WO2013042670A1

WO2013042670A1 - Work machine

Info

Publication number: WO2013042670A1
Application number: PCT/JP2012/073863
Authority: WO
Inventors: 竜二白谷; 山本　正明
Original assignee: 住友建機株式会社
Priority date: 2011-09-22
Filing date: 2012-09-18
Publication date: 2013-03-28
Also published as: JPWO2013042670A1; JP6054297B2

Abstract

　A grapple (6) is attached to the distal end of an arm (5). The grapple (6) is driven by a bucket cylinder (9), and the arm (5) is driven by an arm cylinder (8). A switching mechanism (80) switches at least one of the bucket cylinder (9) and the arm cylinder (8) between a controlled state actuated by hydraulic pressure and a non-controlled state actuated by external force. By setting at least one of the bucket cylinder (9) and the arm cylinder (8) to the non-controlled state, the grapple (6) can be set so as to hang vertically downward from the distal end of the arm (5).

Description

Work machine

The present invention relates to a work machine that operates by operating an attachment attached to the tip of an arm.

Work machines with grapples are used to pick up and move objects to be transported, such as waste materials and wood. The grapple is an attachment that is driven by a hydraulic cylinder to grasp a material to be transported such as waste material or wood. Grapples are often attached to the tip of an excavator arm instead of a bucket. The machine to which the grapple is attached is not limited to the shovel, and may be a work machine having an arm that can move and turn like the shovel. A work machine having a grapple attached to the tip of the arm is hereinafter referred to as a “grapple specification machine”.

グ A grapple-type machine sometimes picks up and moves objects in large underground pits. The grapple attached to the tip of the arm is put in the underground pit to grab the object to be transported, and the hydraulic cylinder is operated to drive the boom, arm and grapple, thereby moving the object to be grabbed by the grapple.

In such a work, for example, when driving the boom and arm by gripping the object to be transported near the inner wall of the underground pit, when lifting the object from the underground pit, raising the boom and opening the arm The frequency of performing is increased. In this case, regardless of whether the boom is raised or the boom is opened, the amount of the grapple coming out from the tip of the arm becomes large. Therefore, depending on the angle of the grapple attached to the tip of the arm, the grapple may come into contact with the inner wall of the underground pit. For example, the driver of the grapple specification machine is not skilled in the work, and when driving the boom and arm, the grapple may be mistakenly brought into contact with the inner wall of the underground pit.

In order to prevent the grapple from coming into contact with the inner wall of the underground pit, it is necessary to adjust the position of the grapple at the tip of the arm by driving the grapple after gripping the object to be transported. Usually, since the grapple is moved out of the underground pit by lifting the grapple that has driven the boom and the arm, the grapple is preferably directed vertically downward from the tip of the arm. However, since the grapple arranged in the underground pit cannot be accurately observed, the angle of the grapple cannot often be adjusted when the boom and the arm are driven.

Here, a construction machine in which a grapple is attached to the tip of an arm in a suspended manner has been proposed (see, for example, Patent Document 1). According to this construction machine, the grapple is attached while being suspended from the tip of the arm, so that the grapple is always directed vertically downward from the tip of the arm.

Japanese Patent Laid-Open No. 08-40681

Since the grapple of a construction machine disclosed in Patent Document 1 is always directed vertically downward, when the object to be conveyed is gripped by the grapple, the grapple can only grasp the object to be conveyed from above. For example, in an operation process including a sorting operation, it is often necessary to grip the grapple at an appropriate angle, and it is not preferable to use a hanging grapple in such an application. In addition, the grapple needs to be directed to an appropriate angle when the objects to be transported are stacked upward.

Therefore, it is desirable to develop a work machine that can efficiently grab and release the object to be transported by changing the angle of the grapple and set the grapple to be suspended from the tip of the arm when the grapple moves. It is rare.

According to one embodiment of the present invention, an arm having a work attachment attached to a tip thereof, a first hydraulic cylinder that drives the work attachment, a second hydraulic cylinder that drives the arm, and the first A work machine is provided that includes a switching mechanism that switches between at least one of the hydraulic cylinder and the second hydraulic cylinder between a control state that operates by hydraulic pressure and a non-control state that operates by external force.
Other objects, features and advantages of the present invention will become more apparent upon reading the following detailed description of the invention with reference to the accompanying drawings.

According to the above-described invention, when the work attachment is moved, the work attachment can be set in a vertically suspended state.

It is a side view of a grapple specification machine operating at a work site. It is a block diagram which shows the structure of the hydraulic system of the grapple specification machine by which the switching mechanism was provided in the hydraulic circuit of the bucket cylinder. It is a figure which shows an example of the hydraulic circuit which comprises a switching mechanism. It is a figure which shows the other example of the hydraulic circuit which comprises the switching mechanism. It is a block diagram which shows the structure of the hydraulic system of the grapple specification machine by which the switching mechanism was provided also in the hydraulic circuit of the arm cylinder.

Next, embodiments will be described with reference to the drawings.

Fig. 1 is a side view of a grapple specification machine operating at the work site. The grapple specification machine 100 is a work machine in which a grapple is attached to the tip of an excavator arm as a work attachment. The work machine is not limited to using the main body of the shovel, and any work machine may be used as long as it has a drivable arm.

At the work site shown in FIG. 1, an operation of picking up and transporting the waste material 300 cut by the large cutting machine 200 from the take-out port of the storage unit 400 is performed.

The excavator constituting the main part of the grapple specification machine 100 has a lower traveling body 1 as a drive unit for traveling. An upper swing body 3 is mounted on the lower traveling body 1 via a swing mechanism 2. A boom 4 is attached to the upper swing body 3. An arm 5 is attached to the tip of the boom 4, and a grapple 6 is attached to the tip of the arm 5. The boom 4 and the arm 5 are hydraulically driven by the boom cylinder 7 and the arm cylinder 8, respectively.

The grapple 6 includes two sets (a total of four) of gripping claws 6A provided by shifting the gripping direction by 90 degrees by taking two sets facing each other so that the object can be gripped. The waste material 300 is sandwiched and held between the gripping claws 6A. The grapple 6 is rotatably attached to the tip of the arm 5 and is connected to the bucket cylinder 9 via a link 9A. The angle of the grapple 6 with respect to the arm 5 can be changed by supplying hydraulic pressure to the bucket cylinder 9 and driving the bucket piston 9a. A hydraulic cylinder that drives the grapple 6 is referred to as a bucket cylinder 9. When not using the grapple specification, a bucket is attached to the tip of the arm 5 as a work attachment. For this reason, the bucket cylinder 9 does not particularly mean only a hydraulic cylinder for driving the bucket. In the case of the grapple specification machine 100, the grapple cylinder 9 may be referred to instead of the bucket cylinder 9. In the present specification, a hydraulic cylinder for driving the grapple 6 is referred to as a bucket cylinder 9.

The upper swing body 3 is provided with a cabin 10 as a driver's cab in which a driver's seat and a control device are arranged. A power source such as an engine, a hydraulic pump, a hydraulic circuit, and the like are mounted on the upper swing body 3 behind the cabin 10.

In this embodiment, after gripping the waste material 300 by operating the grapple 6 attached to the tip of the arm 5 and before moving the grapple 6 by driving the arm 5, the grapple 6 is oriented vertically downward. Set as follows. That is, when lifting the grapple 6 by raising the tip of the arm 6, the grapple 6 does not make an angle to the outside of the tip of the arm 5, so that the grapple 6 is less likely to contact the surrounding wall surface or the like. .

In this embodiment, the grapple 6 is used as a work attachment for grasping the object to be transported. However, the work attachment is not limited to a grapple, and for example, a fork, a lifting magnet, or the like may be used as the work attachment. .

As described above, the angle of the grapple 6 can be changed by the bucket cylinder 9. The operator of the work machine may operate the bucket cylinder 9 to set the grapple 6 in a vertically downward posture. However, the operator may make a mistake in his or her eyes or concentrate on other operations to operate the grapple 6. May be neglected. Thus, in the present embodiment, the bucket cylinder 9 for manipulating the angle of the grapple 6 is set to a non-control state so that the grapple 6 can move freely without being constrained by the bucket cylinder 9. When the restraint by the bucket cylinder 9 is eliminated, the grapple 6 is naturally directed vertically downward without being operated by the operator.

In this embodiment, a switching mechanism is provided in a hydraulic circuit that supplies hydraulic pressure to the bucket cylinder 9 to switch the bucket cylinder 9 between a control state (restraint state) and a non-control state (non-restraint state). Here, the control state is a state where hydraulic pressure is supplied from the control valve 17 to the bucket cylinder 9 and the rod of the bucket cylinder 9 is driven or held. By driving the bucket cylinder 9 in the controlled state, the angle of the grapple 6 can be changed. On the other hand, the non-control state is a state in which the hydraulic circuit is set so that the hydraulic pressure is not supplied from the control valve 17 to the bucket cylinder 9 and the rod (piston 9a) of the bucket cylinder 9 can move freely. Switching from the control state to the non-control state is performed by a switching mechanism provided in a hydraulic circuit between the control valve 17 and the bucket cylinder 9.

Next, the switching mechanism will be described. FIG. 2 is a block diagram showing the configuration of the hydraulic system of the grapple specification machine 100 shown in FIG. In FIG. 2, the mechanical power system is indicated by a double line, the hydraulic line is indicated by a solid line, the electric system is indicated by a thick line, and the control system is indicated by a broken line.

The grapple specification machine 100 includes an engine 11 made of an internal combustion engine. A variable displacement hydraulic pump 28 (hereinafter referred to as a first hydraulic pump 28) and a variable displacement hydraulic pump 14 (hereinafter referred to as a second hydraulic pump 14) are mechanically connected to the engine 11.

The first hydraulic pump 28 is, for example, a variable swash plate hydraulic pump, and the pump output can be changed by changing the angle of the swash plate. In other words, the angle of the swash plate can be adjusted by changing the control current to the first hydraulic pump 28, thereby changing the output of the first hydraulic pump 28. The first hydraulic pump 28 is driven by the output of the engine 11 and discharges high-pressure hydraulic oil.

The second hydraulic pump 14 is, for example, a variable swash plate hydraulic pump, and the pump output can be changed by changing the angle of the swash plate. In other words, the angle of the swash plate can be adjusted by changing the control current to the second hydraulic pump 14, thereby changing the output of the second hydraulic pump 14. The second hydraulic pump 14 is driven by the output of the engine 11 and discharges high-pressure hydraulic oil.

The first hydraulic pump 28 and the second hydraulic pump 14 are connected to various associated actuators via a control valve 17 by a hydraulic circuit. In the example shown in FIG. 2, the various actuators are a traveling right motor 1 A for driving the right wheel of the grapple specification machine 100, a traveling left motor 1 B for driving the left wheel, and a turning motor for driving the turning mechanism 2. 21, a boom cylinder 7 for driving the boom 4 up and down, an arm cylinder 8 for opening and closing the arm 5, and a bucket cylinder 9 for driving the grapple 6.

The control valve 17 includes a plurality of switching valves 171-178. The plurality of switching valves 171 to 178 include a switching valve 171 to 174 provided in the first oil passage 42 connecting the discharge side of the first hydraulic pump 28 and the reservoir tank 40, and the discharge side and reservoir of the second hydraulic pump 14. And a switching valve 175-178 provided in the second oil passage 44 connecting the tanks 40.

The switching valve 171 switches the supply state of hydraulic oil for realizing the traveling operation by the traveling left motor 1B. The switching valve 173 switches the supply state of hydraulic oil for realizing the turning operation by the turning motor 21. The switching valve 173 switches the supply state of hydraulic oil for realizing the boom raising operation (second speed) by the boom cylinder 7. The switching valve 174 switches the supply state of hydraulic oil for realizing the arm opening / closing operation (first speed) by the arm cylinder 8.

The switching valve 175 switches the supply state of hydraulic oil for realizing the traveling operation by the traveling right motor 1A. The switching valve 176 switches the supply state of hydraulic oil for realizing the bucket opening / closing operation by the bucket cylinder 9. The supply state of hydraulic oil for realizing the boom raising / lowering operation (first speed) by the switching valve 177 and the boom cylinder 7 is switched. The switching valve 178 switches the supply state of hydraulic oil for realizing the arm opening / closing operation (second speed) by the arm cylinder 8.

In the first oil passage 42 on the first hydraulic pump 28 side, a negative control throttle 46 (a throttle for negative feedback) is inserted between the downstream side of the switching valve 174 and the reservoir tank 40. The negative control pressure (upstream pressure of the negative control throttle 46) Pn1 is negatively fed back to the regulator 54 via the negative control throttle 46. A variable relief valve 50 that adjusts the relief pressure of the first oil passage 42 is connected to the first oil passage 42. The controller 30 and the regulator 54 control the first hydraulic pump 28 in a manner that reduces the loss of the discharge flow rate of the first hydraulic pump 28 that returns to the reservoir tank 40 based on the negative control pressure Pn1 (so-called negative control control). Do).

Similarly, in the second oil passage 44 of the second hydraulic pump 14, a negative control throttle 48 (a throttle for negative feedback) is inserted between the downstream side of the switching valve 178 and the reservoir tank 40. The negative control pressure (upstream pressure of the negative control throttle 48) Pn2 is negatively fed back to the regulator 56 via the negative control throttle 48. A variable relief valve 52 that adjusts the relief pressure of the second oil passage 44 is connected to the second oil passage 44. The controller 30 and the regulator 56 control the second hydraulic pump 14 in a manner that reduces the loss of the discharge flow rate of the second hydraulic pump 14 that returns to the reservoir tank 40 based on the negative control pressure Pn2 (so-called negative control control is performed). Do). Thus, the first hydraulic pump 28 and the second hydraulic pump 14 are mechanically separated.

Further, a relief valve 60 that restricts the maximum pressure of the hydraulic circuit is connected to the first oil passage 42 and the second oil passage 44. The relief valve 60 operates when the pressure in the hydraulic circuit exceeds a predetermined set pressure, and causes the reservoir tank 62 to communicate with the hydraulic circuit.

Next, the switching mechanism will be described. The switching mechanism 80 is provided in a hydraulic circuit between the control valve 17 and the bucket cylinder 9 in the hydraulic system shown in FIG. As described above, the switching mechanism 80 is a mechanism for switching the bucket cylinder 9 between the control state and the non-control state.

FIG. 3 is a view showing an example of a hydraulic circuit constituting the switching mechanism 80. In the example shown in FIG. 3, the switching mechanism 80 includes a short-circuit on-off valve 82, a tank-side on-off valve 84, and a change-over switch 86 that switches between these on-off valves. The short-circuiting on-off valve 82 and the tank-side on-off valve 84 are on-off valves that are controlled to open and close by hydraulic pressure or electricity, and the control hydraulic pressure is supplied from the changeover switch 86.

The short-circuit opening / closing valve 82 is provided between a hydraulic line 90A that connects the control valve 17 and the rod side of the bucket cylinder 9 and a hydraulic line 90B that connects the control valve 17 and the bottom side of the bucket cylinder 9. When the short-circuiting on-off valve 82 is opened, the hydraulic line 90A and the hydraulic line 90B are connected, and a closed circuit that connects the rod side and the bottom side of the bucket cylinder 9 is formed.

The tank side opening / closing valve 84 is provided between the hydraulic line 90A and the reservoir tank 40. When the tank side opening / closing valve 84 is opened, the hydraulic line 90A and the reservoir tank 40 are connected. Accordingly, the hydraulic oil can flow from the hydraulic line 90A to the reservoir tank 40, and conversely, the hydraulic oil can be supplied from the reservoir tank 40 to the hydraulic line 90A. The position where the tank side opening / closing valve 84 is connected is not limited to the hydraulic line 90A. As long as the above-mentioned closed circuit is formed by opening the short-circuit on-off valve 82, the tank-side on-off valve 84 may be connected anywhere.

Here, the flow of hydraulic oil to the bucket cylinder 9 when the changeover switch 86 is operated to switch the bucket cylinder 9 to the non-control state will be described.

