阅读说明：本技术 挖土机 (Excavator ) 是由 山本崇司 于 2020-03-17 设计创作，主要内容包括：本发明涉及一种挖土机,能够进一步提高吊起作业时的操作性。本发明的一个实施方式所涉及的挖土机(100)具备：下部行走体(1)；上部回转体(3),回转自如地搭载于下部行走体(1)；附属装置,包括安装于上部回转体(3)的动臂(4)及安装于动臂(4)的前端的斗杆(5)；动臂缸(7),驱动动臂(4)；斗杆缸(8),驱动斗杆(5)；主泵(14),对动臂缸(7)及斗杆缸(8)供给工作油；及控制器(30),控制主泵(14),当进行利用附属装置的吊起作业时,控制器(30)使主泵(14)的待机流量比进行吊起作业以外的其他作业时加大。(The invention relates to a shovel which can further improve the operability during the hoisting operation. An excavator (100) according to an embodiment of the present invention includes: a lower traveling body (1); an upper revolving structure (3) which is rotatably mounted on the lower traveling structure (1); an attachment device including a boom (4) attached to the upper slewing body (3) and an arm (5) attached to the front end of the boom (4); a boom cylinder (7) that drives the boom (4); a boom cylinder (8) that drives the boom (5); a main pump (14) that supplies working oil to the boom cylinder (7) and the arm cylinder (8); and a controller (30) that controls the main pump (14), wherein when the main pump (14) is suspended by the attachment, the controller (30) increases the standby flow rate of the main pump (14) as compared to when the main pump is suspended by other than the attachment.)

1. A shovel is provided with:

a lower traveling body;

an upper revolving structure rotatably mounted on the lower traveling structure;

an attachment including a boom attached to the upper slewing body and an arm attached to a front end of the boom;

a boom cylinder that drives the boom;

a boom cylinder that drives the boom;

a hydraulic pump that supplies working oil to the boom cylinder and the arm cylinder; and

a control device that controls the hydraulic pump,

when the lifting work using the attachment is performed, the control device increases the standby flow rate of the hydraulic pump compared to when the other work other than the lifting work is performed.

2. The shovel of claim 1,

when the hoisting operation is performed, the control device increases the standby flow rate of the hydraulic pump in accordance with an increase in the hoisting load.

3. The shovel of claim 1,

the hydraulic pump includes a 1 st pump for supplying the boom cylinder and the arm cylinder with hydraulic oil, and a 2 nd pump different from the 1 st pump,

the control device increases the standby flow rate of only the 1 st pump out of the 1 st pump and the 2 nd pump when the hoisting operation is performed, compared with when other operations than the hoisting operation are performed.

4. The shovel of claim 3,

the 2 nd pump supplies working oil to a slewing hydraulic motor that drives the upper slewing body.

5. The shovel of claim 3,

the 1 st pump supplies working oil to a 1 st traveling hydraulic motor that drives one crawler belt of the lower traveling body,

the 2 nd pump supplies working oil to a 2 nd traveling hydraulic motor that drives the other crawler belt of the lower traveling body,

the control device reduces a standby flow rate of the 1 st pump when performing an operation related to the lower traveling body during the hoisting operation.

6. The shovel of claim 1,

the control device reduces a standby flow rate of the hydraulic pump when performing a swing operation of the upper swing body during the hoisting operation.

7. The shovel of claim 1,

when the lifting operation is performed, the control device reduces a change in the flow rate of the hydraulic pump with respect to a change in the operation amount of at least one of the boom cylinder and the arm cylinder, as compared to when the other operation than the lifting operation is performed.

8. The shovel of claim 1,

has a predetermined operation mode selected when the hoisting operation is performed,

when the predetermined work mode is selected, the control device increases the standby flow rate of the hydraulic pump as compared to when the predetermined work mode is not selected.

9. A shovel is provided with:

a lower traveling body;

an upper revolving structure rotatably mounted on the lower traveling structure;

an attachment including a boom attached to the upper slewing body and an arm attached to a front end of the boom;

a boom cylinder that drives the boom;

a boom cylinder that drives the boom;

a hydraulic pump that supplies working oil to the boom cylinder and the arm cylinder; and

a control device that controls the hydraulic pump,

the control device changes the standby flow rate of the hydraulic pump according to at least one of the magnitude of a hoisting load, the load state of a boom cylinder, a difference in a predetermined work mode of the excavator, the operation state of the lower traveling structure, and the rotation state of the upper revolving structure.

Technical Field

The present invention relates to an excavator.

Background

Conventionally, there is known a technique for improving the turning operability of an upper revolving structure when a hoisting operation (also referred to as a crane operation) using an attachment of a shovel is performed (for example, patent document 1).

Prior art documents

Patent document

Patent document 1: japanese laid-open patent publication No. 2002-129602

Disclosure of Invention

Technical problem to be solved by the invention

However, there is a need to improve the operability of the attachment.

In view of the above problems, an object of the present invention is to provide a technique capable of further improving the operability at the time of the lifting operation in the excavator.

Means for solving the technical problem

In order to achieve the above object, according to one embodiment of the present invention, there is provided a shovel including:

a lower traveling body;

an upper revolving structure rotatably mounted on the lower traveling structure;

an attachment including a boom attached to the upper slewing body and an arm attached to a front end of the boom;

a boom cylinder that drives the boom;

a boom cylinder that drives the boom;

a hydraulic pump that supplies working oil to the boom cylinder and the arm cylinder; and

a control device that controls the hydraulic pump,

when the lifting work using the attachment is performed, the control device increases the standby flow rate of the hydraulic pump compared to when the other work is performed except the lifting work.

