JP2021152290A - Shovel and control method of shovel - Google Patents

Abstract

To provide a shovel capable of reducing load of an operator.SOLUTION: A shovel in accordance with the present invention is provided with: a lower traveling body; an upper structure rotatably mounted on the lower traveling body; an attachment attached on the upper structure and including a bucket; and a controller controlling motion of the attachment, wherein the controller limits and controls the attachment so as to reduce speed of the bucket before the bucket abuts a work object based on hardness information of the work object.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to excavators and methods of controlling excavators.

Conventionally, a shovel that controls the toe angle of a bucket with respect to the excavation target ground based on the transition of the attitude of the attachment, the information on the current shape of the excavation target ground, and the operation content of the operation device related to the attachment has been known (for example, a patent). Reference 1).

International Publication No. 2017/047695

In the above-mentioned excavator, since the toe angle of the bucket with respect to the excavation target ground is controlled by the control device, the burden on the excavator operator is reduced. However, in order to reduce the damage to the attachment, the operator of the excavator performs detailed operations other than the angle of the toe of the bucket, which is a burden on the operator.

Therefore, it is desirable to provide an excavator that can further reduce the burden on the operator.

The excavator according to the embodiment of the present invention comprises a lower traveling body, an upper rotating body rotatably mounted on the lower traveling body, an attachment attached to the upper rotating body and including a bucket, and an operation of the attachment. The control device includes a control device for controlling, and the control device limits and controls the attachment so as to reduce the bucket speed before the bucket abuts on the work object based on the hardness information of the work object.

The above-mentioned excavator can further reduce the burden on the operator.

Side view of the excavator according to the embodiment of the present invention The figure which shows the configuration example of the drive control system of a shovel Schematic diagram showing a configuration example of a hydraulic system mounted on an excavator The figure which shows an example of the table which the attachment restriction setting part has Side view to explain the movement of the bucket in the excavation operation Flow chart showing an example of excavation support processing The figure which shows an example of the time transition of a lever operation amount, a bucket toe lowering speed and a stress

Hereinafter, modes for carrying out the invention will be described with reference to the drawings. In each drawing, the same components may be designated by the same reference numerals and duplicate description may be omitted.

First, the overall configuration of the excavator PS according to the embodiment of the present invention will be described with reference to FIG. FIG. 1 is a side view of the excavator PS according to the embodiment of the present invention.

The lower traveling body 1 of the excavator PS is mounted with the upper rotating body 3 so as to be able to turn via the turning mechanism 2. A boom 4 is attached to the upper swing body 3. An arm 5 is attached to the tip of the boom 4. A bucket 6 is attached to the tip of the arm 5 as an end attachment (working part). As the end attachment, a slope bucket, a dredging bucket, a breaker, or the like may be attached.

The boom 4, arm 5, and bucket 6 form an excavation attachment as an example of the attachment, and are hydraulically driven by the boom cylinder 7, the arm cylinder 8, and the bucket cylinder 9, respectively.

A boom angle sensor S1 is attached to the boom 4, an arm angle sensor S2 is attached to the arm 5, and a bucket angle sensor S3 is attached to the bucket 6. The boom angle sensor S1, the arm angle sensor S2, and the bucket angle sensor S3 are collectively referred to as a "posture sensor". Further, a strain sensor S4 is attached to the boom 4.

The boom angle sensor S1 detects the rotation angle of the boom 4. The boom angle sensor S1 is, for example, an acceleration sensor that detects the rotation angle of the boom 4 with respect to the upper swing body 3 by detecting the inclination of the boom 4 with respect to the horizontal plane.

The arm angle sensor S2 detects the rotation angle of the arm 5. The arm angle sensor S2 is, for example, an acceleration sensor that detects the rotation angle of the arm 5 with respect to the boom 4 by detecting the inclination of the arm 5 with respect to the horizontal plane.

The bucket angle sensor S3 detects the rotation angle of the bucket 6. The bucket angle sensor S3 is, for example, an acceleration sensor that detects the rotation angle of the bucket 6 with respect to the arm 5 by detecting the inclination of the bucket 6 with respect to the horizontal plane.

The boom angle sensor S1, the arm angle sensor S2, and the bucket angle sensor S3 are a potentiometer using a variable resistor, a stroke sensor that detects the stroke amount of the corresponding hydraulic cylinder, and a rotary encoder that detects the rotation angle around the connecting pin. Etc., and may be composed of a combination of an acceleration sensor and a gyro sensor.

