Method for controlling shovel

Abstract

To provide a method for controlling a shovel capable of improving operability.SOLUTION: A method for controlling a shovel comprising a lower traveling body, an upper rotating body provided rotatably relatively to the lower traveling body, and an attachment provided on the upper rotating body, comprises: reducing a rotation command value for rotating the upper rotating body when an operation related to the operation of the attachment is decreased during a combined operation of the operation of the attachment and the rotation operation of the upper rotating body.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a control method for an excavator.

Background Art

[0002] Patent Document 1 discloses an excavator including a hydraulic system that performs negative control, having a plurality of directional control valves in a center bypass pipeline to which hydraulic oil is supplied from a main pump, and a negative control throttle provided between the most downstream control valve and an oil tank. (Mainly refer to FIG. 4.)

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, when the operation of the attachment is decelerated during a combined operation in which the operation of the attachment and the turning operation of the upper swing body are performed simultaneously, the operability of the turning operation may deteriorate.

[0005] Therefore, in view of the above problems, an object of the present invention is to provide a control method for an excavator that improves operability.

Means for Solving the Problems

[0006] To achieve the above object, a control method for an excavator according to an embodiment of the present invention is a control method for an excavator including a lower traveling body, an upper swing body rotatably provided with respect to the lower traveling body, and an attachment provided on the upper swing body, and when an operation related to the operation of the attachment decreases during a combined operation of the operation of the attachment and the turning operation of the upper swing body, a turning command value for turning the upper swing body is decreased. [Effect of the Invention]

[0007] According to the above embodiment, a control method for an excavator that improves operability can be provided. [Brief Description of the Drawings]

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

[0009] First, with reference to FIG. 1, an excavator 100 as a drilling machine according to an embodiment of the present invention will be described. FIG. 1 is a side view of the excavator 100.

[0010] In the present embodiment, the lower traveling body 1 of the excavator 100 includes crawlers. The crawlers are driven by a traveling hydraulic motor 2M as a traveling actuator mounted on the lower traveling body 1. Specifically, the crawlers include a left crawler and a right crawler. The left crawler is driven by a left traveling hydraulic motor 2ML, and the right crawler is driven by a right traveling hydraulic motor 2MR.

[0011] The upper slewing body 3 is mounted on the lower traveling body 1 via a slewing mechanism 2 so as to be slewed. The slewing mechanism 2 is driven by a slewing hydraulic motor 2A serving as a slewing actuator mounted on the upper slewing body 3. However, the slewing actuator may be a slewing motor generator serving as an electric actuator.

[0012] A boom 4 is attached to the upper slewing body 3. An arm 5 is attached to the tip of the boom 4, and a bucket 6 serving as an end attachment is attached to the tip of the arm 5. The boom 4, the arm 5, and the bucket 6 constitute an attachment AT which is an example of an attachment. The boom 4 is driven by a boom cylinder 7, the arm 5 is driven by an arm cylinder 8, and the bucket 6 is driven by a bucket cylinder 9. The boom cylinder 7, the arm cylinder 8, and the bucket cylinder 9 constitute an attachment actuator. In the example shown in FIG. 1, the bucket 6 is an excavation bucket, but it may be a skeleton bucket or a (debris removal bucket). Further, the bucket 6 may be provided with a bucket tilt mechanism.

[0013] A cabin 10 serving as a driver's cab is provided in the upper slewing body 3, and a power source such as an engine 11 is mounted. An operating device 26, a controller 30, etc. are provided inside the cabin 10. Further, a space recognition device 70, etc. are attached to the upper slewing body 3. In this document, for the sake of convenience, the side of the upper slewing body 3 where the attachment AT is attached is defined as the front, and the side where the counterweight is attached is defined as the rear.

[0014] The space recognition device 70 is configured to recognize objects existing in the three-dimensional space around the excavator 100. Further, the space recognition device 70 may be configured to calculate the distance to the objects recognized from the space recognition device 70 or the excavator 100. The space recognition device 70 includes, for example, an ultrasonic sensor, a millimeter-wave radar, an imaging device, a LIDAR, a distance image sensor, an infrared sensor, etc., or any combination thereof. The imaging device is, for example, a monocular camera or a stereo camera. In the present embodiment, the space recognition device 70 includes a front sensor 70F attached to the front end of the upper surface of the cab 10, a rear sensor 70B attached to the rear end of the upper surface of the upper swing body 3, a left sensor 70L attached to the left end of the upper surface of the upper swing body 3, and a right sensor (not shown) attached to the right end of the upper surface of the upper swing body 3. An upper sensor for recognizing an object existing in the space above the upper swing body 3 may be attached to the excavator 100.

[0015] The operation device 26 is a device used by the operator for operating the actuator. The operation device 26 includes, for example, an operation lever and an operation pedal. The actuator includes at least one of a hydraulic actuator and an electric actuator.

[0016] The controller 30 is a control device for controlling the excavator 100. In the present embodiment, the controller 30 is composed of a computer including a CPU, a volatile memory device, a non-volatile memory device, and the like. Then, the controller 30 reads out a program corresponding to each function from the non-volatile memory device and loads it into the volatile memory device, and causes the CPU to execute the corresponding process. Each function includes, for example, a machine guidance function for guiding (guiding) the manual operation of the excavator 100 by the operator, and a machine control function for assisting the manual operation of the excavator 100 by the operator or operating the excavator 100 automatically or autonomously. The controller 30 may include a contact avoidance function for automatically or autonomously operating or stopping the excavator 100 in order to avoid contact between an object existing within the monitoring range around the excavator 100 and the excavator 100. The monitoring of the objects around the excavator 100 is performed not only within the monitoring range but also outside the monitoring range.

[0017] Next, with reference to FIG. 2, a configuration example of the hydraulic system mounted on the excavator 100 will be described. FIG. 2 is a diagram showing a configuration example of the hydraulic system mounted on the excavator 100. In FIG. 2, the mechanical power transmission system, the hydraulic oil line, the pilot line, and the electric control system are shown by double lines, solid lines, broken lines, and dotted lines, respectively.

[0018] The hydraulic system of the excavator 100 mainly includes an engine 11, a regulator 13, a main pump 14, a pilot pump 15, a control valve unit 17, an operating device 26, a discharge pressure sensor 28, an operation sensor 29, a controller 30, and the like.

[0019] In FIG. 2, the hydraulic system is configured such that hydraulic oil can be circulated from the main pump 14 driven by the engine 11 to the hydraulic oil tank through the center bypass pipeline 40 or the parallel pipeline 42.

