Safety device for gripping-type digging pole erection vehicle

Abstract

To provide a safety device for a gripping-type digging pole erection vehicle, which can prevent falling of a gripped object.SOLUTION: This safety device for a gripping-type digging pole erection vehicle comprises: an operation control unit 101 that controls supplying / discharging of pressure oil to / from a gripper cylinder 99 in accordance with an operation of a gripper opening / closing operation lever 32g; a gripper cylinder pressure detector 141 that detects pressure in a rod side oil chamber of the gripper cylinder 99; a gripping determination unit 103 that determines gripping of an object by a gripper when the pressure detected by the gripper cylinder pressure detector 141 is equal to or higher than first set pressure; and a gripping force control unit 104 that executes control for supplying pressure oil to the rod side oil chamber when the gripping determination unit 103 determines gripping of the object by the gripper and the pressure detected by the gripper cylinder pressure detector 141 is equal to or lower than second set pressure higher than the first set pressure in a state where the gripper opening / closing operation lever 32g is not operated.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to a safety device for a gripping type pole - driving vehicle equipped with a gripping part for gripping an object such as a utility pole.

Background Art

[0002] As a pole - driving vehicle which is one type of work vehicle, there is known a gripping type pole - driving vehicle provided with a swivel base rotatably provided on a vehicle body, a boom provided on the swivel base so as to be able to move up and down and extend and contract, an auger device attached to the boom for excavating a pole - driving hole for driving a utility pole, and a gripping device provided at the tip of the boom for gripping a columnar object such as a utility pole (for example, see Patent Document 1). When excavating a pole - driving hole on the ground using this gripping type pole - driving vehicle, with the auger device suspended from the tip of the boom, the boom is appropriately operated, and the auger device is rotated at a predetermined excavation position, whereby a pole - driving hole of a predetermined depth can be formed. After the excavation of this pole - driving hole is completed, the auger device is pulled up and stored on the side of the boom, and the utility pole is gripped by the gripping device provided at the tip of the boom. By appropriately operating the boom while gripping the utility pole, the utility pole can be directly driven into the excavated pole - driving hole. In such a gripping type pole - driving vehicle, a series of pole - driving operations can be performed more efficiently compared to the case where the utility pole is suspended and worked using a winch or a crane.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the conventional technology described above had a problem: if a leak (hydraulic leak) occurred in the hydraulic circuit of the gripping device while the utility pole was being gripped by the gripping device, the gripping force of the gripping device would decrease over time, and there was a risk that the utility pole would fall from the gripping device due to insufficient gripping force.

[0005] This invention has been made in view of the above problems, and aims to provide a safety device for a gripping-type hole-digging and pole-erecting vehicle that can prevent the gripped object from falling. [Means for solving the problem]

[0006] To solve the above problems, the safety device for a gripping-type hole-digging pole-erecting vehicle according to the present invention comprises a boom mounted on the vehicle body so as to be at least movable up and down, a gripping part having an openable and closable gripping claw capable of gripping an object in a closed state, a support mechanism provided between the tip of the boom and the gripping part to change the posture of the gripping part relative to the tip of the boom, a gripping cylinder for opening and closing the gripping claw, a gripping operation device for operating the gripping cylinder, a pressurized oil supply control unit for controlling the supply and discharge of pressurized oil to the rod-side oil chamber and the bottom-side oil chamber of the gripping cylinder in accordance with the operation of the gripping operation device, and the rod-side oil chamber The pressurized oil supply control unit includes a pressure detection unit that detects the pressure in the closed oil chamber, which is the oil chamber on the side to which the gripping claw is supplied when the gripping claw is operated in the closing direction, and a gripping determination unit that determines that the gripping part is gripping an object when the pressure detected by the pressure detection unit is equal to or greater than a first set value, and when the gripping determination unit determines that the gripping part is gripping an object, and the gripping operating device is not being operated, the pressure detected by the pressure detection unit becomes less than or equal to a second set value which is greater than the first set value, and the pressurized oil supply control unit The system is characterized by performing control to supply pressurized oil.

[0007] In the safety device for the gripping-type hole-digging pole-erecting vehicle with the above configuration, it is preferable that the pressurized oil supply control unit performs control to supply pressurized oil to the closed-side oil chamber until the pressure detected by the pressure detection unit reaches a third setting value greater than the second setting value, when the gripping determination unit determines that the gripping unit is gripping an object and the gripping operation device is not being operated, and the pressure detected by the pressure detection unit is less than or equal to the second setting value. [Effects of the Invention]

[0008] According to the safety device for the gripping-type hole-digging and pole-erecting vehicle of the present invention, even if a hydraulic leak or the like occurs and the pressure in the closed oil chamber of the gripping cylinder decreases while the gripping part is gripping an object, when the pressure detected by the pressure detection unit drops to a second set value, pressurized oil is supplied to the closed oil chamber of the gripping cylinder and the control is performed to automatically pressurize it, thereby ensuring that the necessary gripping force to grip the object can be reliably maintained. This prevents the object from falling from the gripping part due to insufficient gripping force, thereby improving safety. Furthermore, in the present invention, even if the operation of the gripping operation device is released immediately after gripping an object with the gripping part (when the detected pressure at the time of initial gripping falls below the second set value), pressurized oil is supplied to the closed oil chamber of the gripping cylinder and the control is performed to automatically pressurize it. This makes it possible to generate sufficient gripping force without requiring any additional operation of the gripping operation device, thus achieving both convenience of operation and safety.

