JP6585401B2 - Control device for work machine - Google Patents

Description

  The present invention relates to a control device for a work machine that is provided in a work machine such as a hydraulic excavator and is suitable for driving a work machine by discharging hydraulic oil from a plurality of hydraulic pumps to a hydraulic actuator.

  Conventionally, loss of throttling of hydraulic pump discharge by bleed-off control in order to achieve lower fuel consumption of work machines such as excavators and higher efficiency of hydraulic systems used to drive work machines such as arms As one of the prior arts that improve the operating performance by improving the energy efficiency and controlling the discharge pressure of the hydraulic pump according to the operation amount of the operating device, for example, the following patent A control device for a work machine described in Document 1 is known.

  In this prior art work machine control device, the controller calculates a target pump discharge pressure that increases as the operation amount signal increases, based on the operation amount signal from the operation amount detector; A pump flow rate upper limit setting unit that calculates a pump flow rate upper limit value that increases as the operation amount signal increases based on the operation amount signal, and the target pump discharge pressure calculated by the target pump pressure setting unit and the pump flow rate upper limit value The tilt amount of the hydraulic pump is controlled based on the pump flow rate upper limit value calculated by the setting unit and the discharge pressure of the hydraulic pump detected by the pressure detector.

International Publication No. 2014/073541

  In the prior art work machine control device disclosed in Patent Literature 1 described above, even in a work machine having a plurality of hydraulic actuators for one hydraulic pump, there is no independent operation interference with other hydraulic actuators. As a result, there is no loss of excess oil from the hydraulic pump, and excellent flow efficiency can be obtained in the hydraulic system. However, in order to increase the operating speed of the hydraulic actuator, the flow rates of hydraulic oil (pressure oil) discharged from a plurality of hydraulic pumps such as two hydraulic pumps and three hydraulic pumps are combined to act on the hydraulic actuator. When the above-described prior art work machine control device is applied to a work machine such as a hydraulic excavator, there is a possibility that a problem may occur.

  For example, since the operation of an arm of a hydraulic excavator requires a higher speed than that of a boom or bucket, when operating the arm at a high speed in a work machine including a plurality of hydraulic pumps, Among them, after the hydraulic oil discharged from the first hydraulic pump and the second hydraulic pump is circulated to the directional control valves, these hydraulic oils are joined by the oil passages / pipings connected to the arm cylinder. Supplying to an arm cylinder is generally performed.

  On the other hand, in the control device for a work machine of the prior art, the amount of tilt of the hydraulic pump is determined based on the target pump discharge pressure calculated by the controller at the target pump pressure setting unit and the discharge pressure of the hydraulic pump detected by the pressure detector. In consideration of the flow of hydraulic oil to the arm cylinder in the above-mentioned work machine, there is a difference in the accuracy of pressure control of each hydraulic pump, or a pipe or directional control valve connected to the hydraulic circuit, etc. Due to variations in equipment such as the resistance of oil passages and piping resulting from differences in configuration, there is a possibility of deviation from what was planned to be the distribution of the discharge amount of the first hydraulic pump and the second hydraulic pump There is. In this case, since the discharge pressure is controlled for each of the first hydraulic pump and the second hydraulic pump, the amount of hydraulic oil supplied from the flowable side of these hydraulic pumps increases, The amount of hydraulic oil supplied from the difficult side is reduced. As described above, there is a concern that the flow rate of the hydraulic oil from the first hydraulic pump and the second hydraulic pump is not determined as expected due to variations in devices, and the control performance of the hydraulic actuator is degraded.

  The present invention has been made in view of the actual situation of the prior art as described above, and the object thereof is due to variations in equipment even in a working machine in which a hydraulic actuator is operated by hydraulic oil discharged from a plurality of hydraulic pumps. An object of the present invention is to provide a control device for a work machine that can solve the problem and obtain good control performance of a hydraulic actuator.

In order to achieve the above object, a control device for a work machine according to the present invention includes a plurality of hydraulic pumps that are driven by a prime mover and have a control unit for controlling a flow rate, and hydraulic oil discharged from the plurality of hydraulic pumps. A hydraulic actuator that operates according to the above, an operating device that instructs the operation of the hydraulic actuator, and a first and a second that respectively control the flow of hydraulic oil discharged from the first and second hydraulic pumps of the plurality of hydraulic pumps Provided in a work machine having a directional control valve 2 and a merging circuit that causes the hydraulic oil flowing through the first and second directional control valves to merge and act on the hydraulic actuator. In response to the above, in the control device for a work machine including a hydraulic control unit that controls a flow rate of hydraulic oil discharged from the plurality of hydraulic pumps to the hydraulic actuator, Between the discharge pressure detector for detecting a delivery pressure of the hydraulic pump, a speed detecting device for detecting the speed of the hydraulic actuator, and the first and second hydraulic pumps and said first and second directional control valve Provided with first and second pressure control valves that respectively control the pressure of hydraulic fluid discharged from the first and second hydraulic pumps to the first and second directional control valves, The hydraulic control unit is configured to calculate a target speed for operating the hydraulic actuator based on an operation amount of the operating device, the first and second hydraulic pumps, and the first and second hydraulic pumps. A storage unit that stores connection information in which a connection relationship with the directional control valve is set according to an operation amount of the operation device, a target speed calculated by the target speed calculation unit, and connection information stored in the storage unit Based on the above And a target flow rate calculation unit for calculating each target flow rate of hydraulic fluid supplied from the second directional control valve to the hydraulic actuator, a speed detected by the speed detection device, and each target calculated by the target flow rate calculation unit Based on the flow rate, the target drive pressure of the hydraulic actuator is calculated, and the target drive pressure is corrected according to the target flow rate calculated by the target flow rate calculation unit and a predetermined pressure control characteristic. the a first target driving pressure calculating section for calculating a first and second target driving pressure of the hydraulic fluid to act on the hydraulic actuator in the second direction control valve, which is detected by the discharge pressure detecting device wherein Based on the discharge pressures from the first and second hydraulic pumps and the first and second target drive pressures calculated by the target drive pressure calculation unit, each of the first and second hydraulic pumps A target discharge amount calculation unit that calculates a target discharge amount and outputs the result to the control units of the first and second hydraulic pumps, wherein the predetermined pressure control characteristic is the first and second pressures. The secondary pressure of the first and second pressure control valves decreases as the flow rate of hydraulic fluid passing through the control valve increases, and the first pressure control valve calculates the target drive pressure. By the control signal according to the first target drive pressure calculated by the unit, the second pressure control valve is controlled by the control signal according to the second target drive pressure calculated by the target drive pressure calculator. Each is characterized by being driven .

