Tunnel excavator with crawler drive and roof support bearing frames

The tunnel excavator (1) includes a cutter supporting body (3) provided with cutters (2) for excavating the earth. The tunnel excavator also includes crawlers (13) for moving backwards and forwards, and upper and side bearing frames (15, 16) which move radiantly until they contact an inner surface of the excavation (12). Forwards movement is accomplished by propelling the cutter supporting body (3) with the crawlers (13) while the bearing frames (15, 16) are in contact with the inner surface of the excavation (12). Forwards movement without lateral slippage can be achieved because the cutter supporting body (3) is guided through the excavation (12) by the bearing frames (15, 16). Backwards movement is achieved by radially withdrawing the bearing frames (15, 16) from the inner surface of the excavation (12) and reversing the crawlers (13). Tunneling can therefore be accomplished regardless of the state of the floor. Internal instruments can be protected from falling earth because the earth can be supported by the bearing frames (15, 16).

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention relates to a tunnel excavator for tunneling into the
 ground, such as in coal mines.
 2. Description of the Related Art
 Tunnel excavators used in excavating ground such as in coal mines include
 those comprising a forward body which is provided with a cutter for
 excavating the ground and rear body connected to the forward body by a
 propulsion jack. Such tunnel excavators bore into the ground as they move
 like inchworms, expanding and contracting the propulsion jack while a rear
 gripper established on the rear body and front gripper established on the
 forward body alternately push against and are separated from the tunnel.
 Specifically, the propulsion jack is extended with the front gripper
 separated from the tunnel while the rear gripper is pressed against the
 tunnel and the front body moves forward relative to the rear body. Next,
 once the propulsion jack has extended by the prescribed stroke length, the
 propulsion jack is contracted with the rear gripper separated from the
 tunnel while the front gripper is pressed against the tunnel and the rear
 body is drawn forward to the forward body.
 With this tunnel excavator, the propulsion reaction force of the propulsion
 jack is borne by the tunnel through the front gripper or rear gripper. In
 areas having faults, therefore, the propulsion reaction force is not
 attained from the grippers because the ground is broken up and it becomes
 impossible to tunnel forward. In areas where the ground is not strong,
 tunneling becomes impossible because the tunnel (walls) is destroyed by
 the pressure of the grippers. Backwards movement of the excavator is also
 difficult.
 On the other hand, there are tunnel excavators which move forwards on
 crawlers instead of using grippers. This type of tunnel excavator is often
 difficult to operate because lateral sliding or the like occurs in areas
 where the coefficient of friction of the tunnel floor in contact with the
 crawlers is different on each side of the crawlers. Such tunnel excavators
 do not have a bearing frame to support the earth (i.e., roof and ribs of
 the tunnel). In the event of a fall, the various instruments constituting
 the excavator are damaged.
 SUMMARY OF THE INVENTION
 It is an object of the present invention to provide a tunnel excavator
 which can tunnel without being influenced by the state of the ground or
 earth (floor, ribs and roof of the tunnel).
 Another object of the present invention is to provide a tunnel excavator
 which can easily move backwards regardless of the conditions of the ground
 or earth.
 Still another object of the present invention is to provide a tunnel
 excavator which can prevent lateral slippage regardless of the conditions
 of the ground or earth.
 Yet another object of the present invention is to provide a tunnel
 excavator which can protect instruments associated there-with from falling
 earth.
 According to one aspect of the present invention, there is provided a
 tunnel excavator including bearing frames which are movable in a radial
 direction (or radiantly) to contact the inner surface of an excavation
 (tunnel). The excavator further includes crawlers to provide forwards and
 backwards propulsion. The crawlers are installed on a cutter supporting
 body which is originally provided for a cutter for excavating earth. With
 this tunnel excavator, forwards movement is carried out by the crawlers
 propelling the cutter supporting body with the bearing frames in contact
 with the inner surface of the excavation. Since the cutter supporting body
 is guided within the excavation by the bearing frames as it moves forward,
 forwards movement without lateral sliding can thereby be achieved.