[0009] Furthermore, in the safety device for the gripping-type hole-digging and pole-erecting vehicle according to the present invention, when the gripping part is gripping an object, if the pressure detected by the pressure detection unit drops to a second set value, pressurized oil is supplied to the closed side oil chamber of the gripping cylinder to automatically pressurize it until the detected pressure reaches a third set value. This prevents the occurrence of a phenomenon (chattering phenomenon) in which pressurization control is frequently executed and stopped in the region near the second set value, and makes it possible to always generate sufficient gripping force. [Brief explanation of the drawing]

[0010] [Figure 1] This is a side view of the gripping type hole-digging and pole-erecting vehicle according to this embodiment. [Figure 2] The above is a plan view of the gripping-type hole-digging and pole-erecting vehicle. [Figure 3] This is a side view showing the usage state of the gripping-type hole-digging and pole-erecting vehicle described above. [Figure 4] This is a perspective view of the gripping device provided on the gripping-type hole-digging and pole-erecting vehicle described above. [Figure 5] This is a perspective view of the main part of the gripping device shown above, taken from the right. [Figure 6] This is a perspective view of the main part of the gripping device shown above, taken from the left. [Figure 7] This is a cross-sectional view of the gripping device described above. [Figure 8] This is a longitudinal cross-sectional view of the gripping device described above. [Figure 9] The above is a functional block diagram of the gripping-type hole-digging and pole-erecting vehicle. [Figure 10] This figure shows the hydraulic circuit of the gripping device described above. [Figure 11] This figure shows the change in the detected pressure of the gripper cylinder pressure detector when a hydraulic leak occurs while gripping a utility pole. [Modes for carrying out the invention]

[0011] Preferred embodiments of the present invention will be described below with reference to the drawings. First, the overall configuration of the gripping-type hole-digging and pole-erecting vehicle 1 according to this embodiment will be described with reference to Figures 1 to 3.

[0012] As shown in Figure 1, the gripping-type hole-digging and pole-erecting vehicle 1 has a driver's cabin 7 at the front of the vehicle body 2 and is based on a truck vehicle that can move using a pair of left and right tires 5 arranged at the front and rear of the vehicle body 2. There are four points on the front, rear, left and right of the vehicle body 2 for lifting and supporting the vehicle body 2. Jack 9 is provided. Each jack 9 drives a jack cylinder (not shown) provided inside thereof to extend downward, thereby lifting and supporting the vehicle body 2, and thus making the entire vehicle body 2 in a stable state. The operation of the jack 9 is performed by operating a jack operating device (not shown) provided at the rear part of the vehicle body 2.

[0013] In the mounting area behind the driver's cab 7 of the vehicle body 2, a turntable 12 is provided which is driven by a slewing motor 14 (see FIG. 9) and is configured to be horizontally slewingly movable around a vertical axis. At the turntable 12, the base end portion of the boom 13 is attached so as to be swingable (up-and-down movable) in the vertical direction.

[0014] The boom 13 has a configuration in which a base boom 13a, an intermediate boom 13b, and a tip boom 13c are combined in a telescopic manner in order from the turntable 12 side. By the telescopic drive of a telescopic cylinder 15 (see FIG. 9) provided inside thereof, the boom 13 can be telescopically moved in the axial direction (longitudinal direction). Further, a tilting cylinder 16 is spanned between the base boom 13a and the turntable 12. By driving the tilting cylinder 16 to expand and contract, the entire boom 13 can be tilted in the upper and lower surfaces (vertical plane).

[0015] An auger device 20 for excavating a building column hole is attached to the boom 13 via an auger support 17 that can be selectively connected to the base boom 13a and the tip boom 13c. The auger device 20 includes an auger motor 21 with a speed reducer and an earth auger 22 that is rotated around an axis by driving the auger motor 21 to rotate. Further, an auger storage device 18 for holding the auger device 20 in a stored state is disposed on the side surface of the base boom 13a. The auger device 20 is attached to the auger support 17 so as to be vertically swingable in a vertical plane, and can be swung between a storage position where the auger device 20 is stored along the side of the base boom 13a by the auger storage device 18 and a working position where the auger device 20 is removed from the auger storage device 18 and the earth auger 22 is in a substantially vertical posture with respect to the ground.

[0016] When using the auger device 20, as shown in I of FIG. 3, connect the auger support 17 to the tip boom 13c, swing the auger device 20 removed from the auger storage device 18 to the working position (with the earth auger 22 in a substantially vertical posture with respect to the ground), and rotate the earth auger 22 while interlocking the lowering movement and the shrinking movement of the boom 13 to move linearly downward, thereby enabling the excavation work of the building column hole. On the other hand, when not using the auger device 20, as shown in II of FIG. 3, connect the auger support 17 to the base boom 13a, and store and hold the auger device 20 in the storage position along the side of the base boom 13a by the auger storage device 18. In the state where the auger device 20 is in the storage position, various operations such as the building column operation of the utility pole (indicated by reference numeral D in FIG. 3: the same applies hereinafter) and the relocation operation of obstacles can be performed using the gripping device 50 described later.

[0017] A boom head 19 is fixed to the tip of the tip boom 13c. A gripping device 50 for gripping an object (columnar object) such as a utility pole D is attached to the boom head 19. The configuration of this gripping device 50 will be described with additional reference to FIGS. 4 to 8. In FIGS. 7 to 8, for the sake of easy viewing of the drawings, the hatching indicating the cross section is omitted. Also, hereinafter, for the sake of convenience of explanation, based on the posture of the gripping device 50 shown in FIG. 4, the arrow directions of front-rear, left-right, and up-down shown in the drawings will be referred to as the front-rear direction, left-right direction, and up-down direction for explanation.

[0018] The gripping device 50 includes an arm 51 attached to the boom head 19 so as to be swingable (flexible) in the up-down direction, a first joint member 60 attached to the tip of the arm 51 so as to be swingable (vertical head swing) in the up-down direction, a second joint member 70 attached to the first joint member 60 so as to be swingable (horizontal head swing) in the left-right direction, and a member rotatably attached to the second joint member 70 The system is configured to include an attached gripper 80. In this embodiment, a support mechanism is configured to change the posture of the gripping portion 81 of the gripper 80, consisting of an arm 51, a first joint member 60, a second joint member 70, a vertical swivel cylinder 62 (described later), a horizontal swivel cylinder 71, a gripper motor 79, and the like.

