Shovel

Abstract

To provide a shovel improved in operability.SOLUTION: A shovel includes a hydraulic pump 14, a hydraulic actuator 7, a directional control valve 175 for controlling working fluid to be supplied from the hydraulic pump to the hydraulic actuator, an electromagnetic proportional valve for controlling a pilot pressure of the directional control valve, an operation lever 29, and a controller 30 to which an operation amount of the operation lever is input and which generates a command value to the electromagnetic proportional valve. The controller generates the command value to the electromagnetic proportional valve so that the hydraulic actuator does not move when the operation lever is not operated.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] Patent Document 1 discloses an excavator that adjusts the discharge rate of a main pump by controlling a regulator according to a negative control pressure detected by a negative control pressure sensor. Patent Document 1 also discloses a hydraulic system for an excavator that has a neutral cut valve installed upstream of a negative control throttle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-172638 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, a hydraulic oil leak may cause the attachment to move without being operated.

[0005] In view of the above problems, an object of the present invention is to provide a shovel that improves operability. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, a shovel according to an embodiment of the present invention includes a hydraulic pump, a hydraulic actuator, a directional control valve that controls hydraulic oil supplied from the hydraulic pump to the hydraulic actuator, an electromagnetic proportional valve that controls the pilot pressure of the directional control valve, an operating lever, and a controller that receives an operation amount of the operating lever and generates a command value for the electromagnetic proportional valve, and the controller generates a command value for the electromagnetic proportional valve so that the hydraulic actuator does not move when the operating lever is not operated. Effect of the Invention

[0007] According to the above-described embodiment, a shovel with improved operability can be provided. [Brief description of the drawings]

[0008] [Figure 1] FIG. [Diagram 2] FIG. 1 is a diagram showing a configuration example of a hydraulic system mounted on a shovel. [Diagram 3] FIG. 2 is a diagram illustrating a hydraulic system portion related to the operation of a bucket cylinder. [Figure 4] FIG. 2 is a schematic diagram of a control valve. [Diagram 5] 5 is a graph showing an example of an opening area of ​​a control valve during bucket operation. [Figure 6] 4 is a flowchart showing a first control example of the shovel. [Figure 7] 13 is a flowchart showing a second control example of the shovel. [Figure 8] 13 is a flowchart showing a third control example of the shovel. 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 Fig. 1. Fig. 1 is a side view of the shovel 100.

[0010] In this embodiment, the lower traveling structure 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 structure 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 (see FIG. 2 described later).

[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 FIG. 1, the bucket 6 is an excavation bucket, but 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 (see FIG. 2 described later), a controller 30, 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 (not shown) attached to the right end of the upper surface of the upper rotating body 3. An upward sensor (not shown) 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 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.

[0017] Next, a configuration example of a hydraulic system mounted on the shovel 100 will be described with reference to Fig. 2. Fig. 2 is a diagram showing a configuration example of a hydraulic system mounted on the shovel 100. In Fig. 2, 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.

[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 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.

[0020] 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.

[0021] 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.

[0022] The regulator 13 is configured 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.

[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, 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.

[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 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.

[0025] 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 through a pilot line to pilot ports of the corresponding control valves 171 to 176 in the control valve unit 17 through a proportional valve 31 controlled by a controller 30. 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.

[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 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.

[0028] 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.

[0029] 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.

[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 traveling hydraulic motor 2ML and to discharge the hydraulic oil discharged by the left traveling 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 traveling hydraulic motor 2MR and to discharge the hydraulic oil discharged by the right traveling 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 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[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, 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] In the example shown in FIG. 2, 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.

[0043] In addition, a switch NS is provided on the left operation lever 26L. In this embodiment, the switch NS is a push button switch provided on 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 may be provided at another position in the cabin 10.

[0044] 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.

[0045] 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.

[0046] In the example shown in FIG. 2, 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.

[0047] The travel lever 26D is used to operate the crawlers. Specifically, the left travel lever 26DL is used to operate 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 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. 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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 a control pressure sensor 19 provided upstream of the throttle (negative control throttle) 18, and outputs a control command to the regulator 13 as necessary, thereby changing the discharge volume 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.

[0052] 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.

[0053] Specifically, as shown in FIG. 2, 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.

