Deep foundation drilling machine

Abstract

To automatically remove slack in an opening / closing wire rope so that a bucket can be closed sufficiently, to suppress a delay in a response of a bucket operation to a closing operation of a bucket and to improve operability.SOLUTION: A deep foundation excavator comprises: a lifting cylinder for raising and lowering a clamshell bucket; an opening / closing cylinder opening and closing the clamshell bucket; a slack removal cylinder removing slack in an opening / closing wire rope; a connecting oil passage connecting a first oil passage connecting a bottom side oil chamber of the lifting cylinder and a direction switching valve with a second oil passage connecting a bottom side oil chamber of the slack removal cylinder and the direction switching valve; and a solenoid valve opening and closing the connecting oil passage. When a lowering operation of the clamshell bucket and slack in the opening / closing wire rope are detected, the solenoid valve is opened to supply pressurized oil discharged from the lifting cylinder to the slack removal cylinder, to tension the opening / closing wire rope while the clamshell bucket is lowered.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a deep foundation excavator used for shaft excavation and the like.

Background Art

[0002] At the construction site of a high-rise building, a deep foundation excavator for excavating a shaft may be used so that underground work can be stably carried out even on soft ground. The deep foundation excavator includes a self-propelled vehicle body and a working device having a clam shell bucket (hereinafter abbreviated as a bucket). When excavating earth and sand with the bucket, the bucket is opened and landed, and the bucket buried in the ground is closed and the bucket holding the earth and sand is lifted. A mechanical bucket is lifted and opened and closed by paying out and pulling a wire rope for lifting and opening and closing (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a deep foundation excavator using a wire rope for lifting and opening and closing a bucket, appropriate slack is required for the wire ropes for lifting and opening and closing so that the bucket can hold earth and sand. However, if the wire rope for opening and closing is slack more than necessary when closing the bucket, the bucket may not be fully closed.

[0005] In the technology described in Patent Document 1, when a bucket closing operation is performed while slack in the opening / closing wire rope is detected, a slack-removing cylinder automatically activates to remove the slack in the opening / closing wire rope. However, the slack-removing cylinder operates by temporarily switching the supply of pressurized oil to the opening / closing cylinder, which opens and closes the bucket, in conjunction with the bucket closing operation. Therefore, the opening / closing cylinder does not operate until the slack in the opening / closing wire rope is removed and the supply of pressurized oil switches from the slack-removing cylinder to the opening / closing cylinder, causing a delay in the bucket closing operation. When there is a delay between the closing operation and the bucket closing in this way, a discrepancy occurs between the actual operation of the bucket and the imagined operation for an operator who is not aware that the slack-removing cylinder is operating.

[0006] The object of the present invention is to provide a deep foundation excavator that can automatically remove slack in the opening and closing wire rope so that the bucket closes sufficiently, thereby suppressing the response delay of the bucket's movement to the bucket closing operation and improving operability. [Means for solving the problem]

[0007] To achieve the above objective, the present invention comprises a self-propelled vehicle body, a work device attached to the vehicle body, an operating device for instructing the operation of the work device, an operating sensor for detecting the operation of the operating device, a hydraulic system for driving the work device in accordance with the operation of the operating device, and a controller for controlling the hydraulic system, wherein the work device comprises a boom rotatably connected to the vehicle body vertically, an arm rotatably connected to the tip of the boom, a clamshell bucket suspended from the arm by a wire rope for lifting and a wire rope for opening and closing, and The apparatus comprises a bucket drive device supported by an arm and driving the clamshell bucket, the lifting wire rope is wound around a lifting guide sheave which is a fixed pulley and a lifting sheave which is a movable pulley, with its base end fixed to the arm and its tip fixed to the clamshell bucket, the opening and closing wire rope is wound around an opening and closing guide sheave which is a fixed pulley, a first opening and closing sheave which is a movable pulley, a second opening and closing sheave and a loosening sheave, with its base end fixed to the arm and its tip fixed to the clamshell bucket, the bucket drive device comprises the lifting guide sheave and the The hydraulic system comprises a lifting cylinder that moves the lifting sheave and the first opening / closing sheave relative to the opening / closing guide sheave to raise and lower the clamshell bucket, an opening / closing cylinder that moves the second opening / closing sheave relative to the first opening / closing sheave to open and close the clamshell bucket, a loosening cylinder that moves the loosening loosening sheave relative to the first opening / closing sheave to remove looseness from the opening / closing wire rope, and a looseness sensor that detects looseness from the opening / closing wire rope, and the hydraulic system drives the lifting cylinder, the opening / closing cylinder and the loosening loosening cylinder. The controller comprises a hydraulic pump that discharges moving pressurized oil, a directional control valve that controls the direction of supply of pressurized oil from the hydraulic pump to the lifting cylinder, the opening / closing cylinder, and the loosening cylinder, a connecting oil passage that connects a first oil passage connecting the bottom oil chamber of the lifting cylinder and the directional control valve, and a second oil passage connecting the bottom oil chamber of the loosening cylinder and the directional control valve, and a solenoid valve that opens and closes the connecting oil passage, and the controller, based on the output of the operation sensor and the loosening sensor, detects the lowering operation of the clamshell bucket and the loosening of the opening / closing wire rope,The present invention provides a deep foundation excavator that opens the solenoid valve to supply pressurized oil discharged from the lifting cylinder to the loosening cylinder, and tensions the opening and closing wire rope during the descent of the clamshell bucket. [Effects of the Invention]

[0008] According to the present invention, slack in the opening and closing wire rope is automatically removed so that the bucket closes completely, and the response delay of the bucket's movement to the bucket closing operation is suppressed, thereby improving operability. [Brief explanation of the drawing]

[0009] [Figure 1] Left side view showing the external appearance of a deep foundation drilling machine according to one embodiment of the present invention. [Figure 2] Schematic diagram of the internal structure of a bucket drive device provided in a deep foundation excavator according to one embodiment of the present invention. [Figure 3] Circuit diagram of the main components of the hydraulic system installed in a deep foundation drilling machine according to one embodiment of the present invention. [Figure 4] A flowchart illustrating the control procedure of a solenoid valve by a controller installed in a deep foundation drilling machine according to one embodiment of the present invention. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described below with reference to the drawings.