FIG. 3 (a) is a diagram showing the flow of hydraulic oil by arrows when the grapple 6 rotates to the airframe side and hangs vertically downward when switched to the non-controlled state. That is, FIG. 3- (a) shows a state where the grapple 6 is supported by the bucket cylinder 9 at an angle such that the grapple 6 is positioned in front of the vertical direction, and the changeover switch 86 is operated to bring the bucket cylinder 9 into an uncontrolled state. The flow of hydraulic oil when set is shown. In this case, first, the short-circuit on-off valve 82 is opened, so that a closed circuit for connecting the rod side and the bottom side of the bucket cylinder 9 is formed. At this time, an external force in the pulling direction is applied to the rod of the bucket cylinder 9 in an attempt to rotate the grapple 6 so as to return to the airframe side due to gravity. For this reason, as shown by the arrow in FIG. 3A, the hydraulic oil on the rod side of the bucket cylinder 9 flows to the bottom side through the short-circuit on-off valve 82 through the closed circuit.

Here, when the rod extends from the cylinder, the volume change on the rod side of the cylinder is smaller than the volume change on the bottom side. Therefore, it is necessary to add an amount of hydraulic oil corresponding to the difference in volume change to the hydraulic oil flowing out from the rod side. Therefore, in the example shown in FIG. 3, the hydraulic oil can be supplied from the reservoir tank 40 by opening the tank side opening / closing valve 84. Accordingly, the hydraulic oil supplied from the reservoir tank 40 is added to the hydraulic oil that has moved in the direction in which the rod of the bucket cylinder 9 extends and has flowed out from the rod side, and flows into the bottom side of the bucket cylinder 9. That is, an amount of hydraulic oil corresponding to the difference between the volume change amount on the rod side and the volume change amount on the bottom side is sucked from the reservoir tank 40 into the closed circuit. Thereby, the rod (piston 9a) of the bucket cylinder 9 can be moved in the extending direction with almost no resistance by being pulled by the grapple 6.

When the rod (piston 9a) of the bucket cylinder 9 is pulled by the rotational force of the grapple 6 due to its own weight, the bucket cylinder 9 is suspended vertically downward from the position where the grapple 6 is rotatably attached. The force for pulling the rod (piston 9a) is lost. Accordingly, the grapple 6 stops in a state where it is suspended vertically downward. If the bucket cylinder 9 is maintained in an uncontrolled state, the grapple 6 can always be kept suspended vertically even when the arm 5 moves and its angle changes.

In the present embodiment, a throttle 92 is provided in the hydraulic line between the tank side opening / closing valve 84 and the reservoir tank 40. By adjusting the amount of hydraulic oil flowing into the closed circuit from the reservoir tank 40 or the amount of hydraulic oil flowing out into the reservoir tank 40 with the throttle 92, the operation between the rod side and the bottom side of the bucket cylinder 9 is performed. The moving speed of the oil can be adjusted. As a result, the moving speed of the grapple 6 is adjusted. If the grapple 6 moves suddenly when the bucket cylinder 9 is set to the non-control state, an impact may be transmitted to the arm 5 or the grapple 6 may swing like a pendulum. In order to prevent such a phenomenon from occurring, the rotation speed of the grapple 6 is adjusted by the diaphragm 92 so that the grapple 6 rotates slowly.

The position where the throttle 92 is provided is not limited to the hydraulic line between the tank side opening / closing valve 84 and the reservoir tank 40. The rotational speed of the grapple 6 can be adjusted no matter where the diaphragm 92 is arranged in the middle of the closed circuit. Further, by providing the diaphragm 92, the swinging of the grapple 6 when the grapple 6 is in a suspended state can be suppressed.

FIG. 3 (b) shows the state in which the grapple 6 is supported by the bucket cylinder 9 at an angle such that the grapple 6 is positioned on the airframe side from the vertical direction, and the changeover switch 86 is operated to set the bucket cylinder 9 to the non-control state. It shows the flow of hydraulic oil when it is done. In this case, first, the short-circuit on-off valve 82 is opened, so that a closed circuit for connecting the rod side and the bottom side of the bucket cylinder 9 is formed. At this time, an external force in the direction of pushing into the rod (piston 9a) of the bucket cylinder 9 is applied to rotate the grapple 6 so as to return to the front side due to gravity, so that as shown by the arrow in FIG. Through the closed circuit, the hydraulic fluid on the bottom side of the bucket cylinder 9 flows to the rod side through the short-circuit on-off valve 82.

Here, when the rod extends from the cylinder, the volume change on the bottom side of the cylinder is larger than the volume change on the rod side. Therefore, it is necessary to subtract the amount of hydraulic oil corresponding to the difference in volume change from the hydraulic oil flowing out from the bottom side. Therefore, in the example shown in FIG. 3B, the hydraulic oil can be flowed from the closed circuit to the reservoir tank 40 by opening the tank side opening / closing valve 84. Therefore, a part of the hydraulic oil that has moved in the direction in which the rod (piston 9a) of the bucket cylinder 9 is pushed and flows out from the bottom side flows to the reservoir tank 40, and the remaining hydraulic oil flows to the rod side of the bucket cylinder 9. Inflow. That is, an amount of hydraulic oil corresponding to the difference between the volume change amount on the bottom side and the volume change amount on the rod side flows out from the closed circuit to the reservoir tank 40. Thereby, the rod (piston 9a) of the bucket cylinder 9 can be moved in the pushing direction with almost no resistance by being pushed by the grapple 6.

When the rod (piston 9a) of the bucket cylinder 9 is pushed in by the rotational force of the grapple 6 due to its own weight, the bucket cylinder 9 is suspended vertically downward from the position where the grapple 6 is rotatably attached. The force to push in the rod (piston 9a) is lost. Accordingly, the grapple 6 stops in a state where it is suspended vertically downward. If the bucket cylinder 9 is maintained in an uncontrolled state, the grapple 6 can always be kept suspended vertically even when the arm 5 moves and its angle changes.

As described above, by setting the bucket cylinder 9 to the non-control state by the switching mechanism 80 having the configuration shown in FIG. 3, the grapple 6 is maintained in a state of being hung vertically downward by the action of its own weight. In this state, the length of the portion of the grapple 6 that protrudes laterally from the line of the arm 5 descending in the vertical direction is the shortest, and the grapple 6 may contact the side wall or the like while the arm 5 is moving. Is the lowest.

Next, the operation of the work machine using the present invention will be described.

When putting the attachment into the housing part 400 from the outside of the housing part 400, the driver operates the changeover switch 86 to bring the bucket cylinder 9 into a control state in order to bring the grapple 6 close to the object to be gripped with high accuracy. . After that, normally, when the object is gripped by the grapple 6, the object is gripped while being pressed by the grapple 6. For this reason, the driver maintains the bucket cylinder 9 in the control state even when the grapple 6 holds the object. Thus, since the bucket cylinder 9 can be pressed and gripped, a large amount of objects can be gripped in one operation. After gripping by the grapple 6, the driver operates the boom 4 and the turning mechanism 2 to take out the gripped object from the storage unit 400 to the outside of the storage unit 400. At this time, the driver operates the changeover switch 86 to put the bucket cylinder 9 in a non-control state. As a result, the position of the grapple 6 is determined below the arm 5, so that the grapple 6 can be prevented from coming into contact with the side wall or the like of the housing portion 400 even when the arm 5 is moved. The efficiency of taking out from 400 can be improved.

When the object is desired to be released after the object is taken out from the storage unit 400, the driver operates the boom or the like while the bucket cylinder 9 is in an uncontrolled state, and releases the object far away. On the other hand, when it is desired to accurately place the object on the truck bed or the like, the driver operates the changeover switch 86 to bring the bucket cylinder 9 into the control state. Thereby, after making the grapple 6 approach the truck bed, the object can be released from the grapple 6 with high accuracy.

FIG. 4 is a view showing another example of the hydraulic circuit constituting the switching mechanism 80. As shown in FIG. 4, parts that are the same as the parts shown in FIG. 3 are given the same reference numerals, and descriptions thereof will be omitted. In the example shown in FIG. 4, the switching mechanism 80 includes another tank side opening / closing valve 88 instead of the short circuit opening / closing valve 82. The tank-side on-off valve 88 is an on-off valve that is controlled to open and close by hydraulic pressure, and the control hydraulic pressure is supplied from the changeover switch 86.

In the example shown in FIG. 4, the tank side on / off valve 84 is referred to as a first tank side on / off valve 84, and the tank side on / off valve 88 is referred to as a second tank side on / off valve 88. The first tank side opening / closing valve 84 has a function equivalent to that of the tank side opening / closing valve 84 shown in FIG. 3, but the connection position is limited between the hydraulic line 90 A and the reservoir tank 40.