In another embodiment of the present invention, there is provided a shovel including:

a lower traveling body;

an upper revolving structure rotatably mounted on the lower traveling structure;

an attachment including a boom attached to the upper slewing body and an arm attached to a front end of the boom;

a boom cylinder that drives the boom;

a boom cylinder that drives the boom;

a hydraulic pump that supplies working oil to the boom cylinder and the arm cylinder; and

a control device that controls the hydraulic pump,

the control device changes the standby flow rate of the hydraulic pump according to at least one of the magnitude of a hoisting load, the load state of a boom cylinder, a difference in a predetermined work mode of the excavator, the operation state of the lower traveling structure, and the rotation state of the upper revolving structure.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the above embodiment, a technique capable of further improving the operability in the lifting work of the shovel can be provided.

Drawings

Fig. 1 is a side view of an excavator.

Fig. 2 is a diagram showing an example of the structure of the shovel.

Fig. 3 is a flowchart schematically showing an example of control processing performed by the controller.

Fig. 4 is a diagram showing an example of a suspended load selection screen.

Fig. 5 is a diagram showing an example of the negative control characteristic diagram.

Detailed Description

Hereinafter, embodiments will be described with reference to the drawings.

[ brief description of the excavator ]

First, an outline of a shovel 100 according to the present embodiment will be described with reference to fig. 1.

Fig. 1 is a side view of a shovel 100 according to the present embodiment.

The shovel 100 according to the present embodiment includes: a lower traveling body 1; an upper revolving structure 3 rotatably mounted on the lower traveling structure 1 via a revolving mechanism 2; a boom 4, an arm 5, and a bucket 6 as attachment devices (construction devices); and a cockpit 10.

The lower traveling body 1 includes, for example, a pair of left and right crawler belts, and each crawler belt is hydraulically driven by traveling hydraulic motors 1L and 1R (see fig. 2) to cause the shovel 100 to travel (self-run).

The upper slewing body 3 is driven by a slewing hydraulic motor 2A (see fig. 2) to slew with respect to the lower traveling body 1.

A boom 4 is pivotally attached to the front center of the upper revolving structure 3 so as to be tiltable, an arm 5 is pivotally attached to the front end of the boom 4 so as to be vertically pivotable, and a bucket 6 is pivotally attached to the front end of the arm 5 so as to be vertically pivotable. The boom 4, the arm 5, and the bucket 6 are hydraulically driven by a boom cylinder 7, an arm cylinder 8, and a bucket cylinder 9, which are hydraulic actuators, respectively.

A hook 80 for a lifting operation (crane operation) using an attachment is attached to the bucket 6 as the end attachment. The base end of the hook 80 is rotatably coupled to a bucket pin that couples the arm 5 and the bucket 6. Thus, when performing work other than lifting work such as excavation work, the hook 80 is accommodated in the hook accommodating space formed between the two bucket links.

The cab 10 is a cabin on which an operator or the like sits, and is mounted on the left side of the front portion of the upper revolving structure 3.

The shovel 100 operates driven elements such as the lower traveling structure 1 (left and right crawler belts), the upper revolving structure 3, the boom 4, the arm 5, and the bucket 6 in accordance with an operation of an operator seated in the cab 10.

The shovel 100 may be configured to be operated by an operator seated in the cab 10, or may be configured to be remotely operated (long-distance operation) from the outside of the shovel 100. When the excavator 100 is remotely operated, the inside of the cab 10 may be in an unmanned state. The following description is made on the assumption that the operation by the operator includes at least one of the operation by the operator in the cab 10 on the operation device 26 and the remote operation by an external operator.

The remote operation includes, for example, a mode of operating the shovel 100 by an operation input related to an actuator of the shovel 100 by a predetermined external device. In this case, the shovel 100 may transmit image information (captured image) output from an imaging device that captures the periphery of the upper revolving structure 3 to an external device, for example, and display the image information on a display device provided in the external device (hereinafter, referred to as "display device for remote operation"). Various information images (information screens) displayed on a display device 50 described later in the cab 10 of the shovel 100 may be displayed on a remote operation display device of an external device in the same manner. Thus, the operator of the external device can remotely operate the shovel 100 while checking display contents such as a captured image and an information screen showing the state of the surroundings of the shovel 100 displayed on the remote operation display device, for example. The shovel 100 can drive driven elements such as the lower traveling structure 1 (left and right crawler belts), the upper revolving structure 3, the boom 4, the arm 5, and the bucket 6 by operating the actuator in accordance with a remote operation signal indicating the content of the remote operation received from an external device.

The remote operation may include, for example, a mode of operating the shovel 100 by a person (for example, a worker) around the shovel 100 performing voice input, gesture input, and the like from the outside to the shovel 100. Specifically, the shovel 100 recognizes a voice uttered by a surrounding operator or the like, a gesture made by the operator or the like, and the like, by a voice input device (for example, a microphone) and a gesture input device (for example, an imaging device) or the like mounted on the shovel 100. The shovel 100 can drive the driven elements such as the lower traveling structure 1 (left and right crawler belts), the upper revolving structure 3, the boom 4, the arm 5, and the bucket 6 by operating the actuator according to the recognized contents such as the voice and the gesture.

Moreover, the shovel 100 may automatically operate the actuator regardless of the operation content of the operator. As a result, the shovel 100 realizes a function (so-called "automatic operation function" or "machine control function") of automatically operating at least a part of driven elements such as the lower traveling structure 1 (left and right crawler tracks), the upper revolving structure 3, the boom 4, the arm 5, and the bucket 6.

The automatic operation function may include a function of automatically operating a driven element (hydraulic actuator) other than the driven element (hydraulic actuator) of the operation target in accordance with the operation of the operation device 26 by the operator and the remote operation (so-called "semi-automatic operation function"). The automatic operation function may include a function of automatically operating at least a part of the plurality of driven elements (hydraulic actuators) on the premise that there is no operation of the operation device 26 by the operator or remote operation (so-called "full-automatic operation function"). In the excavator 100, when the full-automatic running function is effective, the inside of the cab 10 may be left unattended. The operation contents of the driven elements (hydraulic actuators) including the objects to be automatically operated, such as the semi-automatic operation function and the full-automatic operation function, may be automatically determined according to a predetermined rule. The semi-automatic operation function, the full-automatic operation function, and the like may include a mode (so-called "autonomous operation function") in which the shovel 100 autonomously makes various determinations and autonomously determines the operation content of a driven element (hydraulic actuator) to be automatically operated based on the determination result.

[ Structure of excavator ]

Next, the structure of the shovel 100 will be described with reference to fig. 2 in addition to fig. 1.

Fig. 2 is a diagram showing an example of the structure of the shovel 100 according to the present embodiment.

In the figure, the mechanical power line is indicated by a double line, the high-pressure hydraulic line is indicated by a solid line, the pilot line is indicated by a broken line, and the electric drive control line is indicated by a dotted line.

< Hydraulic drive System >

As described above, the hydraulic drive system of the excavator 100 according to the present embodiment includes hydraulic actuators for hydraulically driving driven elements such as the lower traveling structure 1, the upper revolving structure 3, the boom 4, the arm 5, and the bucket 6. The hydraulic actuators include traveling hydraulic motors 1L and 1R, a turning hydraulic motor 2A, a boom cylinder 7, an arm cylinder 8, a bucket cylinder 9, and the like. The hydraulic drive system of the shovel 100 according to the present embodiment includes the engine 11, the main pumps 14L and 14R, and the control valve 17.

The engine 11 is a main power source in the hydraulic drive system, and is mounted on the rear portion of the upper slewing body 3, for example. Specifically, engine 11 is rotated at a predetermined target rotation speed under the control of controller 30, and drives main pumps 14L and 14R and pilot pump 15. The engine 11 is, for example, a diesel engine using diesel oil as fuel.

The main pumps 14L, 14R are mounted on the rear portion of the upper revolving structure 3, for example, in the same manner as the engine 11, and supply hydraulic oil to the control valve 17 through a high-pressure hydraulic line. The main pumps 14L, 14R are driven by the engine 11 as described above. The main pumps 14L and 14R are, for example, variable displacement hydraulic pumps, and the stroke lengths of the pistons are adjusted by adjusting the angles (tilt angles) of swash plates by the regulators 13L and 13R under the control of a controller 30 described later, whereby the discharge flow rate (discharge pressure) can be controlled.

The control valve 17 is mounted, for example, in the central portion of the upper slewing body 3, and is a hydraulic control device that controls the hydraulic drive system based on an operation (an operation to the operation device 26 and a remote operation) related to a driven element (corresponding hydraulic actuator) performed by an operator or the like and an operation command related to a driven element (hydraulic actuator) corresponding to the automatic operation function. The control valve 17 is connected to the main pumps 14L and 14R via the high-pressure hydraulic line as described above, and selectively supplies the hydraulic oil supplied from the main pumps 14L and 14R to the travel hydraulic motor 1L (for the left crawler belt), the travel hydraulic motor 1R (for the right crawler belt), the swing hydraulic motor 2A, the boom cylinder 7, the arm cylinder 8, and the bucket cylinder 9, which are hydraulic actuators, in accordance with the state of the operation related to the driven component by the operator (the operation of the operation device 26 and the remote operation) and the content of the operation command related to the driven component corresponding to the automatic running function. Specifically, the control valve 17 includes control valves 171, 172, 173, 174, 175L, 175R, 176L, 176R that control the flow rate and the flow direction of the hydraulic oil supplied from the main pumps 14L, 14R to the hydraulic actuators, respectively.

The hydraulic drive system of the excavator 100 circulates hydraulic oil from the main pumps 14L, 14R driven by the engine 11 to the hydraulic oil tank via the center bypass oil passages C1L, C1R and the parallel oil passages C2L, C2R, respectively.

The center bypass oil passage C1L passes through the control valves 171, 173, 175L, and 176L disposed in the control valve 17 in order from the main pump 14L and reaches the hydraulic oil tank.

The center bypass oil passage C1R passes through the control valves 172, 174, 175R, and 176R disposed in the control valve 17 in order from the main pump 14R and reaches the hydraulic oil tank.

The control valve 171 is a spool valve that supplies the hydraulic oil discharged from the main pump 14L to the traveling hydraulic motor 1L and discharges the hydraulic oil discharged from the traveling hydraulic motor 1L to a hydraulic oil tank.

The control valve 172 is a spool valve that supplies the hydraulic oil discharged from the main pump 14R to the traveling hydraulic motor 1R and discharges the hydraulic oil discharged from the traveling hydraulic motor 1R to a hydraulic oil tank.

The control valve 173 is a spool valve that supplies the hydraulic oil discharged from the main pump 14L to the swing hydraulic motor 2A and discharges the hydraulic oil discharged from the swing hydraulic motor 2A to a hydraulic oil tank.

The control valve 174 is a spool valve that supplies the hydraulic oil discharged by the main pump 14R to the bucket cylinder 9 and discharges the hydraulic oil in the bucket cylinder 9 to a hydraulic oil tank.