[0011] -Deep foundation drilling machine- Figure 1 is a left side view showing the external appearance of a deep foundation excavator according to one embodiment of the present invention. The deep foundation excavator 1 illustrated in Figure 1 is manufactured based on a crawler-type hydraulic excavator. This deep foundation excavator 1 consists of a self-propelled crawler-type vehicle 2, a slewing body 3 mounted on the vehicle 2 so as to be able to rotate, and a work device 5 attached to the slewing body 3. The vehicle 2 and the slewing body 3 constitute the body of the deep foundation excavator 1.

[0012] The rotating body 3 is equipped with a cab 4 at its front. An operator sits in this cab 4 to operate the traveling body 2, the work equipment 5, etc. Inside the cab 4 is a driver's seat (not shown) where the operator sits. Various control devices are arranged around the driver's seat.

[0013] The working device 5 comprises a boom 6 rotatably connected to the slewing body 3, an arm 7 rotatably connected to the tip of the boom 6, and a bucket (clamshell bucket) 8 suspended from the arm 7 by wire ropes 27 and 28. The working device 5 also includes a boom cylinder 9 for rotating the boom 6 relative to the slewing body 3, an arm cylinder 10 for rotating the arm 7 relative to the boom 6, and a bucket drive device 11 supported by the arm 7 for driving the bucket 8.

[0014] Arm 7 is a long, straight frame, and a bucket drive device 11 is mounted on the outer wall surface of this arm along its longitudinal direction. Wire ropes 27 and 28 extend downward from the tip of this bucket drive device 11. Wire rope 27 is a wire rope for raising and lowering the bucket 8, and the other wire rope is a wire rope for opening and closing the bucket 8.

[0015] The bucket 8 comprises a bucket support 8A, a pair of shells 8B, a connecting bracket 8C, and sheaves 8D and 8E. The bucket support 8A is the base of the bucket 8. The end of the wire rope 27 for lifting and lowering is fixed to this bucket support 8A. The pair of shells 8B are located below the bucket support 8A and are connected via the connecting bracket 8C so as to be openable and closable. The upper sheave 8D is rotatably mounted on the bucket support 8A, and the lower sheave 8E is rotatably mounted on the connecting bracket 8C. The wire rope 28 for opening and closing is wound around these sheaves 8D and 8E. The end of the wire rope 28 is fixed to the connecting bracket 8C. The connecting bracket 8C also functions as a weight, for example, to stabilize the lifting and lowering movement of the bucket 8 or to bury the bucket 8 in the ground.

[0016] -Bucket drive system- Figure 2 is a schematic diagram of the internal structure of the bucket drive device. In Figure 2, elements identical to those in previously shown drawings are given the same reference numerals and their explanations are omitted. The bucket drive device 11 shown in Figure 2 is a device for raising / lowering the bucket 8, opening / closing the bucket 8, and tightening / loosening the wire rope 28 for opening and closing.

[0017] As shown in Figure 2, the bucket drive unit 11 is composed of a lifting cylinder 12, a first lifting sheave 13, a first opening / closing sheave 15, a second lifting sheave 16, a second opening / closing sheave 18, an opening / closing cylinder 20, and a loosening cylinder 23.

[0018] To explain the general configuration, as shown in Figure 2, a wire rope 27 for lifting and lowering is wound around a lifting guide sheave 24, a first lifting sheave 13, and a second lifting sheave 16. Its base end is fixed to the arm 7 via a sensor 29, and its tip is fixed to the bucket 8. The lifting guide sheave 24 and the second lifting sheave 16 are fixed pulleys, while the first lifting sheave 13 is a movable pulley. Inside the bucket drive device 11, the positions of the lifting guide sheave 24 and the second lifting sheave 16 do not change, while the first lifting sheave 13 is displaced. As the first lifting sheave 13 moves, the wire rope 27 is unwound or pulled via the lifting guide sheave 24, causing the bucket 8 to move up and down.

[0019] Also, a wire rope 28 for opening and closing is wound around an opening and closing guide sheave 25, a first opening and closing sheave 15, a second opening and closing sheave 18, and a slack take-up sheave 21. The proximal end is fixed to the arm 7 via a slack sensor 30, and the distal end is fixed to the bucket 8. The opening and closing guide sheave 25 is a fixed pulley, and the first opening and closing sheave 15, the second opening and closing sheave 18, and the slack take-up sheave 21 are movable pulleys. Inside the bucket drive device 11, the position of the opening and closing guide sheave 25 does not change, and the first opening and closing sheave 15, the second opening and closing sheave 18, and the slack take-up sheave 21 are displaced. As the first opening and closing sheave 15 moves, the wire rope 28 is paid out or pulled together with the wire rope 27 via the opening and closing guide sheave 25. As the second opening and closing sheave 18 moves, the pay-out amount of the wire rope 28 with respect to the wire rope 27 changes, and the bucket 8 opens and closes. As the slack take-up sheave 21 moves, the slack of the wire rope 28 for opening and closing is adjusted.

[0020] Hereinafter, the structure of the bucket drive device 11 will be specifically described.