[0020] The engine 11 is the drive source of the excavator 100. In this embodiment, the engine 11 is, for example, a diesel engine that operates to maintain a predetermined rotational speed. The output shaft of the engine 11 is connected to the input shafts of the main pump 14 and the pilot pump 15, respectively.

[0021] The main pump 14 is configured to be able to supply hydraulic oil to the control valve unit 17 via a hydraulic oil line. In this embodiment, the main pump 14 is a swash plate type variable displacement hydraulic pump.

[0022] The regulator 13 is configured to be able to control the discharge amount of the main pump 14. In this embodiment, the regulator 13 controls the discharge amount of the main pump 14 by adjusting the swash plate tilt angle of the main pump 14 according to a control command from the controller 30.

[0023] The pilot pump 15 is an example of a pilot pressure generating device and is configured to be able to supply hydraulic oil to hydraulic control devices via a pilot line. In this embodiment, the pilot pump 15 is a fixed displacement hydraulic pump. However, the pilot pressure generating device may be realized by the main pump 14. That is, in addition to the function of supplying hydraulic oil to the control valve unit 17 via the hydraulic oil line, the main pump 14 may be provided with a function of supplying hydraulic oil to various hydraulic control devices via the pilot line. In this case, the pilot pump 15 may be omitted.

[0024] The control valve unit 17 is a hydraulic control device that controls the hydraulic system in the excavator 100. In this embodiment, the control valve unit 17 includes control valves (also referred to as direction control valves) 171 to 176. The control valve 175 includes a control valve 175L and a control valve 175R, and the control valve 176 includes a control valve 176L and a control valve 176R. The control valve unit 17 is configured to selectively supply the hydraulic oil discharged from the main pump 14 to one or a plurality of hydraulic actuators through the control valves 171 to 176. The control valves 171 to 176 control, for example, the flow rate of the hydraulic oil flowing from the main pump 14 to the hydraulic actuator and the flow rate of the hydraulic oil flowing from the hydraulic actuator to the hydraulic oil tank. The hydraulic actuators include a boom cylinder 7, an arm cylinder 8, a bucket cylinder 9, a left traveling hydraulic motor 2ML, a right traveling hydraulic motor 2MR, and a swing hydraulic motor 2A.

[0025] The operating device 26 is configured such that an operator can operate the actuator. In this embodiment, the operating device 26 includes a hydraulic actuator operating device configured such that the operator can operate the hydraulic actuator. Specifically, the hydraulic actuator operating device is configured to supply the hydraulic oil discharged from the pilot pump 15 to the pilot ports of the corresponding control valves 171 to 176 in the control valve unit 17 through a proportional valve 31 controlled by the controller 30 via a pilot line. The pressure (pilot pressure) of the hydraulic oil supplied to each of the pilot ports is a pressure corresponding to the operating direction and operating amount of the operating device 26 corresponding to each of the hydraulic actuators.

[0026] The discharge pressure sensor 28 is configured to detect the discharge pressure of the main pump 14. In this embodiment, the discharge pressure sensor 28 outputs the detected value to the controller 30.

[0027] The operation sensor 29 is configured to be able to detect the content of the operation of the operation device 26 by the operator. In the present embodiment, the operation sensor 29 detects the operation direction and operation amount of the operation device 26 corresponding to each actuator, and outputs the detected values to the controller 30.

[0028] The main pump 14 includes a left main pump 14L and a right main pump 14R. The left main pump 14L circulates the hydraulic oil to the hydraulic oil tank through the left center bypass pipeline 40L or the left parallel pipeline 42L, and the right main pump 14R circulates the hydraulic oil to the hydraulic oil tank through the right center bypass pipeline 40R or the right parallel pipeline 42R.

[0029] The left center bypass pipeline 40L is a hydraulic oil line passing through the control valves 171, 173, 175L and 176L arranged in the control valve unit 17. The right center bypass pipeline 40R is a hydraulic oil line passing through the control valves 172, 174, 175R and 176R arranged in the control valve unit 17.

[0030] The control valve 171 is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged by the left main pump 14L to the left travel hydraulic motor 2ML and to discharge the hydraulic oil discharged by the left travel hydraulic motor 2ML to the hydraulic oil tank.

[0031] The control valve 172 is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged by the right main pump 14R to the right travel hydraulic motor 2MR and to discharge the hydraulic oil discharged by the right travel hydraulic motor 2MR to the hydraulic oil tank.

[0032] The control valve 173 is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged by the left main pump 14L to the swing hydraulic motor 2A and to discharge the hydraulic oil discharged by the swing hydraulic motor 2A to the hydraulic oil tank.

[0033] The control valve 174 is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged from the right main pump 14R to the bucket cylinder 9 and to discharge the hydraulic oil in the bucket cylinder 9 to the hydraulic oil tank.

[0034] The control valve 175L is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged from the left main pump 14L to the boom cylinder 7. The control valve 175R is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged from the right main pump 14R to the boom cylinder 7 and to discharge the hydraulic oil in the boom cylinder 7 to the hydraulic oil tank.

[0035] The control valve 176L is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged from the left main pump 14L to the arm cylinder 8 and to discharge the hydraulic oil in the arm cylinder 8 to the hydraulic oil tank.

[0036] The control valve 176R is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged from the right main pump 14R to the arm cylinder 8 and to discharge the hydraulic oil in the arm cylinder 8 to the hydraulic oil tank.

[0037] The left parallel pipeline 42L is a hydraulic oil line parallel to the left center bypass pipeline 40L. When the flow of hydraulic oil through the left center bypass pipeline 40L is restricted or blocked by any one of the control valves 171, 173, and 175L, the left parallel pipeline 42L can supply hydraulic oil to the downstream control valve. The right parallel pipeline 42R is a hydraulic oil line parallel to the right center bypass pipeline 40R. When the flow of hydraulic oil through the right center bypass pipeline 40R is restricted or blocked by any one of the control valves 172, 174, and 175R, the right parallel pipeline 42R can supply hydraulic oil to the downstream control valve. In the control valve 173, the left center bypass pipeline 40L after passing through the PT port of the control valve 171 is connected to the upstream side of the PT port (the opening of the oil passage from the main pump 14 to the hydraulic oil tank). Also, on the upstream side of the PC port (the opening of the oil passage from the main pump 14 to the arm cylinder 8), the left center bypass pipeline 40L after passing through the PT port of the control valve 171 is connected via a check valve, and the left parallel pipeline 42L is connected via a check valve. Thereby, high-pressure hydraulic oil is supplied to the upstream side of the PC port among the left center bypass pipeline 40L and the left parallel pipeline 42L. The same applies to the control valves 174 to 176.