[0054] With the above-described configuration, the hydraulic system of Fig. 2 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. 2 can reliably supply necessary and sufficient hydraulic oil from the main pump 14 to the hydraulic actuator to be operated.

[0055] That is, the controller 30 controls the regulator 13 so that the discharge amount is the smaller of a first discharge amount calculated so that the absorption power (absorption horsepower) of the main pump 14, which is expressed as the product of the discharge pressure and the discharge amount, does not exceed the output power (output horsepower) of the engine 11, and a second discharge amount calculated based on the control pressure detected by the control pressure sensor 19.

[0056] The neutral cut valve 50 is a valve capable of adjusting the flow area of ​​the center bypass pipe 40. In the example shown in FIG. 2, the neutral cut valve 50 is disposed in the right center bypass pipe 40R upstream of the right throttle 18R and downstream of the multiple control valves 172, 174, 175R, and 176R disposed in the right center bypass pipe 40R. The right control pressure sensor 19R detects pressure upstream of the right throttle 18R and downstream of the neutral cut valve 50. The operation of the neutral cut valve 50 is controlled by the controller 30. For example, the neutral cut valve 50 may be an electromagnetic valve whose operation is controlled by the controller 30. Also, the neutral cut valve 50 may be an electromagnetic valve whose operation is controlled by supplying hydraulic oil discharged by the pilot pump 15 to a pilot port of the neutral cut valve 50 via a proportional valve (not shown) controlled by the controller 30.

[0057] The neutral cut valve 50 may be provided in either one of the left and right center bypass pipes 40, or in each of them.

[0058] 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.

[0059] 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 .

[0060] Next, a configuration for the controller 30 to operate the actuators using the machine control function will be described with reference to Fig. 3. Fig. 3 is a diagram extracting a hydraulic system portion related to the operation of the bucket cylinder 9. Note that Fig. 3 has been described using the operation of the bucket cylinder 9 as an example, but is not limited to this, and the same applies to the operation of the boom cylinder 7, the operation of the arm cylinder 8, the operation of the swing hydraulic motor 2A, the operation of the left traveling hydraulic motor 2ML, and the operation of the right traveling hydraulic motor 2MR, and therefore repeated description will be omitted.

[0061] 3, the hydraulic system includes a proportional valve 31. The proportional valve 31 includes a proportional valve 31CL and a proportional valve 31CR.

[0062] 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.

[0063] 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.

[0064] As shown in Fig. 3, the right operating lever 26R is also used to operate the bucket 6. Specifically, the right operating lever 26R utilizes hydraulic oil discharged by the pilot pump 15 to apply a pilot pressure corresponding to operation in the left or right direction to the pilot port of the control valve 174. More specifically, when the right operating lever 26R is operated in the bucket closing direction (left direction), it applies a pilot pressure corresponding to the operation amount to the left pilot port of the control valve 174. Also, when the right operating lever 26R is operated in the bucket opening direction (right direction), it applies a pilot pressure corresponding to the operation amount to the right pilot port of the control valve 174.

[0065] The operation sensor 29RB detects the content of the operation of the right operating lever 26R in the left or right direction by the operator, and outputs the detected value to the controller 30.

[0066] The proportional valve 31CL operates in response to a control command (current command) output by the controller 30. The proportional valve 31CR adjusts the pilot pressure by the hydraulic oil introduced from the pilot pump 15 to the left pilot port of the control valve 174 via the proportional valve 31CL. The proportional valve 31CR operates in response to a control command (current command) output by the controller 30. The proportional valve 31CR adjusts the pilot pressure by the hydraulic oil introduced from the pilot pump 15 to the right pilot port of the control valve 174 via the proportional valve 31CR. The proportional valve 31CL can adjust the pilot pressure so that the control valve 174 can be stopped at any valve position. Similarly, the proportional valve 31CR can adjust the pilot pressure so that the control valve 174 can be stopped at any valve position.

[0067] A pilot pressure sensor 32CL for detecting pilot pressure is provided in a pilot line connecting the proportional valve 31CL and one port of the control valve 174 (the left port of the control valve 174). A pilot pressure sensor 32CR for detecting pilot pressure is provided in a pilot line connecting the proportional valve 31CR and the other port of the control valve 174 (the right port of the control valve 174). Values ​​detected by each of the pilot pressure sensors 32CL, 32CR are transmitted to the controller 30.