  According to the work machine control device of the present invention, even in a work machine in which a hydraulic actuator is operated by hydraulic oil discharged from a plurality of hydraulic pumps, it is possible to eliminate problems caused by variations in equipment and the like to improve the hydraulic actuator. Control performance can be obtained. Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

1 is an external view showing a configuration of a hydraulic excavator cited as an example of a work machine to which a first embodiment of a control device according to the present invention is applied. It is a figure which shows the structure of the hydraulic circuit of the hydraulic shovel which concerns on 1st Embodiment of this invention. It is a figure explaining the composition of the direction control valve concerning a 1st embodiment of the present invention. It is a functional block diagram which shows the structure of the controller which concerns on 1st Embodiment of this invention. It is a functional block diagram which shows the structure of the target drive pressure calculating part for booms shown in FIG. FIG. 5 is a functional block diagram showing a configuration of a target drive pressure calculation unit for an arm shown in FIG. 4. It is a functional block diagram which shows the structure of the target drive pressure calculating part for buckets shown in FIG. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining the structure regarding control of a hydraulic pump among the pressure control mechanisms concerning 1st Embodiment of this invention, (a) A figure shows the pressure control characteristic, (b) The figure is the specific structure. It is a figure which shows an example. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining the structure regarding control of a pressure control valve among the pressure control mechanisms which concern on 1st Embodiment of this invention, (a) A figure shows the pressure control characteristic, (b) The figure is the specific. It is a figure which shows an example of a structure. It is a figure which shows the relationship between the flow volume of the hydraulic fluid which distribute | circulates each directional control valve for arms which concerns on 1st Embodiment of this invention, and a pressure, (a) The figure shows dispersion | variation in equipment in a hydraulic pump and a pressure control valve. FIG. 5B is a diagram in which variations of devices occur in the hydraulic pump and the pressure control valve. It is a figure which shows the structure of the hydraulic circuit of the hydraulic shovel which concerns on 2nd Embodiment of this invention. It is a functional block diagram which shows the structure of the target drive pressure calculating part for arms which concerns on 2nd Embodiment of this invention. It is a figure explaining the structure regarding control of the hydraulic pump which concerns on 2nd Embodiment of this invention, (a) A figure shows the pressure control characteristic, (b) A figure shows an example of the specific structure. It is.

  EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing the control apparatus of the working machine which concerns on this invention is demonstrated based on figures.

[First Embodiment]
1st Embodiment of the control apparatus which concerns on this invention is applied to a working machine, for example, the hydraulic shovel 1 shown in FIG. The hydraulic excavator 1 includes a traveling body 2, a revolving body 3 attached to the upper side of the traveling body 2 via a revolving device 3A, and a swiveling body 3 mounted in front of the revolving body 3 and rotated in the vertical direction. The front work machine 4 is configured.

  The front work machine 4 includes a boom 4A whose base end is pivotally attached to the swing body 3 and pivots in the vertical direction, an arm 4B pivotally attached to the tip of the boom 4A, and the arm And a bucket 4C rotatably attached to the tip of 4B. The swivel body 3 is disposed in the front, the cab 7 on which the operator is boarded, the counter weight 6 that is disposed in the rear and keeps the balance of the vehicle body, and is disposed between the cab 7 and the counter weight 6, and serves as a prime mover. An engine room 5 that stores the engine 11 (see FIG. 2) and a rotation speed sensor 11A (see FIG. 2) that is attached to the engine 11 in the engine room 5 and detects the rotation speed of the engine 11 are provided.

  As shown in FIG. 2, the revolving structure 3 includes an engine 11 and a plurality of variable displacement swash plate types that rotate with the driving force of the engine 11 and discharge hydraulic oil as pressure oil that drives the front work machine 4. Hydraulic pumps (hereinafter referred to as hydraulic pumps for convenience) 12 and 13, regulators 12a and 13a for controlling the tilt angle of a swash plate (not shown) with respect to the rotation shafts of the hydraulic pumps 12 and 13, and regulators 12a and 13a On the other hand, control valves 12b and 13b for outputting a tilt angle command signal and a hydraulic oil tank 14 (see FIG. 3) for storing hydraulic oil are provided. The hydraulic pumps 12 and 13 are not limited to the swash plate type, and other variable displacement mechanisms such as an oblique axis type may be used.

  Further, the swivel body 3 includes a plurality of hydraulic actuators 4a to 4c that are operated by hydraulic oil discharged from the hydraulic pumps 12 and 13, and a direction control valve that controls the flow of hydraulic oil discharged from the hydraulic pumps 12 and 13. 15A, 15B1, 15B2, and 15C, and a pilot pump (not shown) that is connected to the hydraulic oil tank 14 and supplies hydraulic oil as pilot pressure oil to the operation devices 17A to 17C, which will be described later, are provided.

  The hydraulic actuator 4a is a boom cylinder that connects the swing body 3 and the boom 4A, and rotates the boom 4A by expanding and contracting. The hydraulic actuator 4b is an arm cylinder that is disposed above the boom 4A, connects the boom 4A and the arm 4B, and rotates the arm 4B by extending and contracting. The hydraulic actuator 4c is a bucket cylinder that connects the arm 4B and the bucket 4C and rotates the bucket 4C by expanding and contracting. In addition to the hydraulic actuators 4a to 4c, the hydraulic excavator 1 is also equipped with a hydraulic motor for driving a turning device 3A, a hydraulic motor for driving the traveling body 2, and the like (not shown). However, the description regarding the drive of these turning motors and travel motors is omitted.

  The direction control valves 15A and 15B2 are connected in parallel via a conduit 51 between the hydraulic pump 12 and the boom cylinder 4a. The direction control valves 15B1 and 15C are connected between the hydraulic pump 13 and the bucket cylinder 4c. Are connected in parallel through the pipe line 52. Furthermore, the direction control valve 15A is connected to the bottom chamber of the boom cylinder 4a via the conduit 53A and is connected to the rod chamber of the boom cylinder 4a via the conduit 53B.

  The direction control valves 15B1 and 15B2 are connected to the bottom chamber of the arm cylinder 4b via a pipe line 54A and are connected to the rod chamber of the arm cylinder 4b via a pipe line 54B. The direction control valve 15C is connected to the bottom chamber of the bucket cylinder 4c via a pipeline 55A and is connected to the rod chamber of the bucket cylinder 4c via a pipeline 55B. Accordingly, the pipelines 54A and 54B function as a junction circuit that joins the hydraulic oil that has flowed through the direction control valves 15B1 and 15B2 to act on the arm cylinder 4b.

  As shown in FIG. 3, the directional control valves 15A are formed at the left and right ends of the internal spool, respectively, and pressure receiving chambers 15A1, 15A2 into which pilot pressure oil introduced from the pilot pump through the electromagnetic valves 16A1, 16A2 flows. And the spool moves by an amount corresponding to the pilot pressure. Further, the direction control valve 15A is, for example, a closed center type without a center bypass oil passage, and does not include a bleed-off circuit.

  In addition, since a pressure control valve 24A (see FIG. 2), which will be described later, is arranged on the upstream side of the flow of hydraulic oil in the pipeline 51 relative to the direction control valve 15A, there is no need to restrict the meter-in side of the direction control valve 15A. It becomes. As a result, the direction control valve 15A has no meter-in-side throttling function or is set open. In the directional control valve 15A configured as described above, the switching position of the directional control valve 15A is set to the right position by receiving the pressure of the pilot pressure oil (pilot pressure) in the pressure receiving chambers 15A1 and 15A2 and moving the spool in the left-right direction. The position is switched to R, neutral position N, or left position L.

  When the switching position of the directional control valve 15A is switched to the right position R, the directional control valve 15A connects the pipe 51 and the pipe 52A, and the hydraulic oil discharged from the hydraulic pump 12 is sent to the bottom of the boom cylinder 4a. The hydraulic oil in the rod chamber of the boom cylinder 4a is discharged to the hydraulic oil tank 14 while being supplied to the chamber and connecting the pipeline 52B and the pipeline 53. When the switching position of the direction control valve 15A is switched to the neutral position N, the direction control valve 15A cuts off the supply of hydraulic oil to the boom cylinder 4a. When the switching position of the directional control valve 15A is switched to the left position L, the directional control valve 15A connects the pipe 51 and the pipe 52B and discharges hydraulic oil discharged from the hydraulic pump 12 to the rod chamber of the boom cylinder 4a. , And the pipe 52A and the pipe 53 are connected to discharge the hydraulic oil in the bottom chamber of the boom cylinder 4a to the hydraulic oil tank 14. In addition, since the structure of direction control valve 15B1, 15B2, 15C is the same as that of direction control valve 15A mentioned above, the overlapping description is abbreviate | omitted.

  As shown in FIG. 2, the cab 7 includes an operating device 17A for instructing the operation of the boom cylinder 4a, an operating device 17B for instructing the operation of the arm cylinder 4b, and an operating device 17C for instructing the operation of the bucket cylinder 4c. Have. A signal corresponding to the operation amount of the operation device 17A is sent to the electromagnetic valves 16A1 and 16A2 shown in FIG. 3, and the pressure of the pilot pressure oil introduced from the pilot pump is reduced according to the operation amount. The operation devices 17B and 17C also have the same functions as the operation device 17A described above with respect to the directional control valves 15B1, 15B2, and 15C.

  In the first embodiment of the present invention, the directional control valves 15A, 15B1, 15B2, and 15C are provided in the pipelines 51 and 52 that connect the hydraulic pumps 12 and 13, and the discharge pressures of the hydraulic pumps 12 and 13 are detected. Discharge pressure sensors 21 and 22 as discharge pressure detection devices and speed sensors 23A to 23C as speed detection devices for detecting the speeds of the hydraulic actuators 4a to 4c are provided.

  Further, the pressure of the hydraulic oil (drive pressure) that is provided on the upstream side of the flow of the hydraulic oil from the directional control valves 15A and 15B2 in the pipeline 51 and is discharged from the hydraulic pump 12 to the directional control valves 15A and 15B2. ) And pressure control valves 24A, 24B2 for controlling the control oil) and upstream of the flow direction of the hydraulic oil relative to the directional control valves 15B1, 15C in the pipeline 52, respectively, from the hydraulic pump 13 to the directional control valves 15B1, 15C. The pressure control valves 24B1 and 24C for controlling the pressure of the discharged hydraulic oil are connected between the hydraulic pumps 12 and 13 and the pressure control valves 24A, 24B1, 24B2 and 24C, and are discharged from the hydraulic pumps 12 and 13. And a relief valve (not shown) that causes the hydraulic oil to flow out to the hydraulic oil tank 14 when the hydraulic oil becomes excessive.

  The first embodiment of the present invention is a hydraulic control unit that controls the flow rate of hydraulic fluid discharged from the hydraulic pumps 12 and 13 to the hydraulic actuators 4a to 4c in response to operation inputs from the operating devices 17A to 17C. The controller 100 is provided. Note that the controller 100 is connected to the operation devices 17A to 17C and is not illustrated, but as a control unit that controls the discharge pressure sensors 21 and 22, the speed sensors 23A to 23C, and the regulators 12a and 13a. The control valves 12b and 13b and the pressure control valves 24A, 24B1, 24B2 and 24C are connected.

  Hereinafter, the configuration of the controller 100 according to the first embodiment of the present invention will be described in detail with reference to FIG.

  As shown in FIG. 4, the controller 100 includes a target speed calculation unit 101 that calculates a target speed for operating the boom cylinder 4a based on the operation amount of the operation device 17A, and an arm based on the operation amount of the operation device 17B. A target speed calculation unit 102 for calculating a target speed for operating the cylinder 4b, a target speed calculation unit 103 for calculating a target speed for operating the bucket cylinder 4c based on an operation amount of the operating device 17C, and the hydraulic pumps 12, 13 And a storage unit 104 that stores connection information in which connection relations between the directional control valves 15A, 15B1, 15B2, and 15C are set according to the operation amounts of the operation devices 17A to 17C as a connection map.

  In the target speed calculation unit 101, the relationship between the operation amount of the operating device 17A and the target speed of the boom cylinder 4a is set in advance as the relationship between the pilot pressure Pi and the hydraulic oil supply flow rate to the boom cylinder 4a. In the target speed calculation unit 102, the relationship between the operation amount of the operating device 17B and the target speed of the arm cylinder 4b is similarly set. In the target speed calculation unit 103, the relationship between the operation amount of the operating device 17C and the target speed of the bucket cylinder 4b is similarly set. And each target speed calculating part 101-103 inputs each operation signal (pilot pressure) of operating device 17A-17C, applies the operation amount of operating device 17A-17C to each above-mentioned relationship, and booms Each target speed (amount of hydraulic oil supplied) of the cylinder 4a, arm cylinder 4b, and bucket cylinder 4c is calculated.

  The connection map of the storage unit 104 is, for example, based on information such as the usage method and operation frequency of the hydraulic excavator 1 and considering the priority of the hydraulic actuators 4a to 4c. To 4c and the directional control valves 15A, 15B1, 15B2, and 15C are defined in an optimum connection state. The storage unit 104 receives the operation signals of the operation devices 17A to 17C, and extracts connection information indicating connection relationships suitable for the operation of the operation devices 17A to 17C from the connection map.

  Further, the controller 100 calculates a target driving pressure calculating unit 121 that calculates a target driving pressure for driving the boom cylinder 4a based on the speed detected by the speed sensor 23A and the target speed calculated by the target speed calculating unit 101. And target driving pressure calculation for calculating the target driving pressure to be applied to the arm cylinder 4b from the direction control valves 15B1 and 15B2 based on the speed detected by the speed sensor 23B and the target speed calculated by the target speed calculation unit 102. Unit 122 and a target drive pressure calculation unit 123 that calculates a target drive pressure for driving the bucket cylinder 4c based on the speed detected by the speed sensor 23C and the target speed calculated by the target speed calculation unit 103. Contains.

  In the first embodiment of the present invention, calculation of the target drive pressures of the hydraulic actuators 4a to 4c by the target drive pressure calculation units 121 to 123 supplies the target speeds of the hydraulic actuators 4a to 4c to these hydraulic actuators 4a to 4c. The hydraulic fluid is converted into a target flow rate of the hydraulic oil, and the speed (actual speed) of the hydraulic actuators 4a to 4c is converted into the flow rate of the hydraulic oil actually supplied to the hydraulic actuators 4a to 4c.

