Earth drill machine

Abstract

To provide an earth drill machine that can reduce the torsional moment acting on the frame according to the working posture. [Solution] An earth drill machine (1) comprising a rotating body (3) that rotates by a rotating device and an excavation bucket 130 connected to the rotating body (3) via a frame (100) provided on the rotating body (3), characterized in that it is equipped with a rotation output limiting means (24, 25) that limits the rotation output of the rotating device when the height of the excavation bucket (130) relative to the ground is below a predetermined value.

Description

Technical Field

[0001] The present invention relates to an earth drill machine.

Background Art

[0002] As background art in this technical field, for example, Patent Document 1 describes "an earth drill that changes the turning output of a turning motor by setting the relief pressure of the hydraulic oil supplied to the turning motor low when performing a drilling operation mode in which a drilling bucket is rotationally driven with respect to a rotating body, and setting the relief pressure of the hydraulic oil supplied to the turning motor high when performing a crane operation mode in which a crane operation is performed by a winch installed on the rotating body."

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The working postures by an earth drill are diverse, and the torsional moment acting on various frames provided on the rotating body may increase depending on the posture. However, in Patent Document 1, since the turning output is changed depending on whether it is a drilling operation mode or a crane operation mode, there is a problem that the torsional moment acting on various frames cannot be sufficiently reduced according to the working posture.

[0005] The main object of the present invention is to provide an earth drill machine capable of reducing the torsional moment acting on a frame according to the working posture.

Means for Solving the Problems

[0006] To achieve the above objective, a representative example of the present invention is an earth drilling machine comprising a rotating body that rotates by a rotating device and an excavation bucket connected to the rotating body via a frame provided on the rotating body, characterized in that it is provided with a rotation output limiting means that limits the rotation output of the rotating device when the height of the excavation bucket relative to the ground is below a predetermined value.

[0007] According to the present invention, the torsional moment acting on the frame can be reduced according to the working posture. Other problems, configurations, and effects will be clarified by the following description of the embodiments. [Brief explanation of the drawing]

[0008] [Figure 1] This is a side view of the earth drill machine according to this embodiment. [Figure 2] This is a front view of an earth drill machine in a grounded state, with the main body and boom omitted. [Figure 3] This is a front view of an earth drill machine in an excavation state, with the main body and boom omitted. [Figure 4] This diagram illustrates the excavation bucket in the open state (soil removal state) with the bottom cover open (A), in the process of closing the bottom cover (B), and the closed state with the bottom cover closed (C). [Figure 5] This is a diagram showing the configuration of the hydraulic circuit that drives the swing motor. [Figure 6] This is an explanatory diagram illustrating the reference position. [Figure 7] This is a flowchart of the turning output limiting process according to this embodiment. [Figure 8] This is a diagram showing the configuration of a hydraulic circuit related to Modification Example 1. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings. Figure 1 is a side view of the earth drill machine 1 according to this embodiment.

[0010] (Earth drill machine 1) As shown in Figure 1, the earth drill machine 1 according to this embodiment is configured to include a main body 10 consisting of a traveling body 2 and a rotating body 3 that is rotatably supported on the traveling body 2, and a boom-type front attachment 100.

[0011] The vehicle 2 moves by rotational drive of a vehicle motor (not shown). The slewing vehicle 3 rotates relative to the vehicle 2 by a slewing motor 20 (see Figure 5), which will be described later. The slewing vehicle 3 mainly consists of a cab 4, a counterweight 5, a rear winch 6, and a front winch 7.

[0012] The cab 4 is located at the front end of the slewing body 3. The cab 4 has an internal space where the operator of the earth drill machine 1 sits. In addition, the internal space of the cab 4 is equipped with various operating devices (levers, switches) for operating the earth drill machine 1, although these are not shown in the diagram. When the operator sitting inside the cab 4 operates the operating devices, the vehicle 2 moves, the slewing body 3 rotates, and the front attachment 100 operates.

[0013] The counterweight 5 is located at the rear end of the slewing body 3. The counterweight 5 is a heavy object that balances the weight of the front attachment 100 and the load (not shown). The rear winch 6 is rotationally driven by a rear winch hydraulic motor (not shown) to wind up or wind down the main hoisting rope (Kelly rope) 116. The front winch 7 is rotationally driven by a front winch hydraulic motor (not shown) to wind up or wind down the auxiliary hoisting rope 117. Note that the main hoisting rope 116 does not necessarily have to be wound up or wound down by the rear winch 6; it may also be wound up or wound down by the front winch 7.

[0014] (Front attachment 100) The front attachment 100 is of the boom type and performs excavation and lifting operations according to the operation of the control device. Alternatively, a leader-type front attachment may be used instead of the boom type.

