Title:
SHIELD TUNNELING MACHINE WITH ORBITING CUTTERHEAD
United States Patent 3830545
Abstract:
The cutterhead and cutter elements thereon undergo an orbiting radial shifting movement as the shield is advanced. Water is delivered to the cutterhead region forwardly of a water tight bulkhead for admixture with the material being excavated from the tunnel face. The resulting mixture is pumped away from the tunnel face through a removal pipe which extends rearwardly through the bulkhead. The bulkhead includes a fixed outer portion and a flexible diaphragm type seal which closes the space between the cutterhead and said fixed outer portion.
US Patent References:
/1001903.html
Temple - August 1911 - 1001903
/1026412.html
Stone - May 1912 - 1026412
Granular mining machine
Greene - November 1950 - 2528748
/1001903.html
Temple - August 1911 - 1001903
/1026412.html
Stone - May 1912 - 1026412
Granular mining machine
Greene - November 1950 - 2528748
Application Number:
05/384462
Publication Date:
08/20/1974
Filing Date:
08/01/1973
View Patent Images:
Export Citation:
Assignee:
The Robbins Company (Seattle, WA)
Primary Class:
Other Classes:
175/343, 175/106, 175/62, 299/56, 405/144
International Classes:
E21D9/08; E21D9/13; E21D9/12; E01G3/03
Field of Search:
299/31,33,56,58,90 61/84,85 175/62,106,343
Primary Examiner:
Purser, Ernest R.
Attorney, Agent or Firm:
Graybeal, Barnard, Uhlir & Hughes
Claims:
What is claimed is
1. A machine for tunneling through earth formations, comprising:
2. The machine of claim 1, further comprising means for delivering a cutting fluid under pressure to the cutterhead region forwardly of said radial bulkhead, for admixture with the earth material being removed from the tunnel face.
3. The machine of claim 1, wherein said cutterhead comprises a generally radial cutter carrier on which the cutter elements are located, an elongated shaft connected at its forward end to said cutter carrier and extending rearwardly therefrom within said shield, said shield comprises a support for the rear end of said shaft and a universal joint interconnected between said support and the rear end of said shaft, and said means for causing an orbiting radial shifting movement of said cutterhead and the cutter elements thereon comprises a ring of radially disposed piston-cylinder linear motors interconnected between said cuterhead and said shield at a location rearwardly of said radial bulkhead, and means for distributing fluid pressure pulses from each said linear motor to the next in repetitive cyclic fashion around said ring, for producing said orbiting radial shifting movement of the cutterhead and the cutter elements thereon.
4. The machine of claim 3, further comprising means for delivering a fluid under pressure to the cutterhead region forwardly of said radial bulkhead, for mixture with the earth material being removed from the tunnel face.
5. The machine of claim 3, wherein the means for delivering a fluid under pressure to the cutterhead region forwardly of said radial bulkhead comprises a conduit extending axially through said elongated shaft.
6. The machine of claim 3, wherein the fixed portion of the bulkhead comprises an annular wall fixed at its outer periphery to said shield and having an open center through which said elongated shaft extends, and said flexible radial closure wall means is attached to said fixed portion of said bulkhead.
7. The machine of claim 6, wherein said flexible radial closure wall means is annular and radially is substantially larger in dimension than the radial clearance which exists between the cutterhead and the radial inner extent of said fixed wall when said elongated shaft is substantially coincident with the center axis of the shield.
8. The machine of claim 1, wherein said cutterhead comprises a generally radial cutter carrier having an outer periphery spaced relatively close to the side wall means of said shield, with a radial gap being formed about said cutter carrier between its outer periphery and the side wall means of said shield in which said cutter carrier moves during the orbiting radial shifting movement of the cutterhead, with said forwardly directed cutter elements being mounted on said cutter carrier.
9. The machine of claim 8, wherein said means for causing an orbiting radial shifting movement of said cutterhead and the cutter elements thereon comprises a ring of radially disposed piston-cylinder linear motors interconnected between said cutterhead and said shield at a location rearwardly of said radial bulkhead, and means for distributing fluid pressure pulses from each said linear motor to the next in repetitive cyclic fashion around said ring, for producing said orbiting radial shifting movement of the cutterhead and the cutter elements thereon.