[0038] The regulator 13 includes a left regulator 13L and a right regulator 13R. The left regulator 13L controls the discharge amount of the left main pump 14L by adjusting the swash plate tilt angle of the left main pump 14L according to the discharge pressure of the left main pump 14L. Specifically, for example, the left regulator 13L adjusts the swash plate tilt angle of the left main pump 14L in response to an increase in the discharge pressure of the left main pump 14L to reduce the discharge amount. The same applies to the right regulator 13R. This is to ensure that the absorption power (absorption horsepower) of the main pump 14, which is represented by the product of the discharge pressure and the discharge amount, does not exceed the output power (output horsepower) of the engine 11.

[0039] The operating device 26 includes a left operating lever 26L, a right operating lever 26R, and a traveling lever 26D. The traveling lever 26D includes a left traveling lever 26DL and a right traveling lever 26DR.

[0040] The left operation lever 26L is used for slewing operation and the operation of the arm 5. When the left operation lever 26L is operated in the front-rear direction, it utilizes the hydraulic oil discharged by the pilot pump 15 and introduces a control pressure corresponding to the lever operation amount into the pilot port of the control valve 176. Also, when it is operated in the left-right direction, it utilizes the hydraulic oil discharged by the pilot pump 15 and introduces a control pressure corresponding to the lever operation amount into the pilot port of the control valve 173.

[0041] Specifically, when the left operation lever 26L is operated in the arm closing direction, it introduces hydraulic oil into the right pilot port of the control valve 176L and also into the left pilot port of the control valve 176R. Also, when the left operation lever 26L is operated in the arm opening direction, it introduces hydraulic oil into the left pilot port of the control valve 176L and also into the right pilot port of the control valve 176R. Further, when the left operation lever 26L is operated in the left slewing direction, it introduces hydraulic oil into the left pilot port of the control valve 173, and when it is operated in the right slewing direction, it introduces hydraulic oil into the right pilot port of the control valve 173.

[0042] In the example shown in FIG. 2, the left operation lever 26L functions as an arm operation lever when operated in the front-rear direction and functions as a slewing operation lever when operated in the left-right direction.

[0043] The right operation lever 26R is used for the operation of the boom 4 and the operation of the bucket 6. When the right operation lever 26R is operated in the front-rear direction, it utilizes the hydraulic oil discharged by the pilot pump 15 and introduces a control pressure corresponding to the lever operation amount into the pilot port of the control valve 175. Also, when it is operated in the left-right direction, it utilizes the hydraulic oil discharged by the pilot pump 15 and introduces a control pressure corresponding to the lever operation amount into the pilot port of the control valve 174.

[0044] Specifically, when the right operation lever 26R is operated in the boom lowering direction, hydraulic oil is introduced into the left pilot port of the control valve 175R. Also, when the right operation lever 26R is operated in the boom raising direction, hydraulic oil is introduced into the right pilot port of the control valve 175L and at the same time, hydraulic oil is introduced into the left pilot port of the control valve 175R. Further, when the right operation lever 26R is operated in the bucket closing direction, hydraulic oil is introduced into the right pilot port of the control valve 174, and when it is operated in the bucket opening direction, hydraulic oil is introduced into the left pilot port of the control valve 174.

[0045] In the example shown in FIG. 2, the right operation lever 26R functions as a boom operation lever when operated in the front-rear direction and functions as a bucket operation lever when operated in the left-right direction.

[0046] The travel lever 26D is used for operating the crawlers. Specifically, the left travel lever 26DL is used for operating the left crawler. It may be configured to be interlocked with the left travel pedal. When the left travel lever 26DL is operated in the front-rear direction, it uses the hydraulic oil discharged from the pilot pump 15 and introduces a control pressure corresponding to the lever operation amount into the pilot port of the control valve 171. The right travel lever 26DR is used for operating the right crawler. It may be configured to be interlocked with the right travel pedal. When the right travel lever 26DR is operated in the front-rear direction, it uses the hydraulic oil discharged from the pilot pump 15 and introduces a control pressure corresponding to the lever operation amount into the pilot port of the control valve 172.

[0047] The discharge pressure sensor 28 includes a discharge pressure sensor 28L and a discharge pressure sensor 28R. The discharge pressure sensor 28L detects the discharge pressure of the left main pump 14L and outputs the detected value to the controller 30. The same applies to the discharge pressure sensor 28R.

[0048] The operation sensor 29 includes operation sensors 29LA, 29LB, 29RA, 29RB, 29DL, and 29DR. The operation sensor 29LA detects the content of the operation in the front-rear direction on the left operation lever 26L by the operator, and outputs the detected value to the controller 30. The content of the operation is, for example, the lever operation direction, the lever operation amount (lever operation angle), and the like.

[0049] Similarly, the operation sensor 29LB detects the content of the operation in the left-right direction on the left operation lever 26L by the operator, and outputs the detected value to the controller 30. The operation sensor 29RA detects the content of the operation in the front-rear direction on the right operation lever 26R by the operator, and outputs the detected value to the controller 30. The operation sensor 29RB detects the content of the operation in the left-right direction on the right operation lever 26R by the operator, and outputs the detected value to the controller 30. The operation sensor 29DL detects the content of the operation in the front-rear direction on the left travel lever 26DL by the operator, and outputs the detected value to the controller 30. The operation sensor 29DR detects the content of the operation in the front-rear direction on the right travel lever 26DR by the operator, and outputs the detected value to the controller 30.

[0050] The controller 30 receives the output of the operation sensor 29, outputs a control command to the regulator 13 as necessary, and changes the discharge amount of the main pump 14. Further, the controller 30 receives the output of the control pressure sensor 19 provided upstream of the throttle 18, outputs a control command to the regulator 13 as necessary, and changes the discharge amount of the main pump 14. The throttle 18 includes a left throttle 18L and a right throttle 18R, and the control pressure sensor 19 includes a left control pressure sensor 19L and a right control pressure sensor 19R.

