JP2014148994A - Hydraulic control device of work machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device capable of controlling a main actuator and an optional actuator of a work machine to be actuated at a proper velocity.SOLUTION: The device comprises: first and second pumps 11, 12; a first main control valve 15 for introducing emission oil of the first pump 11 to a main actuator 7; an optional control valve 16 for introducing the emission oil of the first pump 11 to an optional actuator 8; a second main control valve 19 for introducing the emission oil of the second pump 12 to the main actuator 7; and throttle switching devices 37A, 37B, 60 for throttling a flow passage area of a first main supply oil passage for supplying working oil to the main actuator 7 through the first main control valve 15 in operating the main actuator 7 and the optional actuator 8 at the same time, and cancelling the throttle when the optional actuator 8 is not operated and only the main actuator 7 is operated.

Description

  The present invention relates to an apparatus for controlling an operation of a hydraulic actuator that is provided in a work machine having a work attachment having a tip portion to which an optional device can be attached, and drives the work attachment and the optional device, respectively. .

  In a working machine having a work attachment that operates so that the tip portion is displaced, an optional device may be mounted on the tip portion. For example, a general hydraulic excavator includes, as its work attachment, a boom that can be raised and lowered, and an arm that is rotatably connected to the tip of the boom, and a bucket is attached to the tip of the arm. Instead, optional devices such as nibbles and breakers, which are crushing devices, may be attached to the tip of the arm.

  Conventionally, an apparatus shown in FIG. 14 is known as an apparatus for hydraulically driving such work attachments and optional devices (Patent Document 1). This device includes a first pump 91, a second pump 92, an arm cylinder 93 for moving the arm of the work attachment, an option cylinder (spare actuator) 94 for moving the optional device, and the first pump. And an arm direction switching valve V1 interposed between the arm cylinder 93 and a spare direction switching valve V2 interposed between the first pump 91 and the option cylinder 94.

  In this apparatus, the bidirectional switching valves V1 and V2 are arranged in series on a common center bypass line connected to the hydraulic pump 91, and via an arm supply oil passage 95 and a spare supply oil passage 96, respectively. The hydraulic pumps 91 are connected in parallel to each other. Accordingly, the hydraulic oil discharged from the hydraulic pump 91 is supplied to the arm cylinder 93 through the arm supply oil passage 95 and the arm direction switching valve V1, and the spare supply oil passage 96 and the spare direction. The option cylinder 94 can be supplied through the switching valve V2.

  However, in this apparatus, the load on the option cylinder 94 for driving the optional device is significantly lighter than the load on the arm cylinder 93 for driving the arm. Most of the hydraulic oil discharged from the fluid 91 flows to the option cylinder 94, which may cause the driving speed of the arm cylinder 93 to be significantly reduced.

  Therefore, the device includes a variable throttle valve 97 and a control valve 98 for adjusting the flow rate distribution when the cylinders 93 and 94 are driven simultaneously. The variable throttle valve 97 is provided in the middle of the spare supply oil passage 96 and has a pilot port. The variable throttle valve 97 has a function of reducing the flow passage area as the pilot pressure supplied to the pilot port increases. The control valve 98 is interposed between the pilot line of the arm direction switching valve 95 and the pilot port of the variable throttle valve 97, and as the pilot pressure input to the arm direction switching valve 95 increases, that is, As the amount of operation of the arm operation lever operated for the arm increases, the pilot pressure of the variable throttle valve 97 is guided to a larger pilot pressure.

  According to this device, the larger the operation amount of the arm operation lever, the smaller the flow passage area of the variable throttle valve 97, and accordingly, the supply flow rate to the arm cylinder 93 is increased. Even when the load is significantly larger than the load 94, the larger the arm lever operation amount for the arm cylinder 93, the greater the hydraulic oil supply flow rate to the arm cylinder 93.

JP-A-9-217385

  In the apparatus, when the option cylinder 94 reaches the stroke end, the flow rate of the hydraulic oil supplied to the option cylinder 94 becomes zero, and at this time, the supply flow rate of the hydraulic oil to the arm cylinder 93 suddenly increases. In addition, there is an inconvenience that the movement of the arm is increased excessively and the movement of the arm is accelerated against the intention of the operator.

  On the other hand, since the load on the arm cylinder 93 is large, there is also a demand for ensuring a sufficient supply flow rate to the arm cylinder 93.

  In view of the circumstances described above, the present invention is a device for controlling the operation of a work actuator and an optional actuator, each of which is driven by hydraulic pressure, and a work actuator of the work machine. It is an object of the present invention to provide a hydraulic control device that can drive the work attachment and the optional device at an appropriate speed regardless of the load difference of the optional device.

  An apparatus provided by the present invention is provided in a work machine having a work attachment having a tip portion to which an optional device can be attached, and operates a main actuator that drives the work attachment by hydraulic pressure and drives the optional device by hydraulic pressure. An apparatus for controlling the operation of each of the optional actuators, the first pump and the second pump each comprising a variable displacement hydraulic pump, and the average of the discharge pressures of the first and second pumps In the region where the average pump pressure, which is the pressure, is less than or equal to the preset pump pressure, the first pump flow rate and the second pump flow rate, which are the flow rates of the hydraulic oil discharged by the first and second pumps, are set to the maximum flow rates, respectively. In the region where the average pump pressure exceeds the set pump pressure, the average pump pressure increases as the average pump pressure increases. A pump flow rate control unit that performs horsepower control to decrease the flow rates of the first and second pumps, a first main supply oil passage that guides hydraulic fluid discharged from the first pump to the main actuator, and an operation that the first pump discharges An optional supply oil passage that guides oil to the option actuator in parallel with the first main supply oil passage; a second main supply oil passage that guides hydraulic oil discharged from the second pump to the main actuator; and the main actuator. A main operating device operated to move, an optional operating device operated to move the optional actuator, and supply of hydraulic oil to the main actuator through the first main supply oil passage of the main operating device. A first main control valve that operates to control based on the operation; An option control valve that operates to control the supply of hydraulic oil to the optional actuator through an oil passage based on the operation of the optional actuator, and the hydraulic oil to the main actuator through the second main supply oil passage The second main control valve that operates so as to control the supply of the main actuator based on the operation of the main actuator, and the operation for moving the main actuator and the operation for moving the option actuator at the same time When the optional actuator reaches the stroke end, an operation for reducing the flow area of the first main supply oil passage so that the average pump pressure exceeds the set pump pressure and moving the optional actuator is performed. The main actuator An aperture switching device that releases the aperture of the flow path area when the main actuator is operated alone to operate the eta.