The control valves 175L and 175R are spool valves that supply the hydraulic oil discharged by the main pumps 14L and 14R to the boom cylinder 7 and discharge the hydraulic oil in the boom cylinder 7 to a hydraulic oil tank, respectively.

The control valves 176L and 176R are spool valves that supply the hydraulic oil discharged by the main pumps 14L and 14R to the arm cylinder 8 and discharge the hydraulic oil in the arm cylinder 8 to a hydraulic oil tank.

The control valves 171, 172, 173, 174, 175L, 175R, 176L, and 176R adjust the flow rate of hydraulic oil supplied to and discharged from the hydraulic actuator or switch the flow direction thereof, respectively, according to the pilot pressure acting on the pilot port.

The parallel oil passage C2L supplies the hydraulic oil of the main pump 14L to the control valves 171, 173, 175L, 176L in parallel with the center bypass oil passage C1L. Specifically, the parallel oil passage C2L is branched from the center bypass oil passage C1L on the upstream side of the control valve 171, and is configured to be able to supply the hydraulic oil of the main pump 14L in parallel with the control valves 171, 173, 175L, and 176R, respectively. Thus, when the flow rate of the hydraulic oil passing through the center bypass oil passage C1L is restricted or blocked by any of the control valves 171, 173, and 175L, the parallel oil passage C2L can supply the hydraulic oil to the control valve further downstream.

The parallel oil passage C2R supplies the hydraulic oil of the main pump 14R to the control valves 172, 174, 175R, 176R in parallel with the center bypass oil passage C1R. Specifically, the parallel oil passage C2R is branched from the center bypass oil passage C1R on the upstream side of the control valve 172, and is configured to be able to supply the hydraulic oil of the main pump 14R in parallel with the control valves 172, 174, 175R, and 176R, respectively. When the flow rate of the hydraulic oil passing through the center bypass oil passage C1R is restricted or blocked by any of the control valves 172, 174, and 175R, the parallel oil passage C2R can supply the hydraulic oil to the control valves further downstream.

< operating System >

The operation system of the shovel 100 according to the present embodiment includes the pilot pump 15 and the operation device 26.

The pilot pump 15 is mounted on the rear portion of the upper slewing body 3, for example, similarly to the engine 11, and supplies a pilot pressure to the operation device 26 via a pilot pipe line 25. The pilot pump 15 is, for example, a fixed displacement hydraulic pump, and is driven by the engine 11 as described above.

The operation device 26 is an operation input mechanism that is provided near an operator's seat of the cab 10, for example, and that is used by an operator to operate various driven elements (the lower traveling structure 1, the upper revolving structure 3, the boom 4, the arm 5, the bucket 6, and the like). In other words, the operation device 26 is an operation input mechanism for performing an operation of driving the hydraulic actuators (i.e., the traveling hydraulic motors 1L and 1R, the turning hydraulic motor 2A, the boom cylinder 7, the arm cylinder 8, the bucket cylinder 9, and the like) of the respective driven elements. The operation device 26 includes, for example, 4 joystick devices for operating the upper slewing body 3, the boom 4, the arm 5, and the bucket 6, respectively. The operating device 26 includes, for example, 2 pedal devices that operate the left crawler belt and the right crawler belt (i.e., the traveling hydraulic motors 1L and 1R) of the lower traveling body 1.

As shown in fig. 2, the operation device 26 is of a hydraulic pilot type that outputs hydraulic oil having a pilot pressure corresponding to the operation content thereof, for example. Specifically, a lever device, a pedal device, and the like included in the operation device 26 are connected to the control valve 17 via a pilot line, and a pilot pressure corresponding to the operation content is output to the control valve 17 by the hydraulic oil supplied from the pilot pump 25. Thus, a pilot signal (pilot pressure) according to the operation state of the lower traveling structure 1, the upper revolving structure 3, the boom 4, the arm 5, the bucket 6, and the like in the operation device 26 is input to the control valve 17. Specifically, pilot pressures on the secondary sides of two pedal devices that operate the left crawler belt (traveling hydraulic motor 1L) and the right crawler belt (traveling hydraulic motor 1R) act on the pilot ports of the control valves 171 and 172, respectively. Then, a pilot pressure on the secondary side of the lever device that operates the upper slewing body 3 (slewing hydraulic motor 2A) acts on a pilot port of the control valve 173. Then, the pilot pressure on the secondary side of the lever device that operates the boom 4 (boom cylinder 7) acts on the pilot ports of the control valves 175L and 175R. Then, the pilot pressure on the secondary side of the lever device that operates the arm 5 (arm cylinder 8) acts on the pilot ports of the control valves 176L and 176R. Then, the pilot pressure on the secondary side of the lever device that operates the bucket 6 (bucket cylinder 9) acts on the pilot port of the control valve 174. Therefore, the control valve 17 can drive the respective hydraulic actuators in accordance with the operation state in the operation device 26.

The operation device 26 may be of an electric type that outputs an electric signal (hereinafter, referred to as an "operation signal") according to the operation content thereof, for example. In this case, an operation signal from the operation device 26 is input to the controller 30, and the controller 30 controls each control valve in the control valve 17 based on the input operation signal, thereby realizing operations of various hydraulic actuators according to the operation content to the operation device 26. For example, the control valve within control valve 17 may be an electromagnetic solenoid type spool valve that is actuated by a command from controller 30. For example, a hydraulic control valve (hereinafter, referred to as "control valve for operation") that operates in accordance with a control command from the controller 30 may be disposed between the pilot pump 15 and the pilot port of each control valve. In this case, when a manual operation is performed by the electric operation device 26, the controller 30 controls the control valve for operation to increase or decrease the pilot pressure in accordance with a control command corresponding to an operation amount (for example, a joystick operation amount) of the manual operation, and thereby can operate each control valve in accordance with the operation content of the operation device 26.

