Device and method for excavating deep trenches

Abstract: The invention is embodied in a device, and method for excavating an underdrainage (a subterainian drain) which is capable of preserving surface vegetation such as grass in pasture in good condition and providing excellent drainage. The device 20 forms an underdrainage in the ground while being hauled by a tractor 10. The underdrainage excavating device has a discard device 40 for discarding the dirt excavated by an endless belt of excavating buckets 25 to scatter the dirt over an extended area of the ground such that the grass and pastures will not be buried and wither. Part of the dirt covers a slit space S such that any dirt entry from outside into the slit space S is prevented. The excavating device 20 also forms an underdrainage by following an inclined plane signal which projects an inclined plane at an angle to a reference horizontal plane such that said underdrainage slopes to provide excellent gravity drainage performance.

Description: The present invention relates to a device for excavating an underdrainage in the ground (that is a subterainian drainage), a system for excavating an underdrainage and a method for excavating an underdrainage and more particularly to a device for positively excavating an underdrainage in the ground, a system therefor and a method therefor by reforming the lower part of a slit space formed by means of excavating buckets to close the intermediate portion of the slit space. It is well known that a device for excavating an underdrainage within the ground is used in order to drain the residual surface water or excess moisture within the ground such that an aquatic environment or soil condition suited to field cultivation is built. Japanese Pat. Appln. Pub. No. 9-60036 discloses a device for excavating an underdrainage comprising an excavator composed of buckets attached to an endless chain, a slit reformer knife member arranged rearwardly of said excavator taken in the direction of excavating work, a pressing member attached to said slit reformer knife member at a vertical intermediate portion thereof, and a casing having a dirt discard opening rearwardly of a top position each bucket takes. Said device for excavating an underdrainage is adapted to discard the excavated dirt into said casing while pressing the vertical intermediate portion of the slit by means of said pressing member to close the slit such that an underdrainage is formed. As a result, the upper part of the reformed slit space is filled with the dirt discarded by each bucket at the time of transition from an upward run to a downward run thereof such that the slit is covered to prevent an unnecessary falling of outside dirt thereinto which might lead to a closure of said underdrainage. However, the underdrainage in its entirety excavating device disclosed in Japanese Pat. Appln. Pub. No. 9-60036 has a problem that the dirt discarded can drop onto a position off the upper part of the slit space to form a ridge at a position adjacent to said upper part of the slit space to cover the grass or pasture in the field, which might be oppressed by said discarded dirt to wither from lack of oxygen. The underdrainage excavating device of this type has another problem of excavating an underdrainage substantially in parallel with the ground surface, said underdrainage lacking in an incline with the result that surplus water in the ground can stay there to mar the drainage performance. The device disclosed in US-A-3 011 278 shows a deflection plate as scattering device for guiding the dist into the trenched slit. In order to solve the problems referred to in the foregoing, the present invention has an object to provide a device, a system and a method for excavating an underdrainage, which are capable of forming an underdrainage with a good drainage. Accordingly the present invention provides a device for excavating an underdrainage according to claim 1 and a method of excavating an underdrainage according to claim 7. Preferred embodiments are defined by the dependent claims. A device system and method for and of forming an underdrainage will now be described by way of example with reference to the accompanying drawings, in which, Fig. 1 is a side elevation of a first embodiment of device for excavating underdrainage attached to a tractor; Fig. 2 is a rear view of the tractor of Fig. 1 without the parts rearward of a slit reformer knife Fig. 3 is a rear view of the underdrainage excavating device in Fig. 2; Fig. 4 is a perspective view of a presser member; Fig. 5 is a sectional plan view showing the presser member of Fig. 4 in operation; Fig. 6 is a side elevation of a dirt discarding section; Fig. 7 is a plan view of the dirt discarding section; Fig. 8 is a front view of the dirt discarding section; Fig. 9A is a plan view of the rotary plate, Fig. 9B is a front view thereof and Fig. 9C is a side elevation thereof; Fig. 10 is a diagram of a link mechanism in the tractor; Fig. 11 is a vertical cross section of a slit space; Fig. 12A is a diagram plan view of the presser member in operation and Fig. 12B is a vertical cross section diagram of the