[0051] In the left center bypass pipeline 40L, a left throttle valve 18L is arranged between the most downstream control valve 176L and the hydraulic oil tank. Therefore, the flow of the hydraulic oil discharged by the left main pump 14L is restricted by the left throttle valve 18L. And the left throttle valve 18L generates a control pressure for controlling the left regulator 13L. The left control pressure sensor 19L is a sensor for detecting this control pressure, and outputs the detected value to the controller 30. The controller 30 controls the discharge amount of the left main pump 14L by adjusting the swash plate tilt angle of the left main pump 14L according to this control pressure. The controller 30 decreases the discharge amount of the left main pump 14L as this control pressure increases, and increases the discharge amount of the left main pump 14L as this control pressure decreases. The discharge amount of the right main pump 14R is also controlled in the same way.

[0052] Specifically, as shown in FIG. 2, in the standby state where none of the hydraulic actuators in the excavator 100 are operated, the hydraulic oil discharged by the left main pump 14L reaches the left throttle valve 18L through the left center bypass pipeline 40L. And the flow of the hydraulic oil discharged by the left main pump 14L increases the control pressure generated upstream of the left throttle valve 18L. As a result, the controller 30 decreases the discharge amount of the left main pump 14L to the allowable minimum discharge amount, and suppresses the pressure loss (pumping loss) when the discharged hydraulic oil passes through the left center bypass pipeline 40L. On the other hand, when any of the hydraulic actuators is operated, the hydraulic oil discharged by the left main pump 14L flows into the operated hydraulic actuator through the control valve corresponding to the operated hydraulic actuator. And the flow of the hydraulic oil discharged by the left main pump 14L decreases or disappears the amount reaching the left throttle valve 18L, and decreases the control pressure generated upstream of the left throttle valve 18L. As a result, the controller 30 increases the discharge amount of the left main pump 14L, circulates sufficient hydraulic oil to the operated hydraulic actuator, and ensures the driving of the operated hydraulic actuator. Note that the controller 30 controls the discharge amount of the right main pump 14R in the same way.

[0053] With the above configuration, in the standby state, the hydraulic system of FIG. 2 can suppress the wasteful energy consumption in the main pump 14. The wasteful energy consumption includes the pumping loss generated by the hydraulic oil discharged from the main pump 14 in the center bypass pipeline 40. Further, when operating the hydraulic actuator, the hydraulic system of FIG. 2 can surely supply sufficient hydraulic oil from the main pump 14 to the hydraulic actuator to be operated.

[0054] That is, the controller 30 controls the regulator 13 so that the smaller of the first discharge amount calculated so that the absorption power (absorption horsepower) of the main pump 14 represented by the product of the discharge pressure and the discharge amount does not exceed the output power (output horsepower) of the engine 11 and the second discharge amount calculated based on the control pressure detected by the control pressure sensor 19 is the discharge amount.

[0055] In addition, a boom rod pressure sensor S7R and a boom bottom pressure sensor S7B are attached to the boom cylinder 7. An arm rod pressure sensor S8R and an arm bottom pressure sensor S8B are attached to the arm cylinder 8. A bucket rod pressure sensor S9R and a bucket bottom pressure sensor S9B are attached to the bucket cylinder 9. The boom rod pressure sensor S7R, the boom bottom pressure sensor S7B, the arm rod pressure sensor S8R, the arm bottom pressure sensor S8B, the bucket rod pressure sensor S9R, and the bucket bottom pressure sensor S9B are collectively also referred to as "cylinder pressure sensors". In addition, a left turn pressure sensor S10L and a right turn pressure sensor S10R are attached to the swing hydraulic motor 2A.

[0056] The boom rod pressure sensor S7R detects the pressure in the rod-side oil chamber of the boom cylinder 7 (hereinafter referred to as "boom rod pressure"). The boom bottom pressure sensor S7B detects the pressure in the bottom-side oil chamber of the boom cylinder 7 (hereinafter referred to as "boom bottom pressure"). The arm rod pressure sensor S8R detects the pressure in the rod-side oil chamber of the arm cylinder 8 (hereinafter referred to as "arm rod pressure"). The arm bottom pressure sensor S8B detects the pressure in the bottom-side oil chamber of the arm cylinder 8 (hereinafter referred to as "arm bottom pressure"). The bucket rod pressure sensor S9R detects the pressure in the rod-side oil chamber of the bucket cylinder 9 (hereinafter referred to as "bucket rod pressure"). The bucket bottom pressure sensor S9B detects the pressure in the bottom-side oil chamber of the bucket cylinder 9 (hereinafter referred to as "bucket bottom pressure"). The left turning pressure sensor S10L detects the pressure of the hydraulic oil in the left port of the swing hydraulic motor 2A. The right turning pressure sensor S10R detects the pressure of the hydraulic oil in the right port of the swing hydraulic motor 2A. The values detected by each sensor are transmitted to the controller 30.

[0057] Next, with reference to FIG. 3, a configuration for the controller 30 to operate the actuator by the machine control function will be described. FIG. 3 is a diagram showing a extracted hydraulic system portion related to the operation of the arm cylinder 8. In FIG. 3, the operation of the arm cylinder 8 is described as an example, but it is not limited thereto. The same applies to the operations of the boom cylinder 7, the bucket cylinder 9, the swing hydraulic motor 2A, the left travel hydraulic motor 2ML, and the right travel hydraulic motor 2MR, and redundant explanations are omitted.

[0058] As shown in FIG. 3, the hydraulic system includes a proportional valve 31. The proportional valve 31 includes a proportional valve 31AL and a proportional valve 31AR.

[0059] The proportional valve 31 functions as a control valve for machine control. The proportional valve 31 is arranged in a pipeline connecting the pilot pump 15 and the pilot port of the corresponding control valve in the control valve unit 17, and is configured to be able to change the flow passage area of the pipeline. In the present embodiment, the proportional valve 31 operates according to a control command output by the controller 30. Therefore, the controller 30 can supply the hydraulic oil discharged by the pilot pump 15 to the pilot port of the corresponding control valve in the control valve unit 17 via the proportional valve 31, regardless of the operation of the operating device 26 by the operator. And the controller 30 can make the pilot pressure generated by the proportional valve 31 act on the pilot port of the corresponding control valve.

[0060] With this configuration, the controller 30 can operate the hydraulic actuator corresponding to the specific operating device 26 even when no operation on the specific operating device 26 is performed. Also, the controller 30 can forcibly stop the operation of the hydraulic actuator corresponding to the specific operating device 26 even when an operation on the specific operating device 26 is being performed.

