JP2018021589A - Pump control device and pump control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pump control device capable of changing setting of a pump flow rate, and to provide a pump control method.SOLUTION: A controller 34 acquires a total sum value and the largest value of a flow rate requested from each hydraulic actuator. The controller 34 sets a pump flow rate command value based on a value to which a value obtained by multiplying the largest value by a specific gain of a difference between the total sum value and the largest value is added. Setting of a pump flow rate can be readily changed by changing the gain value.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pump control apparatus and a pump control method for controlling the flow rate of working fluid discharged from a pump to a plurality of fluid pressure actuators.

  2. Description of the Related Art Conventionally, as a working machine such as a hydraulic excavator, an engine, a variable displacement pump such as a swash plate that is driven by the engine and discharges hydraulic oil, and the hydraulic oil discharged from the pump is supplied. Equipped with a hydraulic system for positive control (positive control) that has multiple hydraulic actuators such as cylinders and motors and discharges only the required flow rate according to the amount of lever operation to operate these hydraulic actuators. Is widely known.

  In such a working machine, there are cases where a complex operation such as an interlocking operation of the front work device is performed while turning, for example, loading of earth and sand into a truck. For such a complex operation, a configuration is known in which, for example, a required flow rate of an actuator is determined in advance and a square root of a sum of squares of the required flow rate of the actuator is calculated as a pump flow rate command value (for example, Patent Documents) 1).

Special table 2013-543086 gazette

  However, in the configuration of Patent Document 1, since the pump flow rate setting method is fixed, the pump flow rate depends on different work modes, for example, when importance is attached to fuel efficiency or productivity or work speed. It is difficult to change the settings.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a pump control device and a pump control method capable of easily changing the setting of the pump flow rate.

  The invention according to claim 1 is a pump control device for controlling the flow rate of the working fluid discharged from the pump with respect to the plurality of fluid pressure actuators operated in accordance with the respective operations of the plurality of operating bodies. The required flow rate from each fluid pressure actuator is obtained according to the signal generated by the operation of the operating body, the total value and maximum value of these required flow rates are obtained, and the difference between the total value and the maximum value with respect to this maximum value. A controller for setting a pump flow rate command value for setting the flow rate of the working fluid from the pump based on a value obtained by adding a value obtained by multiplying the predetermined gain.

  The invention described in claim 2 is the pump control apparatus according to claim 1, further comprising switching means for switching and setting the gain.

  The invention described in claim 3 is a pump control method for controlling the flow rate of the working fluid discharged from the pump with respect to a plurality of fluid pressure actuators, wherein the sum and maximum values of the required flow rates from the fluid pressure actuators, And a pump flow rate command value is set based on a value obtained by adding a value obtained by multiplying the maximum value by a predetermined gain of the difference between the total value and the maximum value.

  According to a fourth aspect of the present invention, in the pump control method according to the third aspect, the gain is switched according to the setting.

  According to the first aspect of the present invention, the controller obtains the total value and the maximum value of the required flow rate from each fluid pressure actuator, and sets a predetermined gain of the difference between the total value and the maximum value with respect to the maximum value. By setting the pump flow rate command value based on the value obtained by adding the multiplied values, the pump flow rate setting can be easily changed by changing the gain value.

  According to the second aspect of the present invention, by setting the gain to be switched by the switching means, for example, the operator can easily change the setting of the pump flow rate according to the work mode by switching the switching means according to the work mode. It becomes.

  According to the third aspect of the present invention, the sum total value and the maximum value of the required flow rates from the respective fluid pressure actuators are obtained, and a value obtained by multiplying the maximum value by a predetermined gain of the difference between the sum total value and the maximum value. By setting the pump flow rate command value based on the value obtained by adding, the pump flow rate setting can be easily changed by changing the gain value.

  According to the fourth aspect of the present invention, the setting of the pump flow rate can be easily changed according to the work mode by switching the gain according to the work mode setting, for example.

It is a block diagram of a controller showing one embodiment of a pump control device and a pump control method according to the present invention. It is a block diagram which shows the actuator required flow volume calculating part of a controller same as the above. It is a block diagram which shows the pump request | requirement flow volume calculating part of a controller same as the above. It is a block diagram which shows the pump flow rate instruction | command calculating part of a controller same as the above. It is a block diagram which shows a pump control apparatus same as the above. It is a circuit diagram which shows the fluid pressure system provided with the pump control apparatus same as the above. It is the schematic which shows the hydraulic shovel as a typical example of the working machine provided with the fluid pressure system same as the above. It is a graph which shows the example of the required flow rate at the time of compound operation of a fluid pressure actuator. (A) is a graph showing a calculation result by the pump control device when the gain based on the required flow rate of FIG. 8 is 0, and (b) is a result of the pump control device when the gain based on the required flow rate of FIG. 8 is 0.3. A graph showing the calculation result, (c) is a graph showing the calculation result by the pump control device when the gain based on the required flow rate of FIG. 8 is 0.5, and (d) is a gain of 1 based on the required flow rate of FIG. It is a graph which shows the calculation result by the pump control apparatus in the case.

  Hereinafter, the present invention will be described in detail based on one embodiment shown in FIGS.

  As shown in FIG. 7, a hydraulic excavator 10 as a work machine includes a crawler type lower traveling body 12 driven by left and right traveling motors 12 ml and 12 mr as a body 11, and a swing bearing on the lower traveling body 12. And an upper swing body 14 that is driven to rotate by a swing motor 14m through a section 13. A boom 15 that is rotated by a boom cylinder 15c and an arm cylinder 16c are rotated on the front side of the upper swing body 14. A working device 18 having a bucket 17 rotated by an arm 16 and a bucket cylinder 17c is mounted. The working device 18 may be detachably equipped with an attachment that is operated by an attachment cylinder (or an attachment motor) (not shown).

  As shown in FIG. 6, the traveling motors 12ml and 12mr, the turning motor 14m, the boom cylinder 15c, the arm cylinder 16c, the bucket cylinder 17c and the attachment cylinder (or attachment motor) are attached to the upper turning body 14 (FIG. 7). This is a hydraulic actuator as a fluid pressure actuator that is driven by hydraulic oil as a working fluid discharged from a pump (main pump) 22 driven by a mounted engine 21.

  The pump 22 is, for example, a variable displacement pump provided with a pump swash plate for variable displacement control. In the present embodiment, the pump 22 includes a (one) pump 22a and a (other) pump 22b. This pump 22 includes a swash plate control device 23 ((one) swash plate control device 23a and (other) swash plate control device 23b), an electromagnetic proportional valve 24 ((one) electromagnetic proportional valve 24a and (other) ) Proportional solenoid valve 24b). The swash plate angles for variable capacity of the pump 22 are controlled by the displacement of the swash plate angle adjusting piston of the swash plate control device 23. These piston displacements are variably controlled by the electromagnetic proportional valve 24. The pump 22 is connected to a control valve 25, and the pressure oil from the pump 22 is distributed to each hydraulic actuator via the control valve 25, and the traveling motor is driven by the pressure oil distributed from the control valve 25. 12 ml, 12 mr, turning motor 14 m, boom cylinder 15 c, arm cylinder 16 c and bucket cylinder 17 c are driven. In the present embodiment, the pump 22a basically discharges pressure oil for driving the left travel motor 12ml, the boom cylinder 15c, the arm cylinder 16c, the bucket cylinder 17c, and the attachment cylinder (or attachment motor), and the pump 22b basically discharges pressure oil for driving the right traveling motor 12mr, turning motor 14m, boom cylinder 15c and arm cylinder 16c, and these use appropriate merging valves and the like as necessary. It can also be merged.

  The control valve 25 is provided with a plurality of flow control valves (spools) for controlling various hydraulic actuators slidably provided therein. Specifically, this control valve 25 includes a left travel flow control valve that controls the flow rate of the pressure oil supplied to the travel motors 12 ml, 12 mr, the swing motor 14 m, the boom cylinder 15 c, the arm cylinder 16 c, and the bucket cylinder 17 c, and the right travel flow rate. A control valve, a turning flow control valve, a plurality of boom flow control valves, a plurality of arm flow control valves, a bucket flow control valve, and the like are provided. In addition, the control valve 25 may include an attachment flow rate control valve that controls the flow rate of the pressure oil supplied to the attachment cylinder (or the attachment motor). Further, the control valve 25 is provided with an electromagnetic proportional valve unit 29 including an electromagnetic proportional valve 29a (FIG. 5) for controlling each flow control valve. Each electromagnetic proportional valve 29a (FIG. 5) of this electromagnetic proportional valve unit 29 responds to the lever operation or pedal operation of the pilot primary pressure oil supplied from the pilot pump 30 which is a sub pump driven by the engine 21, respectively. The pilot secondary pressure is reduced and output. In other words, the control valve 25 is pilot-controlled according to the operation amount indirectly through the electromagnetic proportional valve unit 29 by lever operation or pedal operation. The pilot secondary pressure oil output from the electromagnetic proportional valves 29a (FIG. 5) is supplied to each flow control valve, so that the flow control valves are each controlled in displacement.