[0021] The lifting cylinder 12 is a hydraulic actuator for moving the first lifting sheave 13 and the first opening and closing sheave 15 with respect to the lifting guide sheave 24 and the opening and closing guide sheave 25 to lift and lower the bucket 8. One end of this lifting cylinder 12 is connected to the arm 7. The other end of the lifting cylinder 12 is connected to a shaft member 14 that supports the first lifting sheave 13 and the first opening and closing sheave 15. The second lifting sheave 16 is arranged at an interval in the extending and contracting direction of the lifting cylinder 12 with respect to the first lifting sheave 13 and is rotatably supported by the arm 7 via a shaft member 17. As the lifting cylinder 12 extends and contracts, the first lifting sheave 13 and the first opening and closing sheave 15 move in the longitudinal direction of the arm 7, and the first lifting sheave 13 advances and retreats with respect to the second lifting sheave 16.

[0022] Furthermore, the stroke of the lifting cylinder 12 is detected by the stroke sensor 31 and output to the controller 50 (described later). For example, a rotary encoder can be used as the stroke sensor 31. When a hydraulic cylinder with a stroke sensor is used for the lifting cylinder 12, the stroke sensor provided on the lifting cylinder 12 can be used. Also, in this embodiment, it is sufficient for the stroke sensor 31 to detect that the length of the lifting cylinder 12 is less than a preset length, so a proximity sensor or the like can also be used as the stroke sensor 31.

[0023] The opening / closing cylinder 20 is a hydraulic actuator for opening and closing the bucket 8 by moving the second opening / closing sheave 18 relative to the first opening / closing sheave 15. The second opening / closing sheave 18 is positioned at a distance from the first opening / closing sheave 15 in the direction of extension and retraction of the lifting cylinder 12, and is rotatably supported by the arm 7 via a shaft member 19. The shaft member 19 supporting the second opening / closing sheave 18 is connected to one end of the opening / closing cylinder 20. The other end of the opening / closing cylinder 20 is connected to the arm 7. The opening / closing cylinder 20 extends in the longitudinal direction of the arm 7, just like the lifting cylinder 12. As the opening / closing cylinder 20 extends and retracts, the second opening / closing sheave 18 moves in the longitudinal direction of the arm 7, causing the second opening / closing sheave 18 to move forward and backward relative to the first opening / closing sheave 15.

[0024] The loosening cylinder 23 is a hydraulic actuator used to remove slack in the opening and closing wire rope 28 by moving (separating) the loosening sheave 21 from the first opening and closing sheave 15 when the bucket 8 is scooping up soil or other debris. The loosening sheave 21 is rotatably supported on the arm 7 via a shaft member 22. The loosening sheave 21 is positioned at a distance from the first opening and closing sheave 15 in the direction of extension and retraction of the lifting cylinder 12. The shaft member 22 supporting the loosening sheave 21 is connected to one end of the loosening cylinder 23. The other end of the loosening cylinder 23 is connected to the arm 7. The loosening cylinder 23 extends in the longitudinal direction of the arm 7, similar to the lifting cylinder 12. As the loosening cylinder 23 extends and retracts, the loosening sheave 21 moves in the longitudinal direction of the arm 7, and the loosening sheave 21 moves forward and backward relative to the first opening and closing sheave 15.

[0025] At the tip of the arm 7, a lifting guide sheave 24 and an opening / closing guide sheave 25 are rotatably supported via a shaft member 26. The lifting guide sheave 24 guides the lifting wire rope 27, and the wire rope 27 is unfurled from the bucket lifting device 11 toward the bucket 8 via the lifting guide sheave 24. The opening / closing guide sheave 25 guides the opening / closing wire rope 28, and the wire rope 28 is unfurled from the bucket lifting device 11 toward the bucket 8 via the opening / closing guide sheave 25.

[0026] As described above, the wire rope 27 for lifting is wound around the lifting guide sheave 24, the first lifting sheave 13, and the second lifting sheave 16. The base end of the wire rope 27 is attached to the arm 7 via a sensor 29. The sensor 29 is a sensor that detects the tension (slack) of the wire rope 27 for lifting, and the form is not limited as long as the tension of the wire rope 27 can be detected, but for example, a tension meter using a load cell can be used. A bucket 8 is suspended from the tip of the wire rope 27. Therefore, the bucket 8 moves up and down as the lifting cylinder 12 extends and retracts. The sensor 29 also detects the tension (slack) of the wire rope 27 and outputs it to the controller 50 (described later).

[0027] As described above, the opening and closing wire rope 28 is wound around the opening and closing guide sheave 25, the first opening and closing sheave 15, the second opening and closing sheave 18, and the loosening sheave 21. The base end of the wire rope 28 is attached to the arm 7 via a looseness sensor 30. The looseness sensor 30 is a sensor that detects the tension (looseness) of the wire rope 28. The form is not limited as long as the tension of the wire rope 28 can be detected, but for example, a tension meter using a load cell can be used as the looseness sensor 30. The tip of the wire rope 28 is connected to the connecting bracket 8C of the bucket 8. The bucket 8 opens and closes as the opening and closing cylinder 20 extends and retracts, and the looseness of the wire rope 28 is adjusted as the loosening cylinder 23 extends and retracts. In addition, the tension (looseness) of the wire rope 28 is detected by the looseness sensor 30 and output to the controller 50 (described later).

[0028] - Hydraulic System - Figure 3 is a circuit diagram of the main components of the hydraulic system installed in the deep foundation excavator 1. Figure 3 shows an excerpt of the circuits that drive the lifting cylinder 12, the opening / closing cylinder 20, and the loosening cylinder 23, which are installed in the bucket drive unit 11. In Figure 3, elements identical to those in previously shown drawings are given the same reference numerals as in the previously shown drawings, and their explanations are omitted.

[0029] The hydraulic system shown in Figure 3 drives the work device 5 (bucket drive device 11) in response to the operation of the lifting / lowering control device 35, the opening / closing control device 36, and the loosening control device 37. The lifting / lowering control device 35, the opening / closing control device 36, and the loosening control device 37 are control devices that instruct the operation of the work device 5 (bucket drive device 11), and are located in the cab 4 and are equipped with operating levers or operating pedals. When the lifting / lowering control device 35 is operated, the lifting cylinder 12 extends and retracts; when the opening / closing control device 36 is operated, the opening / closing cylinder 20 extends and retracts; and when the loosening control device 37 is operated, the loosening cylinder 23 extends and retracts.