[0068] With this configuration, controller 30 can supply the hydraulic oil discharged by pilot pump 15 to the left pilot port of control valve 174 via proportional valve 31CL in response to a bucket closing operation by the operator. Moreover, controller 30 can supply the hydraulic oil discharged by pilot pump 15 to the left pilot port of control valve 174 via proportional valve 31CL, regardless of a bucket closing operation by the operator. In other words, controller 30 can close bucket 6 in response to a bucket closing operation by the operator or regardless of a bucket closing operation by the operator.

[0069] Furthermore, in response to a bucket opening operation by the operator, controller 30 can supply the hydraulic oil discharged by pilot pump 15 to the right pilot port of control valve 174 via proportional valve 31CR. Furthermore, regardless of a bucket opening operation by the operator, controller 30 can supply the hydraulic oil discharged by pilot pump 15 to the right pilot port of control valve 174 via proportional valve 31CR. In other words, controller 30 can open bucket 6 in response to a bucket opening operation by the operator or regardless of a bucket opening operation by the operator.

[0070] Furthermore, with this configuration, even when the operator is performing a bucket closing operation, controller 30 can control proportional valve 31CL as necessary to reduce the pilot pressure acting on the closing side pilot port (left side in FIG. 3) of control valve 174, and forcibly stop the closing operation of bucket 6. The same applies to the case where the opening operation of bucket 6 is forcibly stopped when the operator is performing a bucket opening operation.

[0071] Alternatively, even when the operator is performing a bucket closing operation, controller 30 may control proportional valve 31CR as necessary to increase the pilot pressure acting on the opening pilot port of control valve 174 (on the right side in FIG. 3) opposite the closing pilot port of control valve 174, and forcibly return control valve 174 to the neutral position, thereby forcibly stopping the closing operation of bucket 6. The same applies to the case where the opening operation of bucket 6 is forcibly stopped when the operator is performing a bucket opening operation.

[0072] 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.

[0073] Next, the control valve 174 that supplies hydraulic oil to the bucket cylinder 9 will be described with reference to Fig. 4. Fig. 4 is a schematic configuration diagram of the control valve 174.

[0074] The control valve 174 has a control valve body and a spool Vm. The control valve body is formed with an inlet port, an outlet port, a parallel port, cylinder ports CprtA and CprtB, and a tank port Tprt.

[0075] Here, the center bypass passage RC (corresponding to the right center bypass pipe 40R in Fig. 2) is formed in a direction perpendicular to the plane of Fig. 4. In the center bypass passage RC, for example, the front side of the plane of the paper corresponds to the inlet port, and the back side of the plane of the paper corresponds to the outlet port.

[0076] Further, a parallel passage RP (corresponding to the right parallel pipe 42R in Fig. 2) is formed in a direction perpendicular to the plane of the paper in Fig. 4. A check valve Vch is provided between the parallel passage RP and the bridge passage Rb.

[0077] The inlet port is connected to the right center bypass line 40R located upstream of the control valve 174. The inlet port is supplied with hydraulic oil from the main pump 14.

[0078] The outlet port is connected to the right center bypass pipe 40R downstream of the control valve 174. The opening area of ​​the center bypass passage RC from the inlet port to the outlet port is controlled by a spool Vm.

[0079] The cylinder port CprtA (first cylinder port) is connected to a rod side oil chamber of the bucket cylinder 9. The cylinder port CprtB (second cylinder port) is connected to a bottom side oil chamber of the bucket cylinder 9.

[0080] The tank port Tprt is connected to a hydraulic oil tank.

[0081] In addition, a relief valve 52A is provided between the cylinder port CprtA and the tank port Tprt. The relief valve 52A is a valve that opens when the pressure of the hydraulic oil in the cylinder port CprtA reaches or exceeds a predetermined pressure. In addition, a relief valve 52B is provided between the cylinder port CprtB and the tank port Tprt. The relief valve 52B is a valve that opens when the pressure of the hydraulic oil in the cylinder port CprtB reaches or exceeds a predetermined pressure.

[0082] The control valve body has pilot ports on one end side and the other end side of the spool Vm. When pilot pressure is supplied to the pilot ports, the position of the spool Vm is displaced from the neutral position. In this manner, the spool Vm is configured to be movable in the left-right direction in FIG. 4. An annular gap is formed between the control valve body and the spool Vm. A plurality of bleed openings Sbo are formed in the spool Vm. The hydraulic circuit performs bleed-off control by changing the opening area of ​​the bleed openings Sbo.

