JP2007303584A - Hydraulic control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic control device for actualizing adequate relief pressure control corresponding to a load on a hydraulic actuator. <P>SOLUTION: The hydraulic control device 1 comprises a hydraulic pump 11 for feeding operating oil out of a tank 13, the hydraulic actuator 10 driven by the operating oil supplied from the hydraulic pump 11, a control valve 12 for controlling the flow of the operating oil supplied to the hydraulic actuator 10 by the hydraulic pump 11, a solenoid proportional relief valve 15 for controlling pressure in a hydraulic circuit in which the operating oil flows, a pair of pressure gauges 17, 18 for measuring the pressure of the operating oil which actuates the hydraulic actuator 10, and a controller 20 for controlling the solenoid proportional relief valve 15 in accordance with pressure values measured by the pressure gauges 17, 18. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hydraulic control apparatus for driving and controlling a hydraulic actuator constituting a hydraulic construction machine such as a hydraulic motor and a hydraulic cylinder, and in particular, a set value for a relief valve that holds a pressure in a hydraulic circuit within a predetermined value. The present invention relates to a hydraulic control apparatus that automatically adjusts according to work.

In foundation works such as construction and civil engineering, for example, a tubing device that generates high-torque rotation is used to rotationally press-fit a casing or steel pipe pile into the ground. The tubing device includes a chuck mechanism that grips a casing and a steel pipe pile, and is provided with a hydraulic motor that applies a rotational force to the gripped casing and the like, and a hydraulic actuator such as a hydraulic cylinder that raises and lowers the casing. In the tubing device, such a hydraulic actuator is joined to a hydraulic pump, and a hydraulic circuit is configured to be driven by supplied hydraulic oil. The hydraulic circuit is provided with a relief valve that performs pressure control so as to keep the pressure in the passage at a set value.
JP 11-292474 A

  By the way, it is desired that the tubing apparatus can handle a plurality of casings having different diameters. In that case, in order to grip casings and steel pipe piles having different diameters, it is necessary to replace the chuck claws of the chuck mechanism or adjust the rotational torque and pushing force of the hydraulic actuator according to the size. This is because if the small diameter casing is rotationally press-fitted with the rotational torque when constructing the large diameter casing, the small diameter casing with low rigidity may be forcibly twisted and deformed due to the large rotational torque, and may be further broken. . At this time, for example, in order to output a small rotational torque from the hydraulic motor, the set pressure of the relief valve provided in the hydraulic circuit is lowered.

However, if the relief pressure is set low, the hydraulic oil that flows through the hydraulic circuit and is supplied to the hydraulic motor is not able to obtain sufficient pressure when it reaches the hydraulic motor due to pressure loss due to resistance in the piping. For example, when a plunger pump is used as a hydraulic pump, since the flow rate of the horsepower control performed by the plunger pump increases as the pressure is lower, the hydraulic oil pressure in the pipe increases and hydraulic oil is discharged from the relief valve. The motor will not drive.
When the rotational torque is limited to a small value with respect to the small-diameter casing, first, the set pressure of the relief valve is adjusted with the maximum flow rate at the load to be limited. However, as shown in FIG. 6, the relief valve has a characteristic that when the flow rate is reduced, the relief pressure is lower than the set value. Therefore, when the small-diameter casing is rotated at a low speed, the flow rate from the hydraulic pump is reduced. As the pressure decreases, the relief pressure drops and the load on the hydraulic motor does not increase to the limit value.

The hydraulic cylinder, which is a hydraulic actuator for raising and lowering, is loaded with the weight of the tubing device itself such as the frame and chuck mechanism and the weight of the casing. Therefore, in order to set the relief pressure in consideration of the drawing load of the casing, the actual drawing force cannot be obtained unless the load of the casing and the device itself is subtracted, and the pressure setting is a troublesome work.
Therefore, conventionally, for example, it has been difficult to handle a small-diameter casing with a large-sized tubing device that handles a large-diameter casing or the like. Therefore, it has been necessary to prepare a tubing device that supports various-size casings.

