KR950004017B1 - Optimum working flow control device of excavator and its control method - Google Patents

Abstract

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Description

Optimum working flow control device of excavator and its control method

1 is a schematic hydraulic circuit diagram of an excavator equipped with a device according to the invention,

2 is a block diagram of a control system according to the apparatus of the present invention,

3 is a flowchart showing a process of controlling the discharge flow rate and the flow rate distribution of the pump,

Figure 4 is a flow chart showing the sprue operation control process of each control valve for controlling the flow of the operating pressure oil supplied to each actuator when overloaded;

5 is a discharge characteristic curve of the pump with respect to the operation angle of the operation pedal / lever,

6 is a flow chart of the pump flow control discharge characteristics during single joining,

7 is a total horsepower characteristic diagram showing the relationship between the load and the pump discharge amount.

* Explanation of symbols for the main parts of the drawings

1 engine 2 output shaft

3: first pump 4: second pump

5: third pump 6: left driving motor

7: left running control valve 8: differential cylinder

9: differential control valve 10: swing motor

11: Swing control valve 12: Right driving motor

13: Right driving control valve 14: Bucket cylinder

15: bucket control valve 16: pour cylinder

17: pour control valve 18: option valve

19a, 19b: swash plate adjustment valve 20a, 20b: swash plate adjustment mechanism

21: operation lever / pedal 22a, 22b: electronic proportional control valve block

23a, 23b, 23c, 23d, 23e, 23f: displacement sensor 24: electronic controller

25a, 25b: amplifier 26: amplifier.

27a, 27b: cross line

The present invention relates to an optimum operating flow rate control system of an excavator which is configured to optimally control the discharge amount of the hydraulic oil for operating each actuator of the excavator, and in particular, the discharge flow rate of each pump automatically according to the size of the load applied to each actuator An excavator for controlling an amount of pressure oil supplied to each actuator while being in an optimum state relates to an optimum operating flow rate control apparatus and a control method thereof.

In general, heavy construction equipment such as excavators are equipped with several actuators and are hydraulically gained to enable these actuators to exert great forces.

However, if several actuators (hereinafter referred to as actuators) are connected to one hydraulic pump to operate, the capacity of this hydraulic pump must be absolutely large, so that the loss of power due to the operation of a large pump when the operating pressure is small This will be a lot. That is, the power loss of the engine for directly driving the pump is increased.

Various methods have been devised to solve this problem, and one of them is to connect two relatively small pumps in series to the output shaft of the engine, and to connect each of these pumps by half of the number of actuators. The parallel hydraulic circuit uses a parallel hydraulic circuit so that each pump is responsible for only half of the total number of actuators to prevent power loss of the engine. In general, the pump is not operated when the actuator on each side does not operate. Therefore, it is generally used in heavy equipment such as excavators because it reduces the power loss of the engine more efficiently.

However, the parallel circuit, which is designed to simply bear the number of actuators in half, discharges oil from both pumps when a large load is applied to any one actuator because each pump supplies pressure to only the actuator. It is impossible to supply the oil pressure together, so when there is a big load, it is difficult.However, to compensate for this problem, the oil pressure lines of both pumps are connected in advance to the actuator which may be subjected to the heavy load. When the actuator is subjected to an excessive load, the pressure oil discharged from both pumps is simultaneously supplied so that the pump can support a large load without being overwhelmed.

However, in this case, the oil pressure supply lines of both pumps are connected to each other on the required actuator side to supply the mutual pressure oil, but even in this case, both pumps do not take charge of the load uniformly, and the pump directly connected to the actuator Will be responsible for most of the load while the other pump will operate to cover only some of the load.

Therefore, one pump may be excessively operated, but the other one may have a lot of space. Therefore, the pump that is excessively operated may be damaged. In the case where two or more actuators are operated at the same time, if a certain actuator is overloaded, the pump may be loaded. Due to the discharging characteristics of the actuators, no equal amount of hydraulic oil is supplied to each actuator, which causes the actuators to operate at high speed, while the other actuators operate at too slow speed, which makes the excavator unprecedented with the unmatched operating speed of the entire actuator. There may be times when you don't get the job done right.

