Excavator

Abstract

To provide a shovel which prevents shaking.SOLUTION: A shovel comprises an operation device, a hydraulic pump for supplying hydraulic oil, a hydraulic actuator for driving with respect to an operation amount of the operation device, a control valve for controlling hydraulic oil flowing from the hydraulic pump to the hydraulic actuator, and a control device for controlling a moving amount of a spool of the control valve. The control device corrects an operation of the hydraulic actuator corresponding to the operation amount of the operation device, according to the state of the hydraulic actuator in running-in work.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to a shovel. [Background technology]

[0002] A working machine is known that includes a lower traveling body, an upper rotating body that can rotate relative to the lower traveling body, an attachment attached to the upper rotating body, a swing hydraulic motor that rotates the upper rotating body, and a hydraulic actuator that drives the attachment. Patent Document 1 discloses an operating device for a hydraulic working machine. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2018 / 164238 Summary of the Invention [Problem to be solved by the invention]

[0004] By the way, a shovel performs leveling work of leveling earth and sand with a bucket by opening and closing the arm. During this leveling work, there is a risk that the shovel body will shake.

[0005] Therefore, an object of the present invention is to provide a shovel that prevents shaking. [Means for solving the problem]

[0006] A shovel according to an embodiment of the present invention includes an operating device, a hydraulic pump that supplies hydraulic oil, a hydraulic actuator that drives in response to an operation amount of the operating device, a control valve that controls the hydraulic oil flowing from the hydraulic pump to the hydraulic actuator, and a control device that controls a movement amount of a spool of the control valve, and the control device is When the bottom pressure or rod pressure of the hydraulic actuator exceeds a predetermined value during driving of the hydraulic actuator in one direction, the spool of the control valve corresponding to the hydraulic actuator is moved in a direction corresponding to the driving of the hydraulic actuator in the other direction different from the one direction, and the amount of movement of the spool of the control valve corresponding to the hydraulic actuator is made larger than the amount of movement of the spool corresponding to the amount of operation of the operating device. . Effect of the Invention

[0007] According to the present invention, a shovel that prevents shaking can be provided. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a side view of a shovel according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a top view of the excavator of FIG. 1. [Diagram 3] FIG. 2 is a diagram showing a configuration example of a hydraulic system mounted on the excavator shown in FIG. [Figure 4] FIG. 1 is a diagram of a portion of the hydraulic system for operation of the arm cylinder. [Diagram 5] 5 is a flowchart illustrating control during leveling work of the shovel according to the first embodiment. [Figure 6] 5 is a time chart illustrating control during run-in work of a shovel according to a reference example and the shovel according to the first embodiment. [Figure 7] 10 is a flowchart illustrating control during leveling work of a shovel according to a second embodiment. [Figure 8] 6 is a time chart illustrating control during run-in work of a shovel according to a reference example and a shovel according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] First, a shovel 100 as an excavator according to an embodiment of the present invention will be described with reference to Figures 1 and 2. Figure 1 is a side view of the shovel 100, and Figure 2 is a top view of the shovel 100.

[0010] In this embodiment, the lower traveling structure 1 of the excavator 100 includes a crawler 1C. The crawler 1C is driven by a traveling hydraulic motor 2M as a traveling actuator mounted on the lower traveling structure 1. Specifically, the crawler 1C includes a left crawler 1CL and a right crawler 1CR. The left crawler 1CL is driven by a left traveling hydraulic motor 2ML, and the right crawler 1CR is driven by a right traveling hydraulic motor 2MR.

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

[0012] A boom 4 is attached to the upper rotating body 3. An arm 5 is attached to the tip of the boom 4, and a bucket 6 is attached to the tip of the arm 5 as an end attachment. The boom 4, arm 5, and 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, arm cylinder 8, and bucket cylinder 9 constitute an attachment actuator. In the example shown in Figs. 1 and 2, the bucket 6 is an excavation bucket, but it may be a skeleton bucket or a (gravel removal bucket). The bucket 6 may also be equipped with a bucket tilt mechanism.

[0013] The upper rotating body 3 is provided with a cabin 10 as a driver's cab, and is equipped with a power source such as an engine 11. An operation device 26, a controller 30, an operation method switching device SD, etc. are provided inside the cabin 10. In addition, a spatial recognition device 70, etc. are attached to the upper rotating body 3. For convenience, in this specification, the side of the upper rotating body 3 to which the attachment AT is attached is referred to as the front, and the side to which the counterweight is attached is referred to as the rear.

[0014] The spatial recognition device 70 is configured to recognize an object present in a three-dimensional space around the shovel 100. The spatial recognition device 70 may be configured to calculate a distance from the spatial recognition device 70 or the shovel 100 to the recognized object. The spatial 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, or any combination thereof. The imaging device is, for example, a monocular camera or a stereo camera. In this embodiment, the spatial recognition device 70 includes a forward sensor 70F attached to the front end of the upper surface of the cabin 10, a rear sensor 70B attached to the rear end of the upper surface of the upper rotating body 3, a left sensor 70L attached to the left end of the upper surface of the upper rotating body 3, and a right sensor 70R attached to the right end of the upper surface of the upper rotating body 3. An upward sensor that recognizes an object present in the space above the upper rotating body 3 may be attached to the shovel 100.

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

[0016] The operation mode switching device SD is configured to be able to switch the operation mode of the operation lever. For example, the operation mode switching device SD includes a push button switch provided on the right console in the cabin 10, and is configured to be able to switch the operation mode of the operation lever between a first operation mode and a second operation mode each time the push button switch is pressed. For example, the first operation mode is configured such that when the left operation lever 26L (see FIG. 3) is tilted forward, the arm 5 is opened, when the left operation lever 26L is tilted backward, the arm 5 is closed, when the left operation lever 26L is tilted left, a left turn is performed, and when the left operation lever 26L is tilted right, a right turn is performed. The first operation method is configured so that when the right operation lever 26R (see FIG. 3) is tilted forward, the boom 4 is lowered, when the right operation lever 26R is tilted rearward, the boom 4 is raised, when the right operation lever 26R is tilted leftward, the bucket 6 is closed, and when the right operation lever 26R is tilted rightward, the bucket 6 is opened. On the other hand, the second operation method is configured so that when the left operation lever 26L (see FIG. 3) is tilted forward, a right turn is performed, when the left operation lever 26L is tilted rearward, a left turn is performed, when the left operation lever 26L is tilted leftward, the arm 5 is opened, and when the left operation lever 26L is tilted rightward, the arm 5 is closed.