[0061] For example, as shown in FIG. 3, the left operation lever 26L is used to operate the arm 5. Specifically, the left operation lever 26L utilizes the hydraulic oil discharged by the pilot pump 15 and makes the pilot pressure corresponding to the operation in the front-rear direction act on the pilot port of the control valve 176. More specifically, when the left operation lever 26L is operated in the arm closing direction (rear direction), the pilot pressure corresponding to the operation amount acts on the right pilot port of the control valve 176L and the left pilot port of the control valve 176R. Also, when the left operation lever 26L is operated in the arm opening direction (front direction), the pilot pressure corresponding to the operation amount acts on the left pilot port of the control valve 176L and the right pilot port of the control valve 176R.

[0062] The left operation lever 26L is provided with a switch NS. In this embodiment, the switch NS is a push button switch provided at the tip of the left operation lever 26L. The operator can operate the left operation lever 26L while pressing the switch NS. The switch NS may be provided on the right operation lever 26R or at other positions within the cabin 10.

[0063] The operation sensor 29LA detects the content of the operation of the left operation lever 26L in the front-rear direction by the operator, and outputs the detected value to the controller 30.

[0064] The proportional valve 31AL operates in response to a control command (current command) output by the controller 30. Then, it adjusts the pilot pressure by the hydraulic oil introduced from the pilot pump 15 to the right pilot port of the control valve 176L and the left pilot port of the control valve 176R via the proportional valve 31AL. The proportional valve 31AR operates in response to a control command (current command) output by the controller 30. Then, it adjusts the pilot pressure by the hydraulic oil introduced from the pilot pump 15 to the left pilot port of the control valve 176L and the right pilot port of the control valve 176R via the proportional valve 31AR. The proportional valve 31AL can adjust the pilot pressure so that the control valves 176L and 176R can be stopped at arbitrary valve positions. Similarly, the proportional valve 31AR can adjust the pilot pressure so that the control valves 176L and 176R can be stopped at arbitrary valve positions.

[0065] Also, a pilot pressure sensor 32AL for detecting the pilot pressure is provided in the pilot line connecting the proportional valve 31AL and one port of the control valve 176 (the right port of the control valve 176L and the left port of the control valve 176R). Also, a pilot pressure sensor 32AR for detecting the pilot pressure is provided in the pilot line connecting the proportional valve 31AR and the other port of the control valve 176 (the left port of the control valve 176L and the right port of the control valve 176R). The values detected by the respective pilot pressure sensors 32AL and 32AR are transmitted to the controller 30.

[0066] With this configuration, in response to the operator's arm closing operation, the controller 30 can supply the hydraulic oil discharged from the pilot pump 15 to the right pilot port of the control valve 176L and the left pilot port of the control valve 176R via the proportional valve 31AL. Also, regardless of the operator's arm closing operation, the controller 30 can supply the hydraulic oil discharged from the pilot pump 15 to the right pilot port of the control valve 176L and the left pilot port of the control valve 176R via the proportional valve 31AL. That is, the controller 30 can close the arm 5 in response to the operator's arm closing operation or regardless of the operator's arm closing operation.

[0067] Also, in response to the operator's arm opening operation, the controller 30 can supply the hydraulic oil discharged from the pilot pump 15 to the left pilot port of the control valve 176L and the right pilot port of the control valve 176R via the proportional valve 31AR. Also, regardless of the operator's arm opening operation, the controller 30 can supply the hydraulic oil discharged from the pilot pump 15 to the left pilot port of the control valve 176L and the right pilot port of the control valve 176R via the proportional valve 31AR. That is, the controller 30 can open the arm 5 in response to the operator's arm opening operation or regardless of the operator's arm opening operation.

[0068] Also, with this configuration, even when the operator's arm closing operation is being performed, the controller 30 can, if necessary, reduce the pilot pressure acting on the closing-side pilot ports of the control valve 176 (the left pilot port of the control valve 176L and the right pilot port of the control valve 176R) and forcibly stop the closing operation of the arm 5. The same applies when forcibly stopping the opening operation of the arm 5 when the operator's arm opening operation is being performed.

[0069] Alternatively, even when the operator is performing an arm closing operation, the controller 30 may, if necessary, control the proportional valve 31AR to increase the pilot pressure acting on the opening pilot ports of the control valve 176 (the right pilot port of the control valve 176L and the left pilot port of the control valve 176R) that are on the opposite side of the closing pilot port of the control valve 176, and force the control valve 176 back to the neutral position, thereby forcibly stopping the closing operation of the arm 5. The same applies when forcibly stopping the opening operation of the arm 5 when the operator is performing an arm opening operation.

[0070] Also, although the form of the operating device 26 has been described in relation to an electric operating lever, a hydraulic operating lever may be adopted instead of the electric operating lever. In this case, the lever operation amount of the hydraulic operating lever may be detected in the form of pressure by a pressure sensor and input to the controller 30. Also, a solenoid valve may be arranged between the operating device 26 as a hydraulic operating lever and the pilot ports of each control valve. The solenoid valve is configured to operate in response to an electric signal from the controller 30. With this configuration, when a manual operation is performed using the operating device 26 as a hydraulic operating lever, the operating device 26 can move each control valve by increasing or decreasing the pilot pressure according to the lever operation amount. Also, each control valve may be composed of an electromagnetic spool valve. In this case, the electromagnetic spool valve operates in response to an electric signal from the controller 30 corresponding to the lever operation amount of the electric operating lever.

[0071] Next, an example will be described in which the operator operates the left operation lever 26L of the operation device 26 to operate the arm cylinder 8. When the operator operates the left operation lever 26L of the operation device 26, the operation of the left operation lever 26L is detected by the operation sensor 29LA, and the detected operation of the left operation lever 26L is input to the controller 30. The controller 30 controls and outputs the current value (current command, control command) of the proportional valve 31 so as to obtain the secondary pressure (pilot pressure) of the control valve 176 corresponding to the operation amount of the left operation lever 26L. As a result, the pilot pressure acts on the pilot port of the control valve 176, and the spool of the control valve 176 moves, so that the opening areas of the PT opening (opening of the oil passage from the main pump 14 to the hydraulic oil tank), the PC opening (opening of the oil passage from the main pump 14 to the arm cylinder 8), and the CT opening (opening of the oil passage from the arm cylinder 8 to the hydraulic oil tank) of the control valve 176 are controlled.