presser member; Fig. 13A is a diagram plan view of the slit space being reformed by the slit reformer knife and Fig. 13B is diagram plan view in cross section; and Fig. 14 is a side elevation of the underdrainage excavating device of the invention in operation. Referring to Fig. I through Fig. 14 showing a preferred embodiment of the invention, in which a well known crawler type tractor 10 is equipped with an underdrainage excavator 20 actuated by means of a link mechanism composed of an upper link 11, a lower link 12 and a lift link 13; that is, said underdrainage excavator 20 is hauled and controlled through an operation of the upper link 11 and the lower link 12 which respectively act as a three point link. As shown in Fig. I through Fig. 3, said underdrainage excavator 20 is equipped with a mast 21 supported by said link mechanism, the top of said mast 21 being attached with sprocket wheel 22. Said mast 21 has a guide plate 24A, which will be explained later in detail, extending downward. Said guide plate 24A is attached with a sprocket wheel 23 which forms a pair together with said sprocket wheel 22 such that said sprocket wheels 22 and 23 are driven by way of axles 22A and 23A. An endless chain 24 is passed around said sprocket wheels 22 and 23, excavating pawls 25 are attached to said chain with predetermined spacings therebetween. Said chain 24 is adapted to move along the periphery of a guide plate 24A extending downwardly of said mast 21, said guide plate 24A functioning to prevent the distance between the tense side of the chain 24 and the slack side of the chain 24 from becoming less while providing a support of the sprocket wheel 23. The axle 23A of said sprocket wheel 23 is provided to rotate on the guide plate 2 4A. Each bucket-like excavating pawl 25 is attached with a predetermined orientation such that each bucket-like excavating pawl 25 running on the tense side performs an excavating work on the ground surface to be excavated by moving from below to above while the bucket-like excavating pawl 25 on the slack side thereof does no work. There is further provided a drive sprocket 26 to drive the axle 22A of the sprocket wheel 22, said drive sprocket 26 having an axle coaxially with said axle 22A such that a torque is transmitted from the tractor 10 by way of the chain 27 (a drawing of an output sprocket wheel on the tractor side is omitted). With this structure, the tense side of the chain 24 is driven such that the tense side shows an upward motion while the slack side shows a downward motion. Further, there is a casing 28 provided rearwardly of the uppermost end of said mast 21, in other words, rearwardly taken in the direction of excavating work, said casing 28 being formed with an opening 28A for discarding the dirt excavated by means of said excavating pawls 25. Said casing 28 has a shutter 28B for downwardly guiding the dirt discarded from said opening 28A. Therefore, the excavated dirt is discarded through said opening 28A at the time of each bucket-like excavating pawls 25 reversing its motion from the ascending run to the descending run further to be guided downwardly by said shutter 28B. Most of said discarded dirt is scattered over the ground such that part thereof is filled into the upper part of a slit space S which will be explained later, said slit space S being covered with a soil lid H. Further, a reformer knife 31 is provided in a plane containing said guide plate 24A provided rearwardly of said mast 21 taken in the direction of the excavating work, said reformer knife 31 being adapted to reform said slit space S formed by said excavating pawl 25. Further, said reformer knife 31 has a pressing member 32 attached at a vertically intermediate portion thereof, said pressing member 32 being adapted to press the dirt scraped off from both sides such that said slit is closed. In other words, said reformer knife 31 having a relatively thin vertically elongate configuration follows the inside of the slit-like space excavated within the ground, said reformer knife 31 being attached with said pressing member 32. As shown in Fig. 1, said pressing member 32 is attached to said knife 31 at a vertically intermediate portion thereof within the ground. Further as shown in Fig. 4 and Fig. 5, said pressing member 32 is shaped like a gate as viewed from behind and like a modified trapezoid in plan view having rearwardly converging sides. Said pressing member 32 is composed of a base plate 32A and side plates 32B bent therefrom at a right angle. Since said base plate is shaped like a modified trapezoid, the space defined by said side plates 32B becomes rearwardly increasingly narrower in the direction of excavating work. Said reformer knife 31 is slightly wider than that of the slit space in the ground while the opening defined between the rearmost ends of said side plates 32B of the presser member 32 is substantially wider than the width of the slit space S. Further, as shown in Fig. 1, there is provided a space forming plate 33 attached to said knife at a lower part thereof and forwardly thereof taken in the direction of the excavating work, said space forming plate 33 being