The second tank side opening / closing valve 88 is provided between the hydraulic line 90B and the reservoir tank 40. When the second tank side opening / closing valve 88 is opened, the hydraulic line 90B and the reservoir tank 40 are connected. As a result, the hydraulic oil can flow from the hydraulic line 90B to the reservoir tank 40, and conversely, the hydraulic oil can be supplied from the reservoir tank 40 to the hydraulic line 90B.

FIG. 4- (a) is a diagram showing the flow of hydraulic oil by arrows when the grapple 6 rotates to the body side and hangs vertically downward when switched to the non-controlled state. That is, FIG. 4- (a) shows a state where the grapple 6 is supported by the bucket cylinder 9 at an angle such that the grapple 6 is positioned in front of the vertical direction, and the changeover switch 86 is operated to bring the bucket cylinder 9 into the non-controlled state. The flow of hydraulic oil when set is shown. In this case, both the first tank side opening / closing valve 84 and the second tank side opening / closing valve 88 are opened, and the rod side of the bucket cylinder 9 is connected to the reservoir tank 40 through the hydraulic line 90A and the first tank side opening / closing valve 84. Then, the bottom side of the bucket cylinder 9 is connected to the reservoir tank 40 through the hydraulic line 90B and the second tank side opening / closing valve 88.

At this time, as the grapple 6 tries to rotate so as to return to the machine body due to gravity, an external force in the pulling direction is applied to the rod (piston 9a) of the bucket cylinder 9, so that the arrow shown in FIG. In addition, the hydraulic oil on the rod side of the bucket cylinder 9 flows out to the reservoir tank 40 through the hydraulic line 90 A and the first tank side opening / closing valve 84. On the other hand, hydraulic oil flows from the reservoir tank 40 to the rod side of the bucket cylinder 9 through the second tank side opening / closing valve 88 and the hydraulic line 90B. Therefore, the hydraulic oil that has moved in the direction in which the rod of the bucket cylinder 9 extends and has flowed out from the rod side flows out into the reservoir tank 40, and the hydraulic oil in the reservoir tank 40 flows into the bottom side. Thereby, the rod (piston 9a) of the bucket cylinder 9 can be moved in the extending direction with almost no resistance by being pulled by the grapple 6.

When the rod of the bucket cylinder 9 is pulled by the rotational force of the grapple 6 due to its own weight, and the grapple 6 is suspended vertically downward with respect to the pivotally attached position, the rod of the bucket cylinder 9 is pulled. Power is lost. Accordingly, the grapple 6 stops in a state where it is suspended vertically downward. If the bucket cylinder 9 is maintained in an uncontrolled state, the grapple 6 can always be kept suspended vertically even when the arm 5 moves and its angle changes.

FIG. 4- (b) shows the state in which the grapple 6 is supported by the bucket cylinder 9 at an angle such that the grapple 6 is positioned on the airframe side from the vertical direction, and the changeover switch 86 is operated to set the bucket cylinder 9 to the non-control state. It shows the flow of hydraulic oil when it is done. In this case, both the first tank side opening / closing valve 84 and the second tank side opening / closing valve 88 are opened, and the rod side of the bucket cylinder 9 is connected to the reservoir tank 40 through the hydraulic line 90A and the first tank side opening / closing valve 84. Then, the bottom side of the bucket cylinder 9 is connected to the reservoir tank 40 through the hydraulic line 90B and the second tank side opening / closing valve 88.

At this time, as the grapple 6 tries to rotate so as to return to the airframe side due to gravity, an external force in the direction of pushing into the rod (piston 9a) of the bucket cylinder 9 is applied, so as shown by the arrow in FIG. 4- (b). Furthermore, the hydraulic fluid on the bottom side of the bucket cylinder 9 flows out to the reservoir tank 40 through the hydraulic line 90 B and the second tank side opening / closing valve 88. On the other hand, hydraulic oil flows from the reservoir tank 40 to the rod side of the bucket cylinder 9 through the first tank side opening / closing valve 84 and the hydraulic line 90A. Thereby, the rod of the bucket cylinder 9 can be moved in the extending direction with almost no resistance by being pushed in by the grapple 6.