10. The machine of claim 8, wherein the fixed portion of the bulkhead comprises an annular wall fixed at its outer periphery to said shield and having an open center through which a portion of the cutterhead extends, and said flexible radial closure wall means is interconnected between said portion of the cutterhead and said fixed wall.
11. The machine of claim 3, further comprising a second radial bulkhead in said shield spaced rearwardly of said piston-cylinder linear motors and forwardly of said universal joint, said second bulkhead also comprising an annular wall portion fixed at its outer periphery to said shield and having an open center through which said elongated shaft extends, and a second flexible radial closure wall means interconnected between a portion of said cutterhead and said fixed wall portion of the bulkhead.
12. The machine of claim 11, further comprising means for delivering compressed air into the space between the two bulkheads for pressurizing such space.
1. A machine for tunneling through earth formations, comprising:
2. The machine of claim 1, further comprising means for delivering a cutting fluid under pressure to the cutterhead region forwardly of said radial bulkhead, for admixture with the earth material being removed from the tunnel face.
3. The machine of claim 1, wherein said cutterhead comprises a generally radial cutter carrier on which the cutter elements are located, an elongated shaft connected at its forward end to said cutter carrier and extending rearwardly therefrom within said shield, said shield comprises a support for the rear end of said shaft and a universal joint interconnected between said support and the rear end of said shaft, and said means for causing an orbiting radial shifting movement of said cutterhead and the cutter elements thereon comprises a ring of radially disposed piston-cylinder linear motors interconnected between said cuterhead and said shield at a location rearwardly of said radial bulkhead, and means for distributing fluid pressure pulses from each said linear motor to the next in repetitive cyclic fashion around said ring, for producing said orbiting radial shifting movement of the cutterhead and the cutter elements thereon.
4. The machine of claim 3, further comprising means for delivering a fluid under pressure to the cutterhead region forwardly of said radial bulkhead, for mixture with the earth material being removed from the tunnel face.
5. The machine of claim 3, wherein the means for delivering a fluid under pressure to the cutterhead region forwardly of said radial bulkhead comprises a conduit extending axially through said elongated shaft.
6. The machine of claim 3, wherein the fixed portion of the bulkhead comprises an annular wall fixed at its outer periphery to said shield and having an open center through which said elongated shaft extends, and said flexible radial closure wall means is attached to said fixed portion of said bulkhead.
7. The machine of claim 6, wherein said flexible radial closure wall means is annular and radially is substantially larger in dimension than the radial clearance which exists between the cutterhead and the radial inner extent of said fixed wall when said elongated shaft is substantially coincident with the center axis of the shield.
8. The machine of claim 1, wherein said cutterhead comprises a generally radial cutter carrier having an outer periphery spaced relatively close to the side wall means of said shield, with a radial gap being formed about said cutter carrier between its outer periphery and the side wall means of said shield in which said cutter carrier moves during the orbiting radial shifting movement of the cutterhead, with said forwardly directed cutter elements being mounted on said cutter carrier.
9. The machine of claim 8, wherein said means for causing an orbiting radial shifting movement of said cutterhead and the cutter elements thereon comprises a ring of radially disposed piston-cylinder linear motors interconnected between said cutterhead and said shield at a location rearwardly of said radial bulkhead, and means for distributing fluid pressure pulses from each said linear motor to the next in repetitive cyclic fashion around said ring, for producing said orbiting radial shifting movement of the cutterhead and the cutter elements thereon.
10. The machine of claim 8, wherein the fixed portion of the bulkhead comprises an annular wall fixed at its outer periphery to said shield and having an open center through which a portion of the cutterhead extends, and said flexible radial closure wall means is interconnected between said portion of the cutterhead and said fixed wall.
11. The machine of claim 3, further comprising a second radial bulkhead in said shield spaced rearwardly of said piston-cylinder linear motors and forwardly of said universal joint, said second bulkhead also comprising an annular wall portion fixed at its outer periphery to said shield and having an open center through which said elongated shaft extends, and a second flexible radial closure wall means interconnected between a portion of said cutterhead and said fixed wall portion of the bulkhead.
12. The machine of claim 11, further comprising means for delivering compressed air into the space between the two bulkheads for pressurizing such space.
Description:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to tunneling machines and more particularly to shield type tunneling machines operable for excavating tunnels in soft ground.