< control System >

The control system of the shovel 100 according to the present embodiment includes a controller 30. The control system of the shovel 100 according to the present embodiment includes the regulators 13L and 13R, the negative control restrictors (hereinafter, referred to as "negative control restrictors") 18L and 18R, the negative control pressure sensors 19L and 19R, the discharge pressure sensor 28, the operation pressure sensor 29, the display device 50, and the input device 52.

The controller 30 (an example of a control device) performs various controls related to the shovel 100. The functions of the controller 30 may be implemented by any hardware, or any combination of hardware and software. For example, the controller 30 is configured mainly by a computer including a processor such as a CPU (Central Processing Unit), a storage device such as a RAM (Random Access Memory), an auxiliary storage device such as a ROM (Read Only Memory), and various interface devices for input and output. The controller 30 executes one or more programs installed in the auxiliary storage device on, for example, a CPU, thereby realizing various functions.

For example, the controller 30 sets a target rotation speed in accordance with a work mode (for example, a hoisting mode described later) or the like set in advance by an operation of an operator or the like, and performs drive control for constantly rotating the engine 11 directly or via a control device dedicated to the engine 11. The excavator 100 may have a predetermined normal mode for performing normal work such as excavation work and a predetermined work mode (hereinafter, referred to as "lifting mode") corresponding to a lifting work using the attachment (hook 80), and may be selected by an operator or the like through an operation using the input device 52. In this case, when the hoist mode is selected, the controller 30 sets the target rotation speed of the engine 11 relatively low. Thus, the operation of the attachment is relatively slow during the lifting operation. Therefore, the operator can easily perform the lifting operation.

For example, the controller 30 controls the regulators 13L and 13R to adjust the tilt angles of the swash plates of the main pumps 14L and 14R, thereby controlling the discharge rates of the main pumps 14L and 14R.

Specifically, the controller 30 controls the regulators 13L, 13R and controls the discharge amounts of the main pumps 14L, 14R based on the discharge pressures of the main pumps 14L, 14R detected by the discharge pressure sensors 28L, 28R. More specifically, the controller 30 can adjust the swash plate tilt angle of the main pump 14L by the regulator 13L in accordance with an increase in the discharge pressure of the main pump 14L to reduce the discharge amount. The same applies to the regulator 13R. Thus, the controller 30 can control the total horsepower of the main pumps 14L, 14R so that the suction horsepower of the main pumps 14L, 14R, which is expressed by the product of the discharge pressure and the discharge amount, does not exceed the output horsepower of the engine 11.

The controller 30 controls the regulators 13L, 13R and controls the discharge amounts of the main pumps 14L, 14R based on detection signals corresponding to control pressures (hereinafter, referred to as "negative control pressures") generated by the negative control restrictors 18L, 18R and input from the negative control pressure sensors 19L, 19R. More specifically, the controller 30 performs control as follows: the greater the negative control pressure is, the less the discharge amounts of the main pumps 14L, 14R are; the discharge rates of the main pumps 14L, 14R increase as the negative control pressure decreases.

In a standby state (state of fig. 2) in which none of the hydraulic actuators in the shovel 100 is operated, the hydraulic oil discharged from the main pumps 14L, 14R reaches the negative control restrictors 18L, 18R through the center bypass oil passages C1L, C1R. The flow rate of the hydraulic oil discharged from the main pumps 14L, 14R increases the negative control pressure generated upstream of the negative control restrictors 18L, 18R. As a result, the controller 30 reduces the discharge rates of the main pumps 14L, 14R to the minimum allowable discharge rate, and suppresses pressure loss (pump loss) when the discharged hydraulic oil passes through the center bypass oil passages C1L, C1R.

On the other hand, when any one of the hydraulic actuators is operated by the operation device 26, the hydraulic oil discharged from the main pumps 14L, 14R flows into the hydraulic actuator to be operated via the control valve corresponding to the hydraulic actuator to be operated. The flow of the hydraulic oil discharged from the main pumps 14L, 14R decreases or disappears the amount of hydraulic oil reaching the negative control restrictions 18L, 18R, and the negative control pressure generated upstream of the negative control restrictions 18L, 18R decreases. As a result, the controller 30 increases the discharge rate of the main pumps 14L and 14R, circulates sufficient hydraulic oil to the hydraulic actuator to be operated, and can reliably drive the hydraulic actuator to be operated.

In this way, the controller 30 can suppress unnecessary energy consumption of the main pumps 14L, 14R including pump loss generated in the center bypass oil passages C1L, C1R of the hydraulic oil discharged from the main pumps 14L, 14R in the standby state of the hydraulic drive system. When the hydraulic actuator is operated, the controller 30 can supply a sufficient amount of hydraulic oil required from the main pumps 14L and 14R to the hydraulic actuator to be operated.

Further, for example, when the operation device 26 is of an electric type, the controller 30 controls the operation proportional valve as described above so as to operate the hydraulic actuator according to the operation content of the operation device 26.

Also, for example, the controller 30 implements remote operation of the shovel 100 using a proportional valve for operation. Specifically, the controller 30 may output, to the operation proportional valve, a control command corresponding to the content of the remote operation designated by the remote operation signal received from the external device and the voice input, the gesture input, or the like received from the people around the shovel 100. The operation proportional valve outputs a pilot pressure corresponding to a control command from the controller 30 by the hydraulic oil supplied from the pilot pump 15, and applies the pilot pressure to a pilot port of a corresponding control valve in the control valve 17. Thus, the content of the remote operation is reflected in the operation of the control valve 17, and the operation of various operation components (driven components) based on the content of the remote operation is realized by the hydraulic actuator.