  Therefore, an object of the present invention is to provide a hydraulic control device capable of adjusting to an appropriate relief pressure corresponding to a load applied to the hydraulic actuator in order to solve such a problem.

  A hydraulic control apparatus according to the present invention includes a hydraulic pump that sends hydraulic oil in a tank, a hydraulic actuator that is driven by hydraulic oil supplied from the hydraulic pump, and a flow of hydraulic oil that is supplied to the hydraulic actuator by the hydraulic pump. A control valve for controlling, an electromagnetic proportional relief valve for controlling the pressure of a hydraulic circuit through which hydraulic fluid flows, a pair of pressure measuring instruments for measuring the pressure of hydraulic fluid for operating the hydraulic actuator, and the pressure measuring instrument. And a controller that adjusts the electromagnetic proportional relief valve based on the pressure value.

The hydraulic control device according to the present invention stores control data for the controller to specify a relief pressure corresponding to a load received during work, obtains a substantial load from a measurement value of the pressure measuring instrument, It is preferable that the electromagnetic proportional relief valve is adjusted by sending a relief pressure relief command value corresponding to the load.
Further, in the hydraulic control apparatus according to the present invention, the hydraulic actuator is a hydraulic motor, the pressure measuring instrument is provided on both an input side and an output side of hydraulic oil that operates the hydraulic motor, and the controller Stores control data for specifying the relief pressure corresponding to the load received during work, calculates the differential pressure as the actual load from the measured values of the two pressure measuring instruments, and the relief pressure relief command value corresponding to the actual load It is preferable that the electromagnetic proportional relief valve be adjusted by sending

In the hydraulic control apparatus according to the present invention, it is preferable that the control data stored in the controller is configured to reduce the relief pressure as the load received during work increases.
In the hydraulic control device according to the present invention, the control data stored in the controller may be formed in accordance with a relief valve characteristic in which the relief pressure is lower than a set value as the hydraulic oil flow rate decreases. preferable.
Further, the hydraulic control device according to the present invention has a plurality of control data corresponding to the maximum load received by the controller during work and the flow rate sent from the hydraulic pump, and the hydraulic pump is input by inputting the maximum load to be limited. It is preferable that control data corresponding to the maximum flow rate is selected, and a relief command value of the relief pressure corresponding to the substantial load is sent from the control data to adjust the electromagnetic proportional relief valve.
Further, in the hydraulic control device according to the present invention, the controller compares the actual load obtained from the measurement value of the pressure measuring instrument with the maximum load, and when the actual load exceeds the maximum load, It is preferable that the control data is selected and the relief command value of the relief pressure corresponding to the substantial load is sent from the control data to adjust the electromagnetic proportional relief valve.

Therefore, according to the hydraulic control device of the present invention, the substantial load is calculated from the pressure of the hydraulic oil that drives the hydraulic actuator, and the relief pressure is automatically controlled based on the control data, thereby corresponding to the load applied to the hydraulic actuator. It becomes possible to adjust to an appropriate relief pressure.
Therefore, in the present invention, for example, when driving a small-diameter casing having a low strength or the like, when the load at the beginning of driving is small, there is no influence on the casing even if the rotational torque is large, so work is performed with a high relief pressure, When the load increases in accordance with the driving depth, the relief pressure can be lowered in accordance with the load so that excessive rotational torque does not act on the casing.

Next, an embodiment of a hydraulic control apparatus according to the present invention will be described below with reference to the drawings. In the present embodiment, a hydraulic control device constituting a tubing device will be described, and in particular, a hydraulic motor will be described as an example of a hydraulic actuator. Here, FIG. 5 is a diagram showing a tubing device.
In the tubing device 100, the casing 200 passes through the center and is gripped by the chuck 101. For this purpose, the chuck frame 103 is lowered by the contraction of the chuck cylinder 102, the plurality of chucks 101 are strongly inserted between the casing 200 and the cone 104, and the casing 200 is pressed and gripped by the chuck 101 in the axial direction. .