[0017] An operator of the shovel 100 may, for example, select the first operation method when performing excavation work using an excavation bucket, and may select the second operation method when performing gravel removal work using a skeleton bucket (gravel removal bucket).

[0018] The controller 30 is a control device for controlling the shovel 100. In this embodiment, the controller 30 is configured with a computer including a CPU, a volatile storage device, a nonvolatile storage device, and the like. The controller 30 reads out a program corresponding to each function from the nonvolatile storage device, loads it into the volatile storage device, and causes the CPU to execute the corresponding process. Each function includes, for example, a machine guidance function that guides the operator in manually operating the shovel 100, and a machine control function that supports the operator in manually operating the shovel 100 or automatically or autonomously operates the shovel 100. The controller 30 may include a contact avoidance function that automatically or autonomously operates or stops the shovel 100 to avoid contact between the shovel 100 and an object present within a monitoring range around the shovel 100. Monitoring of objects around the shovel 100 is performed not only within the monitoring range but also outside the monitoring range.

[0019] Next, a configuration example of a hydraulic system mounted on the shovel 100 will be described with reference to Fig. 3. Fig. 3 is a diagram showing a configuration example of a hydraulic system mounted on the shovel 100. In Fig. 3, a mechanical power transmission system, a hydraulic oil line, a pilot line, and an electric control system are indicated by double lines, solid lines, dashed lines, and dotted lines, respectively.

[0020] 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.

[0021] In FIG. 3, the hydraulic system is configured to circulate hydraulic oil from a main pump 14 driven by an engine 11 through a center bypass line 40 or a parallel line 42 to a hydraulic oil tank.

[0022] The engine 11 is a drive source of the excavator 100. In this embodiment, the engine 11 is, for example, a diesel engine that operates to maintain a predetermined rotation speed. An output shaft of the engine 11 is connected to input shafts of the main pump 14 and the pilot pump 15.

[0023] The main pump 14 is configured to supply hydraulic oil via a hydraulic oil line to the control valve unit 17. In this embodiment, the main pump 14 is a swash plate type variable displacement hydraulic pump.

[0024] 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 in response to a control command from the controller 30.

[0025] 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, the main pump 14 may have a function of supplying hydraulic oil to various hydraulic control devices via a pilot line, in addition to a function of supplying hydraulic oil to the control valve unit 17 via a hydraulic oil line. In this case, the pilot pump 15 may be omitted.

[0026] 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 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 hydraulic oil discharged by the main pump 14 to one or more hydraulic actuators through the control valves 171 to 176. The control valves 171 to 176 control, for example, the flow rate of hydraulic oil flowing from the main pump 14 to the hydraulic actuators and the flow rate of hydraulic oil flowing from the hydraulic actuators to a 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.

[0027] The operating device 26 is configured to allow an operator to operate the actuator. In this embodiment, the operating device 26 includes a hydraulic actuator operating device configured to allow an operator to operate the hydraulic actuator. Specifically, the hydraulic actuator operating device is configured to supply hydraulic oil discharged from the pilot pump 15 to the pilot port of the corresponding control valve in the control valve unit 17 via a pilot line. The pressure of the hydraulic oil supplied to each pilot port (pilot pressure) is a pressure according to the operation direction and operation amount of the operating device 26 corresponding to each hydraulic actuator.

[0028] 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.

[0029] The operation sensor 29 is configured to detect the content of an operation of the operation device 26 by an operator. In this 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.

[0030] The main pump 14 includes a left main pump 14L and a right main pump 14R. The left main pump 14L circulates hydraulic oil to a hydraulic oil tank via a left center bypass line 40L or a left parallel line 42L, and the right main pump 14R circulates hydraulic oil to a hydraulic oil tank via a right center bypass line 40R or a right parallel line 42R.

[0031] The left center bypass line 40L is a hydraulic oil line that passes through control valves 171, 173, 175L, and 176L arranged in the control valve unit 17. The right center bypass line 40R is a hydraulic oil line that passes through control valves 172, 174, 175R, and 176R arranged in the control valve unit 17.

[0032] 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 traveling hydraulic motor 2ML and to discharge the hydraulic oil discharged by the left traveling hydraulic motor 2ML to the hydraulic oil tank.

[0033] 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 traveling hydraulic motor 2MR and to discharge the hydraulic oil discharged by the right traveling hydraulic motor 2MR to the hydraulic oil tank.

[0034] 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.

[0035] The control valve 174 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 bucket cylinder 9 and to discharge the hydraulic oil in the bucket cylinder 9 to the hydraulic oil tank.

[0036] The control valve 175L 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 boom cylinder 7. The control valve 175R 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 boom cylinder 7 and to discharge the hydraulic oil in the boom cylinder 7 to the hydraulic oil tank.

[0037] The control valve 176L 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 arm cylinder 8 and to discharge the hydraulic oil in the arm cylinder 8 to the hydraulic oil tank.

[0038] The control valve 176R 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 arm cylinder 8 and to discharge the hydraulic oil in the arm cylinder 8 to the hydraulic oil tank.

[0039] The left parallel conduit 42L is a hydraulic oil line that runs parallel to the left center bypass conduit 40L. The left parallel conduit 42L can supply hydraulic oil to a more downstream control valve when the flow of hydraulic oil through the left center bypass conduit 40L is restricted or blocked by any of the control valves 171, 173, and 175L. The right parallel conduit 42R is a hydraulic oil line that runs parallel to the right center bypass conduit 40R. The right parallel conduit 42R can supply hydraulic oil to a more downstream control valve when the flow of hydraulic oil through the right center bypass conduit 40R is restricted or blocked by any of the control valves 172, 174, and 175R.

[0040] 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, 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, for example, to reduce the discharge amount. The same is true for the right regulator 13R. This is to prevent the absorption power (absorption horsepower) of the main pump 14, which is expressed by the product of the discharge pressure and the discharge amount, from exceeding the output power (output horsepower) of the engine 11.

[0041] The operating device 26 includes a left operating lever 26L, a right operating lever 26R, and a travel lever 26D. The travel lever 26D includes a left traveling lever 26DL and a right traveling lever 26DR.

[0042] The left operating lever 26L is used for the rotation operation and the operation of the arm 5. When the left operating lever 26L is operated in the forward / backward direction, the hydraulic oil discharged by the pilot pump 15 is used to introduce a control pressure according to the amount of lever operation into the pilot port of the control valve 176. When the left operating lever 26L is operated in the left / right direction, the hydraulic oil discharged by the pilot pump 15 is used to introduce a control pressure according to the amount of lever operation into the pilot port of the control valve 173.