[0015] The front attachment 100 includes a boom 110, a front frame 112, a rotary frame 113, a main winding sheave 114, an auxiliary winding sheave 115, a main winding rope 116, an auxiliary winding rope 117, a Kelly bar 140, a rotary drive 120, a boom hoisting cylinder 124, a boom telescopic cylinder (not shown), a front frame hoisting cylinder 125, a rotary frame hoisting cylinder 126, a thruster cylinder 127, an excavation bucket 130, and a hook 122. The frames constituting the front attachment 100 such as the boom 110, the front frame 112, the rotary frame 113, and the Kelly bar 140 correspond to the "frame" described in the claims.

[0016] The boom 110 is provided on the swivel body 3 so as to be able to rise and fall. In the present embodiment, the boom 110 is of a telescopic boom type, but it may also be of a lattice boom type. The boom 110 stands up or falls down with respect to the swivel body 3 along with the telescopic operation of the boom hoisting cylinder 124.

[0017] The front frame 112 is provided on the boom 110 so as to be able to rise and fall. The front frame 112 can adjust the angle with respect to the boom 110 along with the telescopic operation of the front frame hoisting cylinder 125.

[0018] The rotary frame 113 is provided at the tip of the front frame 112 so as to be rotatable. The rotary frame 113 can adjust the angle with respect to the front frame 112 along with the telescopic operation of the rotary frame hoisting cylinder 126.

[0019] The rotary drive 120 and the thruster cylinder 127 are attached to the rotary frame 113. The rotary drive 120 moves up and down along with the telescopic operation of the thruster cylinder 127.

[0020] The Kelly bar 140 is suspended from the lower end of the main winding rope 116, which hangs down from the front end of the main winding sheave 114, and a drilling bucket 130 is attached to the tip of the Kelly bar 140. The drilling bucket 130, also called a drilling bucket, excavates the ground by rotating the Kelly bar 140 with a rotary drive 120.

[0021] (Excavation bucket 130) The excavation bucket 130 comprises a cylindrical bucket body 131, a bottom cover 132 attached to the lower end of the bucket body 131, and a cutter (not shown) provided on the lower surface of the bottom cover 132. The upper part of the bucket body 131 is connected to the Kelly bar 140. The excavation bucket 130 is designed so that excavated soil can be taken into the bucket body 131 by the cutter, and the excavated soil can be discharged by opening the bottom cover 132.

[0022] The bucket body 131 and the bottom cover 132 are connected via a hinge (not shown). When the lock mechanism (not shown) is released, the bottom cover 132 rotates around the hinge, opening the bucket (see Figure 4(A)). When the bucket body 131 and the bottom cover 132 are locked by the lock mechanism, the bucket can remain closed (see Figure 4(C)).

[0023] The excavation bucket 130 is given rotational force by the rotary drive 120 which rotates the Kelly bar 140. Then, while the rotary drive 120 rotates the Kelly bar 140, the main hoisting rope 116 is gradually unfurled by the rear winch 6, and thrust is applied to the excavation bucket 130 by the weight of the Kelly bar 140 and the excavation bucket 130, etc., so that the excavation bucket 130 can excavate a vertical shaft VH (see Figure 3) by taking in excavated soil and drilling through the ground.

[0024] Furthermore, as described above, if a predetermined amount of excavated soil accumulates in the bucket body 131 during the process of the excavation bucket 130 drilling through the ground, the main winding rope 116 is reeled in to pull the excavation bucket 130 to the surface and discharge the excavated soil. In the earth drill machine 1, a vertical hole VH of a predetermined depth is excavated by repeating these steps.

[0025] Figure 2 is a front view of the earth drill machine 1 showing the excavation bucket 130 in a ground-contact state, i.e., in contact with the ground G. The main body 10, boom 110, front frame 112, main hoist sheave 114, auxiliary hoist sheave 115, main hoist rope 116, and auxiliary hoist rope 117 are omitted. When the excavation bucket 130 is in a ground-contact state, the slewing body 3 and front attachment 100 may slewing relative to the traveling body 2 by the slewing motor 20. In Figure 2, the slewing is in the direction of arrow A1 (from right to left in the figure), indicated by a dashed line. As the ground-contacting excavation bucket 130 receives resistance from the ground G, the slewing body 3 and front attachment 100 receive a torsional moment in the direction of arrow A2 (counterclockwise), indicated by a solid line.