  According to this device, when the simultaneous operation, that is, when the operation of the optional actuator and the operation of the main actuator are performed simultaneously, the throttle switching device restricts the flow area of the first main supply oil passage, It is possible to prevent a sudden change in the flow rate of hydraulic oil supplied to the main actuator before and after the optional actuator reaches the stroke end. The reason is as follows.

  First, before the optional actuator reaches the stroke end, the first pump oil, which is the hydraulic oil discharged from the first pump, is supplied biased to the main actuator and the optional actuator with a small driving load among the optional actuators. Of the flow rate of the first pump oil, the flow rate that joins the main actuator side through the first main supply oil passage is very small. And since the flow volume of the hydraulic fluid supplied to a main actuator through a 1st main supply oil path is small in this way, there is almost no raise of the 1st pump pressure by restriction | limiting of the flow-path area of the said 1st main supply oil path. Therefore, since the average pump pressure is kept low, there is no limitation on the discharge flow rates of the first and second pumps based on the horsepower control. That is, before the optional actuator reaches the stroke end, most of the hydraulic oil discharged from the first pump is supplied to the optional actuator due to the difference in driving load, and the hydraulic oil (first pump oil) joins to the main actuator side. On the other hand, the discharge flow rates of the first and second pumps are not limited.

  After that, when the optional actuator reaches the stroke end, there is no place for the hydraulic oil from the first pump to the optional actuator at that time, so that the entire amount of the first pump oil flows into the main actuator side. Therefore, if no countermeasure is taken, there is a risk that the supply flow rate of hydraulic oil to the main actuator will suddenly increase when the optional actuator reaches the stroke end, and the main actuator will increase significantly against the operator's will. However, in the apparatus according to the present invention, the combination of the restriction of the flow passage area and the horsepower control in the first main supply oil passage makes it possible to prevent the main actuator from being significantly accelerated. Specifically, when the optional actuator reaches the stroke end and the flow rate of the first pump oil in the first main supply oil passage increases, the restriction of the flow area of the main supply oil passage works and the first pump pressure is increased. The average pump pressure, which is the average pressure of the first pump pressure and the second pump pressure, exceeds the set pump pressure, so that the pump flow rate control unit can control the first and second pumps based on the horsepower control. Reduce the discharge flow rate. As a result, the increase in the supply flow rate of hydraulic oil to the main actuator and the increase in the speed of the main actuator due to the first pump oil joining the main actuator are suppressed.

  That is, according to the present invention, the main actuator before and after reaching the stroke end can be obtained by combining the restriction of the flow area of the first main supply oil passage and the horsepower control without detecting the stroke end of the optional actuator. A sudden change in the supply flow rate of hydraulic oil to the engine can be suppressed.

  On the other hand, when the operation of the optional actuator is not performed, that is, when there is no possibility of fluctuation in the flow rate due to the driving of the optional actuator, the throttle switching device restricts the flow area in the first main supply oil passage. Is released, hydraulic oil can be supplied to the main actuator at a sufficient flow rate through the first main supply oil passage and the second main supply oil passage.

  The throttling of the flow area of the first main supply oil passage and the switching of its release can be performed by various means. Specifically, the first control valve has a neutral position that blocks the first main supply oil passage and a drive position that forms an oil passage that opens the first main supply oil passage, and the main control valve In the case where the flow passage area of the oil passage is increased by opening the valve from the neutral position to the driving position with a stroke corresponding to the operation amount of the operating device, the throttle switching device is used for the simultaneous operation. Then, when the optional actuator reaches the stroke end, the first main control valve is operated from its neutral position corresponding to the operation amount of the main actuator so that the average pump pressure exceeds the set pump pressure. It is effective to limit the stroke and cancel the stroke limitation when the main actuator is operated alone. This restriction switching device can restrict and release the flow area of the first main supply oil passage without using a special restriction valve by limiting the stroke of the first main control valve.

  The stroke can be limited by, for example, a stopper that directly contacts the valve body that operates the stroke in the first main control valve and restricts its movement, but the main operating device corresponds to the operation amount. A remote control valve for inputting the pilot pressure of the magnitude to the first main control valve, and the first main control valve from the neutral position with a stroke corresponding to the magnitude of the pilot pressure inputted from the remote control valve. When the pilot switching valve is operated, the stroke of the first main control valve can be limited by limiting the pilot pressure. Specifically, the throttle switching device includes a pilot pressure limiting valve operable to reduce a pilot pressure input from the remote control valve to the first main control valve, and reducing the pilot pressure during the simultaneous operation. It is effective to include a pilot pressure limit switching unit that operates the pilot pressure limit valve so that the reduction of the pilot pressure is released when the main actuator is operated alone.

  On the other hand, the hydraulic control device according to the present invention includes a joining position that forms an oil passage for joining the working oil discharged from the second pump to the working oil supplied to the optional actuator, and a joining that cuts off the oil passage. A merging switching valve having a shut-off position, and the merging switching valve is switched to the merging position when the optional actuator is operated in a state where the main actuator is not operated, and the merging switching valve is switched during the simultaneous operation. It is preferable to further include a merge switching valve control unit that switches to the merge blocking position. The merging switching valve and the merging switching valve control unit are configured to merge the hydraulic oil discharged from the second pump to the option actuator side when the main actuator alone is operated in which only the option actuator of the main actuator and the option actuator is operated. While the operating speed of the optional actuator is increased, the operating oil discharged from the second pump is lightly driven by shutting off the oil passage for merging when the main actuator and the optional actuator are operated simultaneously. It is possible to ensure normal operation of the main actuator by preventing the supply from being biased to the side.

  The present invention is also a work machine, a base machine, a work attachment, a boom attached to the base machine so as to be raised and lowered, an arm rotatably connected to a tip of the boom, and the boom And an arm cylinder extending and retracting so as to rotate the arm relative to the boom interposed between the boom and the arm, and extending and retracting so as to raise and lower the boom interposed between the boom and the base machine. There is provided a work machine including a boom cylinder and a hydraulic control device. In this work machine, the hydraulic control device can be effectively applied as the main actuator for controlling the operation of the boom cylinder or the arm cylinder.

  As described above, according to the present invention, a device for driving a work attachment of a work machine and an optional device attached thereto by hydraulic pressure, regardless of the load of the work attachment and the optional device. A hydraulic control device capable of driving the work attachment and the optional device at an appropriate speed is provided.

