 is caused to rotate clockwise to 270~
position from the 180~ position in FIG. 14, the rotary
cutter shafts 64a-64d are rotated through the second crank
units 62a-62d, and cutter section 14 is rotated in the
same direction from the 180~ position to 270~ position
through the parallel crank motion of the first crank units
61a-61d.
After the 270~ rotation of the cutter section 14
as in the above, the sequence control circuit continues to
supply the hydraulic pressure still to the pull-side port
in the hydraulic jack 27a, to the pull-side port in the
jack 27b, still to the push-side port in the jack 27c, and
also to the push-side port in the jack 27d, so that the
piston rod 32a will be contracted from the slightly
contracted state, the rod 32b will be slightly contracted
from the expanded state, the rod 32c will be expanded from
the slightly expanded state, and the rod 32d will be
slightly expanded from the contracted state, whereby the
coupling board 45 is caused to rotate clockwise in FIG. 14
from the 270~ position to 360~ position, the rotary cutter
shafts 64a-64d are rotated through the second crank units
62a-62d, and the cutter section 14 is rotated in the same
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direction from the 270~ position to 360~ position through
the parallel crank motion of the first crank units
61a-61d.
The foregoing operation is of one cycle of the
rotation of the cutter section, this cycle is repeated to
rotate the cutter section 14 through the parallel crank
motion thereof, the cutter section 14 is propelled with
the shield machine 11 by means of the shield propelling
jacks 17, the tunnel face ground is excavated by the
cutter bits 22, and the excavated earth is accommodated
into the chamber 38. As occasion demands, such additive
agent as a viscosity providing agent is poured to the
excavated earth within the chamber 38 through the pouring
pipe 37 and opening 36 for ejection of the agent, and the
earth and agent are mixed as kneaded by the kneading wings
22a provided to the cutter section 14. During this, the
underground excavator 11 is propelled by means of the
shield propelling jacks 17 with the repulsive force taken
with respect to the segments 40, to pressurize the
excavated earth in the chamber 38, and the tunnel face
ground is prevented from cllapsing. While thus
maintaining a predetermined pressure in the chamber 38,
the excavated earth is discharged by means of the screw
conveyor 16.
After the excavation of the ground G to a
predetermined extent, next, the segments 40 are assembled
at tail end part of the underground excavator 10. If
desirable, a back-fllling material is poured by a
CA 02234028 1998-04-03
back-filling pouring means into a gap between the outer
periphery of the excavator 10 and just excavate tunnel
wall of the ground G. These proceedings as has been
described are repeated, and the underground excavator is
propelled through the underground.
In another embodiment of the present invention
as shown in FIGS. 15 and 16, the coupling board 45 is
formed to act also as a counterweight, and the crank arms
62 on the second crank unit side are provided to extend in
opposite direction to the crank arms 65 on the cutter
section 14 side, that is, on the first crank unit side, so
that any torque loss due to the weight of the cutter
section 14 at the time when the cutter section 14 shifts
as rotated from downward position to upward position can
be cancelled. The weight of the counterweight should
desirably be one that allows to obtain substantially the
same moment as that attained by multiplying the weight of
the cutter section with the eccentricity. Depending on
mounting radius of the crank arms to the coupling board,
the counterweight needs not be always substantially the
same weight as that of the cutter section. Also, it will
be optimum that the function of the counterweight is
provided to the coupling board by means of a separate
weight made of lead or the like and mounted to the board.
With this arrangement, the load to the hydraulic driving
jacks for the cutter section 14 can be minimized, and it
becomes possible to attain a smooth rotary motion with
well balanced structure.
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CA 02234028 1998-04-03
Other constituents and their functions are the
same as those in the foregoing embodiments, and
substantially the same elements are denoted by the same
reference symbols in FIGS. 15 and 16.