[0026] Figure 3 is a front view of the earth drill machine 1 showing the excavation bucket 130 in the excavation state, i.e., excavating the vertical hole VH. As with Figure 2, the main body 10, boom 110, front frame 112, main hoist sheave 114, auxiliary hoist sheave 115, main hoist rope 116, and auxiliary hoist rope 117 are omitted. When the excavation bucket 130 is in the excavation state, i.e., when the excavation bucket 130 is located below the ground G, the slewing body 3 and front attachment 100 may slewing relative to the traveling body 2 by the slewing motor 20. In Figure 3, it is slewing in the direction of arrow A1 (from right to left in the figure), indicated by a dashed line. As the grounded excavation bucket 130 receives resistance from the vertical hole VH, the slewing body 3 and front attachment 100 receive a torsional moment in the direction of arrow A2 (counterclockwise), indicated by a solid line.

[0027] Figure 4 is an explanatory diagram illustrating the process of closing the bottom cover of the excavation bucket from an open state. Figure 4(A) shows the state in which the main hoisting rope 116 is wound up to lift the excavation bucket 130 to the ground, and the locking mechanism is released to open the bottom cover 132. This allows the excavated soil accumulated in the bucket body 131 to be discharged.

[0028] From the state shown in Figure 4(A), the main winding rope 116 is gradually unwound, and the slewing motor 20 gradually rotates the slewing body 3 and the front attachment 100 in the left-right direction. As a result, as shown in Figure 4(B), one end of the bottom cover 132 touches the ground, and the other end of the bottom cover 132 (the side with the hinge) can be pushed by the weight of the bucket body 131, so that the bottom cover 132 can be gradually closed relative to the bucket body 131.

[0029] Then, from the state shown in Figure 4(B), the main winding rope 116 is gradually extended further, and the slewing motor 20 further rotates the slewing body 3 and the front attachment 100. As a result, as shown in Figure 4(C), the center of the bottom cover 132 touches the ground, and the bottom cover 132 can be completely closed against the bucket body 131. Furthermore, if the bucket body 131 and the bottom cover 132 are locked by the locking mechanism, the closed state can be maintained.

[0030] When closing the bottom cover 132 of the excavation bucket 130 from an open state, a portion of the bottom cover 132 may come into contact with the ground, and the slewing body 3 and the front attachment 100 may be rotated, thus the slewing body 3 and the front attachment 100 may be subjected to a torsional moment.

[0031] As described above, in the earth drill machine 1, the slewing body 3 and the front attachment 100 may be subjected to torsional moments in various working positions, such as when drilling, grounding, and when the bottom cover 132 changes from an open to a closed state. When the slewing body 3 and the front attachment 100 are subjected to torsional moments, if the slewing output from the slewing motor 20 is large, the various frames constituting the slewing body 3 and the front attachment 100 may be damaged.

[0032] (Hydraulic circuit 21) Figure 5 is a diagram of the hydraulic circuit 21 that drives the swing motor 20. The swing motor 20 and the hydraulic circuit 21 constitute the swing device. The hydraulic circuit 21 shown in Figure 5 includes a directional control valve 23, first and second relief valves 24 and 25, a main pump 26, a tank 27, a solenoid switching valve 29, a control device 30, a pilot pump 32, remote control valves 33A and 33B, and a third relief valve 34. In Figure 5, L1 to L8 indicate oil passages, and E1 indicates electrical wiring.

[0033] The main pump 26 is driven by an engine (not shown) and supplies pressurized oil (hydraulic fluid) to the directional control valve 23. The main pump 26 is a variable displacement hydraulic pump. The discharge flow rate of the main pump 26 is adjusted by a regulator (not shown). The engine speed is controlled based on the amount of throttle grip (not shown) operated by the operator.

[0034] The slewing motor 20 is driven by pressurized oil discharged from the main pump 26. The directional control valve 23 controls the flow direction and flow rate of the pressurized oil supplied to the slewing motor 20. By switching the position (spool position) of the directional control valve 23, the slewing motor 20 rotates in the forward or reverse direction.

[0035] The directional control valve 23 has input sections 23a and 23b on its left and right sides for inputting pilot signals. In this embodiment, pilot signals Pr and Pl are pilot pressure signals of the hydraulic fluid supplied from the pilot pump 32. The pilot pump 32 is a fixed-displacement hydraulic pump. The pilot signals Pr and Pl are input to the input sections 23a and 23b, respectively, via oil passages L5 and L6, and the position of the directional control valve 23 is switched.

[0036] The directional control valve 23 is normally in the neutral position O. When a pilot signal Pr is input to the input section 23a, it switches to the right position A. When a pilot signal Pl is input to the input section 23b, it switches to the left position B.