[0019] The arm 51 is pivotally connected to the boom head 19 at one end in the axial direction (longitudinal direction) via a connecting pin 52, and its other end in the axial direction (longitudinal direction) is pivotally connected to the first joint member 60 via a connecting pin 53. An arm cylinder 55 is mounted between the boom head 19 and the first joint member 60. The rod end of the arm cylinder 55 is pivotally connected to the boom head 19 via a connecting pin 56. The bottom end of the arm cylinder 55 is pivotally connected to the first joint member 60 via a connecting pin 57. By extending and retracting this arm cylinder 55, the arm 51 is configured to swing freely (flex and extend freely) in the vertical direction around the connecting pin 52 relative to the boom head 19.

[0020] The first joint member 60 is formed in a bifurcated shape with an open tip, and the second joint member 70 is pivotally connected to both ends of this bifurcated shape via a pair of upper and lower connecting pins 61. A vertical swivel cylinder 62 is provided between the first joint member 60 and the arm 51. The bottom end of the vertical swivel cylinder 62 is pivotally connected to the base end of the arm 51 via a connecting pin 63. The rod end of the vertical swivel cylinder 62 is pivotally connected to the upper end of the first joint member 60 via a connecting pin 64. By extending and retracting this vertical swivel cylinder 62, the first joint member 60 is configured to swing freely in the vertical direction (vertical swivel) relative to the arm 51 around the connecting pin 53.

[0021] The second joint member 70 is supported by the first joint member 60, sandwiched between it from above and below. A lateral swivel cylinder 71 is provided at the upper end of the first joint member 60. The bottom end of the lateral swivel cylinder 71 is pivotally connected to the tip of the first joint member 60, and the rod end is pivotally connected to the rear end of the second joint member 70. By extending and retracting this lateral swivel cylinder 71, the second joint member 70 is configured to swing freely (swivel freely) in the left-right direction around the connecting pin 61 relative to the first joint member 60.

[0022] The gripper 80 comprises a gripping portion 81 for gripping an object, a gripper housing 86 that supports the gripping portion 81 and is rotatably mounted on the second joint member 70, and an opening / closing mechanism 93 for opening and closing the gripping portion 81.

[0023] The gripping portion 81 comprises a pair of gripping claws 82 and a pair of upper and lower support plates 83 that support the pair of gripping claws 82 so that they can be opened and closed in directions that move them toward or away from each other (opening and closing directions). The gripping claws 82 are configured to grip various objects (columnar objects) such as utility poles D. The base ends of the gripping claws 82 are pivotally connected to the upper and lower support plates 83 via connecting pins 84. The tips of the gripping claws 82 have alternating notches 82a and 82b, and these tips are configured to intersect (overlap) with each other. The support plates 83 are provided with a flat upper bracket 85 for detachably attaching an attachment (not shown) (for example, a tree felling device).

[0024] The gripper housing 86 includes a support cylinder portion 87 connected to the upper and lower support plate portions 83 and rotatably supported by the second joint member 70, and a cylinder bracket portion 92 fixed to the base end side of the support cylinder portion 87 and disposed between the first joint member 60 and the second joint member 70.

[0025] The support cylinder portion 87 consists of an inner cylinder portion 88 formed in the shape of a hollow rectangular tube, and the outer circumference of this inner cylinder portion 88. The inner cylinder 88 has a double structure with an outer cylinder portion 89 that is provided on the side and formed in the shape of a hollow cylinder. A sliding member 95 of the opening / closing mechanism 93, described later, is attached to the inner circumference of the inner cylinder portion 88 so as to be slidable in the front-rear direction. A worm wheel 90 is attached to the outer circumference of the outer cylinder portion 89 concentrically with the outer cylinder portion 89. This worm wheel 90 meshes with a worm pinion 91 that is rotatably supported inside the second joint member 70. A gripper motor 79 is attached to the upper end of the second joint member 70, and the worm pinion 91 is connected to the output shaft of this gripper motor 79 via a reduction gear. When this gripper motor 79 is rotated in the forward direction, the entire gripper 80 rotates in a predetermined direction around the rotation axis X (see Figure 7) via the worm pinion 91 and worm wheel 90. On the other hand, when the gripper motor 79 is rotated in the reverse direction, the entire gripper 80 rotates in the opposite direction to the predetermined direction around the rotation axis X (see Figure 7) via the worm pinion 91 and worm wheel 90. In the orientation of the gripping device 50 shown in Figure 4, the rotation axis X direction of the gripper 80 (gripping part 81) corresponds to the front-rear direction, and the opening and closing direction (gripping direction) of the gripping part 81 corresponds to the left-right direction.

[0026] The opening / closing mechanism 93 comprises a pair of link members 94, a sliding member 95 linked to the pair of link members 94, and a gripper cylinder 99 that slides the sliding member 95 back and forth. One end of each link member 94 is pivotally connected to the middle part of the gripping claw 81 via a connecting pin 96. The other ends of the pair of link members 94 are also pivotally connected to the tip of the sliding member 95 via a connecting pin 97, with the other ends of each link member 94 overlapping vertically. The sliding member 95 is inserted into the hollow part of the inner cylindrical portion 88 and is mounted so as to be slidable (reciprocal) along the inner circumferential surface of the inner cylindrical portion 88. A slider 98 made of synthetic resin is attached between the outer circumferential surface of the sliding member 95 and the inner circumferential surface of the inner cylindrical portion 88 to guide the sliding (reciprocating) movement of the sliding member 95. The rod-side end of the gripper cylinder 99 is connected to the base end of the sliding member 95. The bottom end of the gripper cylinder 99 is connected to the cylinder bracket portion 92 of the gripper housing 86. When the gripper cylinder 99 is extended, the sliding member 95 slides in the extension direction, causing the link members 94 to swing away from each other. As a result, the gripping claws 82 swing in the opening direction around the connecting pin 84 as a pivot (the gripping claws 82 operate in the opening direction), releasing the grip on the object. On the other hand, when the gripper cylinder 99 is retracted, the sliding member 95 slides in the retraction direction, causing the link members 94 to swing towards each other. As a result, the gripping claws 82 swing in the closing direction around the connecting pin 84 as a pivot (the gripping claws 82 operate in the closing direction), gripping the object. The opening and closing mechanism 93 is configured symmetrically, so the pair of gripping claws 82 open and close symmetrically.