[0072] Here, when the left operation lever 26L is operated from the neutral position in the tilting direction to operate the arm cylinder 8, the opening area of the PT opening of the control valve 176 decreases, and the pump pressure (pressure of the discharge pressure sensor 28) of the main pump 14 increases. Further, when the left operation lever 26L is operated, the opening area of the PT opening of the control valve 176 further decreases, and the opening areas of the PC opening and the CT opening of the control valve 176 increase.

[0073] When the pump pressure becomes higher than the load pressure, the load check valve is pushed open, and hydraulic oil is supplied from the main pump 14 through the PC opening of the control valve 176 to one chamber (for example, the bottom side oil chamber) of the arm cylinder 8. At the same time, when the control pressure (also referred to as negative control pressure) detected by the control pressure sensor 19 decreases, the regulator 13 controls the discharge amount of the main pump 14 to increase. Then, when the load pressure acts on the arm cylinder 8, the arm cylinder 8 operates, and the hydraulic oil flowing out from the other chamber (for example, the rod side oil chamber) of the arm cylinder 8 returns to the hydraulic oil tank through the CT opening of the control valve 176.

[0074] Next, a combined operation for simultaneously operating the hydraulic actuators of the attachment (boom cylinder 7, arm cylinder 8, bucket cylinder 9) and the slewing hydraulic motor 2A will be described with reference to FIG. 4. FIG. 4 is a graph showing the opening characteristics of the control valve. FIG. 4(a) is a graph showing the opening characteristics of the control valve 176 in the closing operation of the arm 5. FIG. 4(b) is a graph showing the opening characteristics of the control valve 173 in the slewing operation of the upper slewing body 3. The horizontal axis represents the spool stroke. The vertical axis represents the opening areas of the PT opening (shown by the solid line), the PC opening (shown by the broken line), and the CT opening (shown by the one-dot chain line).

[0075] As shown in FIG. 2, the control valve 176L that controls the hydraulic oil of the arm cylinder 8 and the control valve 173 that controls the hydraulic oil of the slewing hydraulic motor 2A are connected such that hydraulic oil is supplied from one left main pump 14L through the left center bypass pipeline 40L and the left parallel pipeline 42L. The left parallel pipeline 42L supplies the hydraulic oil discharged from the left main pump 14L to the PC openings of the control valve 173 and the control valve 176L. Further, the left center bypass pipeline 40L is configured such that the flow path is opened and closed by the PT openings of the control valve 176L and the PT opening of the control valve 173. That is, by controlling the PT opening of the control valve 176L and the PT opening of the control valve 173, among the hydraulic oil flowing into the left center bypass pipeline 40L, the flow rate of the hydraulic oil that passes through the left throttle 18L and returns to the hydraulic oil tank without passing through the hydraulic actuator changes. Also, the control pressure (negative control pressure), which is the pressure on the upstream side of the left throttle 18L, is determined by the flow rate passing through the left throttle 18L. The controller 30 controls the left regulator 13L based on the control pressure (negative control pressure) detected by the left control pressure sensor 19L to control the discharge amount of the left main pump 14L.

[0076] First, the case of decelerating the closing operation of the arm 5 from the state where only the closing operation of the arm 5 is performed will be described. By returning the left operation lever 26L from the state of being tilted backward to the neutral position direction to decelerate the closing operation of the arm 5, the spool of the control valve 176L moves in the neutral position direction. As a result, the PC opening and the CT opening of the control valve 176L decrease, and the PT opening increases (see Fig. 4(a)).

[0077] The hydraulic oil that was flowing into the arm cylinder 8 through the PC opening of the control valve 176L is blocked by the decrease in the PC opening of the control valve 176L. Also, the blocked hydraulic oil flows into the PT opening of the control valve 176L. Therefore, the flow rate flowing through the left throttle 18L increases, and the control pressure (negative control pressure) detected by the left control pressure sensor 19L increases. When the control pressure (negative control pressure) increases, the controller 30 decreases the discharge amount of the left main pump 14L. Thereby, the closing operation of the arm 5 can be decelerated.

[0078] Next, the compound operation of simultaneously performing the closing operation of the arm 5 and the turning operation of the upper swing body 3 will be described. During the compound operation, the spool of the control valve 176L that controls the arm cylinder 8 is stroked, the PT opening is decreased or blocked, and the PC opening and the CT opening are widely opened. Also, the spool of the control valve 173 that controls the swing hydraulic motor 2A is stroked, the PT opening is decreased or blocked, and the PC opening and the CT opening are widely opened.

[0079] Then, the case of decelerating the closing operation of the arm 5 from the state of the compound operation will be described. By returning the left operation lever 26L from the state of being tilted backward in the front-rear direction to the neutral position direction while tilting it in either the left or right direction, the closing operation of the arm 5 is decelerated while continuing the turning of the upper swing body 3. In this case, the spool of the control valve 173 maintains the stroked position, and the spool of the control valve 176L moves in the neutral position direction. As a result, the PC opening and the CT opening of the control valve 176L decrease, and the PT opening increases (see Fig. 4(a)).

[0080] The hydraulic oil that was flowing into the arm cylinder 8 through the PC port of the control valve 176L is blocked by the reduction of the PC port of the control valve 176L. Here, due to the slewing operation of the upper slewing body 3, the PC port of the control valve 173 provided on the upstream side of the control valve 176L is reduced or blocked. Therefore, even if the blocked hydraulic oil tries to flow through the PC port of the control valve 176L, the inflow into the PC port of the control valve 176L is restricted by the narrowed PC port of the control valve 173. Thus, the pressure of the hydraulic oil (discharge pressure) detected by the discharge pressure sensor 28L increases due to the hydraulic oil that has lost its way.

[0081] When the discharge pressure increases, it becomes easier for the hydraulic oil to flow into the slewing hydraulic motor 2A through the PC port of the control valve 173, and the slewing load pressure generated by the slewing hydraulic motor 2A is likely to increase. As a result, in the combined operation of closing the arm 5 and slewing the upper slewing body 3 simultaneously, by decelerating the closing operation of the arm 5, the slewing speed increases and the slewing operability deteriorates. When the slewing operability deteriorates, there is a risk that the upper slewing body 3 will not stop at the target stop position and will overshoot and slew beyond the target stop position.