[0083] Between the left parallel passage RP and cylinder port CprtA, the spool Vm overlaps with an overlap amount of OLPC1, thereby blocking the flow path. Between the cylinder port CprtA and the left tank port Tprt, the spool Vm overlaps with an overlap amount of OLCT2, thereby blocking the flow path. Between the right parallel passage RP and cylinder port CprtB, the spool Vm overlaps with an overlap amount of OLPC2, thereby blocking the flow path. Between the cylinder port CprtB and the right tank port Tprt, the spool Vm overlaps with an overlap amount of OLCT1, thereby blocking the flow path.

[0084] The controller 30 controls the proportional valve 31CL to supply pilot pressure to the left pilot port of the control valve 174. As a result, the spool Vm is displaced from the neutral position to the right. As a result, the right bridge passage Rb communicates with the cylinder port CprtB, and the cylinder port CprtA communicates with the left tank port Tprt. Therefore, the hydraulic oil supplied from the parallel passage RP opens the check valve Vch and is supplied to the bottom side oil chamber of the bucket cylinder 9 through the right bridge passage Rb and the cylinder port CprtB. In addition, the hydraulic oil flowing out from the rod side oil chamber of the bucket cylinder 9 is discharged to the left tank port Tprt through the cylinder port CprtA. In addition, as the spool Vm is displaced from the neutral position to the right, the opening area of ​​the center bypass passage RC (right center bypass pipe 40R) from the inlet port to the outlet port is reduced.

[0085] The controller 30 controls the proportional valve 31CR to supply pilot pressure to the right pilot port of the control valve 174. As a result, the spool Vm is displaced from the neutral position to the left. As a result, the left bridge passage Rb communicates with the cylinder port CprtA, and the cylinder port CprtB communicates with the right tank port Tprt. Therefore, the hydraulic oil supplied from the parallel passage RP opens the check valve Vch and is supplied to the rod side oil chamber of the bucket cylinder 9 through the left bridge passage Rb and the cylinder port CprtA. In addition, the hydraulic oil flowing out from the bottom side oil chamber of the bucket cylinder 9 is discharged to the right tank port Tprt through the cylinder port CprtB. In addition, as the spool Vm is displaced from the neutral position to the left, the opening area of ​​the center bypass passage RC (right center bypass pipe 40R) from the inlet port to the outlet port is reduced.

[0086] FIG. 5 is a graph showing an example of the opening area of ​​the control valve 174 during bucket operation. The horizontal axis indicates the stroke amount of the spool Vm. The (+) direction of the horizontal axis indicates the stroke amount of the spool Vm in the bucket closing operation direction. The (-) direction of the horizontal axis indicates the stroke amount of the spool Vm in the bucket opening operation direction. A state in which the stroke amount is 0 indicates a state in which the spool Vm is disposed in a neutral position. As the stroke amount of the spool Vm in the bucket closing operation direction increases, the spool Vm moves to the right (+ direction). As the stroke amount of the spool Vm in the bucket opening operation direction increases, the spool Vm moves to the left (- direction).

[0087] The graph on the (+) side shows the opening area from the bridge passage Rb to the cylinder port CprtB. From the neutral position to a specified stroke amount (stroke amount ST1), the opening from the bridge passage Rb to the cylinder port CprtB is closed. Then, when the specified stroke amount (stroke amount ST1) is reached, the opening from the bridge passage Rb to the cylinder port CprtB opens. As the stroke amount increases further in the (+) direction, the opening area from the bridge passage Rb to the cylinder port CprtB also increases.

[0088] The opening area from the cylinder port CprtA to the tank port Tprt also changes in the same way. That is, from the neutral position to a predetermined stroke amount, the opening from the cylinder port CprtA to the tank port Tprt is closed. Then, when the predetermined stroke amount is reached, the opening from the cylinder port CprtA to the tank port Tprt opens. When the stroke amount increases further in the (+) direction, the opening area from the cylinder port CprtA to the tank port Tprt also increases. The timing (stroke amount) at which the opening from the bridge passage Rb to the cylinder port CprtB opens and the timing (stroke amount) at which the opening from the cylinder port CprtA to the tank port Tprt opens may be the same or different.