2. Description of the Prior Art
It is known to excavate tunnels in relatively soft ground by the use of "bulkhead" tunneling machines. This type of tunneling machine comprises a tubular caisson, termed a "shield," which is advanced axially through the ground. A transverse bulkhead divides the shield axially. Water or some other liquid is pumped into the region forwardly of the bulkhead to mix with the excavated ground material. The resulting mixture is removed from the region forwardly of the bulkhead via a conduit extending rearwardly through an opening in the bulkhead. Examples of this type of tunneling machine are shown by U.S. Pat. No. 360,959 granted Apr. 12, 1887 to James H. Greathead; by U.S. Pat. No. 3,260,054 granted July 12, 1966 to Hans Lorenz; by U.S. Pat. No. 3,334,945 granted Aug. 8, 1967 to John V. Bartlett; and by U.S. Pat. No. 3,360,061 granted Dec. 26, 1967 to Carlos R. Canalizo.
It is common in tunneling machines of this type to locate a rotating cutterhead or some other type of cutter element forwardly of the bulkhead for mechanical excavating the tunnel face. Each of the foregoing patents discloses some form of a mechanical excavator.
SUMMARY OF THE INVENTION
The present invention relates to the provision of a bulkhead shield type tunneling machine having a cutterhead which undergoes an orbiting radial shifting movement rather than rotation. The orbiting head is easily supported and driven and no rotating-to-stationary parts seal is required. Rather, the bulkhead is provided with a flexible wall section which is connected to a portion of the cutterhead and is sufficiently distortable to permit the orbiting movement of the cutterhead.
Preferably, the cutterhead includes an elongated drive shaft which projects through an opening in a rigid portion of the bulkhead and which is mounted at its rear end onto the shield by means of a universal joint. Preferably, such cutterhead is driven by a ring of radially disposed piston-cylinder linear motors which are interconnected between the shield and a portion of the cutterhead at locations rearwardly of the bulkhead. A fluid pressure generator distributes fluid pressure pulses from each said linear motor to the next in repetitive cyclic fashion around said ring for in this manner producing the orbiting radial shifting movement of the cutterhead and the cutter elements carried thereby. An important advantage of this type of drive system is that it will not stall out in the event the cutterhead encounters hard material which restrains its movement. Instead the input energy is absorbed by the elasticity of the drive fluid.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is an axial sectional view of an embodiment of the invention;
FIG. 2 is a front elevational view, looking towards the face of the cutterhead shown in FIG. 1, showing a representative number of cutter elements which in actuality are substantially evenly spaced over the entire face of the cutterhead;
FIG. 3 is a cross sectional view of the machine shown by FIG. 1, taken substantially along line 3--3 of FIG. 1;
FIG. 4 is a cross sectional view taken along line 4--4 of FIG. 1; and
FIG. 5 is a diagrammatical view of a fluid drive system for the cutterhead.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In preferred form, the tunneling machine of this invention comprises a cylindrical shield 10 having an open forward end bordered by a leading cutting edge 12. Shield 10 may comprise a separate tail ring 14 with respect to which the shield proper may be adjustable for steering purposes. The tail ring 14 may be firmly secured to a forward cylindrical tunnel lining section 16, such as by a plurality of bolts 18. An endwise force (indicated by force arrows F) may be directed against the lining section 16 to move both it and the shield 10 forwardly (not shown) may be added to the lining in succession behind section 16, and each pushed forwardly tommove the shield 10 and the lining segments ahead of it forwardly together. Of course, other techniques of advancing the machine may be employed.
According to the invention, an orbiting type cutterhead 20 is supported within the shield 10 forwardly of bulkhead means which divides the shield 10 axially into a forward wet compartment and a rearward dry compartment. Preferably, cutterhead 20 comprises a radial, generally disc shaped cutter carrier 22 attached to the forward end of an elongated tubular shaft 24. Shaft 24 extends rearwardly through the shield 10 and at its rear end is connected to the first yoke 26 of a universal joint. From yoke 26 shaft 24 extends rearwardly through a trunnion member 28. The second yoke 30 of the universal joint is attached to a support plate 32 which may be rigidly connected to the shield 10 by a plurality of support legs 34 and mounting plates 36, 38 (FIG. 4).
A ring (e.g., three) of equally spaced, radially disposes piston-cylinder linear motors 40 are interconnected between connector plate portions 42 of the cutterhead 20 and anchor plates 44 secured to the shield 10. The respective ends of the motors 40 are connected by pivotal joints to the supports 42, 44. A pressure generator PG (FIG. 5) is provided for distributing fluid pressure pulses from each linear motor 40 to the next in repetitive cyclic fashion around said ring, for producing the orbiting radial shifting movement of the cutterhead 20 and the cutter elements 48 thereon, as will hereinafter be described in greater detail.
The cutter carrier 22 may comprise a spherical forward wall 50 and a planar rear wall 52, both of which are welded or otherwise firmly secured at their centers to the forward portion of the shaft 24. Walls 50 and 52 come together and are secured together at their peripheries. A cylindrical section 54 may project rearwardly from wall 52 to serve as both a reinforcement for the mounting plates 42 and a mounting member for a flexible wall section 56 of a bulkhead 58. In addition to flexible wall section 56 the bulkhead 58 comprises an annular fixed wall 60 which is firmly secured at its outer periphery to the shield 10. A central opening is formed in wall 60 about which a cylindrical mounting ring 62 is secured. The flexible wall 56 is annular in form and has a radial dimension which is substantially larger than the radial space which exists between the two support rings 54, 62 when the shaft 26 is centered within the shield 10. As a result, flexible wall 56 is distortable enough so that it does not interfere with the orbiting movement of the cutterhead 20 while it forms its sealing or closure function.
A second bulkhead 64 may be provided rearwardly of the linear motors 40. The secondary bulkhead 64 may comprise a rigid annular outer portion 66 secured to the shield 10, a fixed annular outer mounting ring 68, an inner movalbe mounting ring 70 which is attached to a radial plate 72 which in turn surrounds the tubular shaft 24, and a second flexible wall section 74. The secondary bulkhead 64 serves as a backup for the primary bulkhead 58 in the event that something happens to the latter.
Flexible wall sections 56, 74 may be made from truck innertubes which are not inflated.
Preferably, compressed air is delivered into the space between the two bulkheads 58, 64. In the event one of the bulkhead seals 56, 74 breaks or a leak otherwise develops in one of the bulkheads 58, 64, the loss of air pressure within the compartment between the two bulkheads 58, 64 may be sensed (by means not shown) and used to produce a signal to the operator that a leak has developed.
The cutter elements 48, which may be short chisel-like elements, are on the cutter carrier 22 in sufficient numbers so that during orbiting movement of the cutterhead 20 a large part of the tunnel face is swept by an orbiting cutter element 48. In FIG. 2 only a representative portion of the cutter elements 48 are shown.
An annular space or gap 78 is formed between the outer periphery 80 of the cutter carrier 72 and the adjacent ring portion 82 of the shield 10. This annular space 78 serves to meter the flow of ground material rearwardly when freely flowing ground material is encountered.
A material removal pipe 83 is provided to pick up the mined material from the annular region immediately surrounding and trailing the peripheral portion 80 of the cutter carrier 22. Such pipe may be a part of a material removal system of the general type disclosed by the aforementioned U.S. Pat. No. 3,334,945.
Under certain ground conditions a cutting fluid (e.g., water, mud, etc.) is delivered to the face region of the tunnel forwardly of the cutter carrier 22. It may be delivered to the face region by way of a delivery conduit 84 which is supported within the hollow shaft 24 and has a discharge nozzle 86 at its forward end. Alternatively, or additionally, the water, mud, etc. may be delivered into the region 78 by a conduit 86. The water, mud, etc., delivered through conduit 84 (and/or conduit 86) serves to fluidize the ground material. Cutter carrier 22 and the cutter elements 48 serve to agitate and mix together the earth material and the water, mud, etc., so as to form a slurry which is easily pumpable rearwardly through the conduit 83. Of course, when wet ground is encountered it is not necessary to deliver a cutting fluid through the conduit 84 (and/or conduit 86). When extremely wet ground is encountered the cutter carrier 22 and the cutter elements 48 will primarily function as a slurrying implement and will not be needed for mechanically breaking the ground material loose from the tunnel face.
The conduits 83, 84, 86 are of sectional construction so that additional sections can be added to them as the shield 10 is moved forwardly through the ground.
Referring now to FIG. 5, a pressure pulse generator 88 is shown connected to the drive motors 40 for the cutterhead 20. The generator 88 may be mounted on a sled (not shown) located in the tunnel rearwardly of the shield 10. Generator 88 is shown to comprise three piston cylinder units 90, each of which is associated with one of the drive motors 40. A crank shaft 92 having a center of rotation 94 provides an eccentric drive for the pistons 96. The cylindrical drive lobe of the crank shaft 92 turns within a central opening formed in a triangular member 98. The inner ends of the pistons 96 include flat portions 100 which make sliding contact with the three bases of member 28 as the crank shaft 92 turns about axis 94. Rotation of shaft 92 about axis 94 drives the member 98 along an orbital path. As it so moves the member 98 changes the position of the pistons 96 relative to their respective cylinders. When a piston 96 is forced radially outwardly the fluid within the chamber outwardly of its head 102 is forced through a conduit 104 into the radially outer chamber within the associated fluid motor 40. Such fluid pushes the piston 106 of the motor 40 radially inwardly to drive the shaft 24 and also forces the fluid which is in the radially inner chamber of the motor 40 to flow from such chamber through a conduit 108 into the radially inner chamber of the associated generator cylinder 90. This type of hydraulic drive system is basically similar to the hydraulic drive system disclosed by my U.S. Pat. No. 3,544,075, granted on Dec. 1, 1970. Of course, it is to be understood that the cutterhead 20 may be driven throughout its orbital path of travel by any suitable drive mechanism.
The tunneling machine of this invention possesses many important advantageous over known prior machines provided for the same purpose. It utilizes a fixed bulkhead. No pressurization is required in the tunnel behind the shield. The pressurization that is done forwardly of the bulkhead is done by the same fluid which is supplied for the purpose of fluidizing the cut ground material. All of the machinery is located in dry areas within the shield or within the tunnel rearwardly of the shield. Since an orbital rather than a rotary motion is employed, no rotary seals or packings are needed. The orbital motion requires only a relatively small amount of movement for any given part on the cutterhead (e.g., a maximum movement of only about 3 inches). Therefore, a diaphragm type seal can be employed between the moving and stationary parts. The machine provides good control of progress because the amount of material being removed can be easily controlled by varying the cutterhead speed and the flow rate of fluid through the cutterhead region. Also, it is believed that deformation of the diaphragm 56 which occurs during orbiting of the cutterhead 20 may produce a peristalic pumping effect forwardly of the bulkhead 58, to aid movement of the water, mud, etc., and the cuttings picked up thereby, from the cutterhead region back through the removal pipe 33.
The direction of cutterhead drive should be reversible so that any counter torque problems which are incurred can be readily resolved by merely reversing the direction of orbit. In some installations the front wall 50 of the cutter carrier 22 may be flat rather than spherical. Also, in some installations the seal sections 56, 74 may be omitted and the orbiting drive motors 40 operated in the wet rather than in the dry.
It is believed that it will always be necessary to supply water or mud to the face of the tunnel. If an attempt were to be made to use only ground water to form a slurry, it would probably lead to a cave in of the ground material in front of the machine. The circulation of water or mud at a controlled pressure can maintain a hydrostatic balance at the tunnel face, (i.e., the ground water pressure can be opposed by an equal pressure) to prevent a collapse of face and an over amount of excavation attended by ground caving and/or systems. Also, the almost complete closure at the face afforded by the orbiting cutterhead with its small amount of movement (compared with a rotating cutterhead), and its metering action, help prevent over excavation of the face.
Another advantage of the tunneling system of this invention is that the density of the circulating fluid can be monitored to provide a means of equating the amount of solid material excavated to the forward advance of the shield. The presence of one or more bulkheads, sealed by flexible diaphragms, permits pressurization of the face by a liquid without having to pressurize the tunnel rearwardly of the bulkhead, thus allowing personnel to work in the tunnel behind the machine under normal atmospheric pressure.
Having thus described the invention, it will be understood that various changes and modifications may be made in the specific form and construction of the various components thereof, without departing from the scope of the appended claims which define the scope of protection.
1. Field of the Invention
This invention relates to tunneling machines and more particularly to shield type tunneling machines operable for excavating tunnels in soft ground.
2. Description of the Prior Art
It is known to excavate tunnels in relatively soft ground by the use of "bulkhead" tunneling machines. This type of tunneling machine comprises a tubular caisson, termed a "shield," which is advanced axially through the ground. A transverse bulkhead divides the shield axially. Water or some other liquid is pumped into the region forwardly of the bulkhead to mix with the excavated ground material. The resulting mixture is removed from the region forwardly of the bulkhead via a conduit extending rearwardly through an opening in the bulkhead. Examples of this type of tunneling machine are shown by U.S. Pat. No. 360,959 granted Apr. 12, 1887 to James H. Greathead; by U.S. Pat. No. 3,260,054 granted July 12, 1966 to Hans Lorenz; by U.S. Pat. No. 3,334,945 granted Aug. 8, 1967 to John V. Bartlett; and by U.S. Pat. No. 3,360,061 granted Dec. 26, 1967 to Carlos R. Canalizo.
It is common in tunneling machines of this type to locate a rotating cutterhead or some other type of cutter element forwardly of the bulkhead for mechanical excavating the tunnel face. Each of the foregoing patents discloses some form of a mechanical excavator.
SUMMARY OF THE INVENTION
The present invention relates to the provision of a bulkhead shield type tunneling machine having a cutterhead which undergoes an orbiting radial shifting movement rather than rotation. The orbiting head is easily supported and driven and no rotating-to-stationary parts seal is required. Rather, the bulkhead is provided with a flexible wall section which is connected to a portion of the cutterhead and is sufficiently distortable to permit the orbiting movement of the cutterhead.
Preferably, the cutterhead includes an elongated drive shaft which projects through an opening in a rigid portion of the bulkhead and which is mounted at its rear end onto the shield by means of a universal joint. Preferably, such cutterhead is driven by a ring of radially disposed piston-cylinder linear motors which are interconnected between the shield and a portion of the cutterhead at locations rearwardly of the bulkhead. A fluid pressure generator distributes fluid pressure pulses from each said linear motor to the next in repetitive cyclic fashion around said ring for in this manner producing the orbiting radial shifting movement of the cutterhead and the cutter elements carried thereby. An important advantage of this type of drive system is that it will not stall out in the event the cutterhead encounters hard material which restrains its movement. Instead the input energy is absorbed by the elasticity of the drive fluid.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is an axial sectional view of an embodiment of the invention;
FIG. 2 is a front elevational view, looking towards the face of the cutterhead shown in FIG. 1, showing a representative number of cutter elements which in actuality are substantially evenly spaced over the entire face of the cutterhead;
FIG. 3 is a cross sectional view of the machine shown by FIG. 1, taken substantially along line 3--3 of FIG. 1;
FIG. 4 is a cross sectional view taken along line 4--4 of FIG. 1; and
FIG. 5 is a diagrammatical view of a fluid drive system for the cutterhead.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In preferred form, the tunneling machine of this invention comprises a cylindrical shield 10 having an open forward end bordered by a leading cutting edge 12. Shield 10 may comprise a separate tail ring 14 with respect to which the shield proper may be adjustable for steering purposes. The tail ring 14 may be firmly secured to a forward cylindrical tunnel lining section 16, such as by a plurality of bolts 18. An endwise force (indicated by force arrows F) may be directed against the lining section 16 to move both it and the shield 10 forwardly (not shown) may be added to the lining in succession behind section 16, and each pushed forwardly tommove the shield 10 and the lining segments ahead of it forwardly together. Of course, other techniques of advancing the machine may be employed.
According to the invention, an orbiting type cutterhead 20 is supported within the shield 10 forwardly of bulkhead means which divides the shield 10 axially into a forward wet compartment and a rearward dry compartment. Preferably, cutterhead 20 comprises a radial, generally disc shaped cutter carrier 22 attached to the forward end of an elongated tubular shaft 24. Shaft 24 extends rearwardly through the shield 10 and at its rear end is connected to the first yoke 26 of a universal joint. From yoke 26 shaft 24 extends rearwardly through a trunnion member 28. The second yoke 30 of the universal joint is attached to a support plate 32 which may be rigidly connected to the shield 10 by a plurality of support legs 34 and mounting plates 36, 38 (FIG. 4).
A ring (e.g., three) of equally spaced, radially disposes piston-cylinder linear motors 40 are interconnected between connector plate portions 42 of the cutterhead 20 and anchor plates 44 secured to the shield 10. The respective ends of the motors 40 are connected by pivotal joints to the supports 42, 44. A pressure generator PG (FIG. 5) is provided for distributing fluid pressure pulses from each linear motor 40 to the next in repetitive cyclic fashion around said ring, for producing the orbiting radial shifting movement of the cutterhead 20 and the cutter elements 48 thereon, as will hereinafter be described in greater detail.
The cutter carrier 22 may comprise a spherical forward wall 50 and a planar rear wall 52, both of which are welded or otherwise firmly secured at their centers to the forward portion of the shaft 24. Walls 50 and 52 come together and are secured together at their peripheries. A cylindrical section 54 may project rearwardly from wall 52 to serve as both a reinforcement for the mounting plates 42 and a mounting member for a flexible wall section 56 of a bulkhead 58. In addition to flexible wall section 56 the bulkhead 58 comprises an annular fixed wall 60 which is firmly secured at its outer periphery to the shield 10. A central opening is formed in wall 60 about which a cylindrical mounting ring 62 is secured. The flexible wall 56 is annular in form and has a radial dimension which is substantially larger than the radial space which exists between the two support rings 54, 62 when the shaft 26 is centered within the shield 10. As a result, flexible wall 56 is distortable enough so that it does not interfere with the orbiting movement of the cutterhead 20 while it forms its sealing or closure function.
A second bulkhead 64 may be provided rearwardly of the linear motors 40. The secondary bulkhead 64 may comprise a rigid annular outer portion 66 secured to the shield 10, a fixed annular outer mounting ring 68, an inner movalbe mounting ring 70 which is attached to a radial plate 72 which in turn surrounds the tubular shaft 24, and a second flexible wall section 74. The secondary bulkhead 64 serves as a backup for the primary bulkhead 58 in the event that something happens to the latter.
Flexible wall sections 56, 74 may be made from truck innertubes which are not inflated.
Preferably, compressed air is delivered into the space between the two bulkheads 58, 64. In the event one of the bulkhead seals 56, 74 breaks or a leak otherwise develops in one of the bulkheads 58, 64, the loss of air pressure within the compartment between the two bulkheads 58, 64 may be sensed (by means not shown) and used to produce a signal to the operator that a leak has developed.
The cutter elements 48, which may be short chisel-like elements, are on the cutter carrier 22 in sufficient numbers so that during orbiting movement of the cutterhead 20 a large part of the tunnel face is swept by an orbiting cutter element 48. In FIG. 2 only a representative portion of the cutter elements 48 are shown.
An annular space or gap 78 is formed between the outer periphery 80 of the cutter carrier 72 and the adjacent ring portion 82 of the shield 10. This annular space 78 serves to meter the flow of ground material rearwardly when freely flowing ground material is encountered.
A material removal pipe 83 is provided to pick up the mined material from the annular region immediately surrounding and trailing the peripheral portion 80 of the cutter carrier 22. Such pipe may be a part of a material removal system of the general type disclosed by the aforementioned U.S. Pat. No. 3,334,945.
Under certain ground conditions a cutting fluid (e.g., water, mud, etc.) is delivered to the face region of the tunnel forwardly of the cutter carrier 22. It may be delivered to the face region by way of a delivery conduit 84 which is supported within the hollow shaft 24 and has a discharge nozzle 86 at its forward end. Alternatively, or additionally, the water, mud, etc. may be delivered into the region 78 by a conduit 86. The water, mud, etc., delivered through conduit 84 (and/or conduit 86) serves to fluidize the ground material. Cutter carrier 22 and the cutter elements 48 serve to agitate and mix together the earth material and the water, mud, etc., so as to form a slurry which is easily pumpable rearwardly through the conduit 83. Of course, when wet ground is encountered it is not necessary to deliver a cutting fluid through the conduit 84 (and/or conduit 86). When extremely wet ground is encountered the cutter carrier 22 and the cutter elements 48 will primarily function as a slurrying implement and will not be needed for mechanically breaking the ground material loose from the tunnel face.