1 is a circuit diagram showing a hydraulic control apparatus according to a first embodiment of the present invention. It is a front view which shows the example of the working machine with which the said hydraulic control apparatus is mounted. It is a block diagram which shows the function structure of the controller of the said hydraulic control apparatus, and its input-output signal. (A) (b) is a graph which shows the example of restriction | limiting of the pilot pressure for arms. It is a graph which shows the characteristic of the average pump pressure and pump capacity | capacitance set for the horsepower control calculation which the said controller performs. It is a circuit diagram which shows the flow of the hydraulic fluid before an option cylinder reaches a stroke end at the time of simultaneous operation of an arm cylinder and an option cylinder. (A) is a circuit diagram showing the flow of hydraulic oil after the option cylinder reaches the stroke end when the pilot pressure of the arm control valve is not restricted during the simultaneous operation, and (b) is the arm control during the simultaneous operation. It is a circuit diagram which shows the flow of the hydraulic fluid after an option cylinder reaches a stroke end in case the pilot pressure of a valve is restrict | limited. It is a time chart which shows the time change of the stroke of an option cylinder, the supply flow rate of the hydraulic oil to an arm cylinder, and the operating speed of an arm cylinder in case the pilot pressure of the arm control valve is not restrict | limited at the time of the said simultaneous operation. It is a time chart which shows the time change of the stroke of an option cylinder, the supply flow rate of the hydraulic oil to an arm cylinder, and the operating speed of an arm cylinder in case the pilot pressure of the arm control valve is restricted at the time of the simultaneous operation. It is a circuit diagram which shows the principal part of the hydraulic control apparatus which concerns on the 2nd Embodiment of this invention. It is a circuit diagram which shows the hydraulic control apparatus which concerns on the 3rd Embodiment of this invention. It is a circuit diagram which shows the hydraulic control apparatus which concerns on the 4th Embodiment of this invention. It is a circuit diagram which shows the hydraulic control apparatus which concerns on the 5th Embodiment of this invention. It is a circuit diagram which shows the hydraulic control apparatus of the conventional working machine.

  A preferred embodiment of the present invention will be described with reference to FIGS.

  FIG. 2 shows an example of a work machine on which the hydraulic control apparatus according to the present invention is mounted. This work machine uses an existing hydraulic excavator as a base body, and includes a base machine 1, a work attachment 2 attached to the base machine 1, and an optional device 3 detachably attached to the tip of the work attachment 2. And comprising. The work attachment 2 includes a boom 4 attached to the base machine 1 so as to be able to move up and down, and an arm 5 rotatably connected to the tip of the boom 4, and the optional device is attached to the tip of the arm 5. 3 is mounted. The optional device 3 according to this embodiment is a so-called nibler for crushing, has a pair of crushing blades, and crushes the object by movement of the crushing blades in the opening / closing direction.

  An extendable boom cylinder 6 is interposed between the base machine 1 and the boom 4. The boom cylinder 6 extends by receiving hydraulic pressure to move the boom 2 in the standing direction. Similarly, an arm cylinder 7 is interposed between the boom 4 and the arm 5, and the arm cylinder 7 extends upon receiving hydraulic pressure to pull the arm 5 (direction approaching the boom 4). ).

  FIG. 1 shows a hydraulic control device for controlling the operation of a hydraulic actuator that drives the work attachment 2 and the optional device 3 by hydraulic pressure, and shows a device according to a first embodiment of the present invention. In addition to the arm cylinder 7 and the boom cylinder 6 (the boom cylinder 6 is shown only in FIG. 2), the hydraulic actuator includes an unillustrated travel motor and an optional cylinder 8 for driving the optional device 3. included. The optional cylinder 8 is provided in the optional device 3, and in this embodiment, is connected to the crushing blades so as to open and close both the crushing blades of the nibbler corresponding to the optional device 3. 3 is connected to the circuit shown in FIG. 1 when mounted on the tip of the arm 5.

  The hydraulic control device shown in FIG. 1 includes a first pump 11, a second pump 12, direction switching valves 14, 15, 16 connected to the first pump 11, and a direction switching valve connected to the second pump 12. 17, 18, 19, an arm operator 31, an option operator 32, a first relief valve 33, and a second relief valve 34.

  The first and second pumps 11 and 12 discharge hydraulic oil in the tank independently of each other, and are each constituted by a variable displacement hydraulic pump. Specifically, regulators 11a and 12a are attached to the first and second pumps 11 and 12, respectively, and these regulators 11a and 12a receive the input of a capacity control signal, which will be described later, thereby the first and second pumps. 11 and 12 are operated to change the capacity.

  The discharge ports of the first and second pumps 11 and 12 can communicate with the tank through the first center bypass line L1 and the second center bypass line L2, respectively, and the direction switching valve on the first center bypass line L1. 14, 15, and 16 are provided, and the direction switching valves 17, 18, and 19 are provided on the second center bypass line L2. These directional control valves 14 to 19 are provided corresponding to each of a plurality of hydraulic actuators (six hydraulic actuators including the boom cylinder 6, the arm cylinder 7 and the optional cylinder 8) provided in the work machine. Operates to control the supply of hydraulic fluid to the hydraulic actuator.

  Further, this circuit is provided with a first parallel line for supplying hydraulic oil discharged from the first pump 11 to the directional control valves 14, 15, 16 separately from the first center bypass line L1. The first parallel line includes a common oil passage 21 that branches from the first center bypass line L1, and a branch that further branches from the common oil passage 21 to the directional control valves 14, 15, and 16. And oil passages 24, 25, 26. In addition to the second center bypass line L2, this circuit has a second parallel line for supplying hydraulic oil discharged from the second pump 12 to the directional control valves 17, 18, and 19. The second parallel line includes a common oil passage 22 branched from the center bypass line L2, and supply oil passages 27, 28, branching further from the common oil passage to the direction switching valves 17, 18, 19, 29.

  Each of the direction switching valves 14 to 19 is constituted by a three-position hydraulic pilot switching valve in this embodiment, and has a neutral position and first and second driving positions on both sides thereof. In the neutral position, the direction switching valves 14 to 19 open the center bypass line L1 or L2 corresponding to the direction switching valve to shut off the actuator corresponding to the direction switching valve from the hydraulic pump and the tank. In the first driving position, hydraulic oil supplied through the branch oil passages 24 to 29 is introduced to the actuator so as to move the actuator in the first direction, and in the second driving position, the actuator is The hydraulic oil supplied through the branch oil passages 24 to 29 is introduced into the actuator so as to move in a second direction opposite to the first direction.