[0089] The graph on the (-) side shows the opening area from the bridge passage Rb to the cylinder port CprtA. From the neutral position to a specified stroke amount (stroke amount ST2), the opening from the bridge passage Rb to the cylinder port CprtA is closed. Then, when the specified stroke amount (stroke amount ST2) is reached, the opening from the bridge passage Rb to the cylinder port CprtA opens. As the stroke amount increases further in the (-) direction, the opening area from the bridge passage Rb to the cylinder port CprtA also increases.

[0090] The opening area from the cylinder port CprtB to the tank port Tprt also changes in the same way. That is, from the neutral position to a predetermined stroke amount, the opening from the cylinder port CprtB to the tank port Tprt is closed. Then, when the predetermined stroke amount is reached, the opening from the cylinder port CprtB to the tank port Tprt opens. When the stroke amount increases further in the (-) direction, the opening area from the cylinder port CprtB to the tank port Tprt also increases. The timing (stroke amount) at which the opening from the bridge passage Rb to the cylinder port CprtA opens and the timing (stroke amount) at which the opening from the cylinder port CprtB to the tank port Tprt opens may be the same or different.

[0091] When the spool Vm is operated in the bucket closing operation direction from the neutral position and reaches a stroke amount ST1, the opening from the bridge passage Rb to the cylinder port CprtB opens. When the spool Vm is in the neutral position, the overlap amount OLPC2 of the spool Vm between the bridge passage Rb and the cylinder port CprtB corresponds to the overlap amount L11.

[0092] Furthermore, when the spool Vm is operated from the neutral position in the bucket opening operation direction and reaches a stroke amount ST2, the opening from the bridge passage Rb to the cylinder port CprtA opens. When the spool Vm is in the neutral position, the overlap amount OLPC1 of the spool Vm between the bridge passage Rb and the cylinder port CprtA corresponds to the overlap amount L12.

[0093] Incidentally, an annular gap is formed between the control valve body and the spool Vm to allow the spool Vm to move left and right within the control valve body. For this reason, even when the spool Vm is in the neutral position, hydraulic oil leaks from the bridge passage Rb to the cylinder port CprtA. In addition, hydraulic oil leaks from the cylinder port CprtA to the tank port Tprt. Similarly, hydraulic oil leaks from the bridge passage Rb to the cylinder port CprtB. In addition, hydraulic oil leaks from the cylinder port CprtB to the tank port Tprt.

[0094] For example, there is a state in which the spool Vm is in the neutral position and the pressure of the hydraulic oil in the parallel passage RP is high. For example, when the spool Vm of the control valve 174 is in the neutral position and at least one of the other control valves 172, 175R, 176R and the neutral cut valve 50 of the right center bypass pipe 40R reduces the flow passage area of ​​the center bypass pipe 40, the control pressure (negative control pressure) detected by the right control pressure sensor 19R decreases. In addition, as the control pressure decreases, the controller 30 issues a flow rate increase command to the right regulator 13R. The right regulator 13R adjusts the swash plate tilt angle of the right main pump 14R in response to this flow rate increase command, thereby increasing the discharge amount of the right main pump 14R. As a result, the spool Vm of the control valve 174 is in the neutral position and the pressure of the hydraulic oil in the parallel passage RP is high.

[0095] When the pressure of the hydraulic oil in the parallel passage RP becomes high (in other words, when the discharge pressure (pump pressure) of the main pump 14 increases), the hydraulic oil leaks from the annular gap, causing the pressure of the hydraulic oil in the cylinder ports CprtA and CprtB to increase. This causes the pressure in the bottom side oil chamber of the bucket cylinder 9 and the rod side oil chamber of the bucket cylinder 9 to increase. Here, the rod of the bucket cylinder 9 moves in the extending direction (the direction in which the bucket 6 closes) due to the difference in pressure-receiving area between the bottom side oil chamber and the rod side oil chamber. Then, the hydraulic oil in the cylinder port CprtA becomes high pressure, and the relief valve 52A opens.

[0096] In this manner, when the pressure of the hydraulic oil in the parallel passage RP becomes high, there is a risk that the bucket 6 will perform a closing operation.

[0097] <First control example> Next, an example of control of the shovel 100 will be described with reference to Fig. 6. Fig. 6 is a flowchart showing a first control example of the shovel 100.