[0027] On the side of the turntable 12 in the vehicle body 2, there is an operator's seat 30 for operating each work device (turntable 12, boom 13, auger device 20, gripping device 50). In front of this operator's seat 30, there is an operating device 31 that can be operated by the operator while seated. As shown in Figure 9, the operating device 31 includes a boom rotation and luffing lever 32a for rotating and luffing the boom 13, a boom extension and bending lever 32b for extending and retracting the boom 13 and bending the arm 51, an auger operating lever 32c for rotating the auger screw 25, a gripper vertical swing lever 32d for vertical swinging the gripper 81, a gripper horizontal swing lever 32e for horizontal swinging the gripper 81, a gripper rotation lever 32f for rotating the gripper 81, and a gripper opening and closing lever 32g for opening and closing the gripper 81. Each of the operating levers 32a to 32g is equipped with an operation detector that detects the operating state (direction and amount of operation) of each operating lever 32a to 32g, and an operation signal corresponding to the operating state of each operating lever 32a to 32g is output to the controller 100, which will be described later.

[0028] Here, the operating mechanisms of the turntable 12, boom 13, auger device 20, gripping device 50, etc., as shown in Figure 9, are configured with a controller 100 that receives operating signals from the operating device 31 and controls the turntable motor 14, telescopic cylinder 15, luffing cylinder 16, auger motor 22, arm cylinder 55, vertical swivel cylinder 62, horizontal swivel cylinder 71, gripper motor 79, and gripper cylinder 99 (hereinafter collectively referred to as "hydraulic actuators"), and a hydraulic unit 110 that supplies hydraulic fluid (pressurized oil) to drive these hydraulic actuators.

[0029] The operation signal output by the operation of the operating device 31 is input to the controller 100. The controller 100 outputs a command signal corresponding to the operation signal to the hydraulic unit 110 (control valve 113).

[0030] The hydraulic unit 110 comprises a hydraulic pump 111 that discharges hydraulic fluid stored in a hydraulic tank 112, and control valves 113 that control the direction and amount of hydraulic fluid supplied from the hydraulic pump 111 to each hydraulic actuator. The hydraulic pump 111 is driven by power taken from the vehicle's engine via a PTO mechanism (not shown). The control valves 113 include an electromagnetic proportional control valve V1 corresponding to the swing motor 14, an electromagnetic proportional control valve V2 corresponding to the telescopic cylinder 15, an electromagnetic proportional control valve V3 corresponding to the luffing cylinder 16, an electromagnetic proportional control valve V4 corresponding to the auger motor 22, an electromagnetic proportional control valve V5 corresponding to the arm cylinder 55, an electromagnetic proportional control valve V6 corresponding to the vertical swivel cylinder 62, an electromagnetic proportional control valve V7 corresponding to the horizontal swivel cylinder 71, an electromagnetic proportional control valve V8 corresponding to the gripper motor 79, and an electromagnetic proportional control valve V9 corresponding to the gripper cylinder 99. Based on command signals from the controller 100, the control valve 113 electromagnetically drives the spools of each electromagnetic proportional control valve V1 to V9 to control the supply direction and amount of hydraulic fluid supplied from the hydraulic pump 111 to each hydraulic actuator, thereby controlling the operating direction and operating speed of each hydraulic actuator (controlling the operating direction and operating speed of the turntable 12, boom 13, auger device 20, and gripping device 50).

[0031] Next, the hydraulic circuit of the gripping device 50 of this embodiment will be described. Figure 10 is a diagram showing the hydraulic circuit of the gripping device 50 of this embodiment.

[0032] As shown in Figure 10, the hydraulic circuit of the gripping device 50 is provided with an electromagnetic proportional control valve V5 that controls the supply and discharge of hydraulic fluid to the arm cylinder 55, an electromagnetic proportional control valve V6 that controls the supply and discharge of hydraulic fluid to the vertical swing cylinder 62, an electromagnetic proportional control valve V7 that controls the supply and discharge of hydraulic fluid to the horizontal swing cylinder 71, an electromagnetic proportional control valve V8 that controls the supply and discharge of hydraulic fluid to the gripper motor 79, and an electromagnetic proportional control valve V9 that controls the supply and discharge of hydraulic fluid to the gripper cylinder 99. Each of the electromagnetic proportional control valves V5 to V9 is composed of a neutral-return type 3-position electromagnetic proportional control valve. Each of the electromagnetic proportional control valves V5 to V9 is connected to the hydraulic pump 111 via an oil passage L1 and to the hydraulic tank 112 via an oil passage L2. In addition, an oil passage L3 that connects oil passages L1 and L2 is provided with a pressure compensation valve 120 that is connected in parallel with the five electromagnetic proportional control valves V5 to V9. Furthermore, pressure reducing valves 121 to 125 are provided in oil passages L4 to L8 that branch off from oil passage L1 to reduce the pressure of the hydraulic fluid discharged from the hydraulic pump 111.