  Specifically, the controller 100 sets the target flow rate of hydraulic oil supplied from the direction control valve 15A to the boom cylinder 4a based on the target speed calculated by the target speed calculation unit 101 and the connection information extracted from the storage unit 104. Based on the target flow rate calculation unit 111 for calculating QBm_ref, the target speed calculated by the target speed calculation unit 102 and the connection information extracted from the storage unit 104, the operation supplied from the direction control valves 15B1 and 15B2 to the arm cylinder 4b Based on the target flow rate calculation unit 112 that calculates each target flow rate QAm1_ref, QAm2_ref of oil, the target speed calculated by the target speed calculation unit 103, and the connection information extracted from the storage unit 104, the bucket cylinder 4c from the direction control valve 15C. Calculates target flow rate QBk_ref of hydraulic fluid supplied to And a target flow rate calculation unit 113 that.

  As shown in FIG. 5, the boom target drive pressure calculation unit 121 converts the boom speed detected by the speed sensor 23A into the flow rate of hydraulic oil actually supplied to the boom cylinder 4a, and a flow rate conversion unit 121A. A PID control unit 121B that performs PID control that combines proportional control, differential control, and integral control based on the deviation between the flow rate converted by the flow rate conversion unit 121A and the target flow rate QBm_ref calculated by the target flow rate calculation unit 111; have.

  The PID control unit 121B performs the PID control on the flow rate converted by the flow rate conversion unit 121A and the target flow rate QBm_ref calculated by the target flow rate calculation unit 111, thereby eliminating the deviation, that is, the boom cylinder 4a. A target driving pressure PBm_ref required to make the speed coincide with the target speed is calculated. In addition, although PID control part 121B uses PID control, what is necessary is just the control system which can make an actual flow volume follow target flow volume QBm_ref, and is not restricted to PID.

  As shown in FIG. 6, the arm target drive pressure calculation unit 122 includes a flow rate conversion unit 122A that converts the arm speed detected by the speed sensor 23B into the flow rate of the hydraulic oil actually supplied to the arm cylinder 4b; Based on the deviation between the flow rate converted by the flow rate conversion unit 122A and the total of the target flow rates QAm1_ref and QAm2_ref calculated by the target flow rate calculation unit 112, PID control that combines proportional control, differential control, and integral control is performed. PID control unit 122B. The PID control unit 122B calculates the target drive pressure PAm_ref in the same manner as the PID control unit 121B described above.

  Furthermore, the target drive pressure calculation unit 122 according to the first embodiment of the present invention corrects the target drive pressure PAm_ref according to each target flow rate QAm1_ref, QAm2_ref calculated by the target flow rate calculation unit 112 and a pressure control characteristic described later. The target drive pressure correction unit 122C that calculates the target drive pressures PAm1_ref and PAm2_ref of the hydraulic oil that is applied to the arm cylinder 4b from the direction control valves 15B1 and 15B2. The configuration showing the specific function of the target drive pressure correction unit 122C will be described in detail later.

  As shown in FIG. 7, the bucket target drive pressure calculation unit 123 includes a flow rate conversion unit 123A that converts the bucket speed detected by the speed sensor 23C into the flow rate of the hydraulic oil actually supplied to the bucket cylinder 4c, A PID control unit 123B that performs PID control that combines proportional control, differential control, and integral control based on the deviation between the flow rate converted by the flow rate conversion unit 123A and the target flow rate QBk_ref calculated by the target flow rate calculation unit 113; have. The PID control unit 123B calculates the target drive pressure PBk_ref in the same manner as the PID control unit 121B described above.

  Then, as shown in FIG. 4, the target drive pressure calculation units 121 to 123 output control signals of the calculated target drive pressures PBm_ref, PAm1_ref, PAm2_ref, and PBk_ref to the corresponding pressure control valves 24A, 24B1, 24B2, and 24C, respectively. To do. The target drive pressure calculation units 121 and 122 output control signals for the calculated target drive pressures PBm_ref and PAm2_ref to a target discharge pressure calculation unit 141, which will be described later, and the target drive pressure calculation units 122 and 123 calculate the calculated target values. The drive pressures PAm1_ref and PBk_ref are output to a target discharge pressure calculation unit 142 described later.

  Further, the controller 100 controls the spool control unit 131 that controls the movement of the spool of the direction control valve 15A based on the target flow rate QBm_ref calculated by the target flow rate calculation unit 111, and each target calculated by the target flow rate calculation unit 112. Based on the flow rates QAm1_ref and QAm2_ref, the spool control unit 132 that controls the movement of the spool of the direction control valve 15B and the spool movement of the direction control valve 15C based on the target flow rate QBk_ref calculated by the target flow rate calculation unit 113. And a spool control unit 133 to be controlled.

  Since the target flow rate Qbm_ref calculated by the target flow rate calculation unit 111 is a target flow rate supplied to the direction control valve 15A, the spool control unit 131 calculates the discharge flow rate QBmmo from the boom cylinder 4a at this time. Then, the spool controller 131 calculates the opening amount of the direction control valve 15A for setting the calculated discharge flow rate QBmmo, and moves the spool of the direction control valve 15A so that the direction control valve 15A opens by this opening amount. To control.

By the way, the discharge flow rate from the hydraulic actuators 4a to 4c described above is equivalent to the flow rate that flows in the case of a motor or the like, but if the pressure receiving area is different as in a single rod cylinder or the like, the area is converted. There is a need. Therefore, Qin is the flow rate of flow into the hydraulic actuators 4a to 4c, Qout is the flow rate of discharge from the hydraulic actuators 4a to 4c, Ab is the cross-sectional area of the bottom side of the hydraulic actuators 4a to 4c, and When the area is Ar, the following formulas (1) and (2) are established. In addition, Formula (1) is a formula when the hydraulic actuators 4a to 4c extend, and Formula (2) is a formula when the hydraulic actuators 4a to 4c contract.

Further, the flow rate through the direction control valve 15A is Q, the opening area is A, the effective differential pressure between the primary side (hydraulic pump 12 side) and the secondary side (boom cylinder 4a side) is ΔP, and the density of hydraulic oil is When ρ and the flow coefficient are C, the following formula (3) is generally established.

When formula (3) is rearranged, formula (4) is established.

  Therefore, the spool control unit 131 calculates the opening area A of the direction control valve 15A by using the mathematical formula (4), and sends a command current (pilot command) corresponding to the calculated opening area A to the electromagnetic valves 16A1, 16A2. Output to the directional control valve 15A, the spool of the directional control valve 15A can be moved to adjust the opening amount of the directional control valve 15A. The spool controllers 132 and 133 are the same as the spool controller 131 described above, and the opening amounts of the directional control valves 15B1, 15B2, and 15C are adjusted to adjust the spools of the directional control valves 15B1, 15B2, and 15C. Control movement.

  Further, the controller 100 detects the discharge pressures detected by the discharge pressure sensors 21 and 22, the target drive pressure PBm_ref calculated by the target drive pressure calculation unit 121, and the target drive pressures PAm1_ref calculated by the target drive pressure correction unit 122C. , PAm2_ref and the target drive pressure PBk_ref calculated by the target drive pressure calculator 123, the target discharge amounts Q1_ref and Q2_ref of the hydraulic pumps 12 and 13 are calculated, and the discharge amounts of the hydraulic pumps 12 and 13 are calculated. The target discharge amounts are controlled to Q1_ref and Q2_ref.

  Specifically, the controller 100 determines the target discharge pressure P1_ref of the hydraulic pump 12 according to the target drive pressure PBm_ref calculated by the target drive pressure calculation unit 121 and the target drive pressure PAm2_ref calculated by the target drive pressure correction unit 122C. The target discharge pressure of the hydraulic pump 13 is calculated according to the target discharge pressure calculation unit 141 that calculates the target drive pressure PAm1_ref calculated by the target drive pressure correction unit 122C and the target drive pressure PBk_ref calculated by the target drive pressure calculation unit 123. And a target discharge pressure calculation unit 142 that calculates the pressure P2_ref.

  Further, the controller 100 calculates a target discharge amount that calculates the target discharge amount Q1_ref of the hydraulic pump 12 according to the discharge pressure detected by the discharge pressure sensor 22 and the target discharge pressure P1_ref calculated by the target discharge pressure calculation unit 141. The target discharge amount calculation unit 152 that calculates the target discharge amount Q2_ref of the hydraulic pump 13 according to the discharge pressure detected by the unit 151 and the discharge pressure sensor 21 and the target discharge pressure P2_ref calculated by the target discharge pressure calculation unit 142. Including.

  The target discharge pressure calculation unit 141 selects the larger of the target drive pressure PBm_ref calculated by the target drive pressure calculation unit 121 and the target drive pressure PAm2_ref calculated by the target drive pressure correction unit 122C, and selects the target of the hydraulic pump 12 Calculated as the discharge pressure P1_ref. Similarly, the target discharge pressure calculation unit 142 selects a larger one of the target drive pressure PAm1_ref calculated by the target drive pressure correction unit 122C and the target drive pressure PBk_ref calculated by the target drive pressure calculation unit 123, and the hydraulic pump 13 as the target discharge pressure P2_ref.

  The target discharge amount calculation unit 151 performs PID control on the discharge pressure detected by the discharge pressure sensor 22 and the target discharge pressure P1_ref calculated by the target discharge pressure calculation unit 141, similarly to the PID control units 121B to 123B. Thus, the deviation between the discharge pressure and the target discharge pressure P1_ref is eliminated, that is, the target discharge amount Q1_ref required to make the discharge pressure of the hydraulic pump 12 coincide with the target discharge pressure P1_ref is calculated.

  The target discharge amount calculation unit 152 performs PID control on the discharge pressure detected by the discharge pressure sensor 21 and the target discharge pressure P2_ref calculated by the target discharge pressure calculation unit 142, similarly to the PID control units 121B to 123B. Thus, the target discharge amount Q2_ref required to eliminate the deviation between these discharge pressures and the target discharge pressure P2_ref, that is, to make the discharge pressure of the hydraulic pump 13 coincide with the target discharge pressure P2_ref is calculated. Then, the target discharge amount calculation units 151 and 152 output control signals for the calculated target discharge amounts Q1_ref and Q2_ref to the control valves 12b and 13b, respectively.

  Here, the hydraulic excavator 1 according to the first embodiment of the present invention is provided with a load flow rate in order to eliminate problems caused by variations in equipment and the like found in a hydraulic system using a plurality of hydraulic pumps 12 and 13 and a junction circuit. In contrast, the pressure control is configured so that the discharge pressure of the hydraulic pumps 12 and 13 and the pressure on the secondary side (direction control valves 15B1 and 15B2 side) of the pressure control valves 24B1 and 24B2 respectively change. A mechanism 30 is provided.

  The pressure control characteristics of the pressure control mechanism 30 are set such that, for example, the discharge pressures of the hydraulic pumps 12 and 13 are decreased as the discharge amounts of the hydraulic pumps 12 and 13 increase. The pressure control characteristic of the pressure control mechanism 30 is such that, for example, the pressure of the hydraulic fluid that has passed through the pressure control valves 24B1 and 24B2 decreases as the flow rate of the hydraulic fluid that has passed through the pressure control valves 24B1 and 24B2 increases. Is set.

  Hereinafter, the configuration of the pressure control mechanism 30 will be described in detail with reference to FIGS. 8 and 9.

  In the pressure control characteristic of the pressure control mechanism 30 shown in FIG. 8A, for example, the slope a of the discharge pressure P1 of the hydraulic pump 12 with respect to the discharge amount Q1 of the hydraulic pump 12 is set to a predetermined negative value (a <0). As shown in FIG. 8B, the pressure control mechanism 30 is a hydraulic pump obtained from the product of the tilt amount q of the hydraulic pump 12 and the rotational speed N with respect to the control feedback system of the discharge pressure P1 of the hydraulic pump 12. Based on the discharge amount Q1 of 12 (= q × N), feedback is performed so that the discharge pressure P1 of the hydraulic pump 12 decreases, whereby the pressure control characteristic shown in FIG. 8A can be obtained. The configuration of the pressure control mechanism 30 is not limited to the configuration illustrated in FIG. 8B described above, and may be other configurations as long as the pressure control characteristics illustrated in FIG. . Further, the configuration related to the control of the hydraulic pump 13 of the pressure control mechanism 30 is the same as the configuration related to the control of the hydraulic pump 12 of the pressure control mechanism 30 described above, and therefore a duplicate description is omitted.

  In the pressure control characteristics of the pressure control mechanism 30 shown in FIG. 9A, for example, the pressure PAm2 on the secondary side (direction control valve 15B2 side) of the pressure control valve 24B2 with respect to the flow rate QAm2 of the hydraulic oil of the pressure control valve 24B2 The slope a is set to a predetermined negative value (a <0). Then, as shown in FIG. 9 (b), the pressure control mechanism 30 increases the lift amount of the pressure control valve 24B2 by the pressure PAm2 of the hydraulic oil as the flow rate QAm2 of the hydraulic oil that has passed through the pressure control valve 24B2 increases. The pressure control valve 24B2 is configured to be increased and pushed back in the closing direction. As a result, it is possible to obtain a pressure control characteristic in which the pressure PAm2 on the secondary side of the pressure control valve 24B2 decreases as the flow rate QAm2 of the hydraulic oil flowing through the pressure control valve 24B2 increases. The configuration of the pressure control mechanism 30 is not limited to the configuration illustrated in FIG. 9B described above, and may be other configurations as long as the pressure control characteristics illustrated in FIG. 9A can be obtained. . Further, the configuration related to the control of the pressure control valve 24B1 of the pressure control mechanism 30 is the same as the configuration related to the control of the pressure control valve 24B2 of the pressure control mechanism 30 described above, and thus a duplicate description is omitted.