[0030] This hydraulic system comprises a hydraulic pump 32, a pilot pump 33, a hydraulic oil tank 34, a control valve unit 40, a solenoid valve (on / off valve) 45, a second directional control valve 47, and a solenoid valve (switching valve) 48. The hydraulic pump 32, pilot pump 33, hydraulic oil tank 34, solenoid valve 45, second directional control valve 47, and solenoid valve 48 are mounted in the machine room of the slewing body 3. Furthermore, the hydraulic system, specifically the solenoid valves 45 and 48 included in the hydraulic system, are controlled by a controller 50 based on the outputs of an operation sensor 38 (described later), a looseness sensor 30, and a stroke sensor 31.

[0031] The following describes the hydraulic pump 32, pilot pump 33, control valve unit 40, solenoid valve 45, second directional control valve 47, solenoid valve 48, and controller 50 in order.

[0032] (Hydraulic pump 32) The hydraulic pump 32 is a pump that draws in hydraulic fluid from the hydraulic fluid tank 34 and discharges pressurized oil to drive the lifting cylinder 12, the opening / closing cylinder 20, and the loosening cylinder 23. This hydraulic pump 32 is driven by a prime mover 39. In Figure 3, an engine (internal combustion engine) is shown as the prime mover 39, but an electric motor may also be used as the prime mover 39. The hydraulic pump 32 may be a fixed-displacement type, but in this embodiment, a variable-displacement type is shown. The hydraulic system may have a configuration with multiple hydraulic pumps 32, in which case the hydraulic source may differ depending on the hydraulic actuator.

[0033] The hydraulic fluid discharged from the hydraulic pump 32 flows through the pump line 32a, which is the discharge piping of the hydraulic pump 32, and is supplied to the lifting cylinder 12, the opening / closing cylinder 20, and the loosening cylinder 23 via the control valve unit 40. The return fluid discharged from each cylinder flows into the tank line 34a via the directional control valves 41-43 and returns to the hydraulic fluid tank 34. Although not shown in the figure, the pump line 32a is equipped with a relief valve that regulates the maximum pressure of the pump line 32a.

[0034] (Pilot pump 33) The pilot pump 33 is a fixed-displacement pump that outputs the primary pressure (main pressure) of the pilot pressure that drives hydraulically driven valves such as directional control valves 41-43. This pilot pump 33 is driven by the prime mover 39, just like the hydraulic pump 32. It is also possible to configure the system to drive the pilot pump 33 with a power source separate from the prime mover 39.

[0035] The pilot line 33a, which is the discharge piping of the pilot pump 33, is connected to the input ports of the lifting / lowering operating device 35, the opening / closing operating device 36, and the loosening operating device 37. The discharge oil from the pilot pump 33, which is input to the input port, is reduced in pressure by pressure reducing valves provided in the lifting / lowering operating device 35, the opening / closing operating device 36, and the loosening operating device 37, respectively, to generate pilot pressure. This pilot pressure is generated according to the amount of operation of the operating levers or pedals provided in the lifting / lowering operating device 35, the opening / closing operating device 36, and the loosening operating device 37, respectively. The generated pilot pressure is output from the output ports of the lifting / lowering operating device 35, the opening / closing operating device 36, and the loosening operating device 37 and input to the corresponding pressure receiving chambers (described later) of the directional control valves 41-43.

[0036] (Control valve unit 40) The control valve unit 40 is comprised of directional control valves 41-43. These directional control valves 41-43 are hydraulically driven control valves (3-position control valves) that control the direction (or direction and flow rate) of supply of pressurized oil from the hydraulic pump 32 to the lifting cylinder 12, the opening / closing cylinder 20, and the loosening cylinder 23, respectively.

[0037] The directional control valve 41 for the lifting cylinder is driven by pilot pressure input from the lifting operating device 35 to the pressure receiving chambers 41a and 41b. Each port of the directional control valve 41 is connected to the pump line 32a and the tank line 34a, as well as to the oil passage 12a which connects to the bottom oil chamber of the lifting cylinder 12, and the oil passage 12b which connects to the rod oil chamber of the lifting cylinder 12.

[0038] When the lifting control device 35 is used to raise the bucket 8, pilot pressure is input from the lifting control device 35 to the pressure receiving chamber 41a, the pump line 32a connects to the oil passage 12a, and the tank line 34a connects to the oil passage 12b. This causes the lifting cylinder 12 to extend and the bucket 8 to rise. When the lifting control device 35 is used to lower the bucket 8, pilot pressure is input from the lifting control device 35 to the pressure receiving chamber 41b, the pump line 32a connects to the oil passage 12b, and the tank line 34a connects to the oil passage 12a. This causes the lifting cylinder 12 to retract and the bucket 8 to lower. When the lifting control device 35 is not operated, the spool of the directional control valve 41 is held in the neutral position by spring force, the oil passages 12a and 12b are closed, and the lifting cylinder 12 is held in place.

[0039] Similarly, the directional control valve 42 for the opening and closing cylinder is driven by pilot pressure input from the opening and closing operating device 36 to the pressure receiving chambers 42a and 42b. Each port of the directional control valve 42 is connected to the pump line 32a, the tank line 34a, the oil passage 20a which connects to the bottom oil chamber of the opening and closing cylinder 20, and the oil passage 20b which connects to the rod-side oil chamber of the opening and closing cylinder 20.