[0082] Although the case where the closing operation of the arm 5 is decelerated in the combined operation of closing the arm 5 and slewing the upper slewing body 3 simultaneously has been described as an example, it is not limited to this. Similarly, in the case where the opening operation of the arm 5 is decelerated in the combined operation of opening the arm 5 and slewing the upper slewing body 3 simultaneously, or in the case where the raising operation of the boom 4 is decelerated in the combined operation of raising the boom 4 and slewing the upper slewing body 3 simultaneously, or in the case where the lowering operation of the boom 4 is decelerated in the combined operation of lowering the boom 4 and slewing the upper slewing body 3 simultaneously, there is also a risk that the slewing operability will deteriorate by decelerating the operation of the attachment during the combined operation of the slewing operation and the attachment operation.

[0083] Note that the maximum opening area of the PC opening of the control valve 175 that controls the flow rate of the hydraulic oil supplied to the boom cylinder 7 is smaller than the maximum opening area of the PC opening of the control valve 176 that controls the flow rate of the hydraulic oil supplied to the arm cylinder 8. For this reason, compared with the case of decelerating the operation of the boom 4 in the combined operation of simultaneously performing the operation of the boom 4 and the turning operation of the upper swing body 3, when decelerating the operation of the arm 5 in the combined operation of simultaneously performing the operation of the arm 5 and the turning operation of the upper swing body 3, a decrease in turning operability is particularly likely to occur.

[0084] Also, the pressure receiving area in the bottom side oil chamber of the arm cylinder 8 is larger than the pressure receiving area in the rod side oil chamber of the arm cylinder 8. For this reason, compared with the case of decelerating the opening operation of the arm 5 in the combined operation of simultaneously performing the opening operation of the arm 5 and the turning operation of the upper swing body 3, when decelerating the closing operation of the arm 5 in the combined operation of simultaneously performing the closing operation of the arm 5 and the turning operation of the upper swing body 3, a decrease in turning operability is particularly likely to occur.

[0085] Next, the control method of the excavator 100 according to the present embodiment will be described with reference to FIG. 5. FIG. 5 is a flowchart for explaining the control method of the excavator 100 according to the present embodiment. In the following description, the case of decelerating the closing operation of the arm 5 in the combined operation of simultaneously performing the closing operation of the arm 5 and the turning operation of the upper swing body 3 will be described as an example.

[0086] In step S101, the controller 30 determines whether the arm operation amount (attachment operation amount) is equal to or greater than a predetermined operation amount (first predetermined operation amount). The controller 30 determines whether the backward operation amount of the left operation lever 26L detected by the operation sensor 29LA is equal to or greater than the predetermined operation amount (first predetermined operation amount). If the arm operation amount is less than the predetermined operation amount (S101·NO), the process of the controller 30 returns to step S101. If the arm operation amount is equal to or greater than the predetermined operation amount (S101·YES), the process of the controller 30 proceeds to step S102.

[0087] Incidentally, the predetermined operation amount (first predetermined operation amount) in step S101 may be, for example, an operation amount corresponding to the spool stroke ST1 of the control valve 176 shown in FIG. 4(a). That is, when it is equal to or greater than the first predetermined operation amount, the opening area of the PC opening of the control valve 176 is large. Note that the spool stroke ST1 of the control valve 176 may be a state where the PT opening is slightly open or a state where the PT opening is closed.

[0088] In step S102, the controller 30 determines whether or not the turning operation amount is equal to or greater than a predetermined operation amount (second predetermined operation amount). The controller 30 determines whether or not the operation amount in the left-right direction of the left operation lever 26L detected by the operation sensor 29LB is equal to or greater than the predetermined operation amount (second predetermined operation amount). If the turning operation amount is not equal to or greater than the predetermined operation amount (S102·NO), the process of the controller 30 returns to step S101. If the turning operation amount is equal to or greater than the predetermined operation amount (S102·YES), the process of the controller 30 proceeds to step S103.

[0089] Incidentally, the predetermined operation amount (second predetermined operation amount) in step S102 may be, for example, an operation amount corresponding to the spool stroke ST2 of the control valve 173 shown in FIG. 4(b). That is, when it is equal to or greater than the second predetermined operation amount, the opening area of the PT opening of the control valve 173 is small or blocked. Note that the spool stroke ST2 of the control valve 173 may be a state where the PT opening is slightly open or a state where the PT opening is closed.

[0090] That is, in steps S101 and S102, the controller 30 determines whether or not it is a combined operation of the closing operation of the arm (operation of the attachment) and the turning operation. If it is a combined operation, the process of the controller 30 proceeds to step S103.

[0091] In step S103, the controller 30 determines whether the arm operation amount has decreased. The controller 30 determines whether the backward operation amount of the left operation lever 26L detected by the operation sensor 29LA has decreased (the left operation lever 26L is moved in the direction of the neutral position). Specifically, the controller 30 determines that the arm operation amount has decreased when the left operation lever 26L is operated from the state of being tilted backward by a predetermined operation amount (third predetermined operation amount) or more per unit time in the direction of the neutral position. Or, the controller 30 determines that the arm operation amount has decreased when the left operation lever 26L is operated from the state of being tilted backward with a predetermined operation acceleration or more in the direction of the neutral position. If the arm operation amount has not decreased (S103·NO), the process of the controller 30 returns to step S101. If the arm operation amount has decreased (S103·YES), the process of the controller 30 proceeds to step S104.

[0092] That is, in steps S101 to S103, the controller 30 determines whether the closing operation of the arm 5 (the operation of the attachment) has been decelerated in the combined operation of simultaneously performing the closing operation of the arm 5 and the turning operation of the upper swing body 3.

[0093] In step S104, the controller 30 sets the turning pilot pressure to a value obtained by subtracting a predetermined value from the turning pilot pressure (turning command value) of the control valve 173.

[0094] Here, the controller 30 determines the secondary pressure (arm pilot pressure, arm command value) of the control valve 176 based on the backward operation amount of the left operation lever 26L detected by the operation sensor 29LA. Then, the controller 30 controls the proportional valve 31 so as to obtain the determined secondary pressure of the control valve 176.

[0095] On the one hand, the controller 30 determines the reference secondary pressure (reference swivel pilot pressure, reference swivel command value) of the control valve 173 based on the amount of operation in the left - right direction of the left operation lever 26L detected by the operation sensor 29LB. Then, the controller 30 controls a proportional valve (not shown) that controls the secondary pressure of the control valve 173 with a corrected secondary pressure (corrected swivel pilot pressure, corrected swivel command value) obtained by subtracting a predetermined value from the reference secondary pressure.