 Backwards movement can be easily achieved by moving the bearing frames in
 a radially inward direction so as to separate from the inner surface of
 the excavation and moving the crawlers in reverse. Tunneling can be
 carried out regardless of the state of the earth because forward movement
 uses crawlers instead of stretching grippers against the tunnel as before.
 Furthermore, the instruments within the excavator can be protected from
 falling earth because the earth are supported by placing the bearing
 frames in contact with the inner surface of the excavation.
 In sum, the present invention enables tunneling without being influenced by
 conditions of the earth, easy backward movements of the excavation
 machine, prevention of lateral sliding of the excavation machine, and
 protection of equipments in the excavation machine.
 An anchor body, which is provided with separate crawlers, may be disposed
 behind the cutter supporting body, and the anchor body and cutter
 supporting body may be connected by means of a propulsion jack. When the
 crawlers of the cutter supporting body do not provide sufficient
 propulsion, greater propulsion can be attained by extending the propulsion
 jack with the anchor body as an element for receiving the reaction force.
 Grippers, to press against or separate from the excavation, may be
 established on the anchor body, so as to fix or release the anchor body
 with respect to the excavation. If that is the case, the propulsion of the
 propulsion jack can be increased because the anchor body can be fixed in
 the excavation by the grippers.
 A sub-cutter, which moves upwards and downwards within a prescribed range,
 may also be installed on the cutter supporting body so as to vary the
 height of the traveling surface of the crawlers. If that is the case, the
 angle at which the excavator tunnels can be directed upwards and downwards
 upon changing the height of the traveling surface of the crawlers by
 moving the sub-cutter upwards or downwards.
 A plurality of propulsion jacks may be disposed in a horizontal direction
 at prescribed intervals. If that is the case, the extension forces and
 strokes of these propulsion jacks may be adjusted to change the excavation
 direction of the excavator to the right or left.

DETAILED DESCRIPTION OF THE INVENTION
 Below, the embodiments of the present invention are described with
 reference to the attached figures.
 FIGS. 1 and 2 show schematic diagrams of a tunnel excavator 1 for tunneling
 into earth mixed with coal in a coal mine. FIGS. 3 through 11 show details
 of the tunnel excavator 1. The same explanation applies to the tunnel
 excavator shown in FIGS. 1 and 2 and the tunnel excavator shown in FIGS. 3
 through 11 because these are essentially the same, although they have some
 differences.
 Referring to FIGS. 1 and 2, this tunnel excavator 1 includes a cutter
 supporting body 3 whereon two cutters 2 for excavating earth are arranged.
 These cutters 2 are mounted in a horizontal row and separated by a
 prescribed distance on the cutter supporting body 3, as shown in FIG. 5.
 The number of cutters 2 is not restricted to two and may be one, three or
 more. When a plurality of cutters 2 is used, the cutters do not have to be
 mounted in a horizontal row and separated by prescribed intervals as shown
 in the pictured example; they may be mounted in a vertical direction and
 separated by prescribed intervals, or disposed in a triangle or square.
 As illustrated in FIGS. 2, 5, 9, and 10, each cutter 2 includes the
 following: a rotating shaft 5 which is rotatably supported by a support
 block 4 established on the cutter supporting body 3, three cutter spokes 6
 mounted at equal intervals around the circumference of the front end of
 the rotating shaft 5, and cutting picks 7 mounted on each cutter spoke 6
 for essentially excavating the earth. The six cutter spokes 6 on the two
 cutter 2 are disposed so as to intermesh without interfering with each
 other. It should be noted that the number of cutter spokes 6 on each
 cutter 2 is not restricted to three and may be two, four, or more.
 The rotating shaft 5 of each cutter 2 is connected by means of a
 synchronization gear box 10 to a drive shaft 9 of an associated driving
 motor 8 (electric or hydraulic motor) mounted on the cutter supporting
 body 3. As shown in FIG. 6, the synchronization gear box 10 contains a
 sequence of plural gears 11, and holds the two rotating shafts 9 of the
 cutters 2 in the prescribed phases respectively while rotating them in
 opposite directions at the same speed. The gear box 10 prevents
 interference (collisions) among the cutter spokes 6 disposed so as to
 intermesh. As indicated by the arrows 12 in FIG. 5, each cutter rotates in
 a direction such that the spoil is scraped to the center.