The strain sensor S4 detects the strain of the attachment. In the present embodiment, the strain sensor S4 is a uniaxial strain gauge that is mounted inside the boom 4 and detects strain due to expansion or compression of the boom 4. However, the strain sensor S4 may be a triaxial strain gauge, or may be a plurality of uniaxial strain gauges attached to a plurality of locations inside the attachment. Further, the strain sensor S4 may be a plurality of triaxial strain gauges, or may be a combination of one or a plurality of uniaxial strain gauges and one or a plurality of triaxial strain gauges. Further, the strain sensor S4 may be mounted at a position where distortion of the attachment can be detected, and may be mounted on the outer surface of the boom 4, or may be mounted on the arm 5 or the bucket 6.

The upper swing 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 covered with a cover 3a. Further, the upper swing body 3 is equipped with a vehicle body inclination sensor S5, a swing angle sensor S6, a space recognition device 70, and the like. A controller 30, a display device 40, an audio output device 43, an input device 45, a storage device 47, and a gate lock lever 49 are provided in the cabin 10. A GPS device (GNSS receiver) P1 and a transmission device T1 are provided at the top of the cabin 10.

The vehicle body tilt sensor S5 detects the tilt angle of the vehicle body of the excavator PS. In the present embodiment, the vehicle body tilt sensor S5 is an acceleration sensor that detects the tilt angle of the vehicle body with respect to the horizontal plane.

The turning angle sensor S6 detects the turning angle of the upper turning body 3 with respect to the lower traveling body 1. In the present embodiment, the turning angle sensor S6 is, for example, a resolver that detects the turning angle of the turning mechanism 2.

The controller 30 is a control device that functions as a main control unit that controls the drive of the excavator PS. The controller 30 is composed of an arithmetic processing unit including a CPU and an internal memory. Various functions of the controller 30 are realized by the CPU executing a program stored in the internal memory.

The display device 40 displays an image including various work information in response to a command from the controller 30. The display device 40 is, for example, an in-vehicle liquid crystal display connected to the controller 30.

The voice output device 43 outputs various voice information in response to a voice output command from the controller 30. The audio output device 43 is, for example, an in-vehicle speaker connected to the controller 30. The voice output device 43 may be an alarm device such as a buzzer.

The input device 45 is a device for the operator of the excavator PS to input various information to the controller 30. The input device 45 includes, for example, a membrane switch provided on the surface of the display device 40. The input device 45 may be a touch panel or the like.

The storage device 47 stores various information. The storage device 47 is, for example, a non-volatile storage medium such as a semiconductor memory. In the present embodiment, the storage device 47 stores the detection values of the boom angle sensor S1, the arm angle sensor S2, the bucket angle sensor S3, the strain sensor S4, the vehicle body inclination sensor S5, and the like, and the output value of the controller 30.

The gate lock lever 49 is provided between the door of the cabin 10 and the driver's seat, and is a mechanism for preventing the shovel PS from being erroneously operated. When the operator gets into the driver's seat and pulls up the gate lock lever 49, the controller 30 controls the gate lock valve 49a (see FIG. 2 to be described later) in the open state, and the operator cannot leave the cabin 10 and various operating devices. Becomes operable. When the operator pushes down the gate lock lever 49, the controller 30 controls the gate lock valve 49a in the closed state, so that the operator can leave the cabin 10 and various operating devices become inoperable.

The GPS device P1 detects the position of the excavator PS by the GPS function and supplies the position data to the controller 30.

The transmission device T1 transmits information to the outside of the excavator PS.

The space recognition device 70 is configured to recognize an object existing in the three-dimensional space around the excavator PS. Further, the space recognition device 70 is configured to calculate the distance from the space recognition device 70 or the excavator PS to the recognized object. The space recognition device 70 is, for example, an ultrasonic sensor, a millimeter wave radar, a monocular camera, a stereo camera, a LIDAR, a distance image sensor, an infrared sensor, or the like. In the present embodiment, the space recognition device 70 is a lidar, and is configured to emit a large number of laser beams in a large number of directions and receive the reflected light to calculate the distance and direction of an object from the reflected light. ing. The same applies to the case where the millimeter wave radar or the like as the space recognition device 70 emits electromagnetic waves toward an object. Specifically, the space recognition device 70 is attached to the front sensor 70F attached to the front end of the upper surface of the cabin 10, the rear sensor 70B attached to the rear end of the upper surface of the upper swing body 3, and the left end of the upper surface of the upper swing body 3. The left sensor 70L and the right sensor 70R attached to the upper right end of the upper swing body 3 are included. An upper sensor that recognizes an object existing in the space above the upper swivel body 3 may be attached to the excavator PS.