  As described above, in the pressure control characteristics of the pressure control mechanism 30, the discharge pressures P1 and P2 of the hydraulic pumps 12 and 13 and the secondary side of the pressure control valves 24B1 and 24B2 are given a certain inclination a with respect to the load flow rate. The pressure PAm1 and PAm2 are characterized by control, and the magnitude of the slope a may be determined by, for example, how much pressure is reduced in the range of the load flow rate from 0 to the maximum value. Specifically, the pressure loss in the pipelines 51 and 52 such as the pipes up to the pipelines 54A and 54B, which is a merging circuit, due to variations in the devices of the hydraulic pumps 12 and 13 and the pressure control valves 24B1 and 24B2. Therefore, it is desirable to set the magnitude of the inclination a so as to have a sufficiently large value with respect to these factors.

  Next, a configuration showing a specific function of the target drive pressure correcting unit 122C of the target drive pressure calculating unit 122 according to the first embodiment of the present invention will be described in detail with reference to FIG.

As shown in FIG. 6, the target drive pressure correction unit 122C is obtained by, for example, multiplying each target flow rate QAm1_ref, QAm2_ref calculated by the target flow rate calculation unit 112 by a gradient a in the pressure control characteristic of the pressure control mechanism 30. The respective values are added to the target drive pressure PAm_ref calculated by the PID control unit 122B, thereby calculating the target drive pressures PAm1_ref and PAm2_ref of the hydraulic oil to be applied to the arm cylinder 4b from the direction control valves 15B1 and 15B2. That is, the following mathematical formulas (5) and (6) are established.

  On the other hand, the pressure control valves 24A and 24C control the pressures of the hydraulic oil supplied to the direction control valves 15A and 15C to the target drive pressures PBm_ref and PBk_ref calculated by the target drive pressure calculation units 121 and 123, respectively. Further, the pressure control valves 24B1 and 24B2 control the pressures of the hydraulic oil supplied to the direction control valves 15B1 and 15B2 to the target drive pressures PAm1_ref and PAm2_ref calculated by the target drive pressure correction unit 122C as described above. .

  Next, the operation of the hydraulic excavator 1 according to the first embodiment of the present invention configured as described above will be described in detail. In the following description, in order to make the contents of the first embodiment of the present invention easy to understand, a case where the pivoting operation of the arm 4B is performed as a single operation of the excavator 1 is shown.

  As shown in FIG. 4, when the operator in the cab 7 operates the operation device 17B, the target flow rate calculation unit 112 determines each target flow rate QAm1_ref, based on the operation amount of the operation device and the connection information extracted from the storage unit 104. QAm2_ref is calculated. Next, as shown in FIG. 6, the target driving pressure calculation unit 122 calculates the sum of the flow rate converted from the speed detected by the speed sensor 23 </ b> B and the target flow rates QAm <b> 1 </ b> _ref and QAm <b> 2 </ b> _ref calculated by the target flow rate calculation unit 112. On the other hand, the target drive pressure PAm_ref is calculated by performing PID control.

  Thereafter, the target drive pressure calculation unit 122 calculates each target drive pressure from the calculated target drive pressure PAm_ref, the target flow rates QAm1_ref and QAm2_ref calculated by the target flow rate calculation unit 112, and the inclination a of the pressure control characteristic of the pressure control mechanism 30. PAm1_ref and PAm2_ref are calculated.

  Then, the target drive pressure calculation unit 122 outputs the control signals of the respective target drive pressures PAm1_ref and PAm2_ref to the pressure control valves 24B1 and 24B2, so that each pressure of the hydraulic oil supplied to the direction control valves 15B1 and 15B2 is a pressure. The target drive pressures PAm1_ref and PAm2_ref are controlled by the control valves 24B1 and 24B2. On the other hand, the spool control unit 132 controls the movement of the spools of the directional control valves 15B1 and 15B2 from the target flow rates QAm1_ref and QAm2_ref calculated by the target flow rate calculation unit 112. That is, the throttle on the meter-out side of the direction control valves 15B1 and 15B2 is adjusted.

  In addition, when the target drive pressure calculation unit 122 outputs a control signal for the target drive pressure PAm2_ref to the target discharge pressure calculation unit 141, the target discharge pressure calculation unit 141 has the target drive pressure PBm_ref being 0, and thus the target drive pressure PAm2_ref. Is calculated as the target discharge pressure P1_ref of the hydraulic pump 12. Similarly, when the target drive pressure calculation unit 122 outputs a control signal of each target drive pressure PAm1_ref to the target discharge pressure calculation unit 142, the target drive pressure calculation unit 142 has a target drive pressure PBk_ref of 0, so the target drive The pressure PAm1_ref is calculated as the target discharge pressure P2_ref of the hydraulic pump 13.

  Next, the target discharge amount calculation unit 151 performs PID control on the discharge pressure detected by the discharge pressure sensor 22 and the target discharge pressure P1_ref calculated by the target discharge pressure calculation unit 141, thereby achieving the target discharge amount Q1_ref. Is calculated. Similarly, the target discharge amount calculation unit 152 performs PID control on the discharge pressure detected by the discharge pressure sensor 21 and the target discharge pressure P2_ref calculated by the target discharge pressure calculation unit 142, so that the target discharge amount Q2_ref Is calculated.

  The target discharge amount calculation units 151 and 152 output control signals of the target discharge amounts Q1_ref and Q2_ref to the control valves 12b and 13b, so that the discharge amounts of the hydraulic pumps 12 and 13 are controlled by the control valves 12b and 13b. The target discharge amounts are controlled to Q1_ref and Q2_ref. As a result, as shown in FIG. 10 (a), the target drive pressures PAm_ref of the arm cylinders 4b required on the directional control valves 15B1 and 15B2 sides, respectively, in the vicinity of the original target flow rates QAm1_ref and QAm2_ref. The flow rates QAm1 and QAm2 of the hydraulic oil can be controlled.

  FIG. 10 (b) shows the relationship between the flow rate and pressure of the hydraulic oil flowing through the directional control valves 15B1 and 15B2 when there is a variation in equipment between the hydraulic pumps 12 and 13 and the pressure control valves 24B1 and 24B2. ing. In FIG. 10B, the broken line indicates the target drive pressure PAm_ref of the arm cylinder 4b with the assumed design specifications, and the solid line indicates the target drive pressure of the hydraulic oil that acts on the arm cylinder 4b from the directional control valves 15B1 and 15B2 during a certain operation. PAm1_ref, PAm2_ref, and alternate long and short dash lines indicate the upper and lower limits when it is assumed that variations in devices occur only on the target drive pressure PAm2_ref side.

  As shown in FIG. 10B, the flow rate QAm2 of the hydraulic oil supplied from the directional control valves 15B1 and 15B2 to the arm cylinder 4b is within the range of the flow rate determined by the slope a in the pressure control characteristic of the pressure control mechanism 30. Since it is controlled, it is understood that the actual flow rate QAm2 is not greatly deviated from the target flow rate QAm2_ref. As described above, even if the devices vary, the hydraulic fluid flow rate is allowed to vary to some extent by providing the inclination a in the pressure control characteristic of the pressure control mechanism 30 with respect to the target drive pressure PAm_ref of the arm cylinder 4b. By doing so, it is possible to absorb an error in the flow rate of the hydraulic oil due to variations in the devices. Thereby, it is possible to suppress the actual flow rates QAm1 and QAm2 from greatly deviating from the target flow rates QAm1_ref and QAm2_ref in the directional control valves 15B1 and 15B2.