Accordingly, the present invention has been made to solve the above-mentioned problems, both pumps to equally discharge the operating pressure oil according to the load applied to each actuator shared in the parallel hydraulic circuit described above, When the actuators are operated in combination at the same time, the total pressure oil discharged from both pumps is distributed proportionally to each actuator in operation according to the load so that each actuator is operated at an equal speed so as to make the best use of the pump discharge performance. It is an object of the present invention to provide an optimum operating flow rate control device for excavators and a control method thereof so as to improve the independent operability of each actuator without difficulty.

In order to achieve the above object and object, the present invention provides an electronic controller having a built-in operation lever / pedal micom that controls an operation displacement sensor of the actuator, and controls the operation of the actuator and the actuator. While electrically connected with the electronic controller, the electronic controller includes a swash plate angle control valve for adjusting the swash plate angles of the first and second pumps driven by the engine to an internal pilot pressure, and a supply amount of the operating pressure oil supplied to the respective actuators. It consists of a structure electrically connected to the electronic proportional control valve block for controlling the sprue movement of each control valve to control the internal pilot pressure, the actuator according to the operation amount of the operating lever / pedal to operate the actuator The amount of discharge of the pump related to the If the swash plate angle is properly adjusted, and if two or more actuators are operated at the same time, the corresponding operation lever / pedal is sensed to detect the operation amount and the displacement speed of the actuator so that the discharge amount of both pumps can be controlled uniformly. When the actuator is overloaded, the sprues connected to each actuator are controlled by the internal pilot pressure so that the total pressure oil discharged from the pump is evenly distributed to all the actuators.

Hereinafter, with reference to the accompanying drawings, the present invention will be described in detail.

FIG. 1 is a schematic diagram of the entire hydraulic circuit of an excavator in which the apparatus of the present invention is employed, and FIG. 2 is a system diagram showing only the control system of the present invention in FIG. When describing the entire hydraulic system, the first and second pumps 3 and 4 for supplying the operating pressure oil of each actuator to the output shaft 2 of the engine 1 and the third pump for supplying the internal pilot pressure oil (5) are connected in series, respectively, the first pump (3) left running control valve (7) for controlling the flow of the operating pressure oil supplied to the left driving motor (6), for example, the left running of the excavator And a differential control valve 9 for controlling the flow of the operating pressure oil supplied to the cylinder 8 for operating the excavator stick of the excavator boom, and for turning the upper body of the excavator to the lower body. Work supplied to the swing motor (10) A pressure swing control valve 11 which controls the flow is significant, each series connection.

In addition, the second pump 4 includes, for example, a right driving control valve 13 for controlling the flow of the operating pressure oil supplied to the right driving motor 12 which is responsible for driving the right side of the excavator, and dirt directly from the excavator. Bucket control valve 15 for controlling the flow of the operating pressure oil supplied to the cylinder 14 for operating the bucket, which is an excavation part, and is supplied to the cylinder 16 for adjusting the boom overall angle of the excavator up and down A boolean control valve 17 for controlling the flow of the working pressure oil and an optional valve for controlling the flow of the working pressure oil for operating a predetermined actuator (not shown) attached as required or as required by the consumer. ) Are connected in series.

On the other hand, while the third pump 5 is smaller than the first and second pumps 3 and 4, the pressurized oil supplied from the third pump 5 is the first and second pumps 3 and 4. It is operated by the internal pilot pressure oil for moving the inclined plate (3a, 4a) and the sprue of each control valve (7, 9, 11, 13, 15, 17, 18), that is, the third pump ( 5) The part of the pressurized oil discharged from the swash plate angle adjusting mechanism 20a directly controls the inclined plates 3a and 4a of the pumps 3 and 4 through the swash plate angle adjusting valves 19a and 19b which are electromagnetic proportional valves. 20b), the internal pilot pressure applied to the swash plate angle control mechanism (20a, 20b) is variable according to the degree of adjustment of the swash plate angle control valve (19a, 19b) of the inclined plate (3a, 3a) While adjusting the inclination angle, the remaining portion of the hydraulic oil discharged from the third pump 5 is electromagnetic proportional valve block 22a, 22b operated by the operation lever / pedal 21 of each actuator through another path. By moving the sprue of each of the control valves (7, 9, 11, 13, 15, 17, 18) to the left and right side by means of the variable pressure of the operating pressure oil flowing into each actuator through each control valve It is supposed to be.

Here, the operation lever / pedal 21 has a number corresponding to the number of each actuator and control valve (7, 9, 11, 13, 15, 17, 18), the electronic proportional control block (22a) 22b) is provided with an electronic proportional control valve (not shown) corresponding to the number of control valves (7, 9, 11 or 13, 15, 17, 18) respectively disposed therein, so as to operate relevant actuators to operate the corresponding actuators. When the lever / pedal 21 is operated, the control valve inside the electromagnetic proportional control valve block 22a or 22b associated therewith operates in proportion to the internal pilot pressure oil discharged from the third pump 5. It is supplied as one of (7, 9, 11, 13, 15, 17, 18) to move the sprue of the corresponding control valve to the left / right.

The control system as shown in FIG. 2 is attached to the structure of the hydraulic circuit as described above, and the respective actuators, that is, the hydraulic motors 6, 10, 12 and the cylinders 8, 14, 16 Displacement detection sensors 23a, 23b, 23c, 23d, 23e, and 23f for detecting a displacement by the operation are provided in each of the operating levers / pedals 21 and both electromagnetic proportional control blocks 22a and 22b. The electronic controller 24 with built-in microcomputer and the amplifiers 25a and 25b are installed and electrically connected, while the electronic controller 24 is also connected to the swash plate adjustment valves 19a and 19b through the amplifier 26. While being electrically connected, it is also electrically connected to the displacement detection sensors 23a, ... installed in the respective actuators.

Such a control system has an electric current proportional to the amount of manipulation of the actuating lever / pedal 21 applied to the electronic controller 24 to be processed and then amplified by the amplifiers 25a and 25b, and then proportional to the control valve. It is applied to the control valve block (22a, 22b) to control the internal pilot pressure oil injected from the third pump 5 to the sprue of each control valve (7, 9, 11, 13, 15, 17, 18) In addition, by inputting a signal corresponding to the displacement amount of each actuator detected by each displacement detection sensor (23a, ...) to the electronic controller 24, the microcomputer inside the electronic controller 24 of the actuator The amount of displacement is computed by the load applied to it and the required discharge amount of the operating pressure oil, so that the first and second pumps 3 and 4 are appropriately adjusted so that both pumps take an equal load in the event of overload. Depending on the flow rate By displacing the sprues of the corresponding control valves (7, 9, 11, 13, 15, 17) so that two or more actuators operate at equal speeds, the workability of each actuator is always maintained while both pumps discharge the optimum flow rate. Excellent control.

In addition, the displacement detection sensors 23a, 23b, 23c, 23d, 23e, and 23f, which detect displacements according to the operation of the actuators 6, 8, 10, 12, 14, and 16, are known in various types of sensors. For example, the sensors 23a, 23b, and 23e attached to the boom cylinder 16, the bucket cylinder 14, and the differential cylinder 8, respectively, may use a variable resistance potential meter or a magnetoresistive body. Using a sensor that counts the number of magnetic materials to output an electrical signal, the sensor attached to the swing motor 10 side is an absolute encoder for detecting the absolute position of the upper frame relative to the lower frame (Absolute type) An encoder is used, and the sensors 23c and 23d attached to the driving motors 6 and 12, respectively, can be configured as incremental encoders.

In addition, the amplifiers 25a, 25b, and 26 connected to the output side of the controller 24 amplify the current signals of the control values calculated in the controller 24 to adjust the swash plate angle with the electronic proportional control blocks 22a and 22b. The current generated according to the operation amount of the operation lever / pedal 21 is calculated by the controller 24 and then amplified by the amplifiers 25a and 26b. The inner pile is applied to the electromagnetic proportional control valve block (22a, 22b) for the control valve and injected into the sprue of each control valve (7, 9, 11, 13, 15, 17, 18) from the third pump (5) The lot pressure oil is controlled, and a signal corresponding to the displacement amount of each actuator detected by the respective displacement detection sensors 23a, ... is inputted to the controller 24 so that the controller 24 of the actuator is used. The amount of displacement is calculated by applying the displacement and the required discharge amount of the operating pressure oil. By properly adjusting the first and second pumps 3 and 4, both pumps take on an equal load in case of overload.

Hereinafter, the control method will be described with reference to FIGS. 3 and 4.

First, FIG. 3 is an example of a flowchart showing a process of controlling the discharge flow rates discharged from both the first and second pumps 3 and 4, and the discharge flow rate control process is an operation lever for each corresponding actuator / When the pedal 21 is operated, an electric signal corresponding to the manipulation amount is applied to the electronic controller 24 and compared with a value previously input in the previous operation, wherein the manipulation lever / pedal 21 If it is determined that the operation is in a neutral state in another state, the electrical signal corresponding to the manipulated amount is sent to the electronic proportional control block 22a or 22b through the amplifier 25a or 25b without undergoing a separate process, and otherwise If the control lever / pedal 21 is operated in a state where the actuator is to be moved forward or backward rather than in a neutral state, it is again judged whether it is the same as the previous operation state. If it is the same as the previous operation state, it maintains the previous output amount (discharge amount) already set, and if it is different from the previous operation state, the operation amount judgment step of the operation lever / pet to apply the control signal to the next processing step ; In this step, when the operation lever / pedal is generated with different electric resistance depending on the operation amount (operation angle), for example, and a current corresponding to the resistance is applied, the actuator to operate according to the magnitude of this current is operated. Calculating the required discharge flow rate of the pump for calculating the required discharge flow rate of the entire pump according to the required amount; Then calculating a required operation amount of the actuator control valve for moving the sprue of the associated control valve so that a corresponding amount of operating pressure oil is injected into the actuator according to the operation amount of the operation lever / pedal; Calculating the discharge flow rate to be in charge of each of the first and second pumps according to the discharge flow rate of the pump calculated in the required discharge amount calculation step of the pump and the operation amount of the control valve calculated in the required operation amount calculation step of the actuator control valve. Discharge amount discharge calculation step; And a signal output step of outputting the final signal processed in the discharge amount distribution calculation step to the swash plate angle adjusting mechanisms 19a and 19b through the amplifier 26.

Specifically, when the discharge flow rate of the pump made through the pump discharge flow rate control process as described above is specifically indicated, first, one related actuator in the operation lever / pedal 21 is operated to operate (single operation) only one actuator. When the bay is operated, the pump is discharged according to the characteristic curve of the discharge flow rate with respect to the operation angle as shown in FIG. 5 by the signal output from the electronic controller 24. That is, the jaw lever // pedal ( The maximum flow rate is discharged when the operating angle is about 99%, and the minimum flow rate is discharged when the operating angle is about 10%.

The following is the case of single joining, that is, when one actuator, for example, a boom cylinder 16 or a differential cylinder 8, which requires a large amount of working flow, is operated, respectively, the first pump 3 on the responsible side thereof. Even if the pump is operated to discharge the maximum amount of discharge, the flow rate is insufficient to operate the actuator, so the pump (3) on the relatively responsible side is too crowded while the other pump (4) does not operate, so that the overall hydraulic system This results in an imbalance.

Therefore, in this case, the respective displacement detection sensors 23a or 23e attached to the boom cylinder 16 or the differential cylinder 8 detect the displacement speed (moving distance per unit time) of the corresponding actuator, and the corresponding operation. In the case where the actuator detects the discharge flow rate of the associated pump according to the operation angle of the lever / pedal 21, the other pump is operated to determine the discharge flow rate Q ₂ discharged from the pump. ₁ ), so that both pumps (3, 4) share the load on the actuator by supplying it to the actuator.

At this time, if the other pump is operated at the same time as soon as the magnetic pump is started, if a large amount of working pressure oil is supplied to one actuator at once, the impact on the load will be great and the equipment will be overwhelmed. As described above, after the magnetic pump is operated, the micromanipulation time is delayed, and then the other pump is operated so that the operation of the actuator is not overwhelmed and the operability is improved.

Next, the case where several actuators operate at the same time (combined operation) will be described.

1) When the actuators which are not cross-connected by the respective control valves 7, 9, 11 and 13, 15, 17 and 18 connected to the first pump 3 and the second pump 4 respectively operate, Since the discharge oil of the pump cannot be absolutely joined, in this case, since it is the same as the operating state of the single actuator by the same single pump as in the first case, no separate control is performed at this time. In this case, if no separate operation flow control is required, the first pump (3) determines in advance the control valve inlet line of the relevant actuator in the case where a large load is applied by judging whether or not the corresponding actuator bears a large load in advance. The connection between the system on the side and the system on the second pump 4, and the actuator that does not handle the large load, does not connect between the two systems, and the operation as described above is automatically performed.

That is, in the hydraulic circuit shown in FIG. 1, a cross line 27a having a check valve is installed between the swing control valve 11 and the pour valve 17, and the left running control valve 7 and Cross lines 27b are also provided between the right-hand drive control valves 13 so that the actuators supplied with the working pressure oil through these control valves receive a supplementary supply of the working pressure oil discharged from both pumps 3 and 4. The other actuators, which are not connected to these crosslines, operate in their own independent operation.

2) When two actuators are operated while only one pump is used, the operating flow rate is discharged as the sum of the required flow rates in each single operation. That is, when the bucket is operated while the buoy is down, it is poured. Since the load for the descent operation of R is relatively small, the flow rate discharged from only one pump is sufficient.

In numerical terms, if the flow rate required for boozedown requires half of the maximum pump discharge rate and the flow rate required to operate the bucket requires 1/4 of the maximum pump discharge flow rate, It is necessary to control the pump to discharge only 3/4 of the maximum discharge amount.

3) However, in the case of a complex operation in which the bucket is to be operated while the boolean is up, the load is increased much more than when the boolean is lowered. Becomes difficult.

Therefore, the magnetic pump of the side where the pour cylinder 16 and the bucket cylinder 14 are commonly connected, that is, in the case of the system of the present invention, the pressure oil discharged from the second pump 4 preferentially operates the bucket cylinder 14. While carrying the required flow rate, the excess pressure oil is sufficient to raise the pour cylinder 16, and the remaining operating demand flow required to raise the pour cylinder 16 is discharged from the other pump, that is, the first pump 3 It is supplemented with the flow rate which becomes.

When the boom cylinder 16 is operated in such a manner as to raise the boom cylinder 16 in this manner, the electric signals applied to the controller 24 and the actuators are actuated by operating the corresponding operation lever / pedal 21, respectively. The operation speed signal sensed by the installed displacement detection sensors 23a and 23b and applied to the controller 24 is processed, and as a result, the bucket cylinder 16 operates normally. If it is determined that the first pump 3 is operated, the control signal is also sent to the swash plate angle control valves 19a and 19b of the respective pumps 3 and 4 so that the swash plate angle adjustment mechanisms 20a and 20b are both pumps ( It is controlled so that the sharing discharge amount of 3, 4) becomes the same.

4) Meanwhile, when the upper body of the excavator rotates with respect to the lower body and the differential and the bucket are operated together, the first pump 3 operates as in the case of 3). The swing motor (10) and the differential cylinder (8) for swinging the upper body of the excavator, and the second pump (4) is responsible for the boom cylinder (16), the degree of load applied to each actuator also As a result, the supply pressure oil on the side of the first pump 3 is supplemented and supplied along the cross line 27a toward the pour cylinder 16, and the supplementary control method is also operated at the operation angle of the operating lever / pedal 21 as described above. The controller performs arithmetic processing on the controller based on the signal according to the signal and the signal detected by the displacement sensor installed in each actuator.

By the way, when the bucket is operated with two or more actuators, for example, raising the boolean, the normal load on each of these actuators can be operated as in the case of 3) above. I can not. As mentioned, because as shown in the seventh degree, the maximum discharge flow rate when the phase characteristics of the pump flow rate curve, the load P ₁ about a load with 2Q _1, but when the load is increased to P ₂ maximum discharge flow rate is in Q ₂ .

Therefore takes a normal load (P ₁₎ in the bucket and the boom is supplied operating pressure oil in each each Q ₁ on either side of the actuator, but to each actuator is operating in a normal operating speed, such as jam is a load (P ₂₎ over-the bucket thereto Since the discharge flow rate is only Q ₂ , when the flow rate of Q ₁ is supplied to the pour cylinder 17, only the remaining flow rate of Q ₂ -Q ₁ is supplied to the bucket cylinder 15, so that the operation speed of the bucket is too slow and normal. In this case, the actuators are supplied with Q ₁ '(= Q2 / 2), which is half the flow rate of Q ₂ , to reduce the operating speed of both actuators. To control the operation.

This control process is shown in a flow chart in FIG. 4, and in this overload supply control process, the electric signal corresponding to the operation angle is operated when the operation lever / pedal 21 of each actuator is operated. Is applied to the electronic controller 24 and compared with the value input in the previous operation, if it is determined that the operation lever / pedal 21 is operated in a neutral state in any other state, it is immediately performed without a separate process. An output amount, and an operation amount judging step of the operation lever / pedal which, when it is determined that the operation lever / pedal 21 is not in a neutral state, applies a signal corresponding to the operation amount to the next processing step; An actuator speed calculation step of calculating the moving speed V ₁ of the actuator and the current speed V _f of the actuator according to the operation amount of the operation lever / pedal 21, respectively; In the speed calculation step, a relative difference (ΔV = V ₁ -V _f ) between the actual moving speed (V _f ) of each actuator and the required moving speed (V ₁ ) according to the manipulation amount of the control lever / pedal 21 is obtained. An overload detection step of determining which actuator is currently overloaded according to the speed difference value; If an overload condition is detected, it is determined whether two or more actuators and the first and second pumps 3 and 4 are operating at the same time, and a composite operation judgment that determines whether the control operation is currently in progress in response to the overload. step; If the control operation corresponding to the overload is already performed in the previous operation process in the combined operation determination step, the input value set in the previous control process is already controlled by the input speed (V _q ) and the current actuator speed (V _f). ), If these two values are judged to be the same, they are continuously output as control values. If the values of V _f and V _q are different, calculate the required ratio of output according to the load on each actuator. Calculating a constant ratio output for the actuator; Control signal output step of outputting the control signal for controlling the control valve of the actuator according to the value calculated in the constant ratio output amount calculation step to the electronic proportional control valve block (22a, 22b) through the amplifier (25a, 25b) Is made of.

This control process allows two or more actuators to operate at the same time and if any one of them is overloaded, the actual actuator operating speed (V _f ) and the operating lever / pedal detected by the displacement sensor of the overloaded actuator. If the difference occurs when the required speed (V ₁ ) is compared with the operation of (21), it is judged that an overload is applied at once, and the actuators that are overloaded and the actuators that are not overloaded are fully loaded with the current maximum discharge flow rate. By distributing at the ratio of the required operating pressure oil, a signal corresponding to the distribution amount is applied to the corresponding control valve in the electromagnetic proportional control valve blocks 22a and 22b. ) Is supplied to the sprue of the control valve (7, 9, 11, 13, 15, 17, 18) connected to each actuator through the control valve from the In order to control the flow of the internal pilot pressure oil to move to the right, and by moving the sprue of each control valve to the left and right as appropriate, through the control valve the first pump (3) and the second pump As shown in FIG. 7, when the P ₂ overload is applied as shown in FIG. 7, the maximum discharge amount Q ₂ is divided into Q ₁ 's by half to uniformly supply the overload. Although not operating at the same normal speed as when not in operation, both actuators operate at relatively equal speeds, allowing the entire excavator to perform its normal operation, albeit at a slightly slower speed, even if a particular actuator is overloaded. do.

As described above, the present invention calculates the displacement signal detected by the displacement sensor installed in each actuator and the signal according to the operation angle of the actuator lever / pedal of the actuator, thereby handling one of the ones in charge according to the flow rate required by each actuator. The pump or both pumps are selectively operated to discharge the optimum flow rate, and when both pumps are operated at the same time, the two pumps share the load applied to the entire operating actuator evenly, and if any actuator is overloaded In this case, the maximum pump discharge flow rate at the time of overload is distributed evenly to each actuator so that continuous work can be performed without stopping the work, thereby improving the independence of each actuator without load on each pump, thereby improving workability. have.