[0033] A double-holding valve 131 is connected to the two oil passages L11 and L12 that connect the arm cylinder 55 and the electromagnetic proportional control valve V5. A double-holding valve 132 is connected to the two oil passages L13 and L14 that connect the vertical swivel cylinder 62 and the electromagnetic proportional control valve V6. A double-holding valve 133 is connected to the two oil passages L15 and L16 that connect the horizontal swivel cylinder 71 and the electromagnetic proportional control valve V7. Furthermore, two oil passages L17 connect the gripper motor 79 and the electromagnetic proportional control valve V8. A double holding valve 134 is connected to L18. Each double holding valve 131-134 is a valve that incorporates two holding valves as one unit. Even if the oil passages connecting the hydraulic actuators 55, 62, 71, 79 and the electromagnetic proportional control valves V5-V8 are damaged and hydraulic fluid leaks out rapidly from them, the double holding valves restrict the flow of hydraulic fluid from the hydraulic actuators 55, 62, 71, 79 to the electromagnetic proportional control valves V5-V8, thereby preventing the hydraulic actuators 55, 62, 71, 79 from suddenly operating.

[0034] The electromagnetic proportional control valve V9 is a neutral-return type 3-position electromagnetic proportional control valve that displaces the valve spool in a direction and amount of movement according to a command signal from the controller 100, thereby controlling the flow of hydraulic fluid between the four ports (port P, port T, port A, port B). This electromagnetic proportional control valve V9 can be switched between a neutral position a, which stops the operation of the gripper cylinder 99; a right position b, which contracts the gripper cylinder 99; and a left position c, which extends the gripper cylinder 99. In addition, pilot check valves 135a and 135b are connected to the oil passages L19 and L20 that connect ports A and B of this electromagnetic proportional control valve V9 to the gripper cylinder 99. The pilot check valves 135a and 135b constitute a double pilot check valve 135 that opens its own oil passage upon receiving pilot pressure from the other oil passage. Furthermore, a pilot check valve 136 is provided as a double safety device between the electromagnetic proportional control valve V9 and the double pilot check valve 135 in the oil passages L19 and L20. In addition, a gripper cylinder pressure detector 141, described later, is provided between the pilot check valve 135a in the oil passage L19 and the rod-side oil chamber of the gripper cylinder 99 to detect the pressure in the rod-side oil chamber (the pressure of the hydraulic fluid supplied to the rod-side oil chamber).

[0035] When the spool of the electromagnetic proportional control valve V9 is in the neutral position a, the supply of hydraulic fluid from the hydraulic pump 111 to the gripper cylinder 99 is stopped by blocking port P from ports A and B, and the residual pressure is released by connecting port T to ports A and B. At this time, each pilot check valve 135a and 135b closes its own oil passage without receiving pilot pressure from the other oil passage, thereby preventing hydraulic fluid from leaking out from the gripper cylinder 99 to the hydraulic tank 112. As a result, even if the spool of the electromagnetic proportional control valve V9 is returned to the neutral position a after the object has been gripped by the gripping section 81 (even if the gripping section opening / closing operation lever 32g is returned to the neutral position), the pressure in the rod-side oil chamber of the gripper cylinder 99 is maintained, and the object does not fall.

[0036] When the spool of the electromagnetic proportional control valve V9 is switched to the right position b, port P and port A are connected, and port T and port B are connected, so that hydraulic fluid from the hydraulic pump 111 is supplied to the rod-side oil chamber of the gripper cylinder 99, causing the gripper cylinder 35 to contract (therefore, the gripping claws 82 move in the closing direction). At this time, the double pilot check valve 135 allows the flow of hydraulic fluid from port P toward the rod-side oil chamber of the gripper cylinder 99, and also allows the flow of hydraulic fluid from the bottom-side oil chamber of the gripper cylinder 99 toward port T.

[0037] When the spool of the electromagnetic proportional control valve V9 is switched to the left position c, port P and port B are connected, and port T and port A are connected, so that hydraulic fluid from the hydraulic pump 111 is supplied to the bottom oil chamber of the gripper cylinder 99, causing the gripper cylinder 99 to extend (therefore, the gripping claws 82 move in the opening direction). At this time, the double pilot check valve 135 allows the flow of hydraulic fluid from port P toward the bottom oil chamber of the gripper cylinder 99, and also allows the flow of hydraulic fluid from the rod-side oil chamber of the gripper cylinder 99 toward port T.

[0038] Next, the safety device provided in the gripping-type hole-digging and pole-erecting vehicle 1 of this embodiment will be described. As shown in Figure 9, the safety device of this embodiment mainly consists of an electromagnetic proportional control valve V9, a gripper cylinder pressure detector 141, and a controller 100.

[0039] The gripper cylinder pressure detector 141 is installed in the oil passage connecting the electromagnetic proportional control valve V9 and the rod-side oil chamber of the gripper cylinder 99, and detects the pressure of the hydraulic fluid supplied to the rod-side oil chamber of the gripper cylinder 99 (pressure in the rod-side oil chamber). This gripper cylinder pressure detector 141 detects the pressure in the rod-side oil chamber of the gripper cylinder 99 and outputs a voltage signal (detection signal) corresponding to the detected pressure to the controller 100. In the following description, the pressure detected by this gripper cylinder pressure detector 141 will be referred to as "detected pressure Pr". Here, the detected pressure Pr detected by this gripper cylinder pressure detector 141 is proportional to the gripping force of the gripping part 81 (the force with which the gripping part 81 grips the object). Therefore, as will be described in detail later, the gripping determination unit 103 of the controller 100 determines whether or not the gripping part 81 is gripping the object based on this detected pressure Pr.