[0098] Here, an example will be described in which a DPF filter is regenerated. The engine 11 of the shovel 100 is, for example, a diesel engine, and the shovel 100 is provided with a filter (DPF: Diesel Particulate Filter) that removes particulate matter from the exhaust gas of the diesel engine. The shovel 100 performs a regeneration process in which the filter is regenerated by supplying high-temperature exhaust gas to the filter at a predetermined timing, thereby burning the particulate matter adsorbed on the filter.

[0099] In step S701, the controller 30 determines whether or not to start filter regeneration. If filter regeneration is not to be started (S701: NO), the controller 30 waits by repeating step S701. If filter regeneration is to be started (S701: YES), the process of the controller 30 proceeds to step S702.

[0100] In step S702, the controller 30 closes the neutral cut valve 50. This causes the control pressure (negative control pressure) detected by the right control pressure sensor 19R to decrease. Furthermore, as the control pressure decreases, the controller 30 issues a flow rate increase command to the regulator 13. Furthermore, the load on the engine 11 increases, and the output of the engine 11 increases. This causes high-temperature exhaust gas to be supplied to the filter from the engine 11, thereby starting filter regeneration. Furthermore, the pressure of the hydraulic oil in the parallel passage RP becomes high pressure.

[0101] In step S703, the controller 30 determines whether or not the operation lever (operation device 26) is being operated. The operation of the operation lever here may be determined by the opening / closing operation of the bucket 6 (left / right operation of the right operation lever 26R), or may be determined by whether or not all operation levers have been operated. If the operation lever is being operated (S703: YES), the processing of the controller 30 proceeds to step S704. If the operation lever is not being operated (S703: NO), the processing of the controller 30 proceeds to step S705.

[0102] In step S704, the controller 30 controls the proportional valve 31 based on the amount of operation detected by the operation sensor 29. Then, the process of the controller 30 proceeds to step S706.

[0103] On the other hand, in step S705, the controller 30 controls the proportional valve 31 to move the spool Vm of the control valve 174 to the side that retracts the rod of the bucket cylinder 9. Then, the process of the controller 30 proceeds to step S706.

[0104] Specifically, the controller 30 moves the spool Vm to a position of the stroke amount STa. In other words, the controller 30 generates a command value for the proportional valve 31 so as to increase the overlap amount OLPC2 of the spool Vm between the bridge passage Rb and the cylinder port CprtB and decrease the overlap amount OLPC1 of the spool Vm between the bridge passage Rb and the cylinder port CprtA. As a result, as shown in FIG. 5, the overlap amount OLPC2 of the spool Vm between the bridge passage Rb and the cylinder port CprtB becomes the overlap amount L21 and increases. That is, the leakage of the hydraulic oil from the bridge passage Rb to the cylinder port CprtB decreases. Also, as shown in FIG. 5, the overlap amount OLPC1 of the spool Vm between the bridge passage Rb and the cylinder port CprtA becomes the overlap amount L22 and decreases. That is, the leakage of the hydraulic oil from the bridge passage Rb to the cylinder port CprtB increases.

[0105] This reduces the pressure of the hydraulic oil in the cylinder port CprtB, thereby preventing the pressure of the hydraulic oil in the cylinder port CprtA caused by the difference in pressure-receiving area from exceeding the relief level, i.e., preventing the bucket 6 from closing.

[0106] In step S706, the controller 30 determines whether or not to end the filter regeneration. If the filter regeneration is to be continued (S706: NO), the process returns to step S703. If the filter regeneration is to be ended (S706: YES), the process of the controller 30 proceeds to step S707.

[0107] In step S708, the controller 30 opens the neutral cut valve 50.

[0108] According to this, the shovel 100 can prevent the bucket 6 from being closed without operating the operating device 26 during filter regeneration. Therefore, the bucket 6 can be maintained in a desired attitude. In other words, the attitude of the bucket 6 can be maintained without the operator performing an operation to keep the bucket 6 open or closed, improving the operability of the shovel 100.

[0109] <Second control example> Next, an example of control of the shovel 100 will be described with reference to Fig. 7. Fig. 7 is a flowchart showing a second control example of the shovel 100.