  When the gripped casing 200 is rotationally press-fitted into the ground, the hydraulic cylinder 110 contracts, whereby the gear frame 105 is lowered via the first guide cylinder 112, and further the chuck frame 103 connected by the chuck cylinder 102. Also descends at the same time. Further, the hydraulic motor 120 is driven, and high torque rotation is transmitted to the cone 104 provided in the gear frame 105. Therefore, the casing 200 gripped by the chuck 101 is pressed into the ground while rotating.

  On the other hand, when the casing 200 is pulled out, the elevating cylinder 110 extends, the gear frame 105 fixed to the first guide cylinder 112 rises, and the chuck frame 103 connected by the chuck cylinder 102 also rises simultaneously. Therefore, the casing 200 gripped by the chuck 101 is pulled out from the press-fitted ground. At this time, the hydraulic motor 120 is reversely rotated, and the casing 200 is pulled out while rotating in the direction opposite to that during press-fitting.

Next, a hydraulic control device provided in such a hydraulic construction apparatus 1 will be described. As described above, a hydraulic motor will be described as an example of the hydraulic actuator. FIG. 1 is a circuit diagram showing the hydraulic control apparatus according to this embodiment.
The hydraulic control device 1 is provided with a hydraulic pump 11 that supplies hydraulic oil to the hydraulic motor 10, and hydraulic oil that is supplied to the hydraulic motor 10 is connected to a hydraulic circuit that connects the hydraulic motor 10 and the hydraulic pump 11. Is connected to a direction switching valve 12 for inverting the input / output. The directional switching valve 12 can be switched between the neutral state shown in the figure, A port connection and B port connection by controlling the pilot pressure with an operation lever.

  The hydraulic pump 11 and the direction switching valve 12 are connected via a supply flow path 21, and the direction switching valve 12 and the tank 13 are connected by a discharge flow path 22. The supply flow path 21 and the discharge flow path 22 are connected via an electromagnetic proportional relief valve 15. In addition to the relief flow path 27 to which the electromagnetic proportional relief valve 15 is connected, the supply flow path 21 is connected to the neutral flow path 25 connected to the neutral port of the direction switching valve 12 and to the input port of the direction switching valve 12. The input channel 26 is branched. A check valve 14 is provided in the input flow path 26 so as to prevent backflow from the direction switching valve 12.

  The hydraulic motor 10 is capable of normal rotation and reverse rotation, and the supply / discharge ports 10 a and 10 b are connected to the direction switching valve 12 by a normal rotation side flow path 23 and a reverse rotation side flow path 24. The hydraulic motor 10 is provided with a braking means 16 by a spring return type hydraulic cylinder having a shoe attached to the tip of a piston rod. By the way, the direction switching valve 12 switches the connection between the supply flow path 21 or the discharge flow path 22, the forward rotation flow path 23, and the reverse rotation flow path 24. Specifically, the supply flow path 21 and the forward rotation flow path 23 are connected when the direction switching valve 12 is switched on the A port side, and the reverse rotation flow path 24 is connected with the supply flow path 21 when the B port side is switched. It has come to be.

  Further, in the hydraulic construction apparatus 1, the pressure sensors 17 and 18 are provided with the forward rotation side flow path 23 and the reverse rotation side flow path 24 in order to measure the input side pressure and the output side pressure of the hydraulic oil that drives the hydraulic motor 10. It is connected to the. A controller 20 is provided for controlling the electromagnetic proportional relief valve 15 based on the measurement values sent from the pressure sensors 17 and 18. Although the electromagnetic proportional relief valve 15 is not shown in detail, for example, an electromagnetic proportional solenoid is attached to the valve body, and the needle at the tip of the push rod that moves in the axial direction is adjusted by this solenoid, and the setting of the relief pressure is adjusted by the operation amount. It is what you do. The controller 20 stores a control program for adjusting the relief pressure by controlling the operation of the electromagnetic proportional relief valve 15.