[0037] When the directional control valve 23 is in the neutral position O, the pressurized oil discharged from the main pump 26 flows through oil passage L1 and then oil passage L4 and returns to the tank 27. When the directional control valve 23 is switched to the right position A, the pressurized oil discharged from the main pump 26 flows through oil passage L1 and then oil passage L2, causing the swing motor 20 to rotate in the forward direction. The pressurized oil discharged from the swing motor 20 flows through oil passage L3 and then oil passage L4 in order and returns to the tank 27.

[0038] On the other hand, when the directional control valve 23 is switched to the left position B, the pressurized oil discharged from the main pump 26 flows through oil passage L1 and then oil passage L3, reversing the slewing motor 20. The pressurized oil discharged from the slewing motor 20 flows through oil passage L2 and then oil passage L4 in order, returning to the tank 27.

[0039] The remote control valves 33A and 33B are normally configured to provide pilot signals Pr and Pl to the directional control valve 23 based on the tilting of the swivel operation lever 35. The third relief valve 34 is installed between the supply-side oil passage L7, which supplies hydraulic fluid from the pilot pump 32 to the remote control valves 33A and 33B, and the oil passage L8, which returns to the tank 27. When one of the remote control valves 33A and 33B is in communication, the other is in a closed state. As a result, the remote control valves 33A and 33B selectively direct the hydraulic fluid discharged from the pilot pump 32 to the forward and reverse-side oil passages L5 and L6.

[0040] Specifically, when the swivel control lever 35 is in the neutral position, both remote control valves 33A and 33B are shut off. When both remote control valves 33A and 33B are shut off, the hydraulic pressure in the oil passage L7 exceeds the relief pressure of the third relief valve 34, causing the third relief valve 34 to operate. As a result, the hydraulic fluid discharged from the pilot pump 32 flows through the oil passage L8 and returns to the tank 27. In other words, the pilot signals Pr and Pl are not applied to the directional control valve 23. Therefore, the directional control valve 23 is normally held in the neutral position O.

[0041] Then, by tilting the slewing lever 35 to the forward rotation side (right side in the diagram), the remote control valve 33A is connected to the pilot pump 32, and the hydraulic fluid supplied from the pilot pump 32, i.e., the pilot signal Pr, flows through the oil passage L5. As a result, the position of the directional control valve 23 is switched to the right position A, causing the slewing motor 20 to rotate in the forward direction.

[0042] On the other hand, by tilting the slewing lever 35 to the reverse side (left side in the diagram), the remote control valve 33B is connected to the pilot pump 32, and the hydraulic fluid supplied from the pilot pump 32, i.e., the pilot signal Pl, flows through the oil passage L6. As a result, the position of the directional control valve 23 is switched to the left position B, and the slewing motor 20 is reversed.

[0043] The first and second relief valves 24 and 25 are installed between the supply oil passage L1 of the main pump 26 and the oil passage L4 that returns to the tank 27. The electromagnetic switching valve 29 is a switching valve that selects whether or not to activate the second relief valve 25. In this embodiment, the first and second relief valves 24 and 25, the electromagnetic switching valve 29 and the control device 30 constitute a swing output limiting means. The switching of the electromagnetic switching valve 29 is controlled by the control device 30 according to the height of the drilling bucket 130 measured by the depth gauge 31.

[0044] Specifically, the electromagnetic switching valve 29 is normally in the shut-off position (the position shown in Figure 5(A)), and when a control signal is input from the control device 30 via the electrical wiring E1, it switches to the communication position (the position shown in Figure 5(B)). The depth gauge 31 consists of, for example, a rotary encoder installed on the rear winch 6, and calculates the height of the excavation bucket 130 from the length of the main winding rope 116 that is determined according to the output signal output from this rotary encoder.

[0045] When the electromagnetic switching valve 29 is in the left shut-off position, only the first relief valve 24 is operational, and the second relief valve 25 is shut off. When only the first relief valve 24 is operational, the hydraulic pressure supplied by the hydraulic circuit 21 to the swing motor 20 is less than or equal to the relief pressure of the first relief valve 24.

[0046] On the other hand, when the electromagnetic switching valve 29 is in the right-hand communication position, the first and second relief valves 24 and 25 are in an operable state. The relief pressure of the second relief valve 25 is set lower than the relief pressure of the first relief valve 24. In other words, when the electromagnetic switching valve 29 is in the right-hand communication position, the second relief valve 25 operates, and the hydraulic pressure supplied by the hydraulic circuit 21 to the swing motor 20 is less than or equal to the relief pressure of the second relief valve 25.

[0047] As described above, the control device 30 switches the electromagnetic switching valve 29 according to the height of the excavation bucket 130 measured by the depth gauge 31. Specifically, the control device 30 switches the electromagnetic switching valve 29 from the communication position to the shut-off position when the height of the excavation bucket 130 relative to the ground G is less than or equal to a predetermined value H (see Figure 6).