[0110] Here, we will explain the case where the pressure of the hydraulic oil in the parallel passage RP becomes high when the pressure of the hydraulic oil in the bottom side oil chamber of the boom cylinder 7 increases due to continued boom-raising operation, causing a relief valve (not shown) to open (boom-raising relief), or when the pressure of the hydraulic oil in the rod side oil chamber of the arm cylinder 8 increases due to continued arm-opening operation, causing a relief valve (not shown) to open (arm-opening relief).

[0111] In step S801, it is determined whether the pump pressure is equal to or greater than the threshold and a certain period of time has elapsed. If the pump pressure is not equal to or greater than the threshold and / or if the certain period of time has not elapsed (S801: NO), step S801 is repeated and the controller 30 waits. If the pump pressure is equal to or greater than the threshold and a certain period of time has elapsed (S801: YES), the controller 30 proceeds to step S802.

[0112] In step S802, the controller 30 determines whether or not the operation lever (operation device 26) is being operated. The operation of the operation lever here is determined based on whether or not an opening / closing operation of the bucket 6 (left / right operation of the right operation lever 26R) is being performed. If the operation lever is being operated (S802: YES), the processing of the controller 30 proceeds to step S803. If the operation lever is not being operated (S802: NO), the processing of the controller 30 proceeds to step S804.

[0113] In step S803, the controller 30 controls the proportional valve 31 based on the amount of operation detected by the operation sensor 29.

[0114] On the other hand, in step S804, the controller 30 controls the proportional valve 31 to move the spool Vm of the control valve 174 to the side where the rod of the bucket cylinder 9 is retracted.

[0115] Specifically, the controller 30 moves the spool Vm to a position of the stroke amount STa. In other words, the controller 30 generates a command value for the proportional valve 31 so as to increase the overlap amount OLPC2 of the spool Vm between the bridge passage Rb and the cylinder port CprtB and decrease the overlap amount OLPC1 of the spool Vm between the bridge passage Rb and the cylinder port CprtA. As a result, as shown in FIG. 5, the overlap amount OLPC2 of the spool Vm between the bridge passage Rb and the cylinder port CprtB becomes the overlap amount L21 and increases. That is, the leakage of the hydraulic oil from the bridge passage Rb to the cylinder port CprtB decreases. Also, as shown in FIG. 5, the overlap amount OLPC1 of the spool Vm between the bridge passage Rb and the cylinder port CprtA becomes the overlap amount L22 and decreases. That is, the leakage of the hydraulic oil from the bridge passage Rb to the cylinder port CprtB increases.

[0116] This reduces the pressure of the hydraulic oil in the cylinder port CprtB, thereby preventing the pressure of the hydraulic oil in the cylinder port CprtA caused by the difference in pressure-receiving area from exceeding the relief level, i.e., preventing the bucket 6 from closing.

[0117] This makes it possible for the excavator 100 to prevent the bucket 6 from closing without operating the operating device 26 when the pressure of the hydraulic oil in the parallel passages RP, such as the boom-raising relief and the arm-opening relief, becomes high. This makes it possible to maintain the bucket 6 in a desired position, whether open or closed. In other words, the position of the bucket 6 can be maintained without the operator having to perform any operation to maintain the bucket 6 open or closed, improving the operability of the excavator 100.

[0118] <Third control example> Next, an example of control of the shovel 100 will be described with reference to Fig. 8. Fig. 8 is a flowchart showing a third control example of the shovel 100.

[0119] Here, an example will be described in which a heavy load, such as liquid or soil containing liquid, is loaded onto bucket 6. In this case, the weight of the load may cause hydraulic oil to leak through the annular gap, which may cause bucket 6 to open without operating the operating lever.

[0120] In step S901, it is determined whether the bucket cylinder bottom pressure detected by the bucket bottom pressure sensor S9B is equal to or greater than a threshold value and a certain period of time has elapsed. If the bucket cylinder bottom pressure is not equal to or greater than the threshold value and / or the certain period of time has not elapsed (S901: NO), step S901 is repeated and the controller 30 waits. If the bucket cylinder bottom pressure is equal to or greater than the threshold value and the certain period of time has elapsed (S901: YES), the process of the controller 30 proceeds to step S902.

[0121] In step S902, the controller 30 determines whether or not the operation lever (operation device 26) is being operated. The operation of the operation lever here may be determined by the opening / closing operation of the bucket 6 (left / right operation of the right operation lever 26R), or may be determined by whether or not all operation levers have been operated. If the operation lever is being operated (S802: YES), the processing of the controller 30 proceeds to step S903. If the operation lever is not being operated (S802: NO), the processing of the controller 30 proceeds to step S904.

[0122] In step S903, the controller 30 controls the proportional valve 31 based on the amount of operation detected by the operation sensor 29.

[0123] On the other hand, in step S904, the controller 30 controls the proportional valve 31 to move the spool Vm of the control valve 174 to the side where the rod of the bucket cylinder 9 is extended.

[0124] Specifically, the controller 30 generates a command value for the proportional valve 31 to increase the overlap amount OLCT1 of the spool Vm between the cylinder port CprtB and the tank port Tprt. This increases the overlap amount OLCT1 of the spool Vm between the cylinder port CprtB and the tank port Tprt. That is, the leakage of hydraulic oil from the cylinder port CprtB to the tank port Tprt is reduced.

[0125] This allows the shovel 100 to prevent the bucket 6 from opening due to the weight of the load. Therefore, the bucket 6 can be maintained open or closed in a desired position. In other words, the position of the bucket 6 can be maintained without the operator having to perform an operation to maintain the bucket 6 open or closed, improving the operability of the shovel 100.

[0126] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0127] 1 Undercarriage 2 Swivel mechanism 3. Upper rotating body 4. Boom 5 Arm 6 Bucket 7 Boom cylinder 8 Arm Cylinder 9 Bucket cylinder (hydraulic actuator) 13 Regulator 14 Main pump (hydraulic pump) 15 Pilot pump 17 Control valve unit 18 Aperture (negative control aperture) 19 Control pressure sensor 174 Control valve (directional control valve) 26 Operating device 26R Right operation lever 26L Left operation lever 30 Controller 31 Proportional valve (electromagnetic proportional valve) 50 Neutral cut valve 100 Shovel

Claims

1. A hydraulic pump; A hydraulic actuator; a directional control valve that controls hydraulic oil supplied from the hydraulic pump to the hydraulic actuator; an electromagnetic proportional valve for controlling a pilot pressure of the directional control valve; An operating lever; a controller to which an operation amount of the operation lever is input and which generates a command value for the solenoid proportional valve, The controller: generating a command value for the electromagnetic proportional valve so that the hydraulic actuator does not move when the operating lever is not operated; Shovel.

2. The directional control valve is a bridge passage to which hydraulic oil is supplied from the hydraulic pump; a first cylinder port connected to a rod side oil chamber of the hydraulic actuator; a second cylinder port connected to a bottom oil chamber of the hydraulic actuator; A tank port connected to the tank; A spool; The controller: generating a command value for the solenoid proportional valve so as to increase an amount of lap of the spool between the bridge passage and the second cylinder port and to decrease an amount of lap of the spool between the bridge passage and the first cylinder port; The shovel according to claim 1.

3. Further, a neutral cut valve is provided upstream of the negative control throttle and downstream of the directional control valve, The controller: a command value for the electromagnetic proportional valve is generated so that the hydraulic actuator does not move when the neutral cut valve is closed and the operation lever is not operated; The shovel according to claim 2.

4. The controller: When the pump pressure of the hydraulic pump is equal to or higher than a threshold value and a certain time has elapsed, and when the operation lever is not operated, a command value for the electromagnetic proportional valve is generated so that the hydraulic actuator does not move. The shovel according to claim 2.

5. The directional control valve is a bridge passage to which hydraulic oil is supplied from the hydraulic pump; a first cylinder port connected to a rod side oil chamber of the hydraulic actuator; a second cylinder port connected to a bottom oil chamber of the hydraulic actuator; A tank port connected to the tank; A spool; The controller: generating a command value for the solenoid proportional valve so as to increase a lap amount of the spool between the second cylinder port and the tank port; The shovel according to claim 1.

6. The controller: generating a command value for the electromagnetic proportional valve so as not to move the hydraulic actuator when the pressure in the bottom-side oil chamber is equal to or higher than a threshold value and a certain time has elapsed, and when the operation lever is not operated; The shovel according to claim 5.

7. The hydraulic actuator is a bucket cylinder that opens and closes a bucket. A shovel according to any one of claims 1 to 6.

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