  In this embodiment, the arm cylinder 7 and the option cylinder 8 correspond to the main actuator and the option actuator according to the present invention, respectively, and the direction switching valves 15, 16 and 19 respectively correspond to the first main control valve according to the present invention. This corresponds to the option control valve and the second main control valve. The common oil passage 21 and the branch oil passage 25 constitute an upstream portion of the first main supply oil passage according to the present invention, and the common oil passage 21 and the branch oil passage 26 are optional supply oil according to the present invention. An upstream portion of the passage is configured, and the common oil passage 22 and the branched oil passage 29 constitute an upstream portion of the second main supply oil passage according to the present invention.

  The direction switching valve 15 has a pair of pilot ports 15a and 15b. When pilot pressure is not input to both pilot ports 15a and 15b, the direction switching valve 15 is held at the neutral position (center position in the figure). When the pilot pressure is input, it is switched to the first drive position (left side position in the figure), and when the pilot pressure is input to the pilot port 15b, it is switched to the second drive position (right side position in the figure). . The direction switching valve 15 shuts off the arm cylinder 7 from the first pump 11 and the tank (that is, shuts off the first main supply oil passage) in the neutral position, and the branch oil in the first drive position. The passage 25 is connected to the head side oil passage 7a connected to the head side chamber of the arm cylinder 7, and the rod side oil passage 7b connected to the rod side chamber of the arm cylinder 7 is connected to the tank line L3. In the driving position, the branch oil passage 25 is connected to the rod side oil passage 7b and the head side oil passage 7a is connected to the tank line L3.

  Similarly, the direction switching valve 16 has a pair of pilot ports 16a and 16b. When pilot pressure is not input to both pilot ports 16a and 16b, the direction switching valve 16 is held at the neutral position (center position in the figure), and the pilot When pilot pressure is input to the port 16a, the first driving position (left side position in the figure) is switched, and when pilot pressure is input to the pilot port 16b, the second driving position (right side position in the figure). Is switched to. The direction switching valve 16 shuts off the option cylinder 8 from the first pump 11 and the tank at the neutral position (that is, shuts off the option supply oil passage), and the branch oil passage 26 at the first drive position. Is connected to the head side oil passage 8a connected to the head side chamber of the option cylinder 8 and the rod side oil passage 8b connected to the rod side chamber of the option cylinder 8 is connected to the tank line L3. The branch oil passage 26 is connected to the rod side oil passage 8b and the head side oil passage 8a is connected to the tank line L3.

  The direction switching valve 19 has a pair of pilot ports 19a and 19b. When pilot pressure is not input to the pilot ports 19a and 19b, the direction switching valve 19 is held at the neutral position (center position in the figure). When pilot pressure is input to 19a, it is switched to the first drive position (left side position in the figure), and when pilot pressure is input to the pilot port 19b, it is switched to the second drive position (right side position in the figure). Switched. The direction switching valve 19 shuts off the arm cylinder 7 from the second pump 12 and the tank in the neutral position (that is, shuts off the second main supply oil passage), and the branched oil in the first drive position. The path 29 is connected to the head side oil path 7c that joins the head side oil path 7a, and the rod side oil path 7d that joins the rod side oil path 7b is connected to the tank line L4, and the second drive position Then, the branch oil passage 29 is connected to the rod side oil passage 7d and the head side oil passage 7c is connected to the tank line L4.

  The arm operating device 31 is used by an operator to operate the arm cylinder 7 and corresponds to a main operating device according to the present invention, and includes a pilot hydraulic pressure source 31a, an arm remote control valve 31b, And an arm operation lever 31c which is a member. The arm operation lever 31c is an operation member that is rotated by an operator, and is pivotally connected to the arm remote control valve 31b. Both sides of the arm operating lever 31c, that is, the arm pulling side and the arm pushing side, are sandwiched by the operator. Can be manipulated.

  The arm remote control valve 31b supplies the pilot pressure output from the pilot pressure supply source 31a to the direction switching valves 15 and 19 in accordance with the operation position of the arm operation lever 31c. Specifically, the arm remote control valve 31b does not supply pilot pressure when the arm operation lever 31c is in the neutral position, and the operation amount when the arm operation lever 31c is operated to the arm pulling side. Is supplied to the pilot ports 15a and 19a of the directional control valves 15 and 19 through the pilot lines 35A and 39A, respectively, and the arm operation lever 31c is operated to the arm push side. Supplies pilot pressure of a magnitude corresponding to the manipulated variable to the pilot ports 15b and 19b of the direction switching valves 15 and 19 through the pilot lines 35B and 39B, respectively.

  The option operating device 32 is used by an operator to operate the option cylinder 8, and includes a pilot hydraulic pressure source 32a, an option remote control valve 32b, and an option operating lever 32c as an operating member. The option operation lever 32c is an operation member that is rotated by an operator, and is rotatably connected to the option remote control valve 32b. Both sides of the neutral position are sandwiched by the operator (in this embodiment, the nibler closing side). And nibbler opening side).

  The option remote control valve 32b supplies the pilot pressure output from the pilot pressure supply source 32a to the direction switching valve 16 in accordance with the operation position of the option operation lever 32c. Specifically, the option remote control valve 32b does not supply pilot pressure when the option operation lever 32c is in the neutral position, and the amount of operation when the option operation lever 32c is operated to the nibbler closing side. Is supplied to the pilot port 16a of the direction switching valve 16 through the pilot line 36A, and when the option operating lever 32c is operated to the nibbler opening side, the magnitude corresponding to the operation amount is supplied. The pilot pressure is supplied to the pilot port 16b of the direction switching valve 16 through the pilot line 36B.

  The tank lines L3 and L4 bypass the center bypass lines L1 and L2, respectively, and connect the discharge ports of the first pump 11 and the second pump 12 and the tank. The tank lines L3 and L4 are respectively connected to the tank lines L3 and L4. A first relief valve 33 and a second relief valve 34 are provided. The relief valves 33 and 34 have discharge pressures of the first and second pumps 11 and 12 (hereinafter referred to as “first pump pressure” and “second pump pressure”, respectively) for the relief valves 33 and 34, respectively. When the pressure exceeds a preset relief set pressure, the valve is opened, whereby the discharge pressures of the first and second pumps 11 and 12 are released to the tank through the tank lines L3 and L4.

  Further, this device is provided with a diaphragm switching device as its feature. In this diaphragm switching device, an operation for moving the arm cylinder 7 as a main actuator (operation of the operation lever 31c) and an operation for moving the option cylinder 8 as an option actuator (operation of the operation lever 32c) are performed simultaneously. When the simultaneous operation is performed, the flow area of the first main supply oil passage is reduced, and the arm cylinder single operation is performed in which the operation for moving the arm cylinder 7 is performed in the state where the operation for moving the option cylinder 8 is not performed. At this time (when the main actuator is operated alone), the throttle of the flow path area is released, and the direction switching valve 15 as the first main control valve is used for switching the throttle.

  Specifically, the throttle switching device includes pilot pressure limiting valves 37A and 37B provided in the middle of the pilot lines 37A and 37B for the direction switching valve 15, respectively. These pilot pressure limiting valves 37A and 37B are constituted by, for example, electromagnetic proportional pressure reducing valves having solenoids, and pilot pressures (from the arm operating device 31 to the pilot ports 15a and 15b up to a pressure corresponding to a command signal input to the solenoids). The pilot pressure supplied to the pressure is reduced.

  On the other hand, the apparatus according to this embodiment includes a merging switching valve 44 provided in the middle of both common oil passages 21 and 22 so as to perform merging switching of the common oil passages 21 and 22, and a position of the merging switching valve 44. A pilot hydraulic power source 45 and a merging switching operation valve 46.

  In this embodiment, the merging switching valve 44 is constituted by a two-position hydraulic pilot switching valve having a single pilot port 44a, and when the pilot pressure is supplied to the pilot port 44a, the two common oil passages 21 are provided. , 22 are connected to each other and switched to a merging position (right side position in FIG. 1) that forms an oil passage that allows merging of the first pump oil and the second pump oil, and as the pilot pressure increases, the merging flow rate increases. While operating to increase, when the pilot pressure is not supplied to the pilot port 44a, the two common oil passages 21 and 22 are not joined but do not join (that is, the oil passage for the joining is shut off) It is held at the position (left side position in FIG. 1).

  The merging switching operation valve 46 is interposed between the pilot hydraulic power source 45 and the pilot port 44a, and is closed when no input of a merging command signal described later is received from the pilot hydraulic power source 45 to the pilot port. The supply of pilot pressure to 44a is blocked, and when the input of the merging command signal is received, the valve is opened at an opening corresponding to the signal to allow the supply of the pilot pressure.

  Note that the merging switching valve 44 may be a simple electromagnetic switching valve, or, for example, a traveling straight valve for preventing traveling deflection when an attachment operation and a traveling operation are performed simultaneously. It is also possible to divert to the merging switching valve 44. In the present invention, the junction switching valve 44 can be omitted as appropriate.

  The apparatus shown in FIG. 1 performs the operation of the pilot pressure limiting valves 37A and 37B, the control of the capacities of the hydraulic pumps 11 and 12, and the switching control of the merging switching valve 44 in addition to the above components. As means, there are provided a plurality of pressure sensors provided in the circuit, and a controller 60 that receives a detection signal generated by these pressure sensors and performs a control operation.

  The pressure sensor includes a first pump pressure sensor 51 that detects a first pump pressure, that is, a discharge pressure of the first pump 11, and a second pump pressure that detects a second pump pressure, that is, a discharge pressure of the second pump 12. A sensor 52, arm pilot pressure sensors 53A and 53B for detecting a head side pilot pressure (arm pulling side pilot pressure) and a rod side pilot pressure (arm pushing side pilot pressure) output from the arm operating unit 31; And optional pilot pressure sensors 54A and 54B for detecting the head side pilot pressure (closed side pilot pressure in the case of nibbler) and the rod side pilot pressure (open side pilot pressure in the case of nibbler), respectively, output from the operating device 32. It is.

  The controller 60 comprises a computer or the like, and has a pilot pressure limit switching unit 62, a pump flow rate control unit 64, and a merging switching valve control unit 66 as shown in FIG.

  In this embodiment, the pilot pressure limit switching unit 62 simultaneously performs an operation for moving the arm cylinder 7 corresponding to the main actuator according to the present invention and an operation for moving the option cylinder 8 corresponding to the option actuator. At the time of simultaneous operation, a command signal is input to the corresponding pilot pressure limiting valve among the pilot pressure limiting valves 37A and 37B to limit the corresponding pilot pressure, thereby increasing the stroke of the direction switching valve 15. While restricting the flow path area at the drive position, while operating for moving the arm cylinder 7 in a state where the operation for moving the optional cylinder 8 is not performed, Stop input of command signals to the pilot pressure limiting valves 37A and 37B and Releasing restriction of pilots pressure (i.e. aperture flow area).

  More specifically, the pilot pressure limit switching unit 62 detects the output of the pilot pressure from one of the arm pilot pressure sensors 53A and 53B and one of the optional pilot pressure sensors 54A and 54B. Then, a command signal (pilot pressure limit command signal) is input to the pilot pressure limit valve corresponding to the detected pilot pressure among the pilot pressure limit valves 37A and 37B. For example, when a pilot pressure for extending the arm cylinder 7, that is, a pilot pressure to be input to the pilot port 15a is detected, the pilot pressure limit switching unit 62 inputs a command signal to the corresponding pilot limit valve 37A. To limit the pilot pressure. Conversely, when a pilot pressure for contracting the arm cylinder 7 is detected, a command signal is similarly input to the pilot restriction valve 37B to limit the pilot pressure.

  On the other hand, when either one of the arm pilot pressure sensors 53A and 53B detects the output of the pilot pressure in a state where both the optional pilot pressure sensors 54A and 54B have not detected the output of the pilot pressure, the pilot pressure The restriction valve 62 stops the input of the command signal and releases the restriction of the pilot pressure.

  Note that the pilot pressure limiting valves 37A and 37B when neither the arm operating unit 31 nor the optional operating unit 32 is operated, or when only the optional operating unit 32 is operated without operating the arm operating unit 31. The operation of is not particularly limited.

  Various modes of limiting the pilot pressure can be set. For example, as shown in FIG. 4A, in a region where the arm operation amount (the operation amount of the operation lever 31c for the arm cylinder 7) is a certain level or more, the pilot pressure for the arm (direction) regardless of the increase in the arm operation amount. The pilot pressure input to the pilot ports 15a and 15b of the switching valve 15) may be kept constant (that is, made to reach a peak), or as shown in FIG. The pilot pressure for the arm corresponding to the arm operation amount may be decreased at an appropriate ratio. The degree of restriction will be described in detail later.