substantially circular such that the space formed by said excavating pawls 25 is enlarged at a lower part thereof. The lowermost end of said space forming plate 33 is positioned at a lowermost level of the locus of the chain 24 such that an excavating pawl 25 is seen protruding downwardly of said space forming plate 33 as viewed from behind in the direction of the excavating work. Further as shown in Fig. 6 and Fig. 8, there is provided a scattering section 40 rearwardly of said mast 21 taken in the direction of the excavating work. Said scattering device 40 is equipped with a support member 41 attached to the casing 28, gear box 42 in turn attached to said support member 41 and rotary plate 43 attached to an axle 42A of said gear box 42 to rotate in a horizontal plane. Said gear box 42 has an axle 42B attached with a sprocket wheel 44 while the axle 22A is attached with a sprocket wheel 45. An endless chain 46 is passed around said sprocket wheels 42 and 45 such that the chains 24 and 46 are driven by a drive source on the tractor side. As shown in Fig. 9, said rotary plate 43 is attached with four vanes 43A extending radially with an equal angular distance therebetween about said axle 42A. The excavated dirt T falls on said rotary plate 43 to be deflected by said vanes 43A to be scattered onto the ground surface. As shown in Fig. 1, a laser beam receiving section 51 to receive a slope signal L in the form of a laser beam indicating a slope at an angle to a horizontal reference plane is attached by way of a pole 51X to an appropriate portion of the mast 21 at a position due above thereof in side elevation. Then, the underdrainage excavating device 20 is controlled to be raised or lowered by the output from the tractor such that the laser beam receiving section 51 is to stay in a laser beam plane. Said lift cylinder 16 is controlled by slope signal L from the laser emitting section 53 to expand and contract by being driven by a hydraulic pressure from a hydraulic pump 56 equipped in the tractor 10 by way of a selector switch 55 and a flow rate control valve 57. In other words, the slope signal L received by the laser receiving section 51 is input into a control circuit 54 having a controlling microcomputer such that said selector valve 55 is select controlled on the basis of the control signal output from said control circuit 54 to control the valve opening area of said flow rate control valve 57. In this connection, the laser emitting section 53 is located at an appropriate position away from the field being worked on and is adapted to rotate in a plane at an angle to a horizontal reference plane while emitting a laser beam to draw an imaginary inclined laser beam plane in the air. Next, the manner of underdrainage excavating work by using the device for excavating an underdrainage according to the present invention will be shown in Fig. 11. First of all, at a field being worked on for excavating an underdrainage, the device 20 for excavating an underdrainage attached to the tractor 10 is lowered by operating a lift mechanism of the tractor 10 before the tractor 10 is run while supplying a driving force to the axle 22A of the sprocket wheel 22 by way of the sprocket wheel 26. At an early stage, the excavating pawls 25 may not stick into the earth but, as the tractor 10 proceeds, the excavating pawls 25 start to stick into the ground to pierce thereinto while excavating the ground down to the predetermined depth. At this time, the excavated dirt is carried by the excavating pawls 25 in the upward run thereof before, as said excavating pawls 25 changes its course from the upward run to the downward run, the dirt carried by the excavating pawls 25 is discarded downward by way of discard opening 28A in the casing 28 by the shutter 28B. Thereafter, the vane 43A provided on the rotary plate 43 deflects the dirt falling onto the rotary plate 43 to be scattered over the ground. Substantially along the excavating work line in the field, a slit space S is formed as shown in Fig. 11 by means of said buckets-like excavating pawls 25. Then, after the passage of the slit reformer knife 31 and the pressing member 32 provided rearwardly of said excavating pawls 25, the dirt pressed and hardened by said pressing member 32 is left in the form of a crossbeam extending horizontally to provide vertical blockage of the slit S. Then, rearwardly of said excavating pawls 25, part of the excavated dirt T being scattered falls drawing an arc into said slit space S as shown in Fig. 14. Said excavated dirt T falls into said slit space S formed after the passage of the slit reforming knife 31 such that the upper part of the slit space S is closed as if a lid H is placed thereover. (Fig. 13) In other words, before part of the excavated dirt T is scattered, the slit space is reformed by the slit reforming knife 31, the slit space T opening at K as shown in Fig. 11. However, part of said excavated dirt T scattered into an air rearwardly of said slit reforming knife 31 falls into said slit space S to accumulate and cover the upper part thereof in the form of the lid H to close the upper part of the slit because the slit space is closed at a vertically intermediate portion. Particularly, at a peat bog in general, the peat bog dirt at the mid-depth of the slit S of 70 cm from the ground surface is scraped off from both sides of the slit space S and pressed by the pressing member 32 after the passage of the tractor 10 to provide a blockage in the form of a crossbeam in said slit space S. In other words, when the underdrainage excavating device 20 of the present invention is hauled by the tractor 10, the slit space S is blocked by said cross beam of dirt formed by the pressing member 32 because a space defined by the side plates 32B of the pressing member 32 becomes increasingly narrower. Then, part of the excavated dirt being scattered is accumulated above said cross beam of dirt formed by the pressing member T to block the slit space, thus forming an underdrainage further preventing the entry of dirt. (Fig. 13B) There are formed a confined part of the slit space and an underdrainage space formed by the passage of the space forming plate 33. Being separated from outside, said underdrainage space is free from entry of the dirt to ensure a long term maintenance of the space as an underdrainage such that the moisture contained in the peat bog dirt oozes out to be drained. In the operation state above, the lift cylinder 16 shown in Fig. 10 receives the slope signal L issued from the laser emitting section 53 for the controlling purpose. In other words, the lift cylinder 16 is adapted to be extended and contracted such that the laser beam receiving section 51 always stays in the inclined laser beam plane defined by the inclined plane signal L, thus controlling the vertical position of the underdrainage excavating device 20. As stated in the foregoing, the underdrainage excavating device 20 is capable of excavating an inclined underdrainage space by ensuring that the laser beam receiving section 51 is kept within said plane defined by inclined plane signal L because the underdrainage excavating device 20 performs an operation in a predetermined inclined plane. If the laser beam receiving section 51 goes off the inclined laser beam plane defined by the inclined signal L issued from the laser beam emitting section 53, the control signal from the control circuit (control box) 54 for the lift mechanism is issued to switch the hydraulic circuit. For example, if the tractor 10 rides over a raised portion in the field, the laser beam emitting 53 is raised above the inclined plane L. With said laser beam receiving section 51 thus going off the inclined plane, the control circuit (control box) 54 issues a control signal, in accordance with which the hydraulic circuit is switched. In other words, to ensure that the inclined plane signal L is received, a signal to instruct that the laser beam receiving section 51 be lowered is issued such that the selector valve 55 is switched over to extend the lift cylinder 16. At this time, the pressure oil is pressed toward the direction to control the orientation of the underdrainage excavating device 20 such that the forward end thereof is lowered by actuating the rod 16A of the lift cylinder 16 into the direction to extend the same. As a result, the lift arm 15 is rotated to press the lift rod 13 to lower the lower link 12 until the laser beam receiving section 51 is lowered down to the level to receive the inclined plane signal L where the forward end of the underdrainage excavating device 20 is positioned to do the desired excavating work. In other words, if the laser beam receiving section 51 goes off the inclined plane of the inclined plane signal L issued from the laser beam emitting section 53 to indicate that the underdrainage excavating device goes off the desired level, the extent of deviation of the laser beam receiving section 51 off the inclined plane is calculated at the control box (control circuit) such that the amount of correction is determined. Then, a signal corresponding to the correction is input into the hydraulic circuit of the lift mechanism equipped in the tractor 10 to control and drive the lower link 12 by way of the lift rod 13. Thus, the orientation of the underdrainage excavating device 20 is controlled such that the laser beam receiving section 51 is located in the inclined plane referred to in the foregoing. As a result, the underdrainage having a slope (inclination of ) is excavated in the ground as shown in Fig. 14. As clearly understood from the explanation in the foregoing, the underdrainage excavator according to the invention scatters the excavated dirt over an extended area of the ground surface to prevent the excavated dirt from accumulating in the form of mounds in a localized area along the slit space to cover the grass or pasture while part of the excavated dirt is filled into the upper part of the slit space, thus preventing an entry of any dirt from outside. Further, the excavating device of the invention is controlled to change its level in accordance with a inclined reference plane while being drawn by a tractor to ensure that the device excavates the ground to form an inclined underdrainage which shows excellent drainage performance.