[0043] Specifically, when the left operating lever 26L is operated in the arm closing direction, it introduces hydraulic oil to the right pilot port of the control valve 176L and introduces hydraulic oil to the left pilot port of the control valve 176R. When the left operating lever 26L is operated in the arm opening direction, it introduces hydraulic oil to the left pilot port of the control valve 176L and introduces hydraulic oil to the right pilot port of the control valve 176R. When the left operating lever 26L is operated in the left turning direction, it introduces hydraulic oil to the left pilot port of the control valve 173, and when operated in the right turning direction, it introduces hydraulic oil to the right pilot port of the control valve 173.

[0044] In the example shown in FIG. 3, the left operating lever 26L functions as an arm operating lever when operated in the forward / rearward direction, and functions as a turning operating lever when operated in the left / right direction.

[0045] The right operating lever 26R is used to operate the boom 4 and the bucket 6. When the right operating lever 26R is operated in the forward / backward direction, it uses the hydraulic oil discharged by the pilot pump 15 to introduce a control pressure corresponding to the amount of lever operation into the pilot port of the control valve 175. When the right operating lever 26R is operated in the left / right direction, it uses the hydraulic oil discharged by the pilot pump 15 to introduce a control pressure corresponding to the amount of lever operation into the pilot port of the control valve 174.

[0046] Specifically, the right operating lever 26R introduces hydraulic oil to the left pilot port of the control valve 175R when operated in the boom lowering direction. Furthermore, the right operating lever 26R introduces hydraulic oil to the right pilot port of the control valve 175L and also introduces hydraulic oil to the left pilot port of the control valve 175R when operated in the boom raising direction. Furthermore, the right operating lever 26R introduces hydraulic oil to the right pilot port of the control valve 174 when operated in the bucket closing direction, and introduces hydraulic oil to the left pilot port of the control valve 174 when operated in the bucket opening direction.

[0047] In the example shown in FIG. 3, the right operating lever 26R functions as a boom operating lever when operated in the forward / rearward direction, and functions as a bucket operating lever when operated in the left / right direction.

[0048] The travel lever 26D is used to operate the crawler 1C. Specifically, the left travel lever 26DL is used to operate the left crawler 1CL. It may be configured to be interlocked with the left travel pedal. When the left travel lever 26DL is operated in the forward / backward direction, it uses the hydraulic oil discharged by the pilot pump 15 to introduce 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 to operate the right crawler 1CR. It may be configured to be interlocked with the right travel pedal. When the right travel lever 26DR is operated in the forward / backward direction, it uses the hydraulic oil discharged by the pilot pump 15 to introduce a control pressure corresponding to the lever operation amount into the pilot port of the control valve 172.

[0049] 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.

[0050] The operation sensor 29 includes operation sensors 29LA, 29LB, 29RA, 29RB, 29DL, and 29DR. The operation sensor 29LA detects the content of the operation of the left operation lever 26L by the operator in the forward / rearward direction, and outputs the detected value to the controller 30. The content of the operation includes, for example, the lever operation direction, the lever operation amount (lever operation angle), etc.

[0051] Similarly, the operation sensor 29LB detects the operation of the left operating lever 26L in the left-right direction by the operator, and outputs the detected value to the controller 30. The operation sensor 29RA detects the operation of the right operating lever 26R in the forward-backward direction by the operator, and outputs the detected value to the controller 30. The operation sensor 29RB detects the operation of the right operating lever 26R in the left-right direction by the operator, and outputs the detected value to the controller 30. The operation sensor 29DL detects the operation of the left traveling lever 26DL in the forward-backward direction by the operator, and outputs the detected value to the controller 30. The operation sensor 29DR detects the operation of the right traveling lever 26DR in the forward-backward direction by the operator, and outputs the detected value to the controller 30.

[0052] The controller 30 receives the output of the operation sensor 29, and outputs a control command to the regulator 13 as necessary, thereby changing the discharge volume of the main pump 14. The controller 30 also receives the output of the control pressure sensor 19 provided upstream of the orifice 18, and outputs a control command to the regulator 13 as necessary, thereby changing the discharge volume of the main pump 14. The orifice 18 includes a left orifice 18L and a right orifice 18R, and the control pressure sensor 19 includes a left control pressure sensor 19L and a right control pressure sensor 19R.

[0053] The left center bypass pipe 40L is provided with a left throttle 18L between the most downstream control valve 176L and the hydraulic oil tank. Therefore, the flow of hydraulic oil discharged by the left main pump 14L is restricted by the left throttle 18L. The left throttle 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 reduces 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 a similar manner.

[0054] Specifically, as shown in FIG. 3, in the case of a standby state in which none of the hydraulic actuators in the excavator 100 are operated, the hydraulic oil discharged by the left main pump 14L passes through the left center bypass pipe 40L and reaches the left throttle 18L. Then, the flow of the hydraulic oil discharged by the left main pump 14L increases the control pressure generated upstream of the left throttle 18L. As a result, the controller 30 reduces the discharge amount of the left main pump 14L to the allowable minimum discharge amount, suppressing the pressure loss (pumping loss) when the discharged hydraulic oil passes through the left center bypass pipe 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 hydraulic actuator to be operated through the control valve corresponding to the hydraulic actuator to be operated. Then, the flow of the hydraulic oil discharged by the left main pump 14L reduces or eliminates the amount of hydraulic oil reaching the left throttle 18L, lowering the control pressure generated upstream of the left throttle 18L. As a result, the controller 30 increases the discharge rate of the left main pump 14L to circulate sufficient hydraulic oil to the hydraulic actuator to be operated, ensuring the drive of the hydraulic actuator to be operated. The controller 30 also controls the discharge rate of the right main pump 14R in a similar manner.

[0055] With the above-described configuration, the hydraulic system of Fig. 3 can suppress unnecessary energy consumption in the main pump 14 in a standby state. The unnecessary energy consumption includes pumping loss caused in the center bypass pipe 40 by the hydraulic oil discharged from the main pump 14. Furthermore, when operating a hydraulic actuator, the hydraulic system of Fig. 3 can reliably supply necessary and sufficient hydraulic oil from the main pump 14 to the hydraulic actuator to be operated.

[0056] 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 referred to as "cylinder pressure sensors." In addition, a left swing pressure sensor S10L and a right swing pressure sensor S10R are attached to the swing hydraulic motor 2A.

[0057] The boom rod pressure sensor S7R detects the pressure in the rod side oil chamber of the boom cylinder 7 (hereinafter referred to as the "boom rod pressure"), and the boom bottom pressure sensor S7B detects the pressure in the bottom side oil chamber of the boom cylinder 7 (hereinafter referred to as the "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 the "arm rod pressure"), and the arm bottom pressure sensor S8B detects the pressure in the bottom side oil chamber of the arm cylinder 8 (hereinafter referred to as the "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 the "bucket rod pressure"), and the bucket bottom pressure sensor S9B detects the pressure in the bottom side oil chamber of the bucket cylinder 9 (hereinafter referred to as the "bucket bottom pressure"). The left swing pressure sensor S10L detects the pressure of the hydraulic oil in the left port of the swing hydraulic motor 2A. The right swing 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 .

[0058] Next, a configuration for the controller 30 to operate the actuator using a machine control function will be described with reference to Fig. 4. Fig. 4 is a diagram of a hydraulic system portion related to the operation of the arm cylinder 8.

[0059] 4, the hydraulic system includes a proportional valve 31. The proportional valve 31 includes proportional valves 31AL and 31AR.

[0060] The proportional valve 31 functions as a control valve for machine control. The proportional valve 31 is disposed in a pipe connecting the pilot pump 15 and a pilot port of a corresponding control valve in the control valve unit 17, and is configured to be able to change the flow passage area of ​​the pipe. In this embodiment, the proportional valve 31 operates in response 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. Then, the controller 30 can apply the pilot pressure generated by the proportional valve 31 to the pilot port of the corresponding control valve.

[0061] With this configuration, the controller 30 can operate the hydraulic actuator corresponding to a specific operating device 26 even when no operation is being performed on that specific operating device 26. Furthermore, the controller 30 can forcibly stop the operation of the hydraulic actuator corresponding to that specific operating device 26 even when an operation is being performed on that specific operating device 26.

[0062] For example, as shown in FIG. 4, the left operating lever 26L is used to operate the arm 5. Specifically, the left operating lever 26L uses hydraulic oil discharged by the pilot pump 15 to apply a pilot pressure corresponding to the operation in the forward / rearward direction to the pilot port of the control valve 176. More specifically, when the left operating lever 26L is operated in the arm closing direction (rearward direction), the left operating lever 26L applies a pilot pressure corresponding to the operation amount to the right pilot port of the control valve 176L and the left pilot port of the control valve 176R. Also, when the left operating lever 26L is operated in the arm opening direction (forward direction), the left operating lever 26L applies a pilot pressure corresponding to the operation amount to the left pilot port of the control valve 176L and the right pilot port of the control valve 176R.

[0063] 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 another position in the cabin 10.

[0064] The operation sensor 29LA detects the content of the operation of the left operation lever 26L in the forward / rearward direction by the operator, and outputs the detected value to the controller 30.

[0065] 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 valve 176L and the control valve 176R can be stopped at any valve position. Similarly, the proportional valve 31AR can adjust the pilot pressure so that the control valve 176L and the control valve 176R can be stopped at any valve position.

[0066] With this configuration, the controller 30 can supply the hydraulic oil discharged by 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 in response to the arm closing operation by the operator. Also, the controller 30 can supply the hydraulic oil discharged by 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, regardless of the arm closing operation by the operator. That is, the controller 30 can close the arm 5 in response to the arm closing operation by the operator or regardless of the arm closing operation by the operator.

[0067] Furthermore, the controller 30 can supply the hydraulic oil discharged by 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 in response to the arm opening operation by the operator. Furthermore, the controller 30 can supply the hydraulic oil discharged by 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, regardless of the arm opening operation by the operator. That is, the controller 30 can open the arm 5 in response to the arm opening operation by the operator or regardless of the arm opening operation by the operator.

[0068] Furthermore, with this configuration, even if the operator is performing an arm closing operation, 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) to forcibly stop the closing operation of the arm 5. The same applies to the case where the opening operation of the arm 5 is forcibly stopped when the operator is performing an arm opening operation.

[0069] Alternatively, even if the operator is performing an arm closing operation, the controller 30 may control the proportional valve 31AR as necessary to increase the pilot pressure acting on the opening pilot port 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 is opposite the closing pilot port of the control valve 176, and forcibly return the control valve 176 to the neutral position, thereby forcibly stopping the closing operation of the arm 5. The same applies to the case where the opening operation of the arm 5 is forcibly stopped when the operator is performing an arm opening operation.

[0070] The excavator 100 also includes a hydraulic system related to the operation of the boom cylinder 7, a hydraulic system related to the operation of the bucket cylinder 9, and a hydraulic system related to the operation of the swing hydraulic motor 2A, similar to the hydraulic system related to the operation of the arm cylinder 8 shown in Fig. 4. The excavator 100 may also be configured to automatically move the lower traveling structure 1 forward and backward. In this case, the hydraulic system portion related to the operation of the left traveling hydraulic motor 2ML and the hydraulic system portion related to the operation of the right traveling hydraulic motor 2MR may be configured in the same manner as the hydraulic system portion related to the operation of the boom cylinder 7, etc.

[0071] Although the description has been given of an electric control lever as a form of the operation device 26, a hydraulic operation lever may be adopted instead of the electric operation lever. In this case, the lever operation amount of the hydraulic operation 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 disposed between the operation device 26 as a hydraulic operation lever and the pilot port 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 manual operation is performed using the operation device 26 as a hydraulic operation lever, the operation device 26 can move each control valve by increasing or decreasing the pilot pressure in response to the lever operation amount. Also, each control valve may be configured as 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 operation lever.

[0072] Next, an example of control by the controller 30 during leveling work by the shovel 100 will be described with reference to Fig. 5. Fig. 5 is a flowchart illustrating control during leveling work by the shovel 100 according to the first embodiment. Note that, during leveling work by the shovel 100, the arm 5 is repeatedly opened and closed to push out soil and sand with the bucket 6, thereby leveling the ground.

[0073] In step S101, the controller 30 determines whether or not an opening operation of the arm 5 has been performed. For example, the controller 30 may determine whether or not an arm opening operation has been performed based on a detection value of an arm angle sensor (not shown) that detects a rotation angle of the arm 5 relative to the boom 4 (hereinafter, "arm angle"). If an arm opening operation has not been performed (S101·No), the process of the controller 30 repeats step S101. If an arm opening operation has been performed (S101·Yes), the process of the controller 30 proceeds to step S102. Note that in the control of the controller 30 shown in FIG. 5, step S101 may be omitted.

[0074] In step S102, the controller 30 determines whether or not an arm closing operation has been performed. For example, the controller 30 may determine whether or not an arm closing operation has been performed based on a detection value of the operation sensor 29LA. If an arm closing operation has not been performed (S102: No), the process of the controller 30 returns to step S101. If an arm closing operation has been performed (S102: Yes), the process of the controller 30 proceeds to step S103.

[0075] In step S103, the controller 30 judges whether or not there is a comoli pressure in the bottom side oil chamber of the arm cylinder 8. Here, in the break-in work, from the opening operation of the arm 5, the movement speed of the arm 5 in the opening direction is decelerated, and then the closing operation of the arm 5 is performed. When the movement speed of the arm 5 in the opening direction is decelerated, the bottom side oil chamber of the arm cylinder 8 becomes high pressure (comoli pressure). For this reason, at the time when the closing operation of the arm 5 is started, comoli pressure may be generated in the bottom side oil chamber of the arm cylinder 8. When the arm bottom pressure detected by the arm bottom pressure sensor S8B is equal to or higher than a predetermined threshold value, the controller 30 judges that there is a comoli pressure in the bottom side oil chamber of the arm cylinder 8.

[0076] When it is determined that there is no common pressure in the bottom-side oil chamber of the arm cylinder 8 (S103 No), the process of the controller 30 proceeds to step S110, which will be described later. In step S110, the controller 30 performs normal control. That is, the controller 30 controls the proportional valves 31AL, 31AR based on the operation amount detected by the operation sensor 29LA, and controls the movement amount of the spool of the control valve 176 (176L, 176R).

[0077] When it is determined that there is a comoli pressure in the bottom side oil chamber of the arm cylinder 8 (S103: Yes), the processing of the controller 30 proceeds to step S104.

[0078] In step S104, the controller 30 estimates the thrust of the arm cylinder 8 due to the commutation pressure based on the commutation pressure.

[0079] In step S105, the controller 30 calculates the closing speed of the arm 5 due to the compression pressure, based on the thrust force due to the compression pressure estimated in step S104.

[0080] In step S106, the controller 30 calculates the amount of movement M1 of the spool of the control valve 176 (176L, 176R) that realizes the closing speed of the arm 5 due to the comor pressure calculated in step S105.

[0081] In step S107, the controller 30 calculates the movement amount M2 of the spool of the control valve 176 (176L, 176R) based on the operation amount detected by the operation sensor 29LA.

[0082] In step S108, the controller 30 determines whether the amount of movement M2 of the spool corresponding to the amount of operation calculated in step S107 is equal to or less than the amount of movement M1 of the spool corresponding to the compressor pressure calculated in step S106.

[0083] If the amount of movement M2 of the spool corresponding to the operation amount is equal to or less than the amount of movement M1 of the spool corresponding to the common pressure (S108: Yes), the process of the controller 30 proceeds to step S109.

[0084] In step S109, the controller 30 controls the proportional valves 31AL and 31AR based on the spool movement amount M1 corresponding to the common pressure calculated in step S106, and controls the spool movement amount of the control valve 176 (176L, 176R). In other words, the controller 30 sets the spool movement amount of the control valve 176 (176L, 176R) to the spool movement amount M1 corresponding to the common pressure calculated in step S106, which is larger than the spool movement amount M2 corresponding to the operation amount calculated in step S107. Note that, after step S109, if the spool movement amount M2 corresponding to the operation amount calculated in step S107 is equal to or smaller than the spool movement amount M1 corresponding to the arm bottom pressure calculated in step S106, the control shown in FIG. 5 is stopped. Also, after step S109, if the operation amount of the arm closing operation is equal to or smaller than a predetermined value, the control shown in FIG. 5 is stopped.

[0085] As described above, according to the excavator 100 of the first embodiment, the operation of the arm cylinder 8 (hydraulic actuator) corresponding to the operation amount of the left operating lever 26L (operating device 26) is corrected according to the state of the arm cylinder 8 (hydraulic actuator) during the leveling operation. That is, according to the excavator 100 of the first embodiment, when the arm bottom pressure of the arm cylinder 8 (hydraulic actuator) exceeds a predetermined threshold value (S103·Yes), the movement amount of the spool of the control valve 176 corresponding to the arm cylinder 8 is controlled by the spool movement amount M1 that is larger than the spool movement amount M2 corresponding to the operation amount of the left operating lever 26L (operating device 26) (see S109). Moreover, the spool movement amount M1 is calculated according to the arm bottom pressure of the arm cylinder 8 (see S104 to S106).

[0086] On the other hand, if the amount of movement M2 of the spool corresponding to the amount of operation is not equal to or less than the amount of movement M1 of the spool corresponding to the common pressure (S108.No), the process of the controller 30 proceeds to step S110.

[0087] In step S110, the controller 30 performs normal control. That is, the controller 30 controls the proportional valves 31AL, 31AR based on the amount of operation detected by the operation sensor 29LA, and controls the amount of movement of the spool of the control valve 176 (176L, 176R). In other words, the controller 30 controls the proportional valves 31AL, 31AR based on the amount of movement M2 of the spool corresponding to the amount of operation calculated in step S107, and controls the amount of movement of the spool of the control valve 176 (176L, 176R).

[0088] 5, the control when switching from the opening operation of the arm 5 to the closing operation of the arm 5 has been described, but the same can also be applied to the control when switching from the closing operation of the arm 5 to the opening operation of the arm 5. The comoli pressure when the arm closing speed is decelerated is generated in the rod side oil chamber of the arm cylinder 8.

[0089] Furthermore, if a predetermined operation is not being performed after the controller 30 controls the control valve 176 with the spool movement amount M1 in step S109, the controller 30 may move the spool of the control valve 176 to the neutral position. This makes it possible to prevent the arm 5 from continuing to perform the closing operation, for example, when the operation of the operation device 26 by the operator has ended.

[0090] Next, in comparison with a shovel according to a reference example, the control during the break-in work of the shovel 100 according to the first embodiment will be described with reference to Fig. 6. Fig. 6 is a time chart for explaining the control during the break-in work of the shovel according to the reference example and the shovel 100 according to the first embodiment.