  The pump flow rate control unit 64 corresponds to the pump flow rate control unit according to the present invention, and the discharge flow rate, that is, the first and second pump flow rates are changed by changing the capacities of the first and second pumps 11 and 12. Control. The pump flow rate control unit 64 according to this embodiment performs both horsepower control (so-called PQ control). Specifically, a) a first pump pressure P1 and a second pump pressure P2 detected by the first pump pressure sensor 51 and the second pump pressure sensor 52, respectively, and b) an average value of both pump pressures (hereinafter, “ It is referred to as “average pump pressure.”) Each hydraulic pump 11 is based on a horsepower characteristic set in advance for the product of Pa (= (P1 + P2) / 2) and the average value of the capacities of the first and second pumps. , 12 is calculated, and the capacity for calculating the horsepower of each of the hydraulic pumps 11, 12 is determined based on the average value q. And a capacity | capacitance control signal is input into the regulators 21a and 22a attached to each hydraulic pump 11 and 12 so that this determined pump capacity | capacitance may be obtained, respectively.

  As the horsepower characteristics, for example, characteristics as shown in FIG. 5 are used. This characteristic is that the pump capacity average value is maintained at the maximum value qmax in the region where the average pump pressure Pa is equal to or lower than the preset pump pressure Pc, and the average pump pressure is maintained in the region where the average pump pressure Pa exceeds the set pump pressure Pc. This is a characteristic of decreasing the pump capacity average value q as the average pump pressure Pa increases so as to keep the product of the pressure Pa and the pump capacity average value q substantially constant.

  The pump flow rate control unit 64 according to this embodiment sets the capacities of both the hydraulic pumps 11 and 12 to the average value q. However, the present invention is not limited to this. For example, the capacities of the first and second pumps 11 and 12 may be slightly different from each other within the range of the condition that the average value q is satisfied.

  Moreover, the pump flow rate control part which concerns on this invention is not limited to what performs only the said horsepower control. For example, the pump flow rate control unit is commensurate with the pump capacity calculated for horsepower control as described above and so-called position control, that is, the operation amounts of the arm operation lever 31c and the option operation lever 32c. The pump capacity calculated for the control for setting the pump capacity may be compared, and the lower one of them may be determined as the final pump capacity.

  The merging switching valve controller 66 does not input a merging command signal to the merging switching operation valve 46 at the time of simultaneous operation in which the arm operating unit 31 and the optional operating unit 32 are operated at the same time. While the pilot pressure input to 44a is blocked and the merging switching valve 44 is held in the non-merging position, the merging switching operation is performed when the optional operating unit 32 is operated without the arm operating unit 31 being operated. The merging command signal is input to the valve 46 to allow the pilot pressure to be input, so that the merging switching valve 44 is switched to the merging position, and the merging flow rate increases as the operation amount of the option operating unit 32 increases. The pilot pressure is changed.

  Next, the specific control contents of the controller 60 and the operation of the apparatus based thereon will be described.

  First, when both the arm operation unit 31 and the option operation unit 32 are operated, that is, when the operation for moving both the arm cylinder 7 and the option cylinder 8 is performed at the same time, the controller 60 The merging switching valve controller 66 holds the merging switching valve 44 at the non-merging position, while the pilot pressure limit switching unit 62 of the controller 60 sends a command signal to the corresponding pilot pressure limiting valve among the pilot pressure limiting valves 37A and 37B. (Pilot pressure limit command signal) is input, thereby suppressing the stroke of the direction switching valve 15, that is, the first main control valve. The suppression of the stroke means the restriction of the flow path area at the direction switching valve 15.

  At the time of this simultaneous operation, the drive load of the option cylinder 8 is smaller than the drive load of the arm cylinder 7, so that the hydraulic oil discharged from the first pump 11, that is, the first pump oil is supplied to both the direction switching valves 15 and 16. Despite being opened, the fuel is supplied biased toward the option cylinder 8 having a small driving load. In addition, since the flow rate of the hydraulic oil supplied from the first pump 11 to the arm cylinder 7 through the direction switching valve 15 is very small, the increase in the first pump pressure P1 due to the throttle of the direction switching valve 15 is hardly increased. Therefore, the average pump pressure Pa is maintained at a pressure lower than the set pump pressure Pc shown in FIG. 5, for example, the pump pressure Pa1 shown in FIG. Therefore, the pump flow rate control unit 64 maintains the capacities of the first and second pumps 11 and 12 at the maximum flow rate qmax, respectively.

  Therefore, in this state, as schematically shown in FIG. 6, the arm cylinder 7 is substantially supplied with hydraulic oil at a flow rate Qm corresponding to the maximum capacity qmax only from the second pump 12, and the option cylinder 8 is substantially Similarly, hydraulic oil is supplied from only the upper first pump 11 at a flow rate Qm corresponding to the maximum capacity qmax.

  Thereafter, when the option cylinder 8 reaches the stroke end, there is no place for hydraulic oil to flow from the first pump 11 to the option cylinder 8 at that time, so that the entire amount of the first pump oil is moved to the arm cylinder 7 side which is the main actuator. Will flow. Therefore, if no countermeasure is taken, as shown in FIGS. 7A and 8, the supply flow rate of hydraulic oil to the option cylinder 8 is 0 when the option cylinder 8 reaches the stroke end. On the other hand, the supply flow rate of the hydraulic oil to the arm cylinder 7 is doubled (≈2Qm), and the arm cylinder 7 may be unduly significantly increased in speed. However, in the apparatus according to this embodiment, the combination of the restriction of the flow path area by limiting the pilot pressure for the directional switching valve 15 and the horsepower control based on the characteristics shown in FIG. Prevent significant acceleration.

  Specifically, when the optional cylinder 8 reaches the stroke end and the flow rate of the first pump oil in the direction switching valve 15 increases, the flow area of the direction switching valve 15 is reduced, and the first pump pressure P1. Rises to a pump pressure at which the average pump pressure Pa, which is the average pressure of the first pump pressure P1 and the second pump pressure P2, exceeds the set pump pressure Pc shown in FIG. 5, for example, to the pump pressure Pa2 shown in FIG. To rise. Correspondingly, the pump flow rate control unit 64 sets the capacity of the first and second pumps 11 and 12 to a capacity smaller than the maximum capacity qmax (for example, the pump pressure Pa2 shown in FIG. 5) based on the horsepower control characteristics shown in FIG. In this case, the pump capacity is reduced to the corresponding pump capacity q2). As a result, the discharge flow rates of the first and second pumps 11 and 12 are suppressed to αQm (α <1), which is a flow rate smaller than the flow rate Qm, as shown in FIG. Even if the total amount is joined to the arm cylinder 7, the supply flow rate is 2αQm, and the difference (= 2αQm−Qm) from the supply amount Qm before reaching the stroke end is kept small by α. In particular, as shown in FIG. 4 (a) or (b) so that α≈0.5, that is, the pump capacity calculated by the pump flow rate control unit 64 is substantially halved before and after reaching the stroke end. If the pilot pressure limiting characteristic is set, as shown in FIG. 9, the flow rate of the hydraulic oil supplied to the arm cylinder 7 will maintain 2αQm≈Qm regardless of the arrival of the stroke end. It is possible to prevent fluctuations in the operating speed of the arm cylinder 7.