[0048] As shown in Figure 6, the predetermined value H, which is the height of the excavation bucket 130 relative to the ground G when the control device 30 switches the electromagnetic switching valve 29, is the height at which at least a portion of the excavation bucket 130 is considered to be in contact with the ground. More specifically, the predetermined value H is the height obtained by adding the diameter R of the bottom cover 132 of the excavation bucket 130 to the reference position P0 when excavating using the excavation bucket 130. Furthermore, the reference position P0 is the higher of the depth gauge zero reset position or the excavation start position.

[0049] The depth gauge zero reset position is the position where the depth gauge 31 is reset to zero, with the height of the excavation bucket 130 when it touches the ground being set. For example, if an error occurs in the payout length due to the expansion or contraction of the main winding rope 116, the operator inputs the value using the control device while the excavation bucket 130 is actually touching the ground G, and the measurement value from the depth gauge 31 at that time is set to zero and stored in a memory unit (not shown).

[0050] The drilling start position is the position where the drilling bucket 130 actually begins drilling. For example, if there is a step in the ground G, the drilling start position may be a different position from the depth gauge zero reset position. In this case, the measurement value from the depth gauge 31 is stored in the memory unit as the drilling start position.

[0051] Next, with reference to Figure 7, the details of the rotation output limiting process by the hydraulic circuit 21 will be explained. Figure 7 is a flowchart showing the processing details of the hydraulic circuit 21 under excavation mode.

[0052] In order to perform excavation work with the earth drill machine 1, the operator first operates the control device to select an excavation mode from among various modes (S1). After selecting the excavation mode, the operator starts the excavation work by operating the control device such as the slewing lever, and the control device 30 starts monitoring the height of the excavation bucket 130 using the depth gauge 31.

[0053] Next, the control device 30 determines whether the height of the excavation bucket 130 measured by the depth gauge 31 is less than or equal to a predetermined value H during the excavation operation (S2). If the height of the excavation bucket 130 measured by the depth gauge 31 exceeds the predetermined value H during the excavation operation (NO in S2), the swing output limit is in the off state (S3). In other words, the first and second relief valves 24 and 25 are not switched by the electromagnetic switching valve 29, and only the first relief valve 24 operates. As a result, the hydraulic pressure supplied by the hydraulic circuit 21 to the swing motor 20 is less than or equal to the relief pressure of the first relief valve 24.

[0054] On the other hand, during excavation work, if the height of the excavation bucket 130 measured by the depth gauge 31 is less than or equal to a predetermined value H (YES in S2), the swing output limit is turned ON (S4), meaning that the electromagnetic switching valve 29 switches, and the second relief valve 25 becomes operational. When the second relief valve 25 is operational, the hydraulic pressure supplied by the hydraulic circuit 21 to the swing motor 20 is less than or equal to the relief pressure of the second relief valve 25. Therefore, the swing motor 20 operates with hydraulic pressure less than or equal to the relief pressure of the second relief valve 25, which is lower than the relief pressure of the first relief valve 24, and thus the swing output of the swing motor 20 is limited.

[0055] Furthermore, the limitation of rotational output includes situations where the rotational torque value for rotating the rotational body 3 is small, the pushing force when rotating the rotational body 3 is small, the speed at which the rotational body 3 is rotated is small, and also situations where these values ​​are 0, i.e., the rotation does not occur.

[0056] The control device 30 then continues the process until the excavation work is completed (S5), determining whether the height of the excavation bucket 130 is below a predetermined value using the depth gauge 31 (S2). If the height of the excavation bucket 130 exceeds the predetermined value (NO in S2), the slewing output limit is turned off (S3). If the height of the excavation bucket 130 is below the predetermined value using the depth gauge 31 (YES in S2), the slewing output limit is turned on (S4).

[0057] As described above, this embodiment provides the following advantages: When the height of the excavation bucket 130 relative to the ground, as measured by the depth gauge 31, is below a predetermined value, the rotational output of the slewing motor 20 is limited. This reduces the torsional moment experienced by the front attachment 100. Furthermore, because the rotational output of the slewing motor 20 is limited, damage to the various frames constituting the slewing body 3 and the front attachment 100 can be prevented.

[0058] Furthermore, the predetermined value H used when determining whether the height of the drilling bucket 130 by the depth gauge 31 is less than or equal to a predetermined value H is the height at which at least a portion of the drilling bucket 130 is considered to be in contact with the ground. Therefore, when at least a portion of the drilling bucket 130 is in contact with the ground, the swing output of the swing motor 20 can be reliably limited. Also, since the predetermined value H is the height obtained by adding the diameter of the bottom cover 132 of the drilling bucket 130 to the reference position when drilling with the drilling bucket 130, the swing output of the swing motor 20 can be limited even when the bottom cover 132 is open, as long as at least a portion of it is in contact with the ground. Moreover, since the reference position is the higher of the depth gauge zero reset position or the drilling start position, the swing output of the swing motor 20 can be further reliably limited even when the bottom cover 132 is open, as long as at least a portion of it is in contact with the ground.

[0059] Furthermore, the hydraulic circuit 21 that supplies hydraulic fluid to the swing motor 20 includes first and second relief valves 24 and 25. When the height of the excavation bucket 130 relative to the ground is less than or equal to a predetermined value H, the electromagnetic switching valve 29 switches, and the second relief valve 25 becomes operational. As a result, the swing motor 20 operates with hydraulic pressure that is lower than or equal to the relief pressure of the second relief valve 25, which is lower than the relief pressure of the first relief valve 24, thus reliably limiting the swing output of the swing motor 20.

[0060] <Example 1> Next, a modified example will be described. Figure 8 shows a hydraulic circuit 41 according to Modified Example 1. The hydraulic circuit 41 drives the swing motor 20, similar to the hydraulic circuit 21 in the above embodiment. The hydraulic circuit 41 according to Modified Example 1 includes a directional control valve 43, a main pump 44, a pilot pump 45, a tank 46, remote control valves 47A and 47B, solenoid switching valves 48A and 48B, a relief valve 49, and a control device 50. Also in Figure 8, L11 to L18 indicate oil passages, and E11 and E12 indicate electrical wiring. In this modified example, the directional control valve 43, remote control valves 47A and 47B, solenoid switching valves 48A and 48B, and the control device 50 constitute a swing output limiting means.

[0061] The main pump 44 is a variable displacement hydraulic pump driven by an engine (not shown), similar to the main pump 26 in the above embodiment. The main pump 44 supplies pressurized oil (hydraulic fluid) to the directional control valve 43. The slewing motor 20 is driven by the pressurized oil discharged from the main pump 44. The directional control valve 43 controls the flow direction and flow rate of the pressurized oil supplied to the slewing motor 20, similar to the directional control valve 23 in the above embodiment.

[0062] The pilot pump 45 is a fixed-displacement hydraulic pump. Similar to the directional control valve 23 in the above embodiment, the pilot signals Pr and Pl of the hydraulic fluid supplied from the pilot pump 45 are input to the input sections 43a and 43b of the directional control valve 43. The pilot signals Pr and Pl are input to the input sections 43a and 43b, respectively, via the oil passages L15 and L16, and the position of the directional control valve 43 is switched.

[0063] The directional control valve 43 is normally in the neutral position O. When a pilot signal Pr is input to the input section 43a, it switches to the right position A. When a pilot signal Pl is input to the input section 43b, it switches to the left position B.

[0064] Similar to the directional control valve 23, when the directional control valve 43 is in the neutral position O, the pressurized oil discharged from the main pump 44 flows from oil passage L11 to oil passage L14 and returns to the tank 46. When the directional control valve 43 is switched to the right position A, the pressurized oil discharged from the main pump 44 flows from oil passage L11 to oil passage L12, causing the swing motor 20 to rotate in the forward direction. On the other hand, when the directional control valve 43 is switched to the left position B, the pressurized oil discharged from the main pump 44 flows from oil passage L11 to oil passage L13, causing the swing motor 20 to rotate in the reverse direction.

[0065] The remote control valves 47A and 47B are normally configured to provide pilot signals Pr and Pl to the directional control valve 43 based on the tilting of the swivel operation lever 51. The relief valve 49 is installed between the supply-side oil passage L17, which supplies hydraulic fluid from the pilot pump 45 to the remote control valves 47A and 47B, and the oil passage L18, which returns to the tank 46. When one of the remote control valves 47A and 47B is in communication, the other is in a closed state. As a result, the remote control valves 47A and 47B selectively direct the hydraulic fluid discharged from the pilot pump 45 to the forward and reverse-side oil passages L15 and L16.

[0066] Specifically, when the slewing lever 51 is in the neutral position, both remote control valves 47A and 47B are in a shut-off state. When both remote control valves 47A and 47B are in a shut-off state, the hydraulic pressure in the oil passage L17 exceeds the relief pressure of the relief valve 49, causing the relief valve 49 to operate. As a result, the hydraulic fluid discharged from the pilot pump 45 flows through the oil passage L18 and returns to the tank 46. In other words, the pilot signals Pr and Pl are not applied to the directional control valve 43. Then, by tilting the slewing lever 51 to the forward rotation side (right side in the figure), the remote control valve 47A comes into communication with the pilot pump 45, and the hydraulic fluid supplied from the pilot pump 45, i.e., the pilot signal Pr, flows through the oil passage L15. As a result, the position of the directional control valve 43 switches to the right position A, causing the slewing motor 20 to rotate in the forward direction.