[0096] In step S105, the controller 30 repeats step S105 until a predetermined time elapses. That is, the controller 30 controls a proportional valve (not shown) that controls the secondary pressure of the control valve 173 with the corrected secondary pressure until a predetermined time elapses.

[0097] In step S106, the controller 30 returns the swivel pilot pressure. That is, the controller 30 determines the reference secondary pressure (reference swivel pilot pressure, reference swivel command value) of the control valve 173 based on the amount of operation in the left - right direction of the left operation lever 26L detected by the operation sensor 29LB. Then, the controller 30 controls a proportional valve (not shown) that controls the secondary pressure of the control valve 173 so that the secondary pressure of the control valve 173 becomes the determined value. Then, the process of the controller 30 returns to step S101.

[0098] Note that in step S104, the controller 30 has been described as reducing the swivel pilot pressure of the control valve 173 by a predetermined value, but it is not limited to this. The controller 30 may be configured to reduce the control command (current command) of a proportional valve (not shown) that controls the secondary pressure of the control valve 173 by a predetermined value. Also, the controller 30 may be configured to reduce the swivel operation amount detected by the operation sensor 29LB by a predetermined value. Even in these cases, the spool of the control valve 173 can be moved in the direction of the neutral position. That is, the opening area of the PT port of the control valve 173 is widened, and the opening area of the PC port is narrowed.

[0099] FIG. 6 is a graph for explaining the effect of the control method of the excavator 100 according to the present embodiment. The vertical axis in (a) indicates the slewing operation amount, and the horizontal axis indicates time. The vertical axis in (b) indicates the arm operation amount, and the horizontal axis indicates time. As shown in (a) and (b), from the combined operation state of the arm operation and the slewing operation in which the left operation lever 26L is operated in the left-right direction with the slewing operation amount RS1 and the left operation lever 26L is operated in the front-rear direction with the arm operation amount AS1, at time t1, the arm operation amount is decreased.

[0100] (c) The vertical axis indicates the slewing speed in the reference example, and the horizontal axis indicates time. When the arm operation amount is decreased from the combined operation state, the discharge pressure increases due to the decrease in the PC opening of the control valve 176L, and the slewing speed of the slewing hydraulic motor 2A increases (increased slewing speed ΔVrs) with a delay of time Δt. As a result, the slewing operability deteriorates.

[0101] (d) The vertical axis indicates the spool stroke (slewing stroke) of the control valve 173 in the control of the present embodiment, and the horizontal axis indicates time. (e) The vertical axis indicates the slewing speed in the present embodiment, and the horizontal axis indicates time.

[0102] When the decrease in the arm operation amount is detected at time t1 (S103·YES), the controller 30 controls a proportional valve (not shown) so as to supply a corrected secondary pressure obtained by subtracting a predetermined value from the reference secondary pressure based on the operation amount of the left operation lever 26L to the control valve 173 (S104). As a result, as shown in FIG. 6(d), the spool stroke (slewing stroke) of the control valve 173 moves in the neutral position direction by the stroke amount ΔST. That is, the PC opening area of the control valve 173 decreases, and the PT opening area of the control valve 173 increases. As a result, as shown in FIG. 6(e), the slewing speed of the slewing hydraulic motor 2A maintains the slewing speed Vrs, and the increase in the slewing speed of the slewing hydraulic motor 2A is prevented. Therefore, the slewing operability can be improved as compared with the reference example (see FIG. 6(c)).

[0103] The embodiments disclosed this time should be considered as illustrative in all respects and not restrictive. The above embodiments may be omitted, replaced, or changed in various forms without departing from the scope and spirit of the appended claims.

Explanation of Signs

[0104] 1 Lower traveling body 2 Swing mechanism 2A Swing hydraulic motor (hydraulic actuator) 3 Upper swing body 4 Boom (attachment) 5 Arm (attachment) 6 Bucket (attachment) 7 Boom cylinder (hydraulic actuator) 8 Arm cylinder (hydraulic actuator) 9 Bucket cylinder (hydraulic actuator) 13 Regulator 14 Main pump (hydraulic pump) 15 Pilot pump 17 Control valve unit 171~176 Control valves 18 Throttle 19 Control pressure sensor 26 Operating device 26R Right operating lever 26L Left operating lever 30 Controller 31 Proportional valve (electromagnetic proportional valve) 100 Excavator

Claims

1. A lower traveling body, an upper swing body rotatably provided with respect to the lower traveling body, and an attachment provided on the upper swing body, and a control method for an excavator comprising: during a combined operation of the operation of the attachment and the swing operation of the upper swing body, when the operation related to the operation of the attachment decreases, decreasing a swing command value for swinging the upper swing body. A control method for an excavator.

2. A hydraulic pump for supplying hydraulic oil, a swing hydraulic motor for swinging the upper swing body, a hydraulic actuator for driving the attachment, a first control valve for controlling the flow rate of the hydraulic oil supplied to the swing hydraulic motor, a second control valve for controlling the flow rate of the hydraulic oil supplied to the hydraulic actuator, a center bypass pipeline connected from the hydraulic pump to an oil tank, having the first control valve, and a second control valve on the downstream side of the first control valve, and a parallel pipeline for supplying hydraulic oil from the hydraulic pump to the first control valve and the second control valve. The control method for an excavator according to Claim 1.

3. The swing command value is the pilot pressure of the first control valve. The control method for an excavator according to Claim 2.

4. The swing command value is the operation amount of an operation device for operating the swing operation of the upper swing body. The control method for an excavator according to Claim 2.

5. Further comprising an electromagnetic proportional valve for controlling the pilot pressure of the first control valve, and the swing command value is a current command to the electromagnetic proportional valve. The control method for an excavator according to Claim 2.

6. When the attachment operation amount of the operation device for operating the operation of the attachment is equal to or greater than a first predetermined operation amount, and the swing operation amount of the operation device for operating the swing operation of the upper swing body is equal to or greater than a second predetermined operation amount, it is determined as the combined operation. The control method for an excavator according to any one of Claims 1 to 5.

7. When the attachment operation amount of the operation device for operating the operation of the attachment decreases by a third predetermined operation amount or more per unit time, it is determined that the operation related to the operation of the attachment has decreased. The control method for an excavator according to Claim 6.

8. When operated at a predetermined operation acceleration or more in the direction of the neutral position of the operation device, it is determined that the operation related to the operation of the attachment has decreased. The control method for an excavator according to Claim 6.

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