  Next, the operation of the hydraulic control device 1 according to the present embodiment will be described on the assumption that the casing is rotationally press-fitted into the ground with the above-described tubing device. When the tubing device is activated, the engine rotates and the hydraulic pump 11 is driven. When the hydraulic oil in the tank 13 is pumped up by the hydraulic pump 11, the hydraulic oil is sent into the hydraulic circuit of the hydraulic control device 1 through the supply passage 21. When the operation lever is in the neutral state, the direction switching valve 12 is in the neutral port state as shown in the figure. Therefore, the hydraulic oil flowing through the supply flow path 21 flows through the neutral flow path 25 and is returned from the discharge flow path 22 to the tank 13.

  When the casing is rotationally press-fitted into the ground, that is, when the hydraulic motor 10 is rotated forward and the casing gripped by the chuck is rotated, the direction switching valve 12 is switched to the A port side by the operation lever. Then, the hydraulic oil pumped up by the hydraulic pump 11 flows from the supply flow path 21 to the input flow path 26, and flows to the forward rotation side flow path 23 via the direction switching valve 12. Therefore, the hydraulic oil supplied to the hydraulic motor 10 flows through the hydraulic motor 10 from the supply / discharge port 10a to 10b, and a positive rotation is generated in the hydraulic motor 10 by the pressure. Then, the hydraulic oil that has passed through the hydraulic motor 10 flows from the reverse flow path 24 to the discharge flow path 22 through the direction switching valve 12 and is returned to the tank 13 again.

  On the other hand, when the casing is pulled out from the ground, the direction switching valve 12 is switched to the B port side by the operation lever. In this case, the hydraulic oil pumped up by the hydraulic pump 11 flows from the supply flow path 21 to the input flow path 26, and flows to the reverse rotation-side flow path 24 via the direction switching valve 12. The hydraulic oil supplied to the hydraulic motor 10 flows from the supply / discharge port 10b to 10a, and reverse rotation occurs in the hydraulic motor 10 due to the pressure. The hydraulic oil that has flowed through the hydraulic motor 10 flows from the forward rotation side flow path 23 through the direction switching valve 12 to the discharge flow path 22 and is returned to the tank 13 again.

  In the tubing device, rotation is given to the casing thus gripped by the rotation of the hydraulic motor 10, but in this embodiment, the relief pressure is controlled by the controller 20 so that casings of various sizes of large and small diameters can be handled. Done. Therefore, as described above, when the hydraulic motor 10 is rotated by the hydraulic oil supplied from the hydraulic pump 11, the hydraulic pressures of the supply / discharge ports 10a and 10b are sequentially measured by the pressure sensors 17 and 18, and the measurement is performed. The value is sent to the controller 20.

  In the controller 20, the differential pressure at the input / output of the hydraulic motor 10 is obtained from the measured values of the pressure sensors 17 and 18, thereby obtaining the actual load applied to the hydraulic motor 10 during work. The controller 20 stores control data for specifying the relief pressure corresponding to the load. FIG. 3 is a diagram showing control data for controlling such an electromagnetic proportional relief valve 15, which shows the relief pressure of the electromagnetic proportional relief valve 15 corresponding to the load of the hydraulic motor 10. A plurality of such control data are provided in accordance with the maximum load N and flow rate to be restricted. In addition, | A−B | is a value indicating a difference between the measurement value A of the pressure sensor 17 and the measurement value B of the pressure sensor 18, and is calculated at both the forward rotation and the reverse rotation. Seeking.

  In the tubing device, the relief pressure of the electromagnetic proportional relief valve 23 is usually set corresponding to the large diameter casing. However, when constructing a small-diameter casing, relief pressure control according to the control data is performed so that excessive rotational torque is not output from the hydraulic motor 10. The small diameter casing has a small resistance to the small diameter casing when the depth to the ground is small, so that even if a large rotational torque is generated, the small diameter casing can be rotationally pressed into the ground without deformation. However, since the load received by the small-diameter casing increases as the press-fitting depth increases, if the operation is continued with a large rotational torque, the small-diameter casing is deformed such as torsion. Therefore, in the present embodiment, the pressure of the hydraulic oil supplied to the hydraulic motor 10 is reduced by controlling the relief pressure in order to reduce the rotational torque as the rotational resistance increases.

  Here, FIG. 2 is a view showing a flowchart for performing the relief pressure control of the electromagnetic proportional relief valve 15. The controller 20 stores a control program for executing this. A tubing device for constructing a small-diameter casing, in which the chuck claw of the chuck mechanism is replaced according to the size of the casing. In the hydraulic control apparatus 1, the large diameter mode is switched to the small diameter mode, and the program shown in the flowchart of FIG. 2 is executed by the controller 20. In the case of the large diameter mode, the relief pressure of the electromagnetic proportional relief valve 15 is set to the maximum, and an operation for generating a high rotational torque from the hydraulic motor 10 is performed.

  On the other hand, in the small-diameter mode, first, the flowchart shown in FIG. Then, a maximum load (rotational torque) N to be limited in advance is input to the controller 20 by the operator. Then, the relief pressure input value K is set from the control data corresponding to the value of the maximum load N (S101). That is, when the operator inputs the maximum load N applied to the casing, the control data shown in FIG. 3 corresponding to the maximum flow rate of the hydraulic pump 11 is selected, and the input value corresponding to the maximum load N is selected from the control data. K is set. Then, a control signal of the command value K is sent from the controller 20 to the electromagnetic proportional relief valve 15, and the relief pressure is adjusted there.

  In the rotary press-fitting of the small-diameter casing, the hydraulic motor 10 is rotated by the hydraulic oil supplied from the hydraulic pump 11 as described above. At this time, each pressure value on the input / output side of the hydraulic motor 10 measured by the pressure sensors 17 and 18 is transmitted to the controller 20. In the controller 20, the differential pressure | A−B | at the input / output of the hydraulic motor 10 is calculated from the measured values A and B, and the differential pressure is compared with the maximum load N previously input as a load applied to the casing. (S102). If the actual load | A−B | is equal to or greater than the maximum load N (S102: NO), the control data is out of the control range as can be seen from the corresponding control data shown in FIG. Then, the maximum load (rotational torque) N to be limited in advance is input, and the input value K associated therewith is reset (S101).

  On the other hand, if the actual load | A−B | is less than the maximum load N (S102: YES), the process proceeds to the next step and it is confirmed whether or not a load is applied to the casing (S103). Normally, resistance is not received until the small-diameter casing enters the ground, so the casing does not receive resistance and the actual load | AB | becomes zero (S103: YES). At this time, the set pressure of the electromagnetic proportional relief valve 15 is controlled to be the maximum relief pressure Kmax from the control data shown in FIG. 3 (S104). That is, the control signal of the maximum value Kmax is sent from the controller 20 to the electromagnetic proportional relief valve 15 to adjust the relief pressure.

  Then, the actual load | A−B | is calculated again from the measured values from the pressure sensors 17 and 18, and compared with the maximum load N (S102). Immediately after the start of construction, since the resistance to the casing that is rotationally press-fitted into the ground is small, the value of the substantial load | AB | is also small (S102: YES). However, the small-diameter casing is subjected to a load due to the resistance at the time of rotational press-fitting (S103: NO). Therefore, the relief pressure of the electromagnetic proportional relief valve 15 becomes, for example, the relief command value Kref (relief pressure k) corresponding to the n value from the control data shown in FIG. 3 when the substantial load | AB− = n. Control is performed as described above (S105). For this purpose, a control signal of the relief command value Kref is sent from the controller 20 to the electromagnetic proportional relief valve 15 to adjust the relief pressure.

  As the work progresses and the casing is driven deep into the ground, the load on the casing gradually increases, and the differential pressure | A−B | obtained from the measured values of the pressure sensors 17 and 18 indicating the value also increases. Then, the controller 20 sequentially calculates a substantial load | A−B | of the casing, and sends a relief command value Kref corresponding to the load to the electromagnetic proportional relief valve 15 as a control signal from the control data shown in FIG. The proportional relief valve 15 repeatedly adjusts the relief pressure of the hydraulic circuit (S102, S103, S105). As the casing is further driven, the rotational resistance to the casing increases and the actual load | AB | exceeds the maximum load N controlled (S102: NO).

  When the load increases in this way, in order to prevent deformation of the small-diameter casing, for example, the flow rate is decreased, the rotation of the hydraulic motor 10 is reduced, and the load is reduced to continue the operation. At that time, in the hydraulic control device 1, the variable hydraulic pump 11 decreases the hydraulic oil feed flow rate in order to reduce the rotation of the hydraulic motor 10. In addition, the relief pressure that has been set decreases as the flow rate of the hydraulic oil flowing through the hydraulic circuit decreases. Since the controller 20 stores control data corresponding to the flow rate in addition to the control data shown in FIG. 3, the substantial load | A−B | is equal to or greater than the maximum load N (S102: NO) as described above. In this case, a load (rotational torque) N is newly input, and an input value K corresponding to the maximum load N is set from another control data.

Therefore, the control signal of the command value K is sent from the controller 20 to the electromagnetic proportional relief valve 15, and the relief pressure is adjusted there. Therefore, in the subsequent work, the relief pressure adjustment by controlling the electromagnetic proportional relief valve 15 by the controller 20 is repeated based on another new control data as shown in FIG. 3 (S102, S103, S105).
In the meantime, the description has been given of the rotary press-fitting of the casing. However, when the casing is pulled out, the resistance gradually decreases and the substantial load | AB | also decreases. Therefore, the controller 20 sends a control signal for the relief command value Kref to the electromagnetic proportional relief valve 15 as the load decreases, and the relief pressure is adjusted there.

In the hydraulic control apparatus 1 of the present embodiment, the substantial load | A−B | is calculated from the differential pressure of the hydraulic oil that drives the hydraulic motor 10 that is a hydraulic actuator, and the relief pressure is automatically controlled based on the control data. It has become possible to adjust the pressure to an appropriate relief pressure corresponding to the load applied to the hydraulic actuator.
Therefore, when driving a small-diameter casing with low strength, etc., when the load at the beginning of driving is small, there is no effect on the casing even if the rotational torque is large. When the load increased, it was possible to reduce the relief pressure according to the load so that excessive rotational torque did not act on the casing.

Moreover, since the load state such as a low load can be determined by measuring the substantial load with the hydraulic sensors 17 and 18, the load is reduced by controlling the electromagnetic proportional relief valve 15 so as to increase the relief pressure. Occasionally, the hydraulic oil discharged through the relief valve can be eliminated, and efficient work can be performed by the hydraulic actuator.
In addition, since the actual load is calculated from the measured values of the hydraulic sensors 17 and 18 and the relief pressure is controlled, even when it is desired to limit the output of the hydraulic actuator to a very small load such as the hydraulic motor 10 or other hydraulic cylinders, the hydraulic pressure is controlled. The relief pressure can be set without being affected by the constant pressure due to the pressure loss or the dead weight in the circuit. Therefore, even if the pressure in the hydraulic circuit is a value close to the relief pressure, the working speed does not become extremely slow.
Furthermore, when the flow rate of hydraulic oil is changed using a plunger pump, the relief pressure is controlled by the control data stored in the controller 20 even if there is a characteristic that the relief pressure falls below the set value due to the change in flow rate. Can be kept constant.

Although one embodiment of the hydraulic control device 1 according to the present invention has been described above, the present invention is not limited to this, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above embodiment, the control data for controlling the electromagnetic proportional relief valve 15 by the controller 20 is shown in FIG. 4, but the relief valve characteristic that the relief pressure drops below the set value due to the flow rate change is shown. Control data as shown in FIG. 4 may be used. According to this, the adjustment control width of the relief command value Kref, that is, the width between the input value K corresponding to the maximum load N and the maximum value Kmax can be reduced.
Further, in the previous embodiment, the description has been made in relation to the tubing device, but the hydraulic control device may be related to another construction device. The hydraulic actuator may be not only a hydraulic motor but also a hydraulic cylinder. In that case, the hydraulic pressure is measured and the actual load is calculated in the same manner as in the above embodiment, and the relief pressure is adjusted and controlled accordingly. You can do it.

It is a circuit diagram showing a hydraulic control device of this embodiment. It is the figure which showed the flowchart which performs relief pressure control of an electromagnetic proportional relief valve. It is the figure shown about the control data for controlling an electromagnetic proportional relief valve. It is the figure shown about the other control data for controlling an electromagnetic proportional relief valve. It is the figure which showed the tubing apparatus. It is the figure which showed the characteristic of relief as a graph.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hydraulic construction apparatus 10 Hydraulic motor 11 Hydraulic pump 12 Direction switching valve 13 Tank 15 Electromagnetic proportional relief valve 17, 18 Pressure sensor 20 Controller 21 Supply flow path 22 Discharge flow path 23 Forward rotation side flow path 24 Reverse rotation side flow path

Claims (7)

A hydraulic pump that delivers hydraulic fluid in the tank;
A hydraulic actuator driven by hydraulic oil supplied from the hydraulic pump;
A control valve for controlling the flow of hydraulic oil supplied to the hydraulic actuator by a hydraulic pump;
An electromagnetic proportional relief valve that controls the pressure of the hydraulic circuit through which hydraulic fluid flows;
A pair of pressure measuring instruments for measuring the pressure of the hydraulic oil that operates the hydraulic actuator;
And a controller that adjusts the electromagnetic proportional relief valve based on the pressure value measured by the pressure measuring instrument. In the hydraulic control device according to claim 1,
The controller stores control data for specifying a relief pressure corresponding to a load received during work, obtains a substantial load from a measurement value of the pressure measuring instrument, and calculates a relief pressure relief command value corresponding to the substantial load. A hydraulic control apparatus characterized in that the electromagnetic proportional relief valve is sent to adjust. In the hydraulic control device according to claim 1,
The hydraulic actuator is a hydraulic motor, and the pressure measuring device is provided on both an input side and an output side of hydraulic oil that operates the hydraulic motor, and the controller applies a relief pressure corresponding to a load received during work. The control data for specifying is stored, the differential pressure is obtained as the actual load from the measured values of the two pressure measuring instruments, and the relief command value of the relief pressure corresponding to the actual load is sent to adjust the electromagnetic proportional relief valve. A hydraulic control device characterized by being performed. In the hydraulic control device according to claim 2 or claim 3,
The control data stored in the controller is such that the relief pressure is lowered as the load received during work increases. In the hydraulic control device according to claim 4,
The control data stored in the controller is formed according to the characteristic of the relief valve in which the relief pressure drops below a set value as the flow rate of hydraulic oil decreases. The hydraulic control device according to any one of claims 2 to 5,
The controller has a plurality of control data corresponding to the maximum load received during work and the flow rate sent from the hydraulic pump, and the control data corresponding to the maximum flow rate of the hydraulic pump is selected by inputting the maximum load to be limited. The hydraulic control device is characterized in that a relief command value of a relief pressure corresponding to the substantial load is sent from the control data to adjust the electromagnetic proportional relief valve. In the hydraulic control device according to claim 6,
The controller compares the actual load obtained from the measurement value of the pressure measuring instrument with the maximum load, and when the actual load exceeds the maximum load, selects another control data, A hydraulic control apparatus, wherein a relief command value of a relief pressure corresponding to a load is sent to adjust the electromagnetic proportional relief valve.

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