[0067] On the other hand, by tilting the slewing lever 51 to the reverse side (left side in the diagram), the remote control valve 47B is put into communication with the pilot pump 45, and the hydraulic fluid supplied from the pilot pump 45, i.e., the pilot signal Pl, flows through the oil passage L16. As a result, the position of the directional control valve 43 is switched to the left position B, and the slewing motor 20 is reversed.

[0068] The electromagnetic switching valves 48A and 48B are installed in the middle of the oil passages L15 and L16. The switching of the electromagnetic switching valves 48A and 48B is controlled by the control device 50 according to the height of the drilling bucket 130 measured by the depth gauge 31. Specifically, the electromagnetic switching valves 48A and 48B are normally in the communication position (position shown in Figure 8), and when a control signal is input from the control device 50 via the electrical wiring E11 and E12, they switch to the shut-off position (position on the right in the figure). Similar to the above embodiment, the depth gauge 31 calculates the height of the drilling bucket 130.

[0069] When the electromagnetic switching valves 48A and 48B are in the left communication position, the oil passages L15 and L16 become operable. When oil passages L15 and L16 are operable, the remote control valves 47A and 47B can selectively send pilot signals Pr and Pl to oil passages L15 and L16. That is, either pilot signal Pr or Pl is input to the input units 43a and 43b via oil passages L15 and L16, and the position of the directional control valve 43 is switched. As a result, the swing motor 20 can be rotated in the forward or reverse direction.

[0070] On the other hand, when the electromagnetic switching valves 48A and 48B are in the right shut-off position, the oil passages L15 and L16 are shut off. When the oil passages L15 and L16 are shut off, the remote control valves 47A and 47B cannot send pilot signals Pr and Pl to the oil passages L15 and L16. In other words, the directional control valve 43 is held in the neutral position, so the swing output from the swing motor 20 becomes 0 (swing stops).

[0071] The steps for limiting the swing output by the hydraulic circuit 41 are the same as in the above embodiment. Specifically, the depth gauge 31 determines whether the height of the excavation bucket 130 is less than or equal to a predetermined value H. During excavation, if the height of the excavation bucket 130 exceeds the predetermined value H, the swing output limit is in the off state. If the height of the excavation bucket 130 is less than or equal to the predetermined value H, the swing output limit is in the on state. In this modified example, as a swing output limit, the electromagnetic switching valves 48A and 48B switch, and the oil passages L15 and L16 that carry the pilot signals Pr and Pl are shut off. As a result, the swing of the swing body 3 and the front attachment 100 by the swing motor 20 is stopped. In other words, the swing output by the swing motor 20 is limited, so the same effect as in the above embodiment can be obtained.

[0072] [Differentiation 2] The hydraulic circuit (not shown) according to Modification 2 drives the swing motor 20 in the same way as the hydraulic circuit 21 of the above embodiment, but the first and second relief valves 24 and 25 and the electromagnetic switching valve 29 are omitted. Furthermore, the swing operation lever is an electric lever that outputs an electrical signal according to the amount of operation, and an electrical signal as pilot signals Pr and Pl is input to the directional control valve 23. This electric lever constitutes a swing output limiting means, and when the height of the excavation bucket 130 relative to the ground as determined by the depth gauge 31 is less than or equal to a predetermined value H, the output of pilot signals Pr and Pl by the electric lever is stopped or disabled. If pilot signals Pr and Pl are not input to the input units 23a and 23b, the directional control valve 23 is held in the neutral position O, so the swing output by the swing motor 20 becomes 0 (swing stops).

[0073] The steps for limiting the swing output by the hydraulic circuit in this modified example are the same as in the above embodiment. Specifically, the depth gauge 31 determines whether the height of the excavation bucket 130 is less than or equal to a predetermined value H. During excavation, if the height of the excavation bucket 130 exceeds the predetermined value H, the swing output limit is in the off state. If the height of the excavation bucket 130 is less than or equal to the predetermined value H, the swing output limit is in the on state. In this modified example, the swing output limit is achieved by stopping or disabling the output of pilot signals Pr and Pl from the electric lever. As a result, the swing of the slewing body 3 and the front attachment 100 by the swing motor 20 is stopped. In other words, the swing output by the swing motor 20 is limited, so the same effect as in the above embodiment can be obtained.