The conduits 83, 84, 86 are of sectional construction so that additional sections can be added to them as the shield 10 is moved forwardly through the ground.
Referring now to FIG. 5, a pressure pulse generator 88 is shown connected to the drive motors 40 for the cutterhead 20. The generator 88 may be mounted on a sled (not shown) located in the tunnel rearwardly of the shield 10. Generator 88 is shown to comprise three piston cylinder units 90, each of which is associated with one of the drive motors 40. A crank shaft 92 having a center of rotation 94 provides an eccentric drive for the pistons 96. The cylindrical drive lobe of the crank shaft 92 turns within a central opening formed in a triangular member 98. The inner ends of the pistons 96 include flat portions 100 which make sliding contact with the three bases of member 28 as the crank shaft 92 turns about axis 94. Rotation of shaft 92 about axis 94 drives the member 98 along an orbital path. As it so moves the member 98 changes the position of the pistons 96 relative to their respective cylinders. When a piston 96 is forced radially outwardly the fluid within the chamber outwardly of its head 102 is forced through a conduit 104 into the radially outer chamber within the associated fluid motor 40. Such fluid pushes the piston 106 of the motor 40 radially inwardly to drive the shaft 24 and also forces the fluid which is in the radially inner chamber of the motor 40 to flow from such chamber through a conduit 108 into the radially inner chamber of the associated generator cylinder 90. This type of hydraulic drive system is basically similar to the hydraulic drive system disclosed by my U.S. Pat. No. 3,544,075, granted on Dec. 1, 1970. Of course, it is to be understood that the cutterhead 20 may be driven throughout its orbital path of travel by any suitable drive mechanism.
The tunneling machine of this invention possesses many important advantageous over known prior machines provided for the same purpose. It utilizes a fixed bulkhead. No pressurization is required in the tunnel behind the shield. The pressurization that is done forwardly of the bulkhead is done by the same fluid which is supplied for the purpose of fluidizing the cut ground material. All of the machinery is located in dry areas within the shield or within the tunnel rearwardly of the shield. Since an orbital rather than a rotary motion is employed, no rotary seals or packings are needed. The orbital motion requires only a relatively small amount of movement for any given part on the cutterhead (e.g., a maximum movement of only about 3 inches). Therefore, a diaphragm type seal can be employed between the moving and stationary parts. The machine provides good control of progress because the amount of material being removed can be easily controlled by varying the cutterhead speed and the flow rate of fluid through the cutterhead region. Also, it is believed that deformation of the diaphragm 56 which occurs during orbiting of the cutterhead 20 may produce a peristalic pumping effect forwardly of the bulkhead 58, to aid movement of the water, mud, etc., and the cuttings picked up thereby, from the cutterhead region back through the removal pipe 33.
The direction of cutterhead drive should be reversible so that any counter torque problems which are incurred can be readily resolved by merely reversing the direction of orbit. In some installations the front wall 50 of the cutter carrier 22 may be flat rather than spherical. Also, in some installations the seal sections 56, 74 may be omitted and the orbiting drive motors 40 operated in the wet rather than in the dry.
It is believed that it will always be necessary to supply water or mud to the face of the tunnel. If an attempt were to be made to use only ground water to form a slurry, it would probably lead to a cave in of the ground material in front of the machine. The circulation of water or mud at a controlled pressure can maintain a hydrostatic balance at the tunnel face, (i.e., the ground water pressure can be opposed by an equal pressure) to prevent a collapse of face and an over amount of excavation attended by ground caving and/or systems. Also, the almost complete closure at the face afforded by the orbiting cutterhead with its small amount of movement (compared with a rotating cutterhead), and its metering action, help prevent over excavation of the face.
Another advantage of the tunneling system of this invention is that the density of the circulating fluid can be monitored to provide a means of equating the amount of solid material excavated to the forward advance of the shield. The presence of one or more bulkheads, sealed by flexible diaphragms, permits pressurization of the face by a liquid without having to pressurize the tunnel rearwardly of the bulkhead, thus allowing personnel to work in the tunnel behind the machine under normal atmospheric pressure.
Having thus described the invention, it will be understood that various changes and modifications may be made in the specific form and construction of the various components thereof, without departing from the scope of the appended claims which define the scope of protection.