[0040] When the bucket 8 is closed using the opening / closing operating device 36, pilot pressure is input from the opening / closing operating device 36 to the pressure receiving chamber 42a, the pump line 32a connects to the oil passage 20a, and the tank line 34a connects to the oil passage 20b. This causes the opening / closing cylinder 20 to extend, and the bucket 8 closes. When the bucket 8 is opened using the opening / closing operating device 36, pilot pressure is input from the opening / closing operating device 36 to the pressure receiving chamber 42b, the pump line 32a connects to the oil passage 20b, and the tank line 34a connects to the oil passage 20a. This causes the opening / closing cylinder 20 to retract, and the bucket 8 opens. When the opening / closing operating device 36 is not operated, the spool of the directional control valve 42 is held in the neutral position by spring force, the oil passages 20a and 20b are closed, and the opening / closing cylinder 20 is held in place.

[0041] The directional control valve 43 for the loosening cylinder is driven by pilot pressure input from the loosening operating device 37 to the pressure receiving chambers 43a and 43b. Each port of the directional control valve 43 is connected to the pump line 32a, the tank line 34a, the oil passage 23a which connects to the bottom oil chamber of the loosening cylinder 23, and the oil passage 23b which connects to the rod oil chamber of the loosening cylinder 23.

[0042] When the loosening operation device 37 is used to loosen the wire rope 28 for opening and closing, pilot pressure is input from the loosening operation device 37 to the pressure receiving chamber 43a, the pump line 32a connects to the oil passage 23a, and the tank line 34a connects to the oil passage 23b. This causes the loosening cylinder 23 to extend, tensing the wire rope 28 and removing the slack. When the loosening operation device 37 is used to loosen the bucket 8, pilot pressure is input from the loosening operation device 37 to the pressure receiving chamber 43b, the pump line 32a connects to the oil passage 23b, and the tank line 34a connects to the oil passage 23a. This causes the loosening cylinder 23 to retract, and the wire rope 28 loosens. When the loosening operation device 37 is not operated, the spool of the directional control valve 43 is held in the neutral position by spring force, the oil passages 23a and 23b are closed, and the loosening cylinder 23 is held in place.

[0043] (Solenoid valve 45) The first oil passage (i.e., oil passage 12a) connecting the bottom oil chamber of the lifting cylinder 12 and the corresponding directional control valve 41, and the second oil passage (i.e., oil passage 23a) connecting the bottom oil chamber of the loosening cylinder and the corresponding directional control valve 43, are connected by a connecting oil passage 44. In this embodiment, a counterbalance valve 46 is provided in oil passage 12a, and the pressurized oil metered out from the bottom oil chamber of the lifting cylinder 12 is controlled by the counterbalance valve 46, thereby limiting the descent speed of the bucket 8. The connecting oil passage 44 branches off from oil passage 12a between the counterbalance valve 46 and the lifting cylinder 12.

[0044] The connecting oil passage 44 is equipped with an electromagnetically driven on-off valve 45 that opens and closes the connecting oil passage 44. When the solenoid valve 45 is closed (i.e., the state shown in Figure 3), the connecting oil passage 44 is shut off, and the oil passages 12a and 23a become independent of each other. When the solenoid valve 45 opens, the connecting oil passage 44 is opened, and the oil passages 12a and 23a are connected via the connecting oil passage 44.

[0045] (Second directional control valve 47 / Solenoid valve 48) In the oil passages 23a and 23b connecting the loosening cylinder 23 and the directional control valve 43 of the control valve unit 40, a second directional control valve 47 for the loosening cylinder is connected in parallel with the directional control valve 43. The pressure-receiving chamber 47a of the second directional control valve 47 is connected to the opening / closing operating device 36 via a solenoid valve 48, and the pressure-receiving chamber 47b of the second directional control valve 47 is connected to the hydraulic oil tank 34. The second directional control valve 47 is driven by pilot pressure introduced into the pressure-receiving chamber 47a via the solenoid valve 48. Each port of the solenoid valve 48 is connected to the output port for closing the opening / closing operating device 36, the pressure-receiving chamber 42a of the directional control valve 42 for the opening / closing cylinder, the hydraulic oil tank 34, and the pressure-receiving chamber 47a of the second directional control valve 47.

[0046] As can be seen from Figure 3, the second directional control valve 47 is driven by a solenoid valve 48, and the solenoid valve 48 is driven by a controller 50. The controller 50 energizes the solenoid of the solenoid valve 48 based on conditions such as the closing operation of the opening / closing operating device 36, the detection of slack in the lifting wire rope 27 by the sensor 29, and the detection of slack in the opening / closing wire rope 28 by the slack sensor 30. The closing operation of the opening / closing operating device 36 is detected by a predetermined operating sensor (not shown). This operating sensor can be, for example, a pressure sensor installed in the oil passage connecting the opening / closing operating device 36 and the pressure receiving chamber 42a of the directional control valve 42 for the opening / closing cylinder, or an angle meter or potentiometer that detects the amount of operation of the operating lever of the opening / closing operating device 36.

[0047] For example, when the solenoid of the solenoid valve 48 is demagnetized (as shown in Figure 3), the opening / closing operating device 36 is connected to the pressure-receiving chamber 42a of the directional control valve 42 for the opening / closing cylinder, and the pressure-receiving chamber 47a of the second directional control valve 47 for the loosening cylinder is connected to the hydraulic oil tank 34. In this state, when the opening / closing operating device 36 is closed, pilot pressure is input from the opening / closing operating device 36 to the pressure-receiving chamber 42a as described above, and the pump line 32a is connected to the oil passage 20a, and the tank line 34a is connected to the oil passage 20b. As a result, the opening / closing cylinder 20 extends and the bucket 8 closes.

[0048] During this time, the pressure-receiving chambers 47a and 47b of the second directional control valve 47 both become tank pressure, and the spool of the second directional control valve 47 is held in the neutral position by spring force. The pump line 32a and the tank line 34a are not connected to the oil passages 23a and 23b of the loosening cylinder 23 via the second directional control valve 47, and the loosening cylinder 23 does not extend or retract in response to the closing operation.