 A pair of crawlers 13 is arranged on the bottom portion of the cutter
 supporting body 3, as shown in FIGS. 2 and 6. These crawlers 13 are spaced
 at a prescribed distance from each other crosswise to the tunnel and
 travel along the floor 12a (FIG. 6) of the excavation 12. As best seen in
 FIG. 6, the right and left crawlers 13 are driven independently by
 associated drive motors (electric or hydraulic motors) and function as the
 means for moving the cutter supporting body 3 forwards and backwards.
 Therefore, the excavation 12 is formed to the rear of the cutters when the
 cutter supporting body 3 is moved forwards by the crawlers 13 with the
 cutters 2 turning. In other words, the present tunnel excavator 1 can
 tunnel regardless of the state of the ground because the excavator 1 is
 moved forwards by the crawlers 13, unlike a conventional excavator which
 uses grippers to stretch the excavation 12 when it moves forwards and
 backwards.
 As illustrated in FIGS. 2, 6, 7, 9, and 10, an upper bearing frame 15 and
 side bearing frames 16 are mounted by means of link mechanisms 17, 18
 (parallel link mechanisms, or the like) and jacks 19, 20 (electric jacks,
 hydraulic jacks, or the like) on the cutter supporting body 3. The upper
 bearing frame 15 and side bearing frames 16 move radially so as to contact
 the roof 12b (upper surface) and ribs (side surfaces) 12c of the
 excavation 12. As best shown in FIGS. 1 and 5, the upper bearing frame 15
 is formed of a generally flat panel and each of the side bearing frames 16
 has a curving form which matches the arc that the associated cutter 2
 draws when it rotates.
 The bearing frames 15, 16 are formed so as to cover the cutter supporting
 body 3 from directly behind the cutters 2 to directly before roof bolters
 21 (will be discussed below). The bearing frames 15, 16 support earth
 dropping from the inner surface (roof and ribs) of the excavation 12 and
 protect the driving motors 8, synchronization gear box 10, link mechanisms
 17, 18, and the like. In other words, because the earth can be supported
 by placing the bearing frames 15, 16 in contact with the inner surface of
 the excavation 12, the bearing frames can protect internal instruments
 from falling earth. The cutter supporting body 3 is moved forward by the
 crawlers 13 with the bearing frames 15, 16 placed in contact with the
 inner surface of the excavation 12 and the jacks 19, 20 extended. The
 cutter supporting body 3 is thereby guided along the excavation 12 without
 any lateral slippage.
 Lateral slippage or the like usually occurs and operation becomes difficult
 when the coefficient of friction of the ground surface (floor 12a of the
 excavation 12) varies between the crawlers 13 on the right and left. In
 the present embodiment, however, stable progress with substantially no
 lateral slippage is ensured even under those conditions because the
 bearing frames 15, 16 are in contact with or very close to the inner
 surface of the excavation 12 and guide the cutter supporting body 3, which
 is moved forwards by the crawlers 13, along the excavation 12. At such a
 time, the bearing frames 15, 16 may be fixed relative to the inner surface
 of the excavation 12 by holding the jacks 19, 20 at a prescribed stroke.
 In this case, there may occasionally be small clearance between the
 bearing frames 15, 16 and the inner surface of the excavation, but such
 small clearance would not affect appropriate guiding without lateral
 slippage. Alternatively, it is also satisfactory that the bearing frames
 15, 16 may always be forced in light contact with the inner surface of the
 excavation 12 by very gently or softly extending the jacks 19, 20.
 As illustrated in FIGS. 2, 5, 9, and 11, sub-cutters 22, 23 are disposed at
 an upper level and lower level on the front portion of the cutter
 supporting body 3. The sub-cutters 22, 23 have the purpose of excavating
 areas out of range of the rotating cutters 2 and which cannot be excavated
 by the cutters 2. This upper sub-cutter 22 and lower sub-cutter 23 are
 disposed to the rear of the cutters 2 as understood from FIG. 1. The lower
 sub-cutter 23 is disposed in front of the crawlers 13 so that it can form
 (excavate) the floor 24 before the crawlers 13 as shown in FIG. 9. As
 shown in FIG. 1, a cutout portion 25 is formed in the upper bearing frame
 15 so as to enclose the upper sub-cutter 22.