Claims: A device for excavating an underdrainage comprising an underdrainage excavator (20) having an endless chain (24) with excavating buckets (25) attached thereto with a predetermined spacing therebetween; a reformer knife (31) provided rearwardly of said underdrainage excavator (20) taken in the direction of an excavating work to form a slit space; a pressing member (32) attached to said reformer knife (31) at a vertically intermediate portion thereof to scrape off dirt from both intermediate sides of said slit space and press said scraped off dirt such that said slit space is closed to form an underdrainage in the ground; and a scattering device (40) provided rearwardly of said underdrainage excavator (20) taken in the direction of excavating work for scattering the dirt excavated by said excavating buckets (25) over the ground, characterised in that said scattering device (40) includes a rotary plate (43) adapted to rotate in a horizontal plane and vanes (43A) radially arranged on said rotary plane to deflect the excavated dirt falling on said rotary plate (43). A device according to claim 1 wherein said underdrainage excavator (20) and said scattering device (40) are adapted to be driven by means of a common drive source. A device according to claim 1 or claim 2 wherein said underdrainage excavator (20) is adapted to be raised and lowered to reform said slit space while being hauled by said tractor such that said pressing member (32) forms an inclined underdrainage. A device for excavating an underdrainage according to claim 3 and having a lift mechanism to raise and lower said underdrainage excavator (20) while being hauled and control means for driving said lift mechanism such that said underdrainage excavator (20) forms an inclined underdrainage in said ground. A device for excavating an underdrainage as set forth in claim 3 or 4, comprising a laser beam receiving means (51) for receiving a laser beam from a location away from the field to be worked on to draw an imaginary slope inclined at an angle to a reference horizontal plane, said underdrainage excavator (20) being adapted to be raised and lowered in accordance with a laser beam signal which said laser beam receiving means (51) receives. A device according to claim 5, wherein said control means is adapted to drive said lift mechanism in accordance with said laser beam received by said laser beam receiving means (51) such that said lift mechanism raises and lowers the underdrainage excavator (20). A method for excavating an underdrainage comprising the steps of reforming an excavated space to form a slit space; scraping dirt from both sides of said slit space at a vertically intermediate level; pressing said scraped dirt such that said slit space is closed to form an underdrainage therebelow; and scattering the excavated dirt by means of a scattering device (40) characterised by the step of scattering being achieved by discharging the dirt onto a plate (43) rotating about a vertical axis so that vanes (43A) arranged radially on said disc deflect the dirt. A method according to claim 7 including the step of raising and lowering an excavator while said excavator is being hauled by a tractor such that said excavator excavates the ground to form an inclined underdrainage. A method according to claim 8, wherein said raising and lowering step includes a step of scanning a laser beam in a beam plane at an angle to a reference horizontal plane, said excavator receiving said laser beam via receiver means (51) and responding to receptio of said laser beam to control a lift mechanism to raise and lower the excavator.

Inventors: NISHIGUCHI MOTOJI, NISHIGUCHI, MOTOJI
Applicants: UNIT SHOJI LTD YK, YUGENKAISHA UNIT SHOJI LIMITED
Application year: 2000
Main classification: E02F5
IPC codes: E02F5, E02B11