When the rod of the bucket cylinder 9 is pushed in by the rotational force of the grapple 6 due to its own weight and the grapple 6 is suspended vertically downward with respect to the pivotally attached position, the rod (piston) of the bucket cylinder 9 The force to push 9a) disappears. Accordingly, the grapple 6 stops in a state where it is suspended vertically downward. If the bucket cylinder 9 is maintained in an uncontrolled state, the grapple 6 can always be kept suspended vertically even when the arm 5 moves and its angle changes.

In the example shown in FIG. 4, a throttle 94 is also provided in the hydraulic line between the second tank side opening / closing valve 88 and the reservoir tank 40. The diaphragm 94 has the same action as the diaphragm 92. If either the diaphragm 92 or the diaphragm 94 is provided, the rotation speed of the grapple can be adjusted. Further, the diaphragm 92 and the diaphragm 94 may be omitted.

As described above, by setting the bucket cylinder 9 to the non-control state by the switching mechanism 80 having the configuration shown in FIG. 4, the grapple 6 is maintained in a state suspended vertically below by the action of its own weight. In this state, the length of the portion of the grapple 6 that protrudes laterally from the line of the arm 5 descending in the vertical direction is the shortest, and the grapple 6 may contact the side wall or the like while the arm 5 is moving. Is the lowest.

In the above-described embodiment, the switching mechanism 80 is provided for the hydraulic circuit of the bucket cylinder 9 to bring the bucket cylinder into an uncontrolled state. However, as shown in FIG. It is good also as providing in a circuit, and good also as providing in either one.

When the switching mechanism 80 is provided in the hydraulic circuit of the arm cylinder 8, the arm 5 can be suspended from the tip of the boom 4 vertically by setting the arm cylinder 8 in a non-control state. When the boom 4 is raised and the grapple 6 is lifted together with the arm 5, the grapple 6 can be made difficult to contact by keeping the arm 5 suspended.

Although the present embodiment has been described based on the system configuration diagram of the hydraulic excavator, the present invention is not limited to the hydraulic excavator, and the electric power generated based on the power of the engine is stored in the capacitor, and the stored electric power is also stored. In addition, the present invention can also be applied to a hybrid excavator in which a pump is driven by an electric motor.

In the present specification, the present invention has been described with the embodiment of the hydraulic excavator. However, the present invention is not limited to the above-described embodiment specifically disclosed, and various modifications can be made without departing from the scope of the present invention. Variations and improvements will be made.

This application is based on priority claim Japanese Patent Application No. 2011-208149 filed on Sep. 22, 2011, the entire contents of which are incorporated herein by reference.

The present invention is applicable to a working machine that operates by operating an attachment attached to the tip of an arm.

DESCRIPTION OF SYMBOLS 1 Lower traveling body 2 Turning mechanism 3 Upper turning body 4 Boom 5 Arm 6 Grapples 6A Grip claw 7 Boom cylinder 8 Arm cylinder 9 Bucket cylinder 9a Piston 9A Link 10 Cabin 11

Engine

14, 28 Variable capacity hydraulic pump 17 Control valve 40 Reservoir Tank 80 switching mechanism 82 Short-circuit on-off

valve

84, 88 Tank-side on-off valve 86

Changeover switch

90A, 90B Hydraulic line 92 Restriction 100 Grapple specification machine 200 Cutting machine 300 Waste material 400 Storage part

Claims

An arm with a work attachment attached to the tip;
A first hydraulic cylinder for driving the work attachment;
A second hydraulic cylinder for driving the arm;
A work machine comprising: a switching mechanism that switches between at least one of the first hydraulic cylinder and the second hydraulic cylinder between a control state that operates by hydraulic pressure and a non-control state that operates by external force.
The work machine according to claim 1,
The switching mechanism includes an on-off valve that connects the at least one bottom side and the rod side of the first hydraulic cylinder and the second hydraulic cylinder to form a closed circuit.
A work machine according to claim 2,
The switching mechanism further includes an on-off valve disposed between the closed circuit and the hydraulic tank.
The work machine according to claim 1,
The switching mechanism includes a first on-off valve disposed between the at least one bottom side of the first hydraulic cylinder and the second hydraulic cylinder and a hydraulic tank, the first hydraulic cylinder, A work machine comprising a second on-off valve disposed between the at least one rod side of a second hydraulic cylinder and the hydraulic tank.