 The upper sub-cutter 22 is mounted on the support block 4 of the cutter
 supporting body 3 by means of the link mechanism 26 as shown in FIG. 2.
 The upper sub-cutter 22 moves upwards and downwards within a prescribed
 range upon extension and contraction of the jacks 27 (electric or
 hydraulic jacks). As shown in FIG. 5, the upper sub-cutter 22 includes a
 rotary shaft 29 which is rotated by a motor 28 and screw blades 30, 31
 which spiral in opposite directions toward the center from each end of the
 rotary shaft 29. This sub-cutter 22 therefore pulls spoil from the ends
 toward the center as it rotates. Cutting picks 32 are mounted on the screw
 blades 30, 31 as shown in FIG. 9.
 As shown in FIGS. 5 and 11, the lower sub-cutter 23 includes a rotary shaft
 33 extending horizontally and screw blades 34, 35, spiraling in opposite
 directions toward the center from each end of the rotary shaft 33. This
 sub-cutter can also gather spoil from the ends towards the center. Cutting
 picks, not shown, like those on the upper sub-cutter 22 are mounted on the
 screw blades 34, 35. The length of the rotary shaft 33 of the lower
 sub-cutter 23, specifically, the length of the excavation zone, is
 determined to match the spacing between the right and left crawlers 13, as
 shown in FIGS. 6 and 11. This guarantees a traveling surface for the
 crawlers 13.
 The rotary shaft 33 of the lower sub-cutter 23 is held by and turns within
 the lower portion of arm elements 36 as shown in FIGS. 5, 9, and 11. In
 the illustrated embodiment, two arm elements 36 are provided in a
 direction crosswise to the tunnel and are separated by a prescribed
 distance. The central portions thereof are rotatably supported by the
 block 38 established on the cutter supporting body 3 by means of pins 37.
 The jacks 41 (electric or hydraulic jacks) are held between the upper
 portions of the arm elements 36 and the block 38 by means of pins 39, 40
 respectively. With this constitution, extending and contracting the jacks
 41 turns the arm elements 36 around the pins 37 and moves the lower
 sub-cutter upwards and downwards within the prescribed range.
 Driving motors 42 (electric or hydraulic motors) are mounted on the upper
 portions of the arm elements 36 in order to drive the rotary shaft 33 of
 the lower sub-cutter 23. Rows of gears, chains, and the like (not shown)
 are housed inside the arm elements 36 for transferring the rotary force of
 the drive motor 42 to the rotary shaft 33 of the lower sub-cutter 23
 respectively. By moving the lower sub-cutter 23 rotated by the driving
 motor 42 upwards and downwards by the jacks 41, the height of the
 traveling surface 24 of the crawlers 13 formed directly behind the lower
 sub-cutter 23 (FIG. 9) can be changed and therefore the up and down
 orientation of the cutter supporting body 3 can be controlled.
 As shown in FIGS. 5 and 11, a collector plate 43 is mounted on the cutter
 supporting body 3 and located to the rear of the cutters 2 and the
 sub-cutter 23. The collector plate 43 gathers the excavated spoil. The
 collector plate 43 tapers towards the spoil outlet 44 in the center so as
 to gather the spoil towards the spoil outlet 44. A chain conveyor 45 for
 transporting spoil towards the rear is located behind the spoil outlet 44.
 The chain conveyor 45 includes a conduit or channel element 46 extending
 towards the rear of the tunnel, as shown in FIGS. 6, 9, and 11. The
 illustrated conduit element 46 includes a plurality of pieces 47 as shown
 in FIG. 4. Additional conduit pieces 47 are attached as the cutter
 supporting body 3 advances for excavation.
 Referring to FIG. 6, the upper surface of the conduit element 46 forms a
 carrier surface 48 and the lower surface forms a return surface 49.