  The electromagnetic proportional valve 24 and the electromagnetic proportional valve unit 29 are controlled by a controller (MECM) 34 shown in FIG. That is, the electromagnetic proportional valve 24, the electromagnetic proportional valve unit 29 (each electromagnetic proportional valve 29a), and the controller 34 constitute a pump control device 35 that controls the pump flow rate. On the input side of the controller 34 are a plurality of operating bodies 36 such as the above-mentioned levers (joysticks) and pedals that are operated by an operator to drive a hydraulic actuator, and a pressure sensor 37 that detects the discharge pressure of the pump 22 (FIG. 6). The (one) pressure sensor 37a and the (other) pressure sensor 37b) and a work mode changeover switch 38 as a switching means (switching unit) operable by an operator are electrically connected. Further, an electromagnetic proportional valve 24, an electromagnetic proportional valve unit 29 (each electromagnetic proportional valve 29a) and the like are electrically connected to the output side of the controller 34. Therefore, the hydraulic system of the present embodiment is of positive control control that controls the pump flow rate based on the operation amount of the operating body 36.

  As shown in FIG. 1, the controller 34 includes an actuator request flow rate calculation unit 41, a pump request flow rate calculation unit 42, and a pump flow rate command calculation unit 43. These calculation units 41 to 43 are sequentially connected in series, for example. It is connected to the. These calculation units 41 to 43 are provided for the pump 22a (FIG. 6) and the pump 22b (FIG. 6), respectively.

  The actuator required flow rate calculation unit 41 calculates and outputs the required flow rate of each hydraulic actuator based on the operation signal Si input according to the operation of the operating body 36. An operating body 36 for inputting an operation signal Si is electrically connected to the input side of the actuator required flow rate calculation unit 41. Further, as shown in FIG. 2, the actuator required flow rate calculation unit 41 calculates a required flow rate from each hydraulic actuator corresponding to each of the operating bodies 36, and a required flow rate signal Qi indicating the required flow rate. An output flow rate setting unit 45 is provided. That is, the actuator required flow rate calculation unit 41 outputs a required flow rate signal Qi via the flow rate setting unit 45.

  The flow rate setting unit 45 is provided with a pair of flow rate setting tables 47 and 48 for setting a flow rate based on the operation signal Si. The flow rate setting unit 45 is provided with a pair of rate limiters 49 and 50 that limit the rising speed of the required flow rate output from the flow rate setting tables 47 and 48. Further, the flow rate setting unit 45 is provided with a maximum value selector 51 for selecting a large value of the flow rate output from the rate limiters 49 and 50.

  The flow rate setting tables 47 and 48 are tables showing the ratio of the pump flow rate to the operation amount of the operating body 36. One flow rate setting table 47 and the other flow rate setting table 48 correspond to opposite operations (cylinder expansion and contraction, forward rotation and reverse rotation of the motor, etc.) of the hydraulic actuator.

  Returning to FIG. 1, the pump required flow rate calculation unit 42 calculates and outputs a pump required flow rate (pump required flow rate signal) based on the required flow rate of each actuator output from the actuator required flow rate calculation unit 41. . On the input side of the pump required flow rate calculation unit 42, an actuator required flow rate calculation unit 41 that inputs a required flow rate signal Qi corresponding to the required flow rate and an operation mode changeover switch 38 that inputs a switching signal SS are electrically connected. Is done. Further, as shown in FIG. 3, the pump required flow rate calculation unit 42 is provided with an adder 54 that outputs a sum obtained by adding the required flow rates (required flow rate signals Qi). Further, the pump required flow rate calculation unit 42 is provided with a maximum value selector 55 that selects and outputs the maximum value of the required flow rate (required flow rate signal Qi). The pump required flow rate calculation unit 42 is provided with a subtractor 56 that outputs the difference between the output of the adder 54 and the output of the maximum value selector 55. Further, the pump required flow rate calculation unit 42 is provided with a gain switching unit 57 that outputs the gain K switched according to the switching signal SS. As the gain K, a predetermined value of 0 to 1 is set. Further, the pump required flow rate calculation unit 42 is provided with a multiplier 58 that multiplies the output of the subtractor 56 and the output of the gain switch 57 and outputs the result. The pump required flow rate calculation unit 42 is provided with an adder 59 that adds the output of the multiplier 58 and the output of the maximum value selector 55 and outputs the result as a pump required flow rate signal Qpr indicating the pump required flow rate. Yes. That is, the pump request flow rate calculation unit 42 is connected to the pump request flow rate (pump request flow rate signal Qpr via the adder 54, the maximum value selector 55, the subtractor 56, the gain switch 57, the multiplier 58, and the adder 59. ) Is output.

  Returning to FIG. 1, the pump flow rate command calculation unit 43 calculates a pump flow rate command value for controlling the discharge flow rate from the pump 22 (FIG. 6) based on the pump request flow rate output from the pump request flow rate calculation unit 42. The pump flow rate command signal Qpc shown is calculated. Specifically, the pump flow rate command calculation unit 43 limits the pump request flow rate (pump request flow rate signal Qpr) output from the pump request flow rate calculation unit 42 with a constant horsepower flow rate obtained from the pump pressure, and the pump flow rate command value (Pump flow rate command signal Qpc) is output. On the input side of the pump flow rate command calculation unit 43, there are a pump request flow rate calculation unit 42 for inputting a pump request flow rate (pump request flow rate signal Qpr) and a pressure sensor 37 for inputting pump pressure (pump pressure signal Pp). Electrically connected. The pump flow rate command calculation unit 43 is provided with a constant horsepower flow rate table 61 for setting a constant horsepower flow rate based on the pump pressure (pump pressure signal Pp), as shown in FIG. Further, the pump flow rate command calculation unit 43 selects the minimum value between the output of the constant horsepower flow rate table 61 and the pump request flow rate (pump request flow rate signal Qpr), and as a pump flow rate command value (pump flow rate command signal Qpc). A minimum value selector 62 for output is provided. That is, the pump flow rate command calculation unit 43 outputs a pump flow rate command value (pump flow rate command signal Qpc) via the constant horsepower flow rate table 61 and the minimum value selector 62.

  The constant horsepower flow rate table 61 is a table showing the ratio of the pump flow rate to the pump pressure.

  The arithmetic units 41 to 43 have basically the same configuration for the pump 22a and the pump 22b, respectively. Therefore, only the details for the pump 22a will be described below, and the description for the pump 22b will be omitted.

  In the present embodiment, as shown in FIG. 2, on the input side of the actuator required flow rate calculation unit 41, an operating body 36tl for traveling left that inputs a traveling left operation signal Stl, and a boom operation that inputs a boom operation signal Sbm. The operation body 36bm for arm operation, the operation body 36am for arm operation for inputting the arm operation signal Sam, and the operation body 36bk for bucket operation for inputting the bucket operation signal Sbk are electrically connected to each other. The flow rate setting unit 45 includes a left travel flow rate setting unit 45tl, a boom flow rate setting unit 45bm, an arm flow rate setting unit 45am, and a bucket flow rate setting unit 45bk corresponding to the operating bodies 36tl, 36bm, 36am, and 36bk. ing.

  The left travel flow rate setting unit 45tl, the boom flow rate setting unit 45bm, and the bucket flow rate setting unit 45bk include a travel left operation signal Stl, a boom operation signal Sbm, and a bucket operation signal from the operation body 36tl, the operation body 36bm, and the operation body 36bk, respectively. Each Sbk is directly input. In addition, the arm flow rate setting unit 45am receives a signal in which the arm operation signal Sam input from the operation body 36am is limited by the boom operation signal Sbm input from the operation body 36bm. Specifically, a minimum value selector 65 is electrically connected to the arm flow rate setting unit 45am. The minimum value selector 65 is supplied with a signal in which the boom operation signal Sbm is restricted by the arm restriction table 66 and the arm operation signal Sam. The minimum value selector 65 selects and outputs a small value of these signals.

  Further, the flow rate setting table 47 and the flow rate setting table 48 correspond to the forward flow rate and the reverse flow rate, for example, in the left traveling flow rate setting unit 45tl. Similarly, the flow rate setting table 47 and the flow rate setting table 48 correspond to the boom up flow rate and the boom down flow rate in the boom flow rate setting unit 45bm, and correspond to the arm in flow rate and the arm out flow rate in the arm flow rate setting unit 45am. The flow rate setting unit 45bk corresponds to the bucket-in flow rate and the bucket-out flow rate.

  Note that an operation body for attachment operation (not shown) that inputs an attachment operation signal may be electrically connected to the input side of the actuator required flow rate calculation unit 41. In this case, the flow rate setting unit 45 may further include an attachment flow rate setting unit.

  Further, as shown in FIG. 3, on the input side of the pump required flow rate calculation unit 42, a flow rate setting unit 45 (flow rate setting units 45tl, 45bm, 45am, 45bk) of the actuator required flow rate calculation unit 41 (FIG. 2) and The work mode changeover switch 38 is electrically connected. In the gain switch 57, a plurality of, for example, three different values of gains K1, K2, and K3 are preset according to the work mode. Therefore, the work mode changeover switch 38 can select, for example, three kinds of work modes.

  As shown in FIG. 4, a pump request flow rate calculation unit 42 and a pressure sensor 37 a that inputs a pump pressure signal Ppa are electrically connected to the input side of the pump flow rate command calculation unit 43.

  Next, the operation of the illustrated embodiment will be described.

  As a rough outline, the controller 34 of the pump control device 35 calculates the total value and the maximum value of the required flow rate from each hydraulic actuator, and multiplies the maximum value by a predetermined gain of the difference between the total value and the maximum value. The pump flow rate command value is set based on the value obtained by adding the values. More specifically, the controller 34 calculates the total value and the maximum value of the required flow rate from each hydraulic actuator, and adds a value obtained by multiplying the maximum value by a predetermined gain of the difference between the total value and the maximum value. The pump flow rate command value is set by limiting the pump required flow rate with a constant horsepower flow rate.

  Specifically, when the operator operates the operation body 36, as shown in FIG. 2, an operation signal Si corresponding to the operation amount of the operation body 36 is input to the flow rate setting unit 45 of the actuator required flow rate calculation unit 41, respectively. The In these flow rate setting units 45, the required flow rate is set by the flow rate setting tables 47 and 48 in response to the operation signal Si, the start-up speed of the output of these flow rate setting tables 47 and 48 is limited by the rate limiters 49 and 50, By selecting the maximum value of the outputs of these rate limiters 49 and 50 by the maximum value selector 51, the required flow rate (required flow rate signal Qi) is set. For example, in FIG. 2, the vehicle travels based on the operation amounts of the operation body 36tl, the operation body 36bm, the operation body 36am, and the operation body 36bk (travel left operation signal Stl, boom operation signal Sbm, arm operation signal Sam, and bucket operation signal Sbk). A left required flow rate (travel left required flow rate signal Qtl), a boom required flow rate (boom required flow rate signal Qbm), an arm required flow rate (arm required flow rate signal Qam), and a bucket required flow rate (bucket required flow rate signal Qbk) are set. These set required flow rates (required flow rate signals Qi) are respectively input to the pump required flow rate calculation unit 42 shown in FIG.

  In the pump required flow rate calculation unit 42, the adder 54 calculates the sum (ΣQi) of the required flow rate (required flow rate signal Qi). Further, the maximum value selector 55 selects the maximum value (Max (Qi)) of these required flow rates (required flow rate signal Qi). Further, the subtracter 56 subtracts the output of the maximum value selector 55 from the output of the adder 54 (ΣQi−Max (Qi)).

  Here, since the work mode changeover switch 38 is switched in accordance with the work mode selected by the operator, the gain changer 57 that is switched by receiving the change signal SS from the work mode changeover switch 38 is set in advance. Any one of the gains K1, K2, and K3 is output as a gain K. The output gain K and the output of the subtractor 56 are multiplied by the multiplier 58 and output (K · (ΣQi−Max (Qi))), and the output of the multiplier 58 and the output of the maximum value selector 55 are output. Are added by an adder 59 to calculate a pump required flow rate (pump required flow rate signal Qpr (= Max (Qi) + K · (ΣQi−Max (Qi))).

  Next, in the pump flow rate command calculation unit 43 shown in FIG. 4, a constant horsepower flow rate (constant horsepower flow rate signal) is set in the constant horsepower flow rate table 61 based on the pump pressure (pump pressure signal Pp) detected by the pressure sensor 37. The pump flow rate command value (pump flow rate command signal) is limited by the constant horsepower flow rate (constant horsepower flow rate signal), which is limited by the minimum value selector 62. Qpc) is calculated. Then, by outputting this pump flow rate command value (pump flow rate command signal Qpc) to the electromagnetic proportional valve 24 shown in FIG. 6, the electromagnetic proportional valve 24 operates the swash plate control device 23 so that the flow rate of the pump 22 is increased. Be controlled.

  Specifically, the pump flow rate when the gain is switched when a plurality of hydraulic actuators are combined is calculated. For example, an example of required flow rates of the boom cylinder 15c, arm cylinder 16c, and bucket cylinder 17c when the boom 15 (operating body 36bm), arm 16 (operating body 36am), and bucket 17 (operating body 36bk) are combined and operated. 8 and FIG. 9A to FIG. 9D show the calculation results of the controller 34 based on these required flow rates. In addition, the broken line in Fig.9 (a) thru | or FIG.9 (d) shows the calculation result which limited the upper limit for the square root of the sum of the squares of each request | requirement flow volume by the pump maximum flow volume as a comparative example. Here, FIG. 9A shows a case where the gain is 0 (a simple maximum value of each required flow rate), FIG. 9B shows a case where the gain is 0.3, and FIG. 9C shows a case where the gain is 0.5. In this case, FIG. 9D shows a case where the gain is 1 (simply the total value of the required flow rates). When the gain is 0.3, it is substantially the same as the comparative example.

  As shown in FIGS. 9 (a) to 9 (d), for example, in the case of work in which fuel efficiency is important, the gain is set low, so that the opening area of each flow control valve of the control valve 25 can be increased in the combined operation. On the other hand, it is possible to improve the fuel consumption by setting the pump flow rate lower and suppressing the energy loss due to the pressure loss of the flow control valve. On the other hand, when emphasizing productivity and work speed, by setting the gain higher, the pump flow rate corresponding to the work can be set by complex operation, and productivity and work speed can be secured.

  As described above, according to the above-described embodiment, the controller 34 calculates the total value and the maximum value of the required flow rates from the respective hydraulic actuators, and determines the difference between the total value and the maximum value with respect to the maximum value. By setting the pump flow rate command value based on a value obtained by adding a value obtained by multiplying the gain of the value, the setting of the pump flow rate can be easily changed by changing the gain value.

  For example, by setting the gain to be switched by the work mode switch 38, the operator can easily change the setting of the pump flow rate according to the work mode by switching the work mode switch 38 according to the work mode. Therefore, it is possible to perform the pump flow rate control in accordance with the work mode desired by the operator especially in the combined operation of a plurality of hydraulic actuators.

  In the above embodiment, the gain may be set to an arbitrary value from 0 to 1, or may be set not only from a plurality of fixed values but also linearly.

  INDUSTRIAL APPLICABILITY The present invention has industrial applicability for business operators involved in manufacturing, sales, etc. of pump control devices or work machines.

12ml, 12mr Traveling motor as fluid pressure actuator
Swivel motor as a 14m fluid pressure actuator
15c Boom cylinder as a fluid pressure actuator
16c Arm cylinder as fluid pressure actuator
17c Bucket cylinder as fluid pressure actuator
22 Pump
34 Controller
35 Pump controller
36 Operation body
38 Work mode selector switch as switching means

Claims (4)

A pump control device that controls the flow rate of working fluid discharged from a pump with respect to a plurality of fluid pressure actuators that are operated in accordance with respective operations of a plurality of operating bodies,
The required flow rate from each fluid pressure actuator is obtained according to the signal generated by the operation of each operating body, and the total value and maximum value of these required flow rates are obtained. A pump control device comprising: a controller that sets a pump flow rate command value that sets a flow rate of a working fluid from a pump based on a value obtained by adding a value obtained by multiplying a predetermined gain of the difference. The pump control apparatus according to claim 1, further comprising switching means for switching and setting the gain. A pump control method for controlling the flow rate of working fluid discharged from a pump to a plurality of fluid pressure actuators,
Find the sum and maximum of the required flow rates from each fluid pressure actuator,
A pump control method, wherein the pump flow rate command value is set based on a value obtained by adding a value obtained by multiplying a maximum value by a predetermined gain of a difference between the total value and the maximum value. The pump control method according to claim 3, wherein the gain is switched according to the setting.

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