The space recognition device 70 may be configured to image the surroundings of the excavator PS. In this case, the space recognition device 70 is a monocular camera having an image sensor such as a CCD or CMOS, and outputs the captured image to the display device 40.

The space recognition device 70 may be configured to detect a predetermined object in a predetermined area set around the excavator PS. That is, the space recognition device 70 may be configured to be able to identify at least one of the type, position, shape, and the like of the object. For example, the space recognition device 70 may be configured to distinguish between a person and a non-human object. Further, the space recognition device 70 may be configured so as to be able to identify the type of terrain around the excavator PS. The type of terrain is, for example, a hole, a sloping surface, or a river. Further, the space recognition device 70 may be configured so as to be able to identify the type of obstacle. The types of obstacles are, for example, electric wires, utility poles, people, animals, vehicles, work equipment, construction machinery, structures, fences, and the like. Further, the space recognition device 70 may be configured so that the type or size of the dump truck as a vehicle can be specified. Further, the space recognition device 70 detects a person by recognizing a helmet, a safety vest, work clothes, or the like, or by recognizing a predetermined mark or the like on the helmet, safety vest, work clothes, or the like. It may be configured as follows. Further, the space recognition device 70 may be configured to recognize the state of the road surface. Specifically, the space recognition device 70 may be configured to specify, for example, the type of an object existing on the road surface. The types of objects present on the road surface are, for example, cigarettes, cans, PET bottles, stones, and the like.

Next, a configuration example of the drive control system of the excavator PS will be described with reference to FIG. FIG. 2 is a diagram showing a configuration example of a drive control system for the excavator PS. In FIG. 2, the mechanical power system, the high-pressure hydraulic line, the pilot line, and the electric drive / control system are shown by double lines, thick solid lines, broken lines, and thin solid lines, respectively.

The engine 11 is connected to the main pump 14 and the pilot pump 15 and is controlled by the engine control unit (ECU) 74. From the ECU 74, various data indicating the state of the engine 11 (for example, data indicating the cooling water temperature (physical quantity) detected by the water temperature sensor 11c, etc.) are constantly transmitted to the controller 30. The controller 30 can store this data in the internal storage unit 30a and appropriately transmit it to the display device 40.

The main pump 14 is a hydraulic pump for supplying hydraulic oil to the control valve 17 via a high-pressure hydraulic line. The main pump 14 is, for example, a swash plate type variable displacement hydraulic pump.

The regulator 14a of the main pump 14, which is a variable displacement hydraulic pump, sends data indicating the swash plate angle to the controller 30. Further, the discharge pressure sensor 14b sends data indicating the discharge pressure of the main pump 14 to the controller 30. These data (data representing physical quantities) are stored in the storage unit 30a. Further, the oil temperature sensor 14c provided in the pipeline between the tank in which the hydraulic oil sucked by the main pump 14 is stored and the main pump 14 outputs data indicating the temperature of the hydraulic oil flowing in the pipeline to the controller 30. Send to.

The pilot pump 15 is a hydraulic pump for supplying hydraulic oil to various hydraulic control devices via a pilot line. The pilot pump 15 is, for example, a fixed-capacity hydraulic pump.

The control valve 17 is a flood control device that controls a flood control system in the excavator PS. The control valve 17 is used in, for example, a boom cylinder 7, an arm cylinder 8, a bucket cylinder 9, a traveling hydraulic motor 1L, 1R (see FIG. 3 described later), a turning hydraulic motor 2A (see FIG. 3 described later), and the like. The hydraulic oil discharged by the main pump 14 is selectively supplied. In the following, the boom cylinder 7, arm cylinder 8, bucket cylinder 9, traveling hydraulic motors 1L, 1R, and swivel hydraulic motor 2A may be referred to as "hydraulic actuators".

The operating lever 26 is provided in the cabin 10 and is used by the operator to operate the hydraulic actuator. When the operating lever 26 is operated, hydraulic oil is supplied from the pilot pump 15 to the pilot ports of the flow control valves corresponding to the respective hydraulