JP5793060B2 - Hydraulic circuit for counterweight desorption device - Google Patents

Description

  The present invention relates to a hydraulic circuit used in an apparatus for attaching / detaching a counterweight to a rear part of a main body of a working machine such as a hydraulic excavator, a dismantling machine, or a crane.

  In work machines such as excavators, demolition machines, and cranes, work equipment for excavation, crushing, cargo handling, etc. is attached to the front part of the work machine body, and the weight balance with these work equipment is attached to the rear part of the work machine body. Equipped with a counterweight for taking Such a counterweight is replaced with a counterweight having a suitable weight according to the work contents and weight of the work device, or a divided counterweight is added or partly removed. In addition, when transporting the work machine, it is necessary to detach it from the work machine body because the counterweight is separately transported and assembled on site. An example of such a counterweight desorbing device is described in Patent Document 1.

  The counterweight detaching apparatus described in Patent Document 1 includes a counterweight lifting / lowering hydraulic cylinder attached to a rear part of a work machine main body so as to be pivotable up and down, and a rear part of the work machine main body. Is constituted by a pivot arm that is pivoted up and down by means of, and a connector that is pivotably suspended from the tip of the pivot arm and is coupled to a counterweight. When attaching the counterweight to the work implement body, the hydraulic cylinder is contracted to lower the rotary arm, the connecting tool is connected to the counterweight placed on the ground, and then the hydraulic cylinder is extended to attach the rotary arm. The counterweight is lifted to the working machine body by raising the counterweight, and the counterweight is fixed to the working machine body with bolts.

  After lifting the counterweight to the work implement body and fixing it to the work implement body in this way, the hydraulic cylinder is slightly shrunk so that the hydraulic cylinder, the rotating arm, and the connector are not restrained by the counterweight. Do the work. In such an unconstrained state, no force is transmitted from the counterweight side to the coupling tool, the rotating arm, and the hydraulic cylinder. After attaching the counterweight to the work implement body in this way, the hydraulic cylinder is slightly shrunk to the unconstrained state because the vibration transmitted from the work implement main body to the counterweight during work is a connecting tool, rotating frame, etc. As a result, it is for preventing damage such as breakage of parts related to the detaching apparatus, in particular, connecting bolts used for the connecting tool.

  FIG. 7 shows a conventional hydraulic circuit used in such a counterweight desorbing device. In FIG. 7, 25 is a hydraulic cylinder for raising and lowering a counterweight (not shown), 50A and 50B are main hydraulic pumps mounted on the work machine body, 51 is a pilot hydraulic pump, 53 is an assembly of control valves 53a to 53i, A control valve 53d for the lifting hydraulic cylinder 25 is switched by the pilot valve 54. A main pipe 56 connects the bottom chamber 25a of the hydraulic cylinder 25 and the control valve 53d. The main pipe 56 is provided with a slow return valve 58 and a pilot check valve 59.

  The slow return valve 58 is provided to prevent the hydraulic cylinder 25 from abruptly dropping due to the weight of the counterweight. The pilot check valve 59 prevents the oil from flowing out from the bottom chamber 25a when the hydraulic cylinder 25 is inoperative. When the hydraulic cylinder 25 is contracted, the hydraulic pressure in the main conduit 57 on the rod chamber 25b side is applied as a pilot pressure. To do. The pilot check valve 59 serves to prevent the hydraulic cylinder 25 from abruptly descending when the main pipeline 56 is damaged and liquid leakage occurs.

  In such a hydraulic circuit of the counterweight desorbing device, when the work implement is operating in a state where the counterweight is attached to the work implement main body, that is, in a state where the counterweight is fixed to the work implement main body, the control valve 53d during operation is operated. The hydraulic cylinder 25 is inadvertently extended due to the leak of pressure oil from the pipe, and as a result, excessive tension is generated in the connecting portion for suspending the counterweight, and the bolts provided in the connecting portion are damaged. .

  In order to prevent the extension of the hydraulic cylinder 25 due to the leak of the pressure oil from the control valve 53d, conventionally, as shown in FIG. 8, the control valve 53d is connected to the bottom chamber 25a and the rod chamber 25b of the hydraulic cylinder 25. Stop valves 60 and 61 are provided in the main pipelines 56 and 57 respectively connecting them, and the stop valves 60 and 61 are closed except when the counterweight is being detached, so that the control is performed except when the counterweight is being detached. A configuration that prevents leakage of pressurized oil from the valve 53d to the hydraulic cylinder 25 is employed.

Japanese Patent No. 2922778

  However, if the stop valves 60 and 61 are closed during operation of the work machine, the bottom chamber 25a and the rod chamber 25b undergo thermal expansion due to radiant heat from the engine during operation and changes in the outside air temperature. Here, since the cross-sectional area of the bottom chamber 25a is wider than the cross-sectional area of the rod chamber 25b, the pressure oil on the bottom chamber 25a side pushes the piston of the hydraulic cylinder 25, and the pressure oil on the rod chamber 25b side The hydraulic cylinder 25 extends beyond the force pushing the piston. When the hydraulic cylinder 25 extends due to thermal expansion of oil, the hydraulic cylinder 25 enters a restrained state in which a load is applied to push up the counterweight fixed to the work implement body by bolts from the unconstrained state. Then, a related part such as a connecting member between the hydraulic cylinder and the counterweight and the rotating arm, particularly the connecting bolt is damaged. Even if the connector or the like is not damaged, the hydraulic oil in the bottom chamber 25a and the rod chamber 25b of the hydraulic cylinder 25 thermally expands, so that an excessive load may be applied to the hydraulic cylinder 25. .

  In view of the above-described problems, the present invention prevents the lifting / lowering hydraulic cylinder of the counterweight from thermally expanding and damaging the connecting portion between the counterweight and the rotating arm, etc. It is an object of the present invention to provide a hydraulic circuit for a counterweight desorbing device that can prevent a load from being generated.

The hydraulic circuit for the counterweight desorbing device of the present invention is
A work machine body provided with a hydraulic power source;
A counterweight detachably mounted on the work implement body;
An elevating hydraulic cylinder that is attached to the work implement body and lifts and lowers the counterweight to be attached to and detached from the work implement body by supplying and discharging hydraulic oil from the hydraulic source to the bottom chamber and the rod chamber;
In a hydraulic circuit for a counterweight desorbing device including a control valve provided between the hydraulic source and the lifting hydraulic cylinder,
Pilot is provided in a first main line between the control valve and the bottom chamber of the lifting hydraulic cylinder, and the second main line between the control valve and the rod chamber of the lifting hydraulic cylinder is piloted. A pilot check valve communicating in the opposite direction as pressure,
A first stop which is provided in series with the pilot check valve between the pilot check valve and the lifting hydraulic cylinder in the first main pipeline and which can communicate and block the first main pipeline. A valve,
A drain pipe provided between a portion of the first main pipeline between the pilot check valve and the control valve and an oil tank;
And a second stop valve provided on the drain pipe and capable of communicating and blocking the drain pipe.

  In the hydraulic circuit of the present invention, when the lifting / lowering hydraulic cylinder is operated to attach / detach the counterweight to / from the work machine body, the first stop valve is opened and the second stop valve is closed to lift / lower the counterweight. The hydraulic cylinder can be expanded and contracted. On the other hand, after the counterweight is mounted on the work implement body and fixed with a bolt or the like, not only the first stop valve but also the second stop valve is opened so that the engine etc. Even if the hydraulic oil in the hydraulic cylinder expands due to radiant heat or changes in the outside air temperature, the hydraulic oil corresponding to the thermal expansion is discharged to the oil tank through the first stop valve and the second stop valve. The cylinder is prevented from extending.