[0049] Therefore, when the bucket 8 is not at the bottom of the shaft and the tension of the opening / closing wire rope 28 is above a predetermined level, the bucket 8 will close in response to the closing operation of the opening / closing operating device 36, and the loosening cylinder 23 will not automatically operate as a result of the closing operation.

[0050] On the other hand, when the solenoid of the electromagnetic valve 48 is energized, the opening / closing operating device 36 is connected to the pressure-receiving chamber 47a of the second directional control valve 47 for the loosening cylinder, and the pressure-receiving chamber 42a of the directional control valve 42 for the opening / closing cylinder is connected to the hydraulic oil tank 34. In this state, the pilot pressure output from the opening / closing operating device 36 acts on the pressure-receiving chamber 47a of the second directional control valve 47, causing the spool of the second directional control valve 47 to move to the pressure-receiving chamber 37b side. Therefore, when the opening / closing operating device 36 is closed, pilot pressure is input from the opening / closing operating device 36 to the pressure-receiving chamber 47a, and the pump line 32a is connected to the oil passage 23a, and the tank line 34a is connected to the oil passage 23b. In other words, the closing operation of the opening / closing operating device 36 temporarily extends the loosening cylinder 23, and the loosening of the opening / closing wire rope 28 is performed.

[0051] During this time, the pressure chambers 42a and 42b of the directional control valve 42 for the opening and closing cylinder both reach tank pressure, the directional control valve 42 is in the neutral position, and the bucket 8 does not move even if the closing operation is performed.

[0052] Therefore, if the wire rope 28 for opening and closing the bucket 8 is loose after it lands, the loosening cylinder 23 will automatically activate when the opening and closing operating device 36 is closed. The bucket 8 will not close even if the closing operation is performed until the wire rope 28 is taut, and the solenoid valve 48 will switch and the bucket 8 will close once the wire rope 28 is taut.

[0053] -controller- The controller 50 is an on-board computer that controls the hydraulic system. This controller 50 has a distinctive function that controls the hydraulic system, specifically the solenoid valves 45 and 48, based on the outputs of the operation sensor 38, the loosening sensor 30, and the stroke sensor 31, and takes slack in the opening and closing wire rope 28 during descent.

[0054] Specifically, the controller 50 determines, based on the outputs of the operation sensor 38, the looseness sensor 30, and the stroke sensor 31, whether there is looseness in the opening and closing wire rope 28 during the lowering operation of the bucket 8, and whether the length of the lifting cylinder 12 is less than a preset length. The length of the lifting cylinder 12 may be excluded from the determination conditions in some cases.

[0055] The operation sensor 38 is a sensor for detecting the lowering operation of the lifting operation device 35. As illustrated in Figure 3, the operation sensor 38 can be a pressure sensor installed in the oil passage connecting the lifting operation device 35 and the pressure receiving chamber 41b of the directional control valve 41 for the lifting cylinder. In this case, the operation sensor 38 detects the pilot pressure acting on the pressure receiving chamber 41b, inputs the detected pilot pressure from the operation sensor 38 to the controller 50, and the controller 50 can detect the lowering operation if the pilot pressure is above a set value. In addition, the operation sensor 38 can also be an angle meter or potentiometer that detects the amount of movement of the operating lever of the lifting operation device 35. In this case, the controller 50 can detect the lowering operation if the amount of inclination of the operating lever toward the lowering operation side detected by the operation sensor 38 is above a predetermined amount.

[0056] Furthermore, if there is slack in the opening and closing wire rope 28, for example, if a tension meter is used for the slack sensor 30, it can be determined that there is slack in the wire rope 28 if the tension detected by the slack sensor 30 is below a predetermined value. Whether the length of the lifting cylinder 12 is less than the set length is determined based on the output of the stroke sensor 31.

[0057] When a descent operation, slack in the wire rope 28, and contraction of the lifting cylinder 12 beyond a predetermined level are detected, the controller 50 outputs a command signal to the solenoid valve 45 (exciting the solenoid of the solenoid valve 45), opening the solenoid valve 45 and connecting the oil passages 12a and 23a via the connecting oil passage 44. As a result, a portion of the pressurized oil discharged from the bottom oil chamber of the lifting cylinder 12 during the descent operation bypasses the hydraulic oil tank 34 and is supplied to the bottom oil chamber of the loosening cylinder 23 via the connecting oil passage 44, where it is regenerated as pressurized oil to extend the loosening cylinder 23. Consequently, the loosening cylinder 23 operates automatically during the descent of the bucket 8, and the opening and closing wire rope 28 is tightened and the slack in the wire rope 28 is removed prior to the bucket 8 landing at the bottom of the shaft.

[0058] When the bucket 8 lands, the slack in the opening and closing wire rope 28 is removed, so when the opening and closing operating device 36 is used to close the bucket 8, it closes quickly. Even if the slack in the wire rope 28 is not sufficiently removed when the bucket 8 lands, as mentioned above, the operation of the solenoid valve 48 and the second directional control valve 47 automatically activates the slack-removing cylinder 23 during the closing operation, removing the slack in the wire rope 28. Even in this case, since the slack in the wire rope 28 is removed to some extent by the operation of the slack-removing cylinder 23 during the bucket's descent, the delay in the bucket 8's closing operation in response to the closing operation is short. Manual operation of the slack-removing cylinder 23 using the slack-removing operating device 37 is also possible.

[0059] -Procedure for removing loose wire ropes used for opening and closing- Figure 4 is a flowchart showing the control procedure of the solenoid valve 45 by the controller 50. The controller 50 repeatedly executes the flow shown in Figure 4 at a predetermined cycle time (for example, about 0.1 s) while power is supplied.

[0060] (Step S101) When the flow shown in Figure 4 is initiated, in step S101, the controller 50 first determines whether an operator has performed an action.