[0074] In Modification 2, when the height of the excavation bucket 130 is determined to be below a predetermined value H and the slewing output limit is turned ON, the control shown is such that the slewing output from the slewing motor 20 becomes 0 (slewing stops). However, the control is not limited to this, and when the slewing output limit is turned ON, the control may be such that the slewing output from the slewing motor 20 is reduced compared to the normal state in response to the control signal corresponding to the amount of operation of the electric lever.

[0075] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention. All technical matters included in the technical concept described in the claims are subject to the present invention. The embodiments described above are preferred examples, but those skilled in the art can realize various alternatives, modifications, variations, or improvements from the contents disclosed herein, and these are included in the technical scope described in the appended claims.

[0076] For example, to determine whether the height of the excavation bucket 130 relative to the ground is below a predetermined value, a depth gauge 31 is provided on the rear winch 6 and detects the height of the excavation bucket 130 from the length of the main winding rope 116 that has been unwound. However, any detection means capable of detecting the height of the excavation bucket 130 relative to the ground is acceptable, and the length of the main winding rope 116 may be detected from a location other than the rear winch 6, for example, from a rotary encoder provided on the main winding sheave 114. Alternatively, the detection means is not limited to detecting the height of the excavation bucket 130 relative to the ground from the length of the main winding rope 116 that has been unwound. For example, a camera that photographs the area including the excavation bucket 130 may be provided as the detection means, and if the excavation bucket 130 moves to a position outside of a predetermined field of view, it may be determined that the height of the excavation bucket 130 relative to the ground is below a predetermined value. [Explanation of Symbols]

[0077] 1. Earth drill machine 2. Running body 3. Rotating body 10 Main Unit 20 Swivel motor 21, 41 Hydraulic circuits 23, 43 Directional control valves 24. First relief valve 25. Second relief valve 26, 44 Main pump 27, 46 tanks 29, 48A, 48B Solenoid switching valve 30, 50 control devices 31 Depth gauge 32, 45 Pilot pump 33A, 33B, 47A, 47B Remote control valve 34 Third relief valve 100 Front Attachment 110 Boom 112 Front Frame 113 Rotary Frame 120 Rotary Drive 130 digging buckets 131 Bucket body 132 Bottom Cover 140 ケリーバ E1, E11, E12 electrical wiring L1~L8, L11~L18 oil circuit

Claims

1. An earth drilling machine comprising a rotating body that rotates by a rotating device, and an excavation bucket connected to the rotating body via a frame provided on the rotating body, An earth drill machine characterized by having a rotation output limiting means that limits the rotation output of the rotation device when the height of the excavation bucket relative to the ground is below a predetermined value.

2. In the earth drill machine according to claim 1, The earth drill machine is characterized in that the predetermined value is a height at which at least a portion of the drilling bucket is considered to be in a ground-contact state.

3. In the earth drill machine according to claim 1, The earth drill machine is characterized in that the predetermined value is the height obtained by adding the diameter of the bottom cover of the drill bucket to the reference position when drilling using the drill bucket.

4. In the earth drill machine according to claim 3, The earth drill machine is characterized in that the aforementioned reference position is the higher of the depth meter zero reset position or the drilling start position.

5. In the earth drill machine according to claim 1, The aforementioned swivel device is Includes a swing motor driven by hydraulic fluid discharged from a hydraulic pump, The aforementioned turning output limiting means is This includes a relief valve provided in the hydraulic circuit that supplies hydraulic fluid from the hydraulic pump to the swing motor, The aforementioned relief valve An earth drill machine characterized in that, when the height of the excavation bucket relative to the ground is less than or equal to the predetermined value, the relief pressure is changed to a lower level than usual.

6. In the earth drill machine according to claim 1, The aforementioned swivel device is Includes a swing motor driven by hydraulic fluid discharged from a hydraulic pump, The aforementioned turning output limiting means is Includes a directional control valve that controls the flow direction of the hydraulic fluid supplied from the hydraulic pump to the swing motor, The aforementioned directional control valve is An earth drill machine characterized in that when the height of the excavation bucket relative to the ground is less than or equal to the predetermined value, it is held in a neutral position to which the hydraulic fluid is returned to the tank.

7. In the earth drill machine according to claim 1, The rotating device is equipped with a rotating operation lever, The aforementioned swivel control lever is, It is an electric lever that outputs an electrical signal corresponding to the amount of operation. The aforementioned turning output limiting means is An earth drill machine characterized in that, when the height of the excavation bucket relative to the ground is less than or equal to the predetermined value, the output of an electrical signal by the electric lever is stopped or disabled.

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