  For this reason, the counterweight is prevented from returning from the unconstrained state to the restrained state due to the expansion accompanying the thermal expansion of the hydraulic oil in the hydraulic cylinder, and the hydraulic cylinder, the rotating arm, the counterweight connecting portion, and the like are prevented from receiving excessive force. In addition, it is possible to prevent damage to the hydraulic cylinder and the connecting portion. On the other hand, during transportation of the work implement, at least the first stop valve is closed to prevent the hydraulic cylinder from contracting, and the pivoting arm pivots in the downward direction during transportation with the counterweight not attached. This can be prevented.

In addition , because one end of the drain pipe is connected between the control valve and the pilot check valve, the first stop valve or the second stop valve should be forgotten to be closed during transportation, etc. Even if it is incomplete, the action of the pilot check valve can prevent the hydraulic cylinder from contracting and the rotating arm from rotating downward.

It is a side view which shows an example of the working machine which applies the hydraulic circuit for the counterweight removal | desorption apparatus of the working machine of this invention. It is a rear view which shows an example of the counterweight desorption apparatus to which the hydraulic circuit for counterweight desorption apparatuses of this invention is applied. It is EE sectional drawing of FIG. In the counterweight desorption apparatus of this example, it is a side view which shows the state which connected the coupler of the counterweight desorption apparatus to the counterweight put on the ground. FIG. 5 is a side view showing an unrestrained state in which the lifting hydraulic cylinder is slightly contracted after the counterweight is attached to the work machine body in the counterweight detaching apparatus of the present example. 1 is a hydraulic circuit diagram showing an embodiment of a hydraulic circuit for a counterweight desorbing device of the present invention. It is a hydraulic circuit diagram which shows the hydraulic circuit for the conventional counterweight removal | desorption apparatus. It is a hydraulic circuit diagram which shows the other example of the hydraulic circuit for conventional counterweight removal | desorption apparatuses.

  FIG. 1 is a side view showing an example of a working machine to which the counterweight desorbing device of the present invention is applied. In this example, the working machine is a hydraulic excavator. In FIG. 1, reference numeral 1 is a lower traveling body, 2 is an upper revolving body (work machine main body) that is installed on the lower traveling body 1 via a revolving device 3, and 4 is an upper revolving body 2. This is a revolving frame as a frame. The swivel frame 4 is equipped with a cab 5 and a machine room 6 that includes a prime mover, a hydraulic pump, and the like and constitutes a hydraulic power unit, a counterweight 7 is mounted at the rear, and a work device 8 is mounted at the front. It is done. The counterweight 7 is provided to balance the weight of the entire work machine with respect to the work device 8 and the like.

  The work device 8 includes a boom 10 attached to the front portion of the revolving frame 4 so as to be able to move up and down by a boom cylinder 9, an arm 12 attached to the tip of the boom 10 so as to be rotatable by an arm cylinder 11, and the arm. The backhoe bucket 14 is rotatably attached to the tip of 12 by a bucket cylinder 13.

  FIG. 2 is a rear view showing an embodiment of the counterweight desorbing device of the present invention, and FIG. In FIG. 3, 4 is a turning frame, and 24 is a counterweight abutting plate provided integrally at the rear end of the turning frame 4. The abutting plate 24 has the same width as the left and right width of the counterweight 7. The front surface of the counterweight 7 is abutted against the abutting plate 24, and the counterweight 7 is fixed to the revolving frame 4 with a long bolt (not shown).

  Reference numeral 20 denotes a counterweight attaching / detaching device attached to the rear end portion of the revolving frame 4 constituting the work machine main body 2. On the front surface of the counterweight 7, a concave portion 7a for accommodating the counterweight detaching device 20 is provided so as to penetrate in the vertical direction. The concave portion 7a is formed as a concave portion 7b whose upper portion is enlarged rearward. A pair of connecting plates 23 for detachably connecting the pair of connecting members 21 shown in FIG. 2 provided in the counterweight detaching device 20 with pins 22 is welded or bolted to the bottom surface of the enlarged recess 7b. It is attached by attaching.