Also, for example, the controller 30 implements an automatic operation function of the shovel 100 by operating the proportional valve. Specifically, the controller 30 may output a control command corresponding to an operation command related to the automatic operation function to the operation proportional valve. The operation command may be generated by the controller 30 or by another control device that performs control related to the automatic operation function. The operation proportional valve outputs a pilot pressure corresponding to a control command from the controller 30 by the hydraulic oil supplied from the pilot pump 15, and applies the pilot pressure to a pilot port of a corresponding control valve in the control valve 17. Thus, the contents of the operation command related to the automatic operation function are reflected in the operation of the control valve 17, and the operation of various operation elements (driven elements) based on the automatic operation function is realized by the hydraulic actuator.

For example, the controller 30 monitors that a predetermined object (hereinafter, referred to as a "monitoring object") intrudes into a predetermined range (hereinafter, referred to as a "monitoring area") near the periphery of the shovel 100. Examples of the work site include an operator who performs work around the shovel 100, a supervisor at the work site, and the like. The monitoring target may include any obstacle other than a person, such as a material temporarily placed on a work site, a stationary non-moving obstacle such as a temporary office of the work site, a moving obstacle such as a vehicle including a truck, or the like. Specifically, the controller 30 may detect the monitoring target in the monitoring area around the shovel 100 based on the information acquired by the surrounding information acquiring device mounted on the shovel 100. Also, when the monitoring object is detected in the monitoring area, the controller 30 may determine (identify) the position of the monitoring object based on the information acquired by the surrounding information acquisition means.

The surrounding information acquiring device acquires information indicating the state of the surroundings of the shovel 100. The periphery information acquiring device may include, for example, an imaging device that acquires image information of the periphery of the shovel 100. The imaging device includes, for example, a monocular camera, a stereo camera, a depth camera, a distance image camera, and the like. The surrounding information acquiring device may include a distance sensor capable of acquiring information on the distance between objects around the shovel 100, such as a LIDAR (Light detection and ranging), a millimeter wave radar, and an ultrasonic sensor.

Further, for example, when the monitoring target is detected in a monitoring area around the shovel 100, the controller 30 may notify the operator of the shovel 100, a worker around the shovel, or the like of the monitoring target. Specifically, when the monitoring target is detected in the monitoring area around the shovel 100, the controller 30 may output an audible alarm to the inside of the cab 10 and the surroundings of the shovel 100 by using a voice output device or the like mounted on the shovel 100. The voice output device includes, for example, a speaker, a buzzer, and the like. When the monitoring target is detected in the monitoring area around the shovel 100, the controller 30 may output a visual alarm to the inside of the cab 10 or the surroundings of the shovel 100 by using a display device, an illumination device, or the like mounted on the shovel 100. Thus, the shovel 100 can recognize whether or not the monitoring target is present in the area near the shovel 100, and urge the workers around the shovel 100 to evacuate from the area near the shovel 100. Therefore, the safety of the shovel 100 can be improved.

Further, for example, when the monitoring object is detected in the monitoring area around the shovel 100, the controller 30 may restrict the operation of the shovel 100 based on the content of the operation command of the automatic operation function regardless of the operation of the operator. The limitation of the operation of the shovel 100 includes a mode of stopping the operation of the shovel 100. The limitation of the operation of the shovel 100 includes a mode of decelerating the operation speed of the shovel 100 to be slower than that in a normal state. Specifically, the controller 30 may control a gate lock valve provided on a pilot line between the pilot pump 15 and the operation device 26, and reduce the pilot pressure supplied to the operation device 26 to restrict the operation of the shovel 100. The controller 30 may control a pressure reducing valve provided in a pilot line between the operation device 26 and the control valve 17, and may reduce a pilot pressure acting on a pilot port of the control valve 17 to restrict the operation of the shovel 100. Further, when the operation device 26 is electrically operated, the controller 30 may control the operation proportional valve such that the pilot pressure output from the control operation proportional valve is smaller than an amount corresponding to the operation signal, thereby restricting the operation of the shovel 100. This can improve the safety of the shovel 100.

Further, when the hoisting work using the attachment is performed, the controller 30 increases the standby flow rate of the main pump 14 as compared to when the normal work (e.g., excavation work or the like) other than the hoisting work is performed. The standby flow rate of main pump 14 is, for example, the flow rate of main pump 14 in a state in preparation for starting the operation of the hydraulic actuator, such as when the hydraulic actuator is not operated or started to be operated, and is a lower limit value of the flow rate of main pump 14. For example, when the hoist mode is selected via input device 52, controller 30 causes the standby flow rate of primary pump 14 to be relatively greater than in the normal mode. The detailed description of the control method will be described later (see fig. 3).

In addition, a part of the functions of the controller 30 may be implemented by other controllers. That is, the functions of the controller 30 may be implemented in a manner dispersed among a plurality of controllers.

The regulators 13L, 13R regulate the discharge rates of the main pumps 14L, 14R by adjusting the tilt angles of the swash plates of the main pumps 14L, 14R, respectively, under the control of the controller 30.

The negative control restrictors 18L, 18R are provided between the respective control valves 176L, 176R located at the most downstream positions of the center bypass oil passages C1L, C1R and the hydraulic oil tanks. Accordingly, the flow rate of the hydraulic oil discharged from the main pumps 14L, 14R is restricted by the negative control restrictors 18L, 18R, and the negative control restrictors 18L, 18R generate the negative control pressure.