  According to the first embodiment of the present invention configured as described above, due to differences in pressure control accuracy of the hydraulic pumps 12 and 13, or differences in configuration of the pipes 51 and 52, the direction control valves 15B1 and 15B2, and the like. Even if there are variations in equipment such as oil path / pipe resistance, the controller 100 controls the discharge amounts of the hydraulic pumps 12 and 13 in consideration of the inclination a in the pressure control characteristics of the pressure control mechanism 30. Thus, it is possible to realize the flow distribution supplied from the hydraulic pumps 12 and 13 to the hydraulic actuators 4a to 4c as expected. Thereby, since favorable control performance of the hydraulic actuators 4a to 4c can be obtained, excellent stability in the operation of the hydraulic excavator 1 can be ensured.

  Further, in the first embodiment of the present invention, in the pressure control valves 24B1 and 24B2, the respective pressures of the hydraulic oil flowing through the direction control valves 15B1 and 15B2 are calculated by the target drive pressures PAm1_ref calculated by the target drive pressure correction unit 122C. , PAm2_ref is controlled so that the flow rate of the hydraulic oil applied from the directional control valves 15B1 and 15B2 to the arm cylinder 4b is limited to the required target flow rates QAm1_ref and QAm2_ref, respectively. , 13 can be used to appropriately operate the arm cylinder 4b. Thereby, in the work of the hydraulic excavator 1, it is possible to sufficiently improve the speed characteristics of the arm 4B in which a higher speed is easily required compared to the boom 4A and the bucket 4C.

[Second Embodiment]
As shown in FIG. 11, the second embodiment of the control device for a work machine according to the present invention is directed from the direction control valves 15B1 and 15B2 to the arm cylinder 4b instead of the pressure control mechanism 30 according to the first embodiment described above. A flow rate detection device 31 for detecting each flow rate QAm1, QAm2 (see FIG. 12) of the supplied hydraulic oil is provided. The target drive pressure calculation unit 122 calculates the target drive pressure PAm_ref of the arm cylinder 4b based on the speed detected by the speed sensor 23B and the target flow rates QAm1_ref and QAm2_ref calculated by the target flow rate calculation unit 112. Further, based on the calculated target drive pressure PAm_ref of the arm cylinder 4b, the target flow rates QAm1_ref, QAm2_ref, and the flow rates QAm1, QAm2 detected by the flow rate detection device 31, the direction control valves 15B1, 15B2 to the arm cylinder 4b. The target drive pressures PAm1_ref and PAm2_ref of the hydraulic oil to be acted on are calculated.

  Specifically, as shown in FIG. 12, the target drive pressure correction unit 122D according to the second embodiment of the present invention includes the target flow rates QAm1_ref and QAm2_ref calculated by the target flow rate calculation unit 112 and the flow rate detection device 31. The target drive pressure PAm_ref is corrected so as to reduce the deviation from each detected flow rate, and the respective target drive pressures PAm1_ref and PAm2_ref of the hydraulic oil that are applied to the arm cylinder 4b from the direction control valves 15B1 and 15B2 are calculated.

  Hereinafter, details of the configuration of the flow rate detection device 31 and the target drive pressure correction unit 122D according to the second embodiment of the present invention will be described in order. In the following description, in order to make the contents of the second embodiment of the present invention easier to understand, as in the first embodiment described above, when the pivoting operation of the arm 4B is performed as a single operation of the excavator 1 The structure of is shown.

  In the second embodiment of the present invention, as shown in FIG. 12, the controller 100 shown in FIG. 11 uses the discharge amounts of the hydraulic pumps 12 and 13 according to the discharge pressures detected by the discharge pressure sensors 21 and 22, respectively. Discharge amount calculation units 161 and 162 for calculating QPmp1 and QPmp2 (see FIG. 12) are included. 12 inputs the calculation results of the discharge amount calculation units 161 and 162 and the conversion results of the flow rate conversion units 121A and 123A, and each of the calculation results by the discharge amount calculation units 161 and 162. Based on the discharge amounts QPmp1 and QPmp2 and the flow rates QBm and QBk converted by the flow rate conversion units 121A and 123A, the flow rates QAm1 and QAm2 of the hydraulic oil supplied from the direction control valves 15B1 and 15B2 to the arm cylinder 4b are calculated. A flow rate calculation unit 122E is included.

Here, regarding the relationship between the flow rate and the speed to the hydraulic actuators 4a to 4c, it operates with respect to a hydraulic circuit in which there is almost no loss of excess oil by the relief valve such as the hydraulic excavator 1 according to each embodiment of the present invention. An idea based on the balance of the oil flow rate can be applied, and the flow rates QAm1 and QAm2 of the hydraulic oil can be easily obtained. That is, the following equations (7) and (8) are established from the configuration of the hydraulic circuit shown in FIG.

Further, when the pivoting operation of the arm 4B is performed as a single operation of the hydraulic excavator 1, the flow rates QBm and QBk are 0. Therefore, when these are substituted into the above formulas (7) and (8), Equations (9) and (10) are established.

  Therefore, the flow rate calculation unit 122E only needs to substitute the discharge amounts QPmp1 and QPmp2 calculated by the discharge amount calculation units 161 and 162 into these mathematical formulas (9) and (10). As described above, in the second embodiment of the present invention, the speed sensors 23A and 23C, the flow rate conversion units 121A and 123A, the discharge amount calculation units 161 and 162, and the flow rate calculation unit 122E function as the flow rate detection device 31.

On the other hand, the target drive pressure correction unit 122D, for example, subtracts the flow rates QAm1 and QAm2 calculated by the flow rate calculation unit 122E from the target flow rates QAm1_ref and QAm2_ref calculated by the target flow rate calculation unit 112 and then a predetermined proportional gain. The target drive pressures PAm1_ref and PAm2_ref are calculated by multiplying a and adding each obtained value to the target drive pressure PAm_ref calculated by the PID control unit 122B. That is, the following mathematical formulas (11) and (12) are established. In Equations (11) and (12), the proportional gain a determines the degree of control compensation, and corresponds to the slope a of the pressure control characteristic of the pressure control mechanism 30 according to the first embodiment. Is.

  With such a configuration of the flow rate detection device 31 and the target drive pressure correction unit 122D, as shown in FIG. 13A, the discharge pressures P1, P2 of the hydraulic pumps 12, 13 and the pressure control valve 24B1, with respect to the load flow rate. A pressure control characteristic can be obtained in which the pressures QAm1 and QAm2 on the secondary side (direction control valves 15B1 and 15B2 side) of 24B2 do not change. The hydraulic excavator 1 according to the second embodiment of the present invention may be configured to control the pressure without depending on the load flow rate, which is a general control characteristic, as shown in FIG. The configuration of the hydraulic circuit in 1 can be simplified. Since the other configurations of the second embodiment are the same as those of the first embodiment described above, the same or corresponding parts as those of the first embodiment are denoted by the same reference numerals, and redundant description is omitted. In the operation of the hydraulic excavator 1 according to the second embodiment of the present invention, the flow rate calculation unit 122E calculates the flow rates QAm1 and QAm2 before the target drive pressure correction unit 122D corrects the target drive pressure PAm_ref. Since it is the same as that of 1st Embodiment mentioned above except that is performed, the overlapping description is abbreviate | omitted.