  The counterweight detaching device 20 is attached to a lifting hydraulic cylinder 25, a rotating arm 26 provided as a movable body that converts expansion and contraction of the lifting hydraulic cylinder 25 into a vertical movement, and a free end of the rotating arm 26. The connector 21 is configured.

  The raising / lowering hydraulic cylinder 25 has a boss 25c at the bottom side end interposed between the brackets 27, 27 welded to the center portion in the left-right direction of the abutting plate 24, and the bracket 27, The pivot pin 29 is inserted into the 27 pin holes, the spacers 28 and 28, and the boss 25c at the bottom end, and is attached so as to be pivotable in the vertical direction around the pivot pin 29.

  Two rotating arms 26 are provided, one on each of the left and right sides of the lifting hydraulic cylinder 25. In order to attach each rotation arm 26, the bracket 30 is welded to the outside of the left and right brackets 27 of the abutting plate 24, respectively. The root portion of the rotating arm 26 is sandwiched between the bracket 30 and the bracket 27 via the annular spacer 31, and the pin hole provided in the brackets 27 and 30, the spacer 31, and the root portion of the rotating arm 26 are provided. The pivot pins 32 are inserted into the pin holes, and the pivot arms 26 are pivotally attached around the pivot pins 32. The pivot pins 32 of the left and right pivot arms 26 are concentric at the same height. Further, the pivot pins 32 of the pivot arms 26 are provided at positions higher than the pivot pins 29 of the lifting hydraulic cylinder 25.

  A boss 25d at the tip of the piston rod of the lifting hydraulic cylinder 25 is sandwiched between the free ends of the rotating arm 26 via cylindrical spacers 34, 34, and a pin hole provided at the free ends of the rotating arms 26, 26. The spacers 34 and 34 and the connecting pins 35 inserted into the bosses 25d are connected to the tips of the rotating arms 26 and 26.

  Pins 37 for attaching the coupling tool 21 are attached to the free ends of the rotary arms 26, 26 so as to be pivotably inserted into pin holes 26a, 26a provided in the rotary arms 26, 26. Bolt insertion holes 37 a are provided in portions of the pin 37 that protrude outward from the rotating arms 26, 26, and connection bolts 38 are inserted into the respective bolt insertion holes 37 a to screw holes 21 a provided in the upper part of the connection tool 21. The coupling tool 21 is attached to both ends of the pin 37 via the coupling bolt 38 by screwing the nut 39 screwed into the coupling bolt 38 onto the upper surface of the coupling tool 21 and press-contacting the nut 39 to the upper surface thereof.

  Each connecting member 21 has a groove 21b that is open at the bottom, and a connecting plate 23 provided on the counterweight 7 is placed in each groove 21b, and a pin hole 23a provided in the connecting plate 23 and a connecting member 21 are provided. The counterweight 7 can be attached to and detached from the connector 21 by removably inserting the pin 22 into the pin hole 21c. As shown in FIG. 3, the pin hole 23a provided in the connecting plate 23 is formed in a horizontally long long hole so that the lifting hydraulic cylinder 25 can be in a retracted state as will be described later.

  When attaching the counterweight 7 using this counterweight desorbing device, as shown in FIG. 4, the rotating arm 26 is lowered by contracting the elevating hydraulic cylinder 25 and the counterweight 7 placed on the ground is lowered. The connecting tool 21 is connected to the connecting plate 23 by pins 22.

  Thereafter, by extending the lifting hydraulic cylinder 25, the pivot arm 26 is pivoted about the pivot pin 32 as shown by the arrow R to lift the counterweight 7. Then, as shown in FIG. 3, the front surface of the counterweight 7 is abutted against the abutting plate 24, and the counterweight 7 is fixed to the revolving frame 4 with a long bolt (not shown).