[0040] The maximum pressure (upper limit) of the rod-side oil chamber of the gripper cylinder 99 is the relief pressure Pmax (for example, 170 kg / cm2) specified by a relief valve (not shown). In other words, even after the retraction operation of the gripper cylinder 99 has almost stopped by gripping an object (after the closing operation of the gripping claws 82 has stopped), if the gripping part opening / closing operation lever 32g is continued to be operated forward (in the gripping direction), the pressure in the rod-side oil chamber of the gripper cylinder 99 will rise due to the hydraulic fluid supplied from the electromagnetic proportional control valve V9, but the maximum value (upper limit) of that pressure will be the relief pressure Pmax. Therefore, the maximum gripping force exerted by the gripping part 81 will be the gripping force corresponding to this relief pressure Pmax. Here, when the operator grips an object with the gripping section 81, it is difficult to recognize the timing of the object being gripped. Therefore, even after the closing movement of the gripping claws 82 stops, the operator continues to operate the gripping section opening / closing lever 32g forward with some margin. For this reason, in normal operation, the pressure in the rod-side oil chamber of the gripper cylinder 99 when gripping an object is at its maximum pressure (relief pressure Pmax). This relief pressure Pmax is set appropriately considering the strength of the object (object to be gripped) and the pressure resistance of the gripper cylinder 99.

[0041] The controller 100 includes an operation control unit 101, an operation determination unit 102, a grip determination unit 103, and a gripping force control unit 104.

[0042] The operation control unit 101 controls the operation of each working device (boom 13, auger device 20, gripping device 50, etc.) by electromagnetically driving the control valve 113 (electromagnetic proportional control valves V1 to V9) based on the operation signals from each operation lever 32a to 32g of the operating device 31 to operate each hydraulic actuator. Specifically, when the boom slewing / luffing operation lever 32a is tilted forward (in the forward, backward, left, and right directions relative to the operator operating it; the same applies below), the luffing cylinder 16 is retracted to lower the boom 13, and when the boom slewing / luffing operation lever 32a is tilted backward, the luffing cylinder 16 is extended to raise and lower the boom 13. Also, when the boom extension / bending operation lever 32b is tilted forward, the extension cylinder 15 is extended to extend the boom 13, and when the boom extension / bending operation lever 32b is tilted backward, the extension cylinder 15 is retracted to retract the boom 13. Furthermore, when the boom slewing / luffing lever 32a is tilted to the left, the slewing motor 14 is operated in the forward direction to slewing the boom 13 counterclockwise, and when the boom slewing / luffing lever 32a is tilted to the right, the slewing motor 14 is operated in the reverse direction to slewing the boom 13 clockwise. Also, when the auger operating lever 32c is tilted forward, the auger motor 22 is operated in the reverse direction to rotate the auger screw 25 in the reverse direction, and when the auger operating lever 32c is tilted backward, the auger motor 22 is operated in the forward direction to rotate the auger screw 25 in the forward direction. Furthermore, when the boom extension / bending operation lever 32b is tilted to the left, the arm 51 is bent downward relative to the tip of the boom 13, and when the boom extension / bending operation lever 32b is tilted to the right, the arm 51 is bent upward relative to the tip of the boom 13. Also, when the gripping part vertical swing operation lever 32d is tilted forward, the vertical swing cylinder 62 is extended to swing the gripping part 81 downward (vertical swing), and when the gripping part vertical swing operation lever 32d is tilted backward, the vertical swing cylinder 62 is retracted to swing the gripping part 81 upward (vertical swing). Furthermore, when the gripping unit lateral swing operation lever 32e is tilted to the left, the lateral swing cylinder 71 is extended to swing the gripping unit 81 to the left (lateral swing motion), and when the gripping unit lateral swing operation lever 32e is tilted to the right, the lateral swing cylinder 71 is retracted to swing the gripping unit 81 to the right (lateral swing motion). Also, when the gripping unit rotation operation lever 32f is tilted forward, the gripper motor 79 is rotated forward to rotate the gripping unit 81 clockwise, and when the gripping unit rotation operation lever 32f is tilted backward, the gripper motor 79 is rotated backward to rotate the gripping unit 81 counterclockwise. Furthermore, when the gripping section opening / closing lever 32g is tilted forward, the gripper cylinder 99 is retracted to operate the gripping section 81 in the closing direction (the direction in which the object is gripped: also referred to as the "gripping direction"), and when the gripping section opening / closing lever 32g is tilted backward, the gripper cylinder 99 is extended to operate the gripping section 81 in the opening direction (the direction in which the object is released from being gripped: also referred to as the "grip release direction").

[0043] The operation determination unit 102 determines, based on operation information from the operation detector provided on the gripping section opening / closing operation lever 32g, whether or not the gripping section opening / closing operation lever 32g is being operated, that is, whether or not an operation is being performed to retract the gripper cylinder 99 and operate the gripping section 81 in the closing direction (gripping direction), or whether or not an operation is being performed to extend the gripper cylinder 99 and operate the gripping section 81 in the opening direction (gripping release direction).

[0044] The gripping determination unit 103 determines that the gripping unit 81 is gripping the object (the gripping unit 81 is in a gripping state) if the detected pressure Pr detected by the gripper cylinder pressure detector 141 is equal to or greater than a predetermined first set pressure P1. In this embodiment, the first set pressure (hydraulic pressure that generates enough gripping force to grip the object) P1 is, for example, 150 kg / cm². 2 While a specific value is set, this is not the only option, and it can be set appropriately depending on the strength of the object (the object being grasped), etc.