  According to the second embodiment of the present invention configured as described above, the same operational effects as the first embodiment described above can be obtained, and the hydraulic pumps 12 and 13 with respect to the load flow rate as in the first embodiment. Therefore, it is not necessary to intentionally change the discharge pressure and the pressure on the secondary side of the pressure control valves 24B1 and 24B2. Therefore, it is possible to accurately control the flow rate of the hydraulic oil supplied to the arm cylinder 4b. Thereby, the control performance of the arm cylinder 4b operated by the hydraulic oil discharged from the hydraulic pumps 12 and 13 can be sufficiently improved.

  In addition, this embodiment mentioned above was described in detail in order to demonstrate this invention easily, and is not necessarily limited to what is provided with all the demonstrated structures. Further, a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment.

  Moreover, although each embodiment of this invention demonstrated the case where the rotation operation | movement of the arm 4B was performed as independent operation | movement of the hydraulic shovel 1, it is not restricted to this case, For example, boom 4A of composite operation | movement of the hydraulic shovel 1 is carried out. The same can be applied to the case where the turning operation and the turning operation of the arm 4B are performed. In such a case, the flow rate calculation unit 122E according to the second embodiment of the present invention uses the discharge amounts QPmp1, QPmp2 calculated by the discharge amount calculation units 161, 162 in the above formulas (7), (8). The flow rates QAm1 and QAm2 can be calculated by substituting the flow rates QBm and QBk converted by the flow rate conversion units 121A and 123A.

  Moreover, although each embodiment of this invention demonstrated the case where the hydraulic shovel 1 was provided with the two hydraulic pumps 12 and 13 and the four direction control valves 15A, 15B1, 15B2, and 15C, a hydraulic pump and a direction control valve were demonstrated. The number is not limited to this case. Moreover, although each embodiment of this invention demonstrated the structure which act | operates on the arm cylinder 4b the hydraulic fluid merged through each of the directional control valves 15B1 and 15B2 via the pipelines 54A and 54B as a merge circuit, Not limited to this, the combined hydraulic oil may be configured to act on the boom cylinder 4a, or various combinations may be applied.

1 Excavator (work machine)
4a Boom cylinder (hydraulic actuator)
4b Arm cylinder (hydraulic actuator)
4c Bucket cylinder (hydraulic actuator)
11 Engine 12, 13 Hydraulic pump 12b, 13b Control valve (control unit)
15A, 15B1, 15B2, 15C Directional control valves 17A to 17C Operating device 21, 22 Discharge pressure sensor (discharge pressure detection device)
23A-23C Speed sensor (speed detector)
24A, 24B1, 24B2, 24C Pressure control valve 30 Pressure control mechanism 31 Flow rate detection device 54A, 54B Pipe line (merging circuit)
100 controller (hydraulic control part)
101-103 Target speed calculation unit 104 Storage unit 111-113 Target flow rate calculation unit 121-123 Target drive pressure calculation unit 121A-123A Flow rate conversion unit 121B-123B PID control unit 122C, 122D Target drive pressure correction unit 122E Flow rate calculation unit 131 ~ 133 Spool control unit 141, 142 Target discharge pressure calculation unit 151, 151 Target discharge amount calculation unit 161, 162 Discharge amount calculation unit

Claims (2)

A plurality of hydraulic pumps driven by a prime mover and having a control unit for controlling the flow rate, a hydraulic actuator operated by hydraulic oil discharged from the plurality of hydraulic pumps, and an operating device for instructing the operation of the hydraulic actuator; The first and second directional control valves for controlling the flow of hydraulic oil discharged from the first and second hydraulic pumps among the plurality of hydraulic pumps, and the first and second directional control valves are circulated. Provided in a work machine having a merging circuit for merging the hydraulic oil and acting on the hydraulic actuator,
In a control device for a work machine that includes a hydraulic control unit that controls the flow rate of hydraulic oil discharged from the plurality of hydraulic pumps to the hydraulic actuator in response to an instruction from the operation device,
A discharge pressure detecting device for detecting discharge pressures of the plurality of hydraulic pumps;
A speed detecting device for detecting the speed of the hydraulic actuator,
Disposed from the first and second hydraulic pumps to the first and second directional control valves respectively provided between the first and second hydraulic pumps and the first and second directional control valves. A first pressure control valve and a second pressure control valve for controlling the pressure of the hydraulic fluid,
The hydraulic control unit
A target speed calculation unit for calculating a target speed for operating the hydraulic actuator based on an operation amount of the operation device;
A storage unit that stores connection information in which a connection relationship between the first and second hydraulic pumps and the first and second directional control valves is set according to an operation amount of the operation device;
Based on the target speed calculated by the target speed calculation unit and the connection information stored in the storage unit, each target flow rate of hydraulic fluid supplied from the first and second directional control valves to the hydraulic actuator is calculated. A target flow rate calculation unit,
Based on the speed detected by the speed detection device and each target flow rate calculated by the target flow rate calculation unit, the target drive pressure of the hydraulic actuator is calculated, and the target drive pressure is calculated as the target flow rate calculation unit. The first and second target drive of the hydraulic fluid to be applied to the hydraulic actuator from the first and second directional control valves , corrected according to each target flow rate and predetermined pressure control characteristic calculated in A target drive pressure calculation unit for calculating pressure,
Based on the discharge pressures from the first and second hydraulic pumps detected by the discharge pressure detection device and the first and second target drive pressures calculated by the target drive pressure calculator, the first And a target discharge amount calculation unit that calculates each target discharge amount of the second hydraulic pump and outputs the result to the control units of the first and second hydraulic pumps,
The predetermined pressure control characteristic is a characteristic in which the pressure on the secondary side of the first and second pressure control valves decreases as the flow rate of the hydraulic oil passing through the first and second pressure control valves increases. Yes,
The first pressure control valve is calculated by the target drive pressure calculator by the control signal corresponding to the first target drive pressure calculated by the target drive pressure calculator. A control device for a work machine that is driven by a control signal corresponding to the second target drive pressure . The work machine control device according to claim 1,
A flow rate detection device for detecting each flow rate of hydraulic oil supplied from the first and second directional control valves to the hydraulic actuator;
The target drive pressure calculation unit calculates a target drive pressure of the hydraulic actuator based on the speed detected by the speed detection device and each target flow rate calculated by the target flow rate calculation unit, and further calculates this A control device for a work machine, wherein the first and second target drive pressures are calculated based on a target drive pressure of a hydraulic actuator, each target flow rate, and each flow rate detected by the flow rate detection device. .