The negative control pressure sensors 19L, 19R detect the negative control pressure, and a detection signal corresponding to the detected negative control pressure is input by the controller 30.

The discharge pressure sensors 28L, 28R detect the discharge pressures of the main pumps 14L, 14R, respectively, and a detection signal corresponding to the detected discharge pressures is input to the controller 30.

The operation pressure sensor 29 detects a pilot pressure on the secondary side of the operation device 26, that is, a pilot pressure corresponding to an operation state of each driven element (hydraulic actuator) in the operation device 26. A detection signal of the pilot pressure corresponding to the operation state of the lower traveling structure 1, the upper revolving structure 3, the boom 4, the arm 5, the bucket 6, and the like in the operation device 26 detected by the operation pressure sensor 29 is input to the controller 30.

When the operation device 26 is electrically operated, the operation pressure sensor 29 is omitted. This is because the controller 30 can grasp the operation state of the operation device 26 based on the content of the operation signal output from the operation device 26.

The display device 50 is provided in a portion (for example, a right front pillar portion in the cabin 10) that is easily recognized by an operator or the like near an operator's seat in the cabin 10, and displays various information screens under the control of the controller 30. The display device 50 may be a liquid crystal display or an organic EL (Electroluminescence) display, or may be a touch panel type having an operation unit.

The input device 52 is provided in a range where an operator or the like seated in the cab 10 can reach the hand, and receives various operations by the operator or the like. The input device 52 includes, for example, an operation input device that receives an operation input from an operator or the like. The operation input device includes a touch panel mounted on a display of the display device 50 for displaying various information images, a touch panel provided separately from the display of the display device 50, a rotary switch provided at a tip of a lever portion of a lever device included in the operation device 26, a push button switch, a lever, a switch key, and the like provided around the display device 50 or disposed at a relatively distant location from the display device 50. The input device 52 includes, for example, a voice input device that receives voice input from an operator or the like. The voice input device includes, for example, a microphone. The input device 52 includes, for example, a gesture input device that receives a gesture input from an operator or the like. The gesture input device includes, for example, an imaging device capable of imaging a gesture state of an operator or the like in the cab 10. A signal corresponding to the input content to the input device 52 is input to the controller 30.

[ detailed description of control method of Main Pump ]

Next, a method of controlling the main pump 14 by the controller 30 will be specifically described with reference to fig. 3 to 5.

Fig. 3 is a flowchart schematically showing an example of control processing for the main pump 14 by the controller 30. For example, when the hoist mode is not selected, that is, when the hoist mode is the normal mode, the processing in the flowchart is repeatedly executed at a predetermined processing cycle.

In step S102, the controller 30 determines whether the lifting work is being performed by the shovel 100. In this example, the controller 30 determines whether the hoist mode is selected. When the hoist mode is selected, the controller 30 proceeds to step S104, and ends this process when the hoist mode is not selected, i.e., when the hoist mode is the normal mode.

In step S102, the controller 30 may determine whether the lifting operation is being performed by the shovel 100 by another method. For example, the controller 30 may determine whether or not the lifting operation is being performed based on the content of the operation device 26 and a measurement value of a sensor (hereinafter, referred to as a "boom cylinder pressure sensor") that detects the pressure of the boom cylinder 7. Specifically, when the measured value of the pressure of the boom cylinder 7 indicates a value that can determine a state where a suspended object is suspended to some extent and the operation device 26 is operated in accordance with the operation content assumed as the suspension operation, it can be determined that the suspension operation is being performed. Further, for example, the controller 30 may recognize the operation and work content of the attachment based on a captured image of an imaging device that captures the front side of the upper revolving structure 3, and determine whether or not the hoisting work is being performed.

In step S104, the controller 30 displays an operation screen for the operator to select the load of the suspended load from the predetermined weight range (hereinafter, referred to as a "suspended load selection screen") on the display device 50, and proceeds to step S106.

For example, fig. 4 is a diagram showing an example of a hoisting load selection screen (hoisting load selection screen 410) displayed on the display device 50.

On the hoisting load selection screen 410, selection icons 411 to 413 corresponding to a relatively large (heavy) weight division ("set 1 large"), a medium weight division ("set 2 medium"), and a relatively small (light) weight division ("set 3 small") are displayed. The operator or the like can select the corresponding weight section by selecting any one of the selection icons 411 to 413 through the input device 52.

Returning again to fig. 3, in step S106, the controller 30 determines whether or not a selection operation for lifting a load has been performed. When the selection operation of the hoisting load is performed on the hoisting load selection screen by the input device 52, the controller 30 proceeds to step S108, and waits until the selection operation is performed when the selection operation of the hoisting load is not performed.

In step S104 of fig. 3, the controller 30 may display an operation screen in which a numerical value of a specific hanging load (weight) is input via the input device 52, instead of the hanging load selection screen. Further, the controller 30 may estimate the load (weight) of the suspended load based on the detection information on the attitude state of the attachment and the pressure measurement value of the boom cylinder pressure sensor. In this case, the processing in steps S104 and S106 is omitted. If the load is not selected after a certain period of time in step S106, the controller 30 may automatically assume that the smallest (light) weight division is selected and proceed to step S108.

In step S108, the controller 30 changes the standby flow rate of the main pump 14 in accordance with the hoisting load, specifically, the weight range of the hoisting load selected on the hoisting load selection screen, and the process proceeds to step S110.