  In other words, according to this device, the stroke end is limited only by the restriction of the pilot pressure and the execution of the horsepower control without detecting the stroke end of the option cylinder 8 and performing complicated control based on the detection. It is possible to automatically mitigate fluctuations in the operating speed of the arm cylinder 7 due to the arrival of.

  On the other hand, when only the operation of the arm cylinder 7 (operation of the operation lever 31c) is performed when the operation of the option cylinder 8 is not performed, the pilot pressure limit switching unit 62 is The pilot pressure limit command signal is not input to the pilot pressure limit valves 37A and 37b. Therefore, the direction switching valve 15 as the first main control valve operates with a stroke corresponding to the operation amount of the operation lever 31c, and the flow passage area is not throttled. As a result, the hydraulic oil can be supplied to the arm cylinder 7 at a sufficient flow rate through both the first and second main supply oil passages to which the direction switching valves 15 and 19 belong, respectively.

  Furthermore, in this embodiment, the merging switching valve controller 66 of the controller 60 keeps the merging switching valve 44 in the non-merging position during the simultaneous operation, and shuts off the merging oil passages (that is, the common oil passages 21, 22). Can be prevented from abruptly changing the hydraulic oil supply flow rate to the arm cylinder 7 when the option cylinder 8 reaches the stroke end, while the option operator 32 is not operated without the arm operator 31 being operated. When only the operation is performed, by switching the merging switching valve 44 to the merging position, hydraulic oil is allowed to be supplied to the option cylinder 8 from both the first and second pumps 11 and 12, and the option cylinder is concerned. Allows a speed increase of 8.

  In the present invention, the stroke limit of the first main control valve represented by the directional switching valve 15 is not limited to the reduction of the pilot pressure, but is physically applied to a valve body (for example, a spool) that operates the stroke in the first main control valve. The stroke may be limited by touching it. An example thereof is shown in FIG. 10 as a second embodiment.

  The apparatus according to the second embodiment is provided with strokes provided in both operating directions of the direction switching valve 15 instead of the pilot pressure limiting valves 37A and 37B according to the pilot pressure limiting valve according to the first embodiment. Restricting devices 70A and 70B are provided. Each of the stroke limiting devices 70A and 70B has stoppers 76A and 76B and switching valves 74A and 74B for switching the operating states of the stoppers 76A and 76B, respectively.

  Each of the stoppers 76A and 76B is composed of a one-way drive type simple hydraulic cylinder, a cylinder main body 76c, a piston 76p loaded therein, and a rod 76r extending from the piston 76p to the outside of the cylinder main body 76c. , And a spring 76s that urges the piston 76p in a direction in which the rod 76r moves backward. The rod 76c protrudes only when hydraulic oil is supplied to the head side chamber of the cylinder body 76c so that the spool stroke of the direction switching valve 15 is limited, that is, the spool stroke is constant. The stoppers 76A and 76B are arranged so that the tip of the rod 76c comes into contact with this to stop further stroke when it reaches.

  The switching valves 74A and 74B are respectively provided in the middle of oil passages connecting the hydraulic pressure source 72 and the head side chambers of the stoppers 76A and 76B. Each switching valve 74A, 74B has a solenoid 75, and when a command signal is not input to this, the rod 76c protrudes by allowing the hydraulic oil to be supplied to each head side chamber by opening the oil passage. The stoppers 76A and 76B are actuated to limit the stroke of the direction switching valve 15. On the other hand, when a command signal is input, the oil passage is shut off and the supply of the working oil is stopped, so that the rod 76c moves backward. The stoppers 76A and 76B are actuated in the direction to release the stroke restriction.

  The controller 60 inputs a command signal to the solenoid 75 of the corresponding switching valve among the switching valves 74A and 74B at the same time when the operation of the option cylinder 8 and the operation of the arm cylinder 7 are performed simultaneously. While the corresponding one of the stoppers 76A and 76B is operated in the extending direction to limit the stroke of the direction switching valve 15, the input of the command signal is stopped when the arm cylinder 7 is operated alone to limit the stroke. Is released.

  The throttle switching device according to the first and second embodiments described above uses the directional switching valve 15 which is the first main control valve to throttle the flow area of the first main supply oil passage and release it. Although performed, the present invention is not limited in terms of the specific means for its throttling and throttling. For example, a variable throttle valve dedicated to throttle switching provided separately from the first main control valve may be used.

  FIG. 11 shows a third embodiment of the present invention. In this embodiment, the direction switching valve 15 is located downstream of the meter-in flow path of the direction switching valve 15 according to the first embodiment. Independent variable throttle valves 80A and 80B are provided. Each of the variable throttle valves 80A and 80B has a valve element that operates to change the flow path area and a solenoid 82, and throttles the flow path area to a degree corresponding to a command signal input to the solenoid 82. Operates on. Each solenoid 82 is connected to the controller 60, and the controller 60 inputs a command signal to the solenoid 82 of the corresponding one of the variable throttle valves 80A and 80B when the option cylinder 8 and the arm cylinder 7 are operated simultaneously (first operation). While the flow area of the main supply oil passage is reduced, when the option cylinder 8 is not operated and only the arm cylinder 7 is operated, the input of the command signal is stopped to reduce the flow area. Release the aperture.

  FIG. 12 shows a fourth embodiment of the present invention. In this embodiment, the branch oil passage 25 located upstream of the direction switching valve 15 in the meter-in oil passage of the arm cylinder 7 is shown. A variable throttle valve 80C equivalent to the variable throttle valves 80A and 80B is provided on the way. It is also possible to switch the throttle of the “first main supply oil passage” according to the present invention by operating the variable throttle valve 80C. As described above, in the present invention, when the throttle valve different from the first main control valve is provided, the arrangement position may be on the upstream side or the downstream side of the first main control valve.