[0091] In the excavator of the reference example, normal control (see S110) is performed. Fig. 6(a) shows the thrust of the arm cylinder 8, the bottom pressure of the arm cylinder 8 (detection value of the arm bottom pressure sensor S8B), the rod pressure of the arm cylinder 8 (detection value of the arm rod pressure sensor S8R), and the pump pressure (detection value of the discharge pressure sensor 28) in the excavator of the reference example. Fig. 6(b) shows the operation amount of the left operating lever 26L (detection value of the operation sensor 29LA) in the excavator of the reference example. The horizontal axis represents time, and the timing when the closing operation of the arm 5 is performed (S102·Yes) is set to time T0.

[0092] In the shovel of the reference example, at the time when the closing operation of the arm 5 starts, a comoli pressure is generated in the bottom oil chamber of the arm cylinder 8. Therefore, the thrust of the arm cylinder 8 can be secured even with a small amount of operation.

[0093] Then, because the common pressure in the bottom oil chamber of the arm cylinder 8 is consumed, the thrust of the arm cylinder 8 decreases even if the operation amount remains the same. Therefore, the operator increases the operation amount. This increases the pump pressure and the thrust of the arm cylinder 8 also increases.

[0094] In this way, in the shovel of the reference example, there occurs a decrease and an increase in the thrust of the arm cylinder 8. This increase and decrease in thrust causes vibrations in the shovel body.

[0095] In the shovel 100 according to the first embodiment, the control shown in Fig. 5 is performed. Fig. 6(c) shows the thrust of the arm cylinder 8, the bottom pressure of the arm cylinder 8 (detection value of the arm bottom pressure sensor S8B), the rod pressure of the arm cylinder 8 (detection value of the arm rod pressure sensor S8R), and the pump pressure (detection value of the discharge pressure sensor 28) in the shovel 100 according to the first embodiment. Fig. 6(d) shows the operation amount (detection value of the operation sensor 29LA) of the left operating lever 26L in the shovel 100 according to the first embodiment. The horizontal axis represents time, and the timing when the closing operation of the arm 5 is performed (S102·Yes) is set to time T0.

[0096] In the shovel 100 according to the first embodiment, at the time when the closing operation of the arm 5 starts, a comoli pressure is generated in the bottom oil chamber of the arm cylinder 8. Therefore, even with a small amount of operation, the thrust of the arm cylinder 8 can be secured.

[0097] The controller 30 controls the control valve 176 based on the amount of movement M1 of the spool corresponding to the comoli pressure. In addition, in Fig. 6(d), the amount of operation corresponding to the amount of movement M1 of the spool is shown by a dashed line. As a result, the pump pressure increases, and the thrust of the arm cylinder 8 also increases.

[0098] As a result, the common pressure in the bottom-side oil chamber of the arm cylinder 8 is consumed, and before the bottom pressure decreases, hydraulic oil can be supplied to the bottom-side oil chamber of the arm cylinder 8. Therefore, according to the shovel 100 according to the first embodiment, it is possible to suppress fluctuations in the thrust of the arm cylinder 8. As a result, it is possible to suppress vibrations from occurring in the shovel 100 body.

[0099] Next, Fig. 7 is a flowchart for explaining control during the run-in operation of the shovel 100 according to the second embodiment. In the control shown in Fig. 5, the controller 30 controls the amount of movement of the spool of the control valve 176 (176L, 176R) after the arm closing operation is performed. In contrast, in the control shown in Fig. 6, the controller 30 starts controlling the amount of movement of the spool of the control valve 176 (176L, 176R) when the arm opening operation is decelerated before the arm closing operation is performed.

[0100] In step S201, the controller 30 determines whether or not an opening operation of the arm 5 is being performed. If an arm opening operation is not being performed (S201: No), the process of the controller 30 repeats step S201. If an arm opening operation is being performed (S201: Yes), the process of the controller 30 proceeds to step S202.

[0101] In step S202, the controller 30 determines whether or not the opening motion of the arm 5 is decelerating. If the arm opening motion is not decelerating (S202: No), the process of the controller 30 returns to step S201. If the arm opening motion is decelerating (S202: Yes), the process of the controller 30 proceeds to step S203.

[0102] In step S203, the controller 30 detects the pressure in the bottom side oil chamber of the arm cylinder 8 (arm bottom pressure) by the arm bottom pressure sensor S8B.

[0103] In step S204, the controller 30 determines whether the arm bottom pressure is equal to or greater than a predetermined threshold. Here, the threshold is, for example, a relief pressure of a relief valve (not shown) provided in the arm cylinder 8. If the arm bottom pressure is not equal to or greater than the predetermined threshold (S204: No), the process of the controller 30 returns to step S201. If the arm bottom pressure is equal to or greater than the predetermined threshold (S204: Yes), the process of the controller 30 proceeds to step S205.

[0104] In step S205, the controller 30 controls the control valve 176 (176L, 176R) to switch to the side for closing the arm 5.

[0105] Thus, according to the excavator 100 of the second embodiment, while the arm cylinder 8 (hydraulic actuator) is being driven in the opening direction (one direction), the spool of the control valve 176 corresponding to the arm cylinder 8 is moved in a direction corresponding to the driving of the arm cylinder 8 in the closing direction (the other direction). Also, according to the excavator 100 of the second embodiment, when the arm bottom pressure exceeds a predetermined threshold value, the spool of the control valve 176 is moved in a direction corresponding to the driving of the arm cylinder 8 in the closing direction (the other direction).

[0106] In step S206, the controller 30 estimates the thrust of the arm cylinder 8 due to the arm bottom pressure, based on the arm bottom pressure.

[0107] In step S207, the controller 30 calculates the closing speed of the arm 5 due to the arm bottom pressure, based on the thrust due to the arm bottom pressure estimated in step S206.

[0108] In step S208, the controller 30 calculates the movement amount M1 of the spool of the control valve 176 (176L, 176R) that realizes the closing speed of the arm 5 due to the arm bottom pressure calculated in step S207.

[0109] In step S209, the controller 30 calculates the movement amount M2 of the spool of the control valve 176 (176L, 176R) based on the operation amount detected by the operation sensor 29LA.

[0110] In step S210, the controller 30 determines whether the amount of movement M2 of the spool corresponding to the amount of operation calculated in step S209 is equal to or less than the amount of movement M1 of the spool corresponding to the arm bottom pressure calculated in step S208.