For example, fig. 5 is a diagram showing a relationship between the operation amount of the hydraulic actuator in the normal mode and the hoist mode (horizontal axis) and the discharge amount of the main pump 14 (vertical axis). Specifically, fig. 5 is a graph showing a relationship between the negative control pressure (horizontal axis) and the discharge rate (vertical axis) of the main pump 14 per unit time (for example, 1 minute) in the normal mode and the hoist mode.

As shown in fig. 5, when the hoist mode is selected, the controller 30 increases the standby flow rate as compared with the normal mode (arrow 501 in the figure).

This increases the discharge pressure of the main pump 14 relatively quickly when the boom cylinder 7 and the arm cylinder 8 start to be operated, and therefore, the responsiveness of the attachment at the time of starting the lifting operation can be improved. Therefore, the operator can perform the inching operation during the lifting operation even in the region where the operation amount of the operation device 26 is small.

The amount of increase in the standby flow rate when the hoist mode is selected may be set to be larger as the hoisting load is larger (heavier). Thus, even when the hoisting load is relatively large (heavy), the discharge pressure of main pump 14 at the start of operation can be increased relatively quickly as in the case where the hoisting load is relatively small (light).

In this example, when the hoist mode is selected, the controller 30 decreases the change in the flow rate of the main pump 14 (the slope of the portion in the figure where the discharge rate per unit time of the main pump 14 increases in accordance with the decrease in the negative control pressure) with respect to the operation amount of the hoist operation (that is, the operation amount of at least one of the boom cylinder 7 and the arm cylinder 8) from the normal mode. Specifically, as shown in fig. 5, in a state where the negative control pressure at which the discharge rate per unit time of the main pump 14 starts to increase is kept the same as in the normal mode, the standby flow rate is increased, and the negative control pressure at which the discharge rate per unit time of the main pump 14 reaches the maximum value is decreased (arrow 502 in the figure). This can improve the micromanipulation performance in the lifting operation.

When the hoist mode is selected, the controller 30 may increase the standby flow rate of only one of the main pumps 14, which supplies the hydraulic oil to the boom cylinder 7 and the arm cylinder 8 for driving the attachment, out of the main pumps 14L and 14R, compared to the normal mode. In this case, only the standby flow rate of main pump 14R, which is different from main pump 14L that supplies hydraulic oil to swing hydraulic motor 2A, may be increased. Accordingly, since the standby flow rate of the main pump 14R is kept the same as the standby flow rate in the normal mode, it is possible to suppress the operation of the upper slewing body 3 according to the slewing operation from being relatively faster than expected by the operator due to the increase in the standby flow rate.

In this case, in a situation where the hoist mode is selected, the controller 30 increases only the standby flow rate of the main pump 14R out of the main pumps 14L and 14R from the normal mode, and when the lower propelling body 1 is operated to propel the vehicle, the flow rate of the main pump 14R is temporarily decreased, that is, the vehicle returns to the normal mode. The left and right crawler belts of the lower traveling body 1 are driven by different traveling hydraulic motors 1L, 1R, and the traveling hydraulic motors 1L, 1R are supplied with hydraulic oil from main pumps 14L, 14R, respectively. This is because the lower traveling body 1 may not travel normally (for example, may not properly travel straight) in a state where only the standby flow rate of the main pump 14R is relatively high.

In a situation where the hoist mode is selected, the controller 30 increases the standby flow rates of both the main pumps 14L and 14R, while the controller 30 may temporarily decrease the standby flow rates when the swing operation is performed. This not only increases the standby flow rate of both the main pumps 14L and 14R for driving the attachment during the lifting operation, but also suppresses the upper slewing body 3 from slewing faster than the speed expected by the operator or the like in response to the slewing operation.

Returning again to fig. 3, in step S110, the controller 30 determines whether or not the state in which the hoist mode is selected continues. When the state in which the hoist mode is selected is not continued, that is, when the hoist mode is not selected and the mode is shifted to the normal mode, the controller 30 proceeds to step S112. On the other hand, when the state in which the hoist mode is selected continues, the controller 30 waits until the hoist mode is released, that is, returns to the normal mode (step S110 is repeated).

In step S112, the controller 30 returns the standby flow rate to the normal state, that is, relatively reduces the standby flow rate from the state of the hoist mode, and ends the present process.

[ Change of deformation ]

The embodiments have been described above in detail, but the present invention is not limited to the specific embodiments, and various modifications and changes can be made within the scope of the gist described in the scope of the claims.

For example, in the above-described embodiment, the excavator 100 is configured such that all of various driven elements such as the lower traveling structure 1, the upper revolving structure 3, the boom 4, the arm 5, and the bucket 6 are hydraulically driven, but may be configured such that some of them are electrically driven. That is, the structure and the like disclosed in the above embodiments can be applied to a hybrid shovel, an electric shovel, and the like.

Finally, with regard to the present application, priority is claimed based on japanese patent application No. 2019-069474, filed on 30/3/2019, and the entire contents of the japanese patent application are incorporated by reference.

Description of the symbols

1-lower traveling body, 1L-traveling hydraulic motor, 1R-traveling hydraulic motor, 2-slewing mechanism, 2A-slewing hydraulic motor, 3-upper slewing body, 4-boom, 5-arm, 6-bucket, 7-boom cylinder, 8-arm cylinder, 9-bucket cylinder, 10-cabin, 11-engine, 13L, 13R-regulator, 14L, 14R-main pump, 15-pilot pump, 17-control valve, 18L, 18R-negative control restrictor, 19L, 19R-negative control pressure sensor, 26-operating device, 28L, 28R-discharge pressure sensor, 29-operating pressure sensor, 30-controller (control device), 50-display device, 52-input device, 100-shovel, 171, 172, 173, 174, 175L, 175R, 176L, 176R-control valve.