[0045] When the gripping part 81 is gripping an object, if the gripping force of the gripping part 81 falls below a predetermined gripping force (a gripping force corresponding to the second set pressure P2 described later), the gripping force control unit 104 automatically pressurizes the rod-side oil chamber of the gripper cylinder 99 to increase the gripping force of the gripping part 81, regardless of the operation of the gripping part opening / closing lever 32g. Specifically, when the gripping determination unit 103 determines that an object is being gripped by the gripping unit 81, and the operation determination unit 102 determines that the gripping unit opening / closing operation lever 32g is not being operated, if the detected pressure Pr detected by the gripper cylinder pressure detector 141 is less than or equal to the second set pressure P2, the gripping force control unit 104, as an automatic pressurizing control, switches the spool of the electromagnetic proportional control valve V9 from the neutral position a to the right position b, and supplies hydraulic fluid to the rod-side oil chamber of the gripper cylinder 99, thereby pressurizing the rod-side oil chamber of the gripper cylinder 99 until the detected pressure Pr reaches the third set pressure P3. In this embodiment, the second set pressure P2 is, for example, 160 [kg / cm²]. 2 The third set pressure P3 is set to, for example, 165 [kg / cm2]. When the detected pressure Pr of the gripper cylinder pressure detector 141 reaches the third set pressure P3, the gripping force control unit 104 switches the spool of the electromagnetic proportional control valve V9 from the right position b to the neutral position a, thereby cutting off the supply of hydraulic fluid to the rod-side oil chamber of the gripper cylinder 99 (stopping automatic pressurization control).

[0046] Furthermore, when the gripping section 81 is gripping an object (when the detected pressure Pr exceeds the second set pressure P2), if the gripping section opening / closing operation lever 32g is operated backward (in the gripping release direction), even if the detected pressure Pr falls below the second set pressure P2 as a result of that operation, the control to automatically pressurize the rod-side oil chamber of the gripper cylinder 99 is not performed, and the gripping claws 82 can be operated in the opening direction in response to the backward (gripping release direction) operation of the gripping section opening / closing operation lever 32g. In other words, in this embodiment, the control to automatically pressurize the rod-side oil chamber of the gripper cylinder 99 is executed when the detected pressure Pr falls below the second set pressure P2 while the gripping section opening / closing lever 32g is not being operated backward (in the gripping release direction). This control is not executed when the detected pressure Pr falls below the second set pressure P2 as a result of operating the gripping section opening / closing lever 32g backward (in the gripping release direction), thus preventing the rod-side oil chamber of the gripper cylinder 99 from being pressurized against the operator's intention (intention to release the grip of the object). As a modification of this embodiment, a dedicated release switch may be provided on the operating device 31, and the automatic pressurization control may be released only when this release switch is operated, so that even if the detected pressure Pr falls below the second set pressure P2 due to the gripping section opening / closing lever 32g being operated backward (in the gripping release direction), the control to automatically pressurize the rod-side oil chamber of the gripper cylinder 99 is not performed.

[0047] Next, we will explain the operation of the safety device of this embodiment, specifically the case where a hydraulic leak occurs while the gripping part 81 is gripping the utility pole D. Figure 11 shows the change in detected pressure Pr when a hydraulic leak occurs while the utility pole D is being gripped. In the graph of Figure 11, the vertical axis represents the detected pressure Pr, and the horizontal axis represents time (time axis).

[0048] First, at time t1, the gripping part 81 is gripping the utility pole D, and the gripping part opening / closing operation lever 32g is in the neutral position (non-operated state). At this time, the detected pressure Pr of the gripper cylinder pressure detector 141 (pressure in the rod-side oil chamber of the gripper cylinder 99) is held at the relief pressure Pmax.

[0049] At time t2, a hydraulic leak occurs in the hydraulic circuit of the gripping device 50, causing the detected pressure Pr of the gripper cylinder pressure detector 141 to gradually decrease.

[0050] At time t3, the detected pressure Pr of the gripper cylinder pressure detector 141 decreases to the second set pressure P2. As a result, the gripping force control unit 104 of the controller 100 determines that the detected pressure Pr has decreased to the second set pressure P2, and switches the spool of the electromagnetic proportional control valve V9 from neutral position a to right position b, thereby supplying hydraulic fluid to the rod-side oil chamber of the gripper cylinder 99 and pressurizing the rod-side oil chamber of the gripper cylinder 99 (starting automatic pressurization control).

[0051] At time t4, the detected pressure Pr of the gripper cylinder pressure detector 141 rises to the third set pressure P3. As a result, the gripping force control unit 104 of the controller 100 determines that the detected pressure Pr of the gripper cylinder pressure detector 141 has risen to the third set pressure P3, returns the spool of the electromagnetic proportional control valve V9 to the neutral position a, and stops the supply of hydraulic fluid to the rod-side oil chamber of the gripper cylinder 99 (terminating automatic pressurization control). In this way, the pressure in the rod-side oil chamber of the gripper cylinder 99 rises to the third set pressure P3, allowing the object to be gripped with a gripping force corresponding to this pressure. Therefore, even if a hydraulic leak occurs, the pressure in the rod-side oil chamber of the gripper cylinder 99 is prevented from falling to the second set pressure P2 or below, thereby preventing the utility pole D gripped by the gripping part 81 from falling.

[0052] In this embodiment, when the gripping part opening / closing lever 32g is operated forward (in the gripping direction), the detected pressure Pr when the object is first gripped does not exceed the second set pressure P2, and the detection Even if the forward (gripping direction) operation of the gripping section opening / closing lever 32g is released before the output pressure Pr reaches the second set pressure P2 (i.e., the gripping section opening / closing lever 32g is returned to the neutral position), automatic pressurization control is performed to supply hydraulic fluid to the rod-side oil chamber of the gripper cylinder 99 and pressurize the rod-side oil chamber of the gripper cylinder 99 until the detected pressure Pr reaches the third set pressure P3. Therefore, in this embodiment, when the gripping determination unit 103 determines that an object has been gripped, regardless of the operation of the gripping section opening / closing lever 32g, the pressure in the rod-side oil chamber of the gripper cylinder 99 is always maintained at or above the second set pressure P2 under automatic pressurization control by the gripping force control unit 104.