[0061] Although not shown in the diagram, just as the operation of commanding the retraction of the lifting cylinder 12 (lowering of the bucket 8) is detected by the operation sensor 38, the operation of the control devices that instruct the operation of each hydraulic actuator is detected by each operation sensor (not shown), and the detection signal is input to the controller 50. For example, the lifting control device 35 detects not only the lowering operation of the bucket 8, but also the actual raising operation. Similarly, the opening / closing operation by the opening / closing control device 36 and the loosening / unloosening operation by the loosening control device 37 are also detected. In addition, the forward / reverse operation of the left and right travel motors of the travel body 2, the right / left rotation operation of the slewing motor of the slewing body 3, and the extension / retraction operations of the boom cylinder 9 and arm cylinder 10 are also detected. Each operation sensor can be a pressure sensor, potentiometer, etc., just like the operation sensor 38.

[0062] In step S101, based on the detection signals from these operation sensors, it is determined whether each hydraulic actuator that drives the deep foundation drilling machine 1 is being operated. If the controller 50 determines that all detection signals from the operation sensors are below the set value and therefore no operation is being performed, the procedure proceeds to step S106. On the other hand, if the controller 50 determines that at least one operation sensor is operating and its detection signal is above the set value, the procedure proceeds to step S102.

[0063] (Step S102) When the procedure moves to step S102, the controller 50 determines whether the bucket 8 is being lowered based on the output of the operation sensor 38. If the detection signal of the operation sensor 38 is less than the set value and the controller determines that the lowering operation is not currently being performed, the controller 50 moves from step S102 to step S106. If the detection signal of the operation sensor 38 is greater than or equal to the set value and the controller determines that the lowering operation is currently being performed, the controller 50 moves from step S102 to step S103.

[0064] (Step S103) When the procedure moves to step S103, the controller 50 determines, based on the output of the stroke sensor 31, whether the lifting cylinder 12 has retracted to a length less than a preset length. The preset length is set to a value such that, for example, when the work device 5 is in a predetermined working position, the bucket 8 is positioned at a predetermined distance above the ground (the contact surface of the deep foundation excavator 1). If the lifting cylinder 12 is at or above the preset length, it is estimated that the bucket 8 is at a predetermined distance above the ground, and if the lifting cylinder 12 is less than the preset length, it is estimated that the bucket 8 is at a position lower than a predetermined distance above the ground. If, in step S103, it is determined that the length of the lifting cylinder 12 is at or above the preset length and the bucket 8 is at a predetermined distance above the ground, the controller 50 moves to step S106. If, in step S103, it is determined that the length of the lifting cylinder 12 is less than the preset length and the bucket 8 is at a position lower than a predetermined distance above the ground, the controller 50 moves from step S103 to step S104.

[0065] (Step S104) When the procedure moves to step S104, the controller 50 determines, based on the output of the looseness sensor 30, whether there is looseness in the opening and closing wire rope 28, specifically whether the tension of the wire rope 28 detected by the looseness sensor 30 is less than a preset value. If the controller 50 determines that there is no looseness in the wire rope 28 and the tension of the wire rope 28 is greater than or equal to the preset value, the controller 50 moves from step S104 to step S106. If the controller 50 determines that there is looseness in the wire rope 28 and the tension of the wire rope 28 is less than the set value, the controller 50 moves from step S104 to step S105.

[0066] (Step S105) When the procedure moves from step S104 to step S105, the controller 50 outputs a command signal to the solenoid valve 45, energizing the solenoid of the solenoid valve 45 to open the solenoid valve 45 and end the flow shown in Figure 4. As described above, when the solenoid valve 45 opens, the connecting oil passage 44 is opened, and the bottom oil chambers of the lifting cylinder 12 and the loosening cylinder 23 are connected via the connecting oil passage 44 and the oil passages 12a and 23a. As a result, during the descent of the bucket 8, the pressurized oil discharged from the bottom oil chamber of the retracting lifting cylinder 12 is supplied to the bottom oil chamber of the loosening cylinder 23 via the connecting oil passage 44. This automatically loosens the opening and closing wire rope 28 in response to the descent operation, and the loosening of the wire rope 28 is suppressed prior to the landing of the bucket 8.

[0067] (Step S106) If the procedure moves from any of steps S101-S104 to step S106, the controller 50 stops outputting a command signal to the solenoid valve 45, demagnetizes the solenoid of the solenoid valve 45, closes the solenoid valve 45, and ends the flow shown in Figure 4. If the solenoid of the solenoid valve 45 was already demagnetized when the procedure moved to step S106, it remains demagnetized. When the solenoid valve 45 is closed, the connecting oil passage 44 is blocked, separating the bottom oil chambers of the lifting cylinder 12 and the loosening cylinder 23. Therefore, even if the bucket 8 is in a high position or there is no slack in the wire rope 28, the pressurized oil metered out from the bottom oil chamber of the lifting cylinder 12 is regenerated to drive the loosening cylinder 23, and the loosening operation will not be performed spontaneously. Similarly, if the lowering operation is not being performed or the bucket 8 is in a high position, the loosening operation will not be performed spontaneously even if there is slack in the wire rope 28. Of course, if there is no slack in the wire rope 28, the slack-removing operation will not be performed automatically, regardless of whether a descent operation is performed or the position of the bucket 8.

[0068] Note that in the flow shown in Figure 4, the order of the decision processes in steps S102-S104 can be changed as appropriate.

[0069] -effect- (1) As described above, according to this embodiment, if there is slack in the wire rope for opening and closing the bucket 8 during the lowering operation of the bucket 8, the slack in the wire rope 28 is automatically taken up during the lowering operation of the bucket 8 prior to the bucket 8 landing. In other words, by the time the bucket 8 is closed to collect soil after the bucket 8 has landed, the slack in the wire rope 28 has already been taken up completely or to some extent, and the delay in the closing operation of the bucket 8 in response to the closing operation can be suppressed. Accordingly, the slack in the wire rope 28 for opening and closing can be automatically taken up so that the bucket 8 closes sufficiently, and the response delay of the closing operation of the bucket 8 in response to the closing operation of the bucket 8 can be suppressed and operability can be improved.