  Thereafter, as shown in FIG. 5, the lifting hydraulic cylinder 25 is slightly contracted to rotate the rotating arm 26 as indicated by the arrow r, and the connecting tool 21 is lowered to the retracted state. In this retracted state, the lifting hydraulic cylinder 25 does not bear the load of the counterweight 7, and the connector 21 does not generate tension due to the counterweight 7.

  When the counterweight 7 is removed from the turning frame 4 and lowered to the ground, the procedure reverse to the above-described process is taken.

FIG. 6 is a hydraulic circuit diagram showing an embodiment of the hydraulic circuit of the counterweight desorbing device according to the present invention. In FIG. 6, 50A and 50B are main hydraulic pumps installed as hydraulic sources in the machine room 6, and 51 is also a pilot hydraulic pump. Reference numeral 53 denotes an assembly of control valves 53a to 53e and 53f to 53i provided in cascade connection to the discharge pipes of the main hydraulic pumps 50A and 50B. This control valve assembly 53 is mounted on the revolving frame 4, 53a is for revolving, 53b and 53i are for boom cylinders, 53c and 53h are for arm cylinders, 53e and 53f are for traveling, 53g Is used for the bucket cylinder, and 53d is used for the lifting hydraulic cylinder 25. 54 is a pilot valve for the control valve 53d in which an operation lever is provided in the cab 5.

56 is a bottom chamber side main pipe (first main pipe) provided between the bottom chamber 25a of the lifting hydraulic cylinder 25 and the control valve 53d, 57 is a rod chamber 25b of the lifting hydraulic cylinder 25 and the control valve 53d. The rod chamber side main pipe (second main pipe) provided between the two . 58 is a slow return valve provided in the bottom chamber side main pipeline 56, 59 is also a pilot check valve provided in the bottom chamber side main pipeline 56 , and the functions of these valves 58 and 59 are as described above. . A pilot circuit 59 a of the pilot check valve 59 is connected to the rod chamber side main pipeline 57.

62 is a first stop valve provided in series with the pilot check valve 59 between the pilot check valve 59 in the bottom chamber side main pipeline 56 and the bottom chamber 25a of the hydraulic cylinder 25, and 63 is a bottom chamber side main pipeline. A drain line 65 provided between a portion between the control valve 53 d and the pilot check valve 59 in 56 and the oil tank 64, and 65 is a second stop valve provided in the drain line 63.

  In this configuration, when the counterweight 7 is raised and lowered, the first stop valve 62 is opened and the second stop valve 65 is closed. Thus, when the control valve 53d is switched by operating the pilot valve 54, the hydraulic oil discharged from the main hydraulic pump 50A passes through the bottom chamber side main pipeline 56 or the rod chamber side main pipeline 57, and the bottom chamber 25a or rod of the hydraulic cylinder 25 Supplyed to the chamber 25b, the hydraulic cylinder 25 expands or contracts, and the counterweight 7 can be raised and lowered.

  On the other hand, when the normal excavation work is performed after the counterweight 7 is attached to the work implement body, both the stop valves 62 and 65 are opened. When the work implement is operated in this state, even if hydraulic oil leaks from the control valve 53d to the bottom chamber side main pipeline 56 by switching operation of the control valves 53a to 53c and 53e to 53i other than the control valve 53d, the leaked operation The oil is discharged from the second stop valve 65 to the oil tank 64.

When hydraulic fluid leaks from the control valve 53d to the rod chamber side main pipeline 57, the hydraulic pressure of the pilot circuit 59a of the pilot check valve 59 rises, so the pilot check valve 59 is opened. That is, the pilot check valve 59 communicates in the reverse direction . For this reason, when the hydraulic oil in the hydraulic cylinder 25 undergoes thermal expansion due to the heat of the operating engine or an increase in external temperature, the slow return valve 58, the first stop valve 62, the pilot check valve 59, and the second stop. The hydraulic oil in the bottom chamber 25 a of the hydraulic cylinder 25 is discharged to the oil tank 64 through the valve 65.

  For this reason, the extension of the hydraulic cylinder 25 due to the thermal expansion of the hydraulic oil in the hydraulic cylinder 25 is prevented. This prevents the counterweight 7 from returning from the unconstrained state shown in FIG. 5 to the constrained state and applying an excessive force to the hydraulic cylinder 25, and a connecting tool between the rotating arm 26 and the counterweight 7. 21, in particular, the bolt 38 and the like are prevented from receiving an excessive force, and damage to the hydraulic cylinder 25 and the coupling tool 21 can be prevented.

  On the other hand, when transporting the work machine with the counterweight 7 not attached or during parking, at least the first stop valve 62 is closed to prevent the hydraulic cylinder 25 from contracting. It is possible to prevent the rotation arm 26 from rotating in the downward direction.

  In this embodiment, since one end of the drain pipe 63 is connected to the portion between the control valve 53d and the pilot check valve 59, the first stop should be provided during transportation or parking. Even if the valve 62 or the second stop valve 65 is forgotten to be closed or the closed state is incomplete, the hydraulic cylinder 25 contracts due to the action of the pilot check valve 59 and the rotating arm rotates in the downward direction. It can be prevented from moving.

  Although the present invention has been described above by the embodiments, the present invention is not limited to the above-described embodiments, and various modifications and additions can be made without departing from the gist of the present invention. The present invention can also be applied, for example, when the work machine body is non-rotating. In addition, the sheave and sprocket are moved up and down by the expansion and contraction of the lifting hydraulic cylinder, and the counterweight is moved up and down by connecting the counterweight to the rope (movable body) hung on the sheave and the chain (movable body) hung on the sprocket. It can also be.

1: Lower traveling body, 2: Upper revolving body (work machine main body), 3: Revolving device, 4: Revolving frame, 5: Driver's cab, 6: Machine room, 7: Counterweight, 7a, 7b: Recess, 8: Working device, 20: Counterweight attaching / detaching device, 21: Connecting tool, 22: Pin, 23: Connecting plate, 24: Abutting plate, 25: Lifting hydraulic cylinder, 26: Rotating arm, 27, 30: Bracket, 29, 32: Pivot pin, 35: Connection pin, 37: Pin, 38: Bolt, 50A, 50B: Main hydraulic pump, 51: Pilot hydraulic pump, 53a to 53i: Control valve, 54: Pilot valve, 56: Bottom chamber side Main pipeline (first main pipeline) 57: Rod chamber side main pipeline (second main pipeline) 58: Slow return valve 59: Pilot check valve 59a: Pilot circuit 62: First stop valve 6 : Drain pipe, 64: oil tank 65: second stop valve

Claims (1)

A work machine body provided with a hydraulic power source;
A counterweight detachably mounted on the work implement body;
An elevating hydraulic cylinder that is attached to the work implement body and lifts and lowers the counterweight to be attached to and detached from the work implement body by supplying and discharging hydraulic oil from the hydraulic source to the bottom chamber and the rod chamber;
In a hydraulic circuit for a counterweight desorbing device including a control valve provided between the hydraulic source and the lifting hydraulic cylinder,
Pilot is provided in a first main line between the control valve and the bottom chamber of the lifting hydraulic cylinder, and the second main line between the control valve and the rod chamber of the lifting hydraulic cylinder is piloted. A pilot check valve communicating in the opposite direction as pressure,
A first stop which is provided in series with the pilot check valve between the pilot check valve and the lifting hydraulic cylinder in the first main pipeline and which can communicate and block the first main pipeline. A valve,
A drain pipe provided between a portion of the first main pipeline between the pilot check valve and the control valve and an oil tank;
A hydraulic circuit for a counterweight desorbing device, comprising: a second stop valve provided on the drain pipe and capable of communicating and blocking the drain pipe.

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