Claims (3)

The operating state of the left driving motor (6), the differential cylinder (8), the swing motor (10), the right driving motor (12), the bucket cylinder (14), and the pour cylinder (16), which are the actuators of the excavator. Displacement detection sensors 23a, 23b, 23c, 23d, 23e, and 23f are installed to control the operation of the sensors, and the operation of each of the sensors and the actuators 23a, 23b, 23c, 23d, 23e, and 23f is controlled. The control lever / pedal 21 is electrically connected to an electronic controller 24 having a built-in microcomputer, and the electronic controller 24 is connected to the first and second pumps 3 and 4 driven by the engine 1. Swash plate control valves 19a and 19b for adjusting the swash plate angle to the internal pilot pressure, and control valves 7, 9, 11, 13, 15 and 17 for controlling the supply amount of the working pressure oil supplied to the respective actuators. Electronic proportional control valve blocks 22a and 22b for adjusting the sprue movement of the crankshaft to the internal pilot pressure, and an operation lever for operating the respective actuators. And the pedal 21 are electrically connected to each other, while the swing control valve 11 and the boolean control valve 17 are connected to each other via a cross line 27a having a check valve and the left travel control valve ( 7) and the right running control valve (13) are also the optimum operating flow control device of the excavator connected to each other via a cross line (27b) having a check valve. An operation amount judging step of the operation lever / pedal 21 for judging an operation amount by receiving an electrical signal of a size corresponding to the operation angle according to the operation of the corresponding operation lever / pedal 21 corresponding to each actuator of the excavator; A required discharge flow rate calculating step of calculating a required discharge flow rate of the first and second pumps 3 and 4 corresponding to the operation requirements of the actuator to be operated according to the operation amount of the operation lever / pedal 21; Calculating a required operation amount of a corresponding actuator control valve for moving a spring of an associated control valve so that a corresponding amount of operating pressure oil is injected into the corresponding actuator according to the operation amount of the operation lever / pedal 21; According to the discharge flow rate of the pump calculated in the required discharge amount calculation step of the pump and the operation amount of the control valve calculated in the required operation amount calculation step of the actuator control valve, the first and second pumps 3 and 4 should each be discharged. A discharge amount distribution calculating step of calculating a flow rate; The excavator outputs a signal output step of outputting the swash plate angle control valves 19a and 19b through the amplifier 26 to adjust the swash plate angle adjustment mechanisms 20a and 20b with the final signal processed in the discharge amount distribution calculation step. Optimal operating flow control method. Determination of the operation amount of the operation lever / pedal 21 to determine the operation amount by receiving the electrical signal of the size corresponding to the operation angle according to the operation of the operation lever / pedal 21 for each actuator of the excavator, and Actuator that calculates the current moving speed (V _f ) of the actuator by the required moving speed (V ₁ ) of the actuator according to the operation amount of the control lever / pedal (21) and the electrical signal detected by the displacement sensor installed in each actuator Speed calculation step; An overload detection step of determining whether or not an actuator is overloaded according to this speed difference value by obtaining the relative difference (ΔV = V _i -V _f ) of the two speeds calculated in the actuator speed calculating step; A composite operation judging step of judging whether two or more actuators and the first and second pumps 3 and 4 are operating at the same time as well as determining whether a control process corresponding to an overload is set the previous time; Compared to the already controlled input speed (V _q ) which is the input value set in the previous control process and the speed of the current actuator (V _f ), if the two values are determined to be the same, they are continuously output as the set control value. Calculating the output ratio of a constant ratio for each actuator for calculating a required output ratio of a predetermined ratio according to the load on each actuator when the values of V _f and V _q are different from each other; Control signal output that outputs a control signal to the electronic proportional control valve block (22, 22b) through the amplifier (25a, 25b) for controlling the control valve of the actuator according to the value calculated in the step of calculating the output ratio of the predetermined ratio Optimal flow control method in case of overload of excavator consisting of two steps.