 Depressed portions 51 to anchor paddles 50 are formed in both sides of the
 surfaces 48, 49. As illustrated in FIG. 11, a plurality of paddles 50 is
 disposed on the carrier surface 48 and return surface 49 at prescribed
 intervals lengthwise to the conduit element 46. A pair of parallel endless
 chains 52 connect these paddles 50. The With this constitution, the spoil
 is transported to the rear by the paddles 50 on the carrier surface 48
 upon the circulation of the endless chains 52 with an associated driving
 means (not shown).
 As illustrated in FIGS. 2, 3, and 4, an anchor body 54, which is provided
 with another crawlers 53, is disposed to the rear of the cutter supporting
 body 3. As also shown in FIG. 8, a pair of crawlers 53, separated by a
 prescribed distance crosswise to the tunnel, are provided on the floor
 portion of the anchor body 54. These crawlers 53 are driven independently
 by driving motors 55 (electric or hydraulic motors). The anchor body 54
 and cutter supporting body 3 are connected by means of a pair of
 propulsion jacks 56 (hydraulic or electric jacks), separated by a
 prescribed distance crosswise to the tunnel, as also depicted in FIGS. 3
 and 11. The stroke length and force of extension for the each of the
 propulsion jacks 56 can be controlled individually.
 The anchor body 54 is used to increase propulsion toward the working face
 in the event of insufficient propulsion when using only the crawlers 13
 provided on the cutter supporting body 3. Specifically, when additional
 propulsion force is needed, the anchor body 54 is halted and the
 propulsion jack 56 is extended, which functions as an element for
 receiving reaction force. In such a case, the forward propulsion of the
 cutter supporting body 3 becomes the sum of the propulsion of the crawlers
 13 on the cutter supporting body 3 and the extension force of the
 propulsion jacks 56. The reaction force thereof is transmitted to the
 floor 12a of the excavation 12 by means of the crawlers 53 on the anchor
 body 54.
 The cutter supporting body 3 can be pushed forward at an angle (i.e.,
 diagonally) by using different extension forces and stroke lengths for
 each jack (right and left jacks) 56 when the propulsion jacks 56 are
 extended. The horizontal orientation of the advancing cutter supporting
 body 3 can thereby be controlled. Controlling the stroke length of each of
 the jacks 56 can result in very precise curves. If the propulsion jacks 56
 are extended to the prescribed stroke length, they are reset when
 contracted by the crawlers 53 moving the anchor body 54 forwards. When a
 curve is formed, the side bearing frames 16 on both sides are withdrawn
 from the ribs of the excavation to leave space for excavation to the
 inside of the curve. A smooth arcuate tunnel can therefore be excavated
 without the side bearing frames 16 scraping on the excavation 12.
 As illustrated in FIGS. 3, 4, and 8, grippers 57 to press against or
 separate from the excavation 12 are established on the anchor body 54, in
 order to affix or release the anchor body 54 to the excavation 12. The
 grippers 57 include the following: rotary arms 59 mounted rotatably on the
 anchor body 54 by means of pins 58; shoes 60 to be pressed against and
 released from the ribs of the excavation 12 and mounted on the rotary arms
 59; and jacks 63 (electric or hydraulic jacks) held between the shoes 60
 and the anchor body 54 by pins 61, 62 for rotating the rotary arms 59
 (FIG. 8).
 It should be noted that the grippers 57 are not limited to the illustrated
 and described constitution. For example, the grippers 57 may have a
 structure similar to the link mechanisms 17, 18 as for the bearing frames
 15, 16 shown in FIGS. 2, 9, and 10. However, a wide working space 63 is
 ensured over the anchor body 54 if the rotary arms 59 as in the present
 embodiment are employed.
 Pressing the shoes 60 of the grippers 57 to the excavation 12 and affixing
 the anchor body 54 to the excavation 12 can prevent the anchor body 54
 from slipping to the rear, which can occur when the propulsion jacks 56
 are extended. Referring particularly to FIG. 8, in the case of a small
 coefficient of friction between the crawlers 53 of the anchor body 54 and
 the floor 12a of the excavation 12, the anchor body 54 slides to the rear
 when the propulsion jacks 56 are extended and cannot effectively transfer
 the extension force of the propulsion jacks 56 to the cutter supporting
 body 3. In the present embodiment, however, the slippage can be prevented
 or significantly reduced by affixing the anchor body 54 to the excavation
 12 with the grippers 57. The extension force of the propulsion jacks 56
 can thereby be transferred to the cutter supporting body 3 with certainty
 and the forward propulsion of the cutter supporting body 3 can be
 increased. Paradoxically, the forward propulsion of the cutter supporting
 body 3 can be increased because the slippage does not occur even if the
 propulsion of the propulsion jacks 56 is increased.