  When the merging switching valve is provided in the present invention, the merging switching valve is connected to the common oil passages 21 and 22 prepared for the first and second pumps 11 and 12, respectively, like the merging switching valve 44 shown in FIG. It is not limited to what is connected. For example, as in the apparatus shown in FIG. 13 as the fifth embodiment, a confluence oil passage 84 that connects the discharge port of the second pump 12 and the inlet port of the direction switching valve 16 that is an optional control valve, It may be provided with a check valve 85 and an on-off valve 86 provided in the middle of the merging oil passage 84. The on-off valve 86 is switched between a position at which the merging oil passage 84 is opened and a position at which the merging oil passage 84 is opened, and the opening / closing switching can also function as a “merging switching valve”.

  The hydraulic actuator corresponding to the “main actuator” according to the present invention is not limited to the arm cylinder 7. For example, the main actuator may be the boom cylinder 6.

DESCRIPTION OF SYMBOLS 1 Base machine 2 Work attachment 3 Optional equipment 4 Boom 5 Arm 6 Boom cylinder 7 Arm cylinder (main actuator)
7a Head side oil passage 7b Rod side oil passage 7c Head side oil passage 7d Rod side oil passage 8 Option cylinder (option actuator)
8a Head side oil passage 8b Rod side oil passage 11 First pump 12 Second pump 15 Direction switching valve (first main control valve)
16-way switching valve (optional control valve)
19 Directional switching valve (second main control valve)
31 Arm controller (main controller)
32 Option actuator 33 First relief valve 37A, 37B Pilot pressure limiting valve 44 Junction switching valve 51, 52 Pump pressure sensor 53A, 53B Arm pilot pressure sensor 54A, 54B Optional pilot pressure sensor 60 Controller 62 Pilot pressure limit switching unit 64 Pump Flow control unit 66 Junction switching valve control unit 70A Stroke limiting device 72 Hydraulic source 74A Switching valve 75 Solenoid 76A Stopper 76c Cylinder body 76p Piston 76r Rod 80A Valve 80C Valve 82 Solenoid 84 Junction oil passage 85 Check valve 86 Open / close valve

Claims (5)

Provided on a work machine having a work attachment having a tip portion to which an optional device can be mounted, and controls the operation of a main actuator that drives the work attachment by hydraulic pressure and the operation of an optional actuator that drives the optional device by hydraulic pressure, respectively. A device for
A first pump and a second pump, each composed of a variable displacement hydraulic pump;
In a region where an average pump pressure, which is an average pressure of each discharge pressure of the first and second pumps, is equal to or lower than a preset pump pressure, the first flow rate is a flow rate of hydraulic oil discharged from the first and second pumps. Horsepower control for setting the pump flow rate and the second pump flow rate to maximum flow rates, respectively, and reducing the first and second pump flow rates as the average pump pressure increases in a region where the average pump pressure exceeds the set pump pressure. A pump flow rate controller for performing
A first main supply oil passage for guiding hydraulic oil discharged from the first pump to the main actuator;
An optional supply oil passage that guides hydraulic oil discharged from the first pump to the optional actuator in parallel with the first main supply oil passage;
A second main supply oil passage for guiding hydraulic oil discharged from the second pump to the main actuator;
A main controller operated to move the main actuator;
An option controller operated to move the option actuator;
A first main control valve that operates to control supply of hydraulic oil to the main actuator through the first main supply oil passage based on an operation of the main operating device;
An option control valve that operates to control supply of hydraulic oil to the option actuator through the option supply oil passage based on operation of the option actuator;
A second main control valve that operates to control the supply of hydraulic oil to the main actuator through the second main supply oil passage based on the operation of the main operating device;
In the simultaneous operation in which the operation for moving the main actuator and the operation for moving the option actuator are performed simultaneously, the average pump pressure exceeds the set pump pressure when the option actuator reaches the stroke end. The flow passage area of the first main supply oil passage is reduced, and the flow passage area is reduced during the single operation of the main actuator in which the operation for moving the main actuator is performed in the state where the operation for moving the optional actuator is not performed. A hydraulic control device for a work machine, comprising: a diaphragm switching device that releases   2. The hydraulic control apparatus for a work machine according to claim 1, wherein the first control valve forms a neutral position that blocks the first main supply oil passage and an oil passage that opens the first main supply oil passage. And increasing the flow passage area of the oil passage by opening the valve from the neutral position to the drive position with a stroke corresponding to the operation amount of the main operating device, In the simultaneous switching operation, the diaphragm switching device corresponds to the operation amount of the main actuator so that the average pump pressure exceeds the set pump pressure when the optional actuator reaches the stroke end. A work machine that restricts the stroke that the control valve operates from its neutral position and releases the stroke restriction when the main actuator is operated alone. Hydraulic control device.   3. The hydraulic control device for a work machine according to claim 2, wherein the main operating unit includes a remote control valve for inputting a pilot pressure having a magnitude corresponding to an operation amount thereof to the first main control valve, The main control valve is a pilot switching valve that operates from the neutral position with a stroke corresponding to the magnitude of the pilot pressure input from the remote control valve, and the throttle switching device moves from the remote control valve to the first main control valve. The pilot pressure limit valve operable to reduce the input pilot pressure, the pilot pressure limit valve is operated to reduce the pilot pressure during the simultaneous operation, and the pilot pressure is controlled when the main actuator is operated alone. An oil for a work machine, including a pilot pressure limit switching unit for canceling the reduction. The control device.   4. The hydraulic control device according to claim 1, wherein a joining position that forms an oil passage for joining the working oil discharged from the second pump to the working oil supplied to the optional actuator; A merge switching valve having a merge blocking position for blocking the oil passage; and when the optional actuator is operated in a state where the main actuator is not operated, the merge switching valve is switched to the merge position; A hydraulic control device for a work machine, further comprising: a merging switching valve control unit that switches the merging switching valve to the merging cutoff position during operation. A working machine,
A base machine,
A work attachment, a boom attached to the base machine so as to be raised and lowered, an arm rotatably connected to a tip of the boom, and interposed between the boom and the arm with respect to the boom Including an arm cylinder that expands and contracts to rotate the arm, and a boom cylinder that extends between the boom and the base machine to expand and contract the boom.
A work machine comprising: the hydraulic control device according to claim 1, wherein the hydraulic control device controls an operation of the boom cylinder or the arm cylinder as the main actuator.

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