[0111] If the amount of movement M2 of the spool corresponding to the operation amount is equal to or less than the amount of movement M1 of the spool corresponding to the arm bottom pressure (S108. Yes), the process of the controller 30 proceeds to step S211.

[0112] In step S211, the controller 30 controls the proportional valves 31AL and 31AR based on the spool movement amount M1 corresponding to the arm bottom pressure calculated in step S208, and controls the spool movement amount of the control valve 176 (176L, 176R). In other words, the controller 30 sets the spool movement amount of the control valve 176 (176L, 176R) to the spool movement amount M1 corresponding to the arm bottom pressure calculated in step S208, which is larger than the spool movement amount M2 corresponding to the operation amount calculated in step S209. Note that, after step S211, if the spool movement amount M2 corresponding to the operation amount calculated in step S209 is equal to or smaller than the spool movement amount M1 corresponding to the arm bottom pressure calculated in step S208, the control shown in FIG. 7 is stopped. Also, after step S211, if the operation amount of the arm closing operation is equal to or smaller than a predetermined value, the control shown in FIG. 7 is stopped.

[0113] As described above, according to the excavator 100 of the second embodiment, the operation of the arm cylinder 8 (hydraulic actuator) corresponding to the operation amount of the left operating lever 26L (operating device 26) is corrected according to the state of the arm cylinder 8 (hydraulic actuator) during the leveling operation. That is, according to the excavator 100 of the second embodiment, when the arm bottom pressure of the arm cylinder 8 (hydraulic actuator) exceeds a predetermined threshold value (S204·Yes), the movement amount of the spool of the control valve 176 corresponding to the arm cylinder 8 is controlled by the spool movement amount M1 that is larger than the spool movement amount M2 corresponding to the operation amount of the left operating lever 26L (operating device 26) (see S211). Moreover, the spool movement amount M1 is calculated according to the arm bottom pressure of the arm cylinder 8 (see S206 to S2086).

[0114] On the other hand, if the amount of movement M2 of the spool corresponding to the operation amount is not equal to or less than the amount of movement M1 of the spool corresponding to the arm bottom pressure (S108.No), the process of the controller 30 proceeds to step S212.

[0115] In step S212, the controller 30 performs normal control. That is, the controller 30 controls the proportional valves 31AL, 31AR based on the amount of operation detected by the operation sensor 29LA, and controls the amount of movement of the spool of the control valve 176 (176L, 176R). In other words, the controller 30 controls the proportional valves 31AL, 31AR based on the amount of movement M2 of the spool corresponding to the amount of operation calculated in step S209, and controls the amount of movement of the spool of the control valve 176 (176L, 176R).

[0116] 7, the control when switching from the opening operation of the arm 5 to the closing operation of the arm 5 has been described, but the control when switching from the closing operation of the arm 5 to the opening operation of the arm 5 can also be applied. In this case, in step S203, the arm rod pressure in the rod side oil chamber of the arm cylinder 8 is detected.

[0117] Next, in comparison with the shovel according to the reference example, the control during the break-in work of the shovel 100 according to the second embodiment will be described with reference to Fig. 8. Fig. 8 is a time chart for explaining the control during the break-in work of the shovel according to the reference example and the shovel 100 according to the second embodiment.

[0118] In the shovel of the reference example, normal control (see S110) is performed. Fig. 8(a) shows the thrust of the arm cylinder 8, the bottom pressure of the arm cylinder 8 (detection value of the arm bottom pressure sensor S8B), the rod pressure of the arm cylinder 8 (detection value of the arm rod pressure sensor S8R), and the pump pressure (detection value of the discharge pressure sensor 28) in the shovel of the reference example. Fig. 8(b) shows the operation amount of the left operating lever 26L (detection value of the operation sensor 29LA) in the shovel of the reference example. The horizontal axis indicates time, and the timing when the closing operation of the arm 5 is performed is set to time T0.

[0119] In the excavator of the reference example, deceleration of the arm opening operation starts at time T1. When the arm opening operation is decelerated, the arm bottom pressure rises. When the arm bottom pressure exceeds the relief pressure, the hydraulic oil is relieved to the hydraulic oil tank via the relief valve. Then, at the time when the closing operation of the arm 5 starts, a comoli pressure is generated in the bottom side oil chamber of the arm cylinder 8. Therefore, the thrust of the arm cylinder 8 can be secured even with a small amount of operation.

[0120] Then, because the common pressure in the bottom oil chamber of the arm cylinder 8 is consumed, the thrust of the arm cylinder 8 decreases even if the operation amount remains the same. Therefore, the operator increases the operation amount. This increases the pump pressure and the thrust of the arm cylinder 8 also increases.

[0121] In this way, in the shovel of the reference example, there occurs a decrease and an increase in the thrust of the arm cylinder 8. This increase and decrease in thrust causes vibrations in the shovel body.

[0122] In the shovel 100 according to the second embodiment, the control shown in Fig. 7 is performed. Fig. 8(c) shows the thrust of the arm cylinder 8, the bottom pressure of the arm cylinder 8 (detection value of the arm bottom pressure sensor S8B), the rod pressure of the arm cylinder 8 (detection value of the arm rod pressure sensor S8R), and the pump pressure (detection value of the discharge pressure sensor 28) in the shovel 100 according to the second embodiment. Fig. 8(d) shows the operation amount (detection value of the operation sensor 29LA) of the left operating lever 26L in the shovel 100 according to the second embodiment. The horizontal axis represents time, and the timing when the closing operation of the arm 5 is performed (S102·Yes) is set to time T0.

[0123] In the shovel 100 according to the second embodiment, deceleration of the arm-opening operation starts at time T1. The arm bottom pressure rises when the arm-opening operation is decelerated. When the arm bottom pressure reaches or exceeds a predetermined threshold at time T2, the controller 30 switches and controls the control valve 176 (176L, 176R) to the closing operation side of the arm 5. Note that in FIG. 8(d), the operation amount corresponding to the movement amount of the spool controlled by the controller 30 is shown typically by a dashed line. Thereafter, the control of the controller 30 (S206 to S212) is performed in the same manner as the control of the controller 30 of the shovel 100 according to the first embodiment (S104 to S110).

[0124] According to the shovel 100 of the second embodiment, the arm bottom pressure generated during deceleration of the arm opening operation can be utilized for the arm closing operation, so that the fuel efficiency of the shovel 100 can be improved.

[0125] Moreover, according to the shovel 100 according to the second embodiment, it is possible to suppress fluctuations in the thrust of the arm cylinder 8. This makes it possible to suppress the occurrence of vibrations in the shovel 100 main body.