[0070] (2) In this embodiment, the execution conditions for automatic control of the loosening cylinder 23 using the solenoid valve 45 include determining whether a descent operation is in progress, whether there is slack in the opening and closing wire rope 28, and whether the lifting cylinder 12 has contracted to less than a predetermined length. As a result, the loosening cylinder 23 will not operate in response to the descent operation when it is clear that the bucket 8 is not at a position higher than a predetermined distance from the ground and is not in a situation where the bucket 8 is holding soil. Therefore, unnecessary operation of the loosening cylinder 23 can be suppressed, and a decrease in energy efficiency can be suppressed.

[0071] (3) By branching the connecting oil passage 44 from the oil passage 12a between the lifting cylinder 12 and the counterbalance valve 46, pressurized oil maintaining a suitable pressure upstream of the counterbalance valve 46 is supplied to the loosening cylinder 23 via the connecting oil passage 44 when the bucket 8 is lowered. This makes it possible to effectively utilize the pressurized oil metered out from the lifting cylinder 12 during the lowering of the bucket 8 as pressurized oil to drive the loosening cylinder 23. [Explanation of Symbols]

[0072] 1…Deep foundation excavator, 2…Traveling body (vehicle body), 3…Slewing body (vehicle body), 5…Working device, 6…Boom, 7…Arm, 8…Clamshell bucket, 11…Bucket drive device, 12…Lifting cylinder, 12a…Oil passage (first oil passage), 13…First lifting sheave (lifting sheave), 15…First opening / closing sheave, 18…Second opening / closing sheave, 20…Opening / closing cylinder, 21…Removal sheave, 23…Removal cylinder, 23a…Oil passage (second oil passage), 24 ...Lifting guide sheave, 25...Opening / closing guide sheave, 27...Lifting wire rope, 28...Opening / closing wire rope, 30...Looseness sensor, 31...Stroke sensor, 32...Hydraulic pump, 35...Lifting operating device (operating device), 36...Opening / closing operating device (operating device), 37...Loosening operating device (operating device), 38...Operating sensor, 41-43...Directional control valve, 44...Connecting oil passage, 45...Solenoid valve, 46...Counterbalance valve, 50...Controller

Claims

1. The system comprises a self-propelled vehicle body, a work device attached to the vehicle body, an operating device for instructing the operation of the work device, an operating sensor for detecting the operation of the operating device, a hydraulic system for driving the work device in response to the operation of the operating device, and a controller for controlling the hydraulic system. The work device comprises a boom rotatably connected to the vehicle body, an arm rotatably connected to the tip of the boom, a clamshell bucket suspended from the arm by a wire rope for lifting and a wire rope for opening and closing, and a bucket drive device supported by the arm for driving the clamshell bucket. The aforementioned lifting wire rope is wound around a lifting guide sheave, which is a fixed pulley, and a lifting sheave, which is a movable pulley, with its base end fixed to the arm and its tip fixed to the clamshell bucket. The opening and closing wire rope is wound around a fixed pulley (opening and closing guide sheave), a movable pulley (first opening and closing sheave, second opening and closing sheave, and loosening sheave), with its base end fixed to the arm and its tip fixed to the clamshell bucket. The bucket drive device, A lifting cylinder that moves the lifting sheave and the first opening / closing sheave relative to the lifting guide sheave and the opening / closing guide sheave to raise and lower the clamshell bucket, An opening / closing cylinder that moves the second opening / closing sheave relative to the first opening / closing sheave to open and close the clamshell bucket, A loosening cylinder that moves the loosening sheave relative to the first opening / closing sheave to remove looseness from the opening / closing wire rope, A loosening sensor for detecting loosening of the opening and closing wire rope, Equipped with, The hydraulic system is, A hydraulic pump that discharges pressurized oil to drive the lifting cylinder, the opening / closing cylinder, and the loosening cylinder, A directional control valve controls the direction of supply of pressurized oil from the hydraulic pump to the lifting cylinder, the opening / closing cylinder, and the loosening cylinder. A first oil passage connecting the bottom oil chamber of the lifting cylinder and the directional control valve, and a connecting oil passage connecting the bottom oil chamber of the loosening cylinder and the directional control valve, A solenoid valve that opens and closes the aforementioned oil passage and Equipped with, Based on the outputs of the operation sensor and the looseness sensor, the controller detects the lowering operation of the clamshell bucket and the loosening of the opening / closing wire rope, opens the solenoid valve, and supplies the pressurized oil discharged from the lifting cylinder to the loosening removal cylinder, thereby tensing the opening / closing wire rope during the lowering of the clamshell bucket. A deep foundation excavator characterized by the following features.

2. In the deep foundation drilling machine according to claim 1, The system includes a stroke sensor that detects the stroke of the lifting cylinder, Based on the outputs of the operation sensor, the loosening sensor, and the stroke sensor, the controller detects the lowering operation of the clamshell bucket, the loosening of the opening / closing wire rope, and that the length of the lifting cylinder is less than a preset length. In such cases, the controller opens the solenoid valve and supplies the pressurized oil discharged from the lifting cylinder to the loosening removal cylinder, thereby tensing the opening / closing wire rope during the lowering of the clamshell bucket. A deep foundation excavator characterized by the following features.

3. In the deep foundation drilling machine according to claim 1, The first oil passage is equipped with a counterbalance valve, The aforementioned connecting oil passage branches off from the first oil passage between the lifting cylinder and the counterbalance valve. A deep foundation excavator characterized by the following features.

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