 As illustrated in FIGS. 2, 3, and 4, working deck 65, to provide a work
 area for workers, are attached to the anchor body 54. The front sections
 65a of the working deck 65 are slidably placed on the rear portion of the
 cutter supporting body 3. The working deck 65 is held still in relation to
 the excavation 12, even when the propulsion jacks 56 are extended and the
 cutter supporting body 3 is moving forwards with respect to the anchor
 body 54. In other words, even if the cutter supporting body 3 moves
 forwards, the working deck 65 does not move as long as the propulsion
 jacks 56 are actuated within the range of their strokes. In this way, the
 working deck 65, which provides work areas for workers, remains stationary
 even while the cutter supporting body 3 is tunneling ahead and can
 therefore provide a stable work environment for workers.
 Roof bolters or rock bolting devices 21 are provided on the front portions
 65a of the working decks 65 and located directly to the rear of the upper
 bearing frame 15. The roof bolters 21 fire roof bolts 66 into the roof 12b
 of the excavation 12. The roof bolters 21 fire the roof bolts 66 into the
 roof 12b of the excavation 12 exposed to the rear of the upper bearing
 frame 15 as the cutter supporting body 3 moves forward. The roof bolts 66
 provide support the roof 12b of the excavation 12 so that the roof 12b
 does not fall in. The roof bolters 21 are installed on the working deck 65
 and can therefore be held stationary with respect to the excavation 12,
 regardless of the advance of the cutter supporting body 3 within the range
 of the extension stroke of the propulsion jacks 56. As a result, the
 firing of the roof bolts 66 can be carried out at the same time that the
 cutter supporting body 3 is moving forwards (tunneling).
 Referring to FIG. 4, the roof 12b of the excavation 12 formed by excavation
 with the cutters 2 is generally in a state where it can easily fall as
 stress supported up to then by the earth is released all at once. In the
 illustrated embodiment, the roof 12b is immediately supported by the upper
 bearing frame 15 so that such a fall is prevented by the pressure from the
 upper bearing frame 15. Accordingly, the roof 12b enters a stable state
 because the stress is gradually released during travel of the upper
 bearing frame 15. After that, the fall is prevented by the roof bolts 66
 struck into the roof 12b by the roof bolters directly after the roof is
 exposed to the rear of the upper bearing frame 15.
 As illustrated in FIG. 7, backwards movement of the tunnel excavator 1 is
 achieved by reverse rotation of the crawlers 13, 53 with the bearing
 frames 15, 16 withdrawn from the inner surface of the excavation 12 and
 moving the anchor body 54 and cutter supporting body 3 backwards as a
 single unit. It is of course that the upper bearing frame 15 is lowered by
 an amount sufficient for the upper bearing frame 15 not to interfere with
 the roof bolts 66 installed in the roof 12b of the excavation 12.
 FIGS. 12 through 14 illustrate a modification. Specifically, these drawings
 show the tunnel excavator 1 equipped with a collecting paddle unit 67. The
 collecting paddle unit 67 guides the spoil excavated by the cutters 2 and
 sub-cutters 22, 23 to the outlet 44. The collecting paddle unit 67 include
 a rotary shaft 68 supported between right and left arm elements 36, and
 rods 69 mounted on and radiating from the rotary shaft 68. The rotary
 shaft 68 is connected to and rotated by the driving motor 42 for driving
 the lower sub-cutter 23, by means of chains and rows of gears housed
 within the arm elements 36, as shown by arrows 70, 71 in FIG. 13. The
 spoil is thereby moved with great efficiency to the outlet 44.
 This application claims the priority rights of Japanese Patent Application
 No. 10-141511 filed May 22, 1998