[0053] As described above, according to the safety device of this embodiment, even if a hydraulic leak or the like occurs and the pressure in the rod-side oil chamber of the gripper cylinder 99 decreases while the gripping part 81 is gripping an object, when the detected pressure Pr drops to the second set pressure P2, the device automatically supplies hydraulic fluid to the rod-side oil chamber of the gripper cylinder 99 to pressurize it. This ensures that the necessary gripping force to grip the object is reliably maintained, preventing the object from falling from the gripping part 81 due to insufficient gripping force, thereby improving safety. Furthermore, in the safety device of this embodiment, even if the forward (gripping direction) operation of the gripping part opening / closing lever 32g is released immediately after gripping an object with the gripping part 81 (when the detected pressure Pr at the time of initial gripping becomes less than or equal to the second set pressure P2), the control is performed to automatically pressurize by supplying hydraulic fluid to the rod-side oil chamber of the gripper cylinder 99. This makes it possible to generate sufficient gripping force without requiring any additional operation of the gripping part opening / closing lever 32g, thus achieving both convenience of operation and safety.

[0054] Furthermore, in the safety device according to this embodiment, when the gripping portion 81 is gripping an object, if the detected pressure Pr drops to the second set pressure P2, hydraulic fluid is supplied to the rod-side oil chamber of the gripper cylinder 99 to automatically pressurize it until the detected pressure Pr reaches the third set pressure P3. This prevents the occurrence of a phenomenon (chattering phenomenon) in which pressurization control is frequently executed and stopped in the region near the second set pressure P2, and makes it possible to always generate sufficient gripping force.

[0055] It should be noted that the present invention is not limited to the embodiments described above, and can be appropriately improved without departing from the spirit of the invention.

[0056] In the above embodiment, the gripping claws 82 moved in the closing direction (the direction in which the utility pole D is gripped) when the gripper cylinder 99 retracted. However, the configuration is not limited to this, and the gripping claws 82 may be configured to move in the closing direction (the direction in which the utility pole D is gripped) when the gripper cylinder 99 extends. In that case, the pressure in the bottom oil chamber of the gripper cylinder 99 (the pressure of the hydraulic fluid supplied to the bottom oil chamber) will be proportional to the gripping force of the gripping part 81, and the gripper cylinder pressure detector 141 will detect the pressure in the bottom oil chamber.

[0057] In the above embodiment, the gripping portion 81 was configured to have a pair of openable and closable gripping claws 82, but the configuration is not limited to this, and the gripping portion 81 may be configured to have an openable and closable movable claw and a fixed fixed claw.

[0058] In the above embodiment, when the detected pressure Pr falls below the second set pressure P2, hydraulic fluid is supplied to the rod-side oil chamber of the gripper cylinder 99 until the detected pressure Pr reaches the third set pressure P3. However, the configuration is not limited to this, and when the detected pressure Pr falls below the second set pressure P2, hydraulic fluid may be supplied to the rod-side oil chamber of the gripper cylinder 99 until the detected pressure Pr reaches the relief pressure Pmax.

[0059] In the above embodiment, the operating device 31 is provided in the operating seat 30 on the vehicle body 2, but the configuration is not limited to this, and for example, the operating device 31 may be configured as a wired or wireless remote control operating device (portable operating device).

[0060] Furthermore, while the above embodiment illustrates a PTO-driven hole-digging and pole-erecting vehicle that uses a PTO (power take-off) mechanism to extract engine power and drive a hydraulic pump, the configuration is not limited to this. An electric-driven (battery-driven) hole-digging and pole-erecting vehicle or a hybrid vehicle equipped with both, which selectively switches the power source, may also be used. [Explanation of symbols]

[0061] 1 Gripping type hole digging pole erecting vehicle 2 car bodies 13 Boom 31 Operating device 32g Grip opening / closing operation lever (grip operation device) 50 Gripping device 51. Arm (support mechanism) 60. First joint member (support mechanism) 70. Second joint member (support mechanism) 80 Grippa 81 Gripping part 82 Gripping claw 99. Gripper Cylinder (Gripping Cylinder) 100 controllers 101 Operation Control Unit (Pressurized Oil Supply Control Unit) 102 Operation judgment section 103 Grip determination section 104 Gripping force control section (pressure oil supply control section) 141 Gripper cylinder pressure detector (pressure detection unit) V9 Electromagnetic proportional control valve (pressure oil supply control unit)

Claims

1. a boom provided on the vehicle body so as to be at least capable of being raised and lowered; a gripping portion having openable and closable gripping claws that can grip an object in a closed state; a support mechanism provided between the tip of the boom and the gripping part, which changes the attitude of the gripping part with respect to the tip of the boom; a gripping cylinder that opens and closes the gripping claws; a gripping operation device for operating the gripping cylinder; a pressure oil supply control unit that controls supply and discharge of pressure oil to and from a rod-side oil chamber and a bottom-side oil chamber of the gripping cylinder in response to operation of the gripping operation device; a pressure detection unit that detects the pressure of a closing-side oil chamber, which is an oil chamber to which hydraulic oil is supplied when the gripping jaws are operated in a closing direction, out of the rod-side oil chamber and the bottom-side oil chamber; a grip determination unit that determines that the grip unit is gripping an object when the pressure detected by the pressure detection unit is equal to or greater than a first set value, A safety device for a gripping-type hole-digging and pole-setting vehicle, characterized in that the pressurized oil supply control unit executes control to supply pressurized oil to the closing oil chamber when the gripping determination unit determines that the gripping unit is gripping an object and when the gripping operation device is not being operated and the pressure detected by the pressure detection unit is less than a second set value that is greater than the first set value.

2. The safety device for a gripping-type hole-digging pole construction vehicle as described in claim 1, characterized in that when the gripping determination unit determines that the gripping unit is gripping an object and the gripping operation device is not being operated and the pressure detected by the pressure detection unit is below the second set value, the pressure oil supply control unit executes control to supply pressure oil to the closing oil chamber until the pressure detected by the pressure detection unit reaches a third set value that is greater than the second set value.

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