[0126] In the shovel 100 according to the first and second embodiments, the leveling work in which the opening and closing operation of the arm 5 is repeated has been described as an example, but the present invention is not limited to this. The present invention may be applied to a work in which the up and down movement of the boom 4 is repeated, or to a work in which the opening and closing operation of the bucket 6 is repeated.

[0127] The control may also be applied to the control of the swing hydraulic motor 2A that swings the upper swing body 3. For example, when the upper swing body 3 swinging in one rotation direction stops rotating, the upper swing body 3 rotates due to inertial force, causing the swing hydraulic motor 2A to function as a hydraulic pump, and a commutation pressure is generated in one port of the swing hydraulic motor 2A. Then, when the upper swing body 3 is rotated in another rotation direction different from the one rotation direction, the commutation pressure causes the upper swing body 3 to swing faster, causing vibration in the excavator body.

[0128] When the pressure of one port or the pressure of the other port of the swing hydraulic motor 2A detected by the left swing pressure sensor S10L or the right swing pressure sensor S10R exceeds a predetermined value (see S103, S204), the controller 30 calculates the amount of movement of the spool of the control valve 173 according to the pressure of one port or the pressure of the other port (see S104 to S106, S206 to S208). Then, the controller 30 controls the amount of movement of the spool based on the calculated amount of movement of the spool and the amount of movement of the spool corresponding to the amount of operation of the left operating lever 26L (see S107 to S110, S209 to S212). This makes it possible to suppress the occurrence of vibration in the excavator 100 body. [Explanation of symbols]

[0129] 100 Shovel 1 Undercarriage 2 Swivel mechanism 2A Swing Hydraulic Motor (Hydraulic Actuator) 3. Upper rotating body 4. Boom 5 Arm 6 Bucket 7 Boom cylinder (hydraulic actuator) 8 Arm cylinder (hydraulic actuator) 9 Bucket cylinder (hydraulic actuator) 14 Main pump (hydraulic pump) 17 Control valve unit 171~176 Control valve 26 Operating device 28 Discharge pressure sensor 29 Operation Sensor 30 Controller (control device) 31 Proportional valve S8R Arm rod pressure sensor S8B Arm bottom pressure sensor S10L Left turning pressure sensor S10R Right turning pressure sensor

Claims

1. An operating device; A hydraulic pump for supplying hydraulic fluid; a hydraulic actuator that is driven in response to an operation amount of the operation device; a control valve for controlling hydraulic oil flowing from the hydraulic pump to the hydraulic actuator; a control device for controlling a movement amount of a spool of the control valve, The control device includes: When the bottom pressure or rod pressure of the hydraulic actuator exceeds a predetermined value during driving of the hydraulic actuator in one direction, The spool of the control valve corresponding to the hydraulic actuator is moved in a corresponding direction during driving of the hydraulic actuator in another direction different from the one direction; a movement amount of the spool of the control valve corresponding to the hydraulic actuator is made larger than a movement amount of the spool corresponding to an operation amount of the operating device; Shovel.

2. An operating device; A hydraulic pump for supplying hydraulic fluid; an arm cylinder that drives an arm in response to an operation amount of the operation device; a control valve for controlling hydraulic oil flowing from the hydraulic pump to the arm cylinder; a control device for controlling a movement amount of a spool of the control valve, The control device includes: When the bottom pressure or rod pressure of the arm cylinder exceeds a predetermined value during driving in the arm opening direction or the arm closing direction, The spool of the control valve corresponding to the arm cylinder is moved in a direction corresponding to a direction opposite to a drive direction of the arm cylinder, a movement amount of the spool of the control valve corresponding to the arm cylinder is made larger than a movement amount of the spool corresponding to an operation amount of the operating device; Shovel.

3. The control device includes: When a bottom pressure or a rod pressure of the hydraulic actuator exceeds a predetermined value, a movement amount of the spool is calculated according to the bottom pressure or the rod pressure; controlling a movement amount of the spool of the control valve corresponding to the hydraulic actuator by the calculated movement amount of the spool; The shovel according to claim 1.

4. The control device includes: When a bottom pressure or a rod pressure of the arm cylinder exceeds a predetermined value, a movement amount of the spool is calculated according to the bottom pressure or the rod pressure, controlling a movement amount of the spool of the control valve corresponding to the arm cylinder by the calculated movement amount of the spool; The shovel according to claim 2.

5. The control device includes: moving the spool to a neutral position if a predetermined action is not being performed; A shovel according to any one of claims 1 to 4.

6. The control device When, during driving of the hydraulic actuator in the one direction, the hydraulic actuator switches from a state in which it operates in the one direction to a state in which the operation in the one direction is decelerated, and a bottom pressure or a rod pressure of the hydraulic actuator exceeds a predetermined value, The spool of the control valve corresponding to the hydraulic actuator is moved in a corresponding direction during driving of the hydraulic actuator in another direction different from the one direction; a movement amount of the spool of the control valve corresponding to the hydraulic actuator is made larger than a movement amount of the spool corresponding to an operation amount of the operating device; The shovel according to claim 1.

7. The control device During driving of the arm cylinder in the driving direction, the state of the arm cylinder moving in the driving direction is switched to a state in which the movement of the arm cylinder in the driving direction is decelerated, and a bottom pressure or a rod pressure of the arm cylinder exceeds a predetermined value. moving the spool of the control valve corresponding to the arm cylinder in a direction corresponding to a direction opposite to the drive direction of the arm cylinder; a movement amount of the spool of the control valve corresponding to the arm cylinder is made larger than a movement amount of the spool corresponding to an operation amount of the operating device; The shovel according to claim 2.

8. An operating device; A hydraulic pump for supplying hydraulic fluid; a hydraulic swing motor that drives a swing mechanism in response to an operation amount of the operation device; a control valve for controlling hydraulic oil flowing from the hydraulic pump to the swing hydraulic motor; a control device for controlling a movement amount of a spool of the control valve, The control device includes: When the pressure on one side or the pressure on the other side of the swing hydraulic motor exceeds a predetermined value while the swing hydraulic motor is being driven in one direction, The spool of the control valve corresponding to the swing hydraulic motor is moved in a corresponding direction during driving of the swing hydraulic motor in another direction different from the one direction; a movement amount of the spool of the control valve corresponding to the swing hydraulic motor is made larger than a movement amount of the spool corresponding to an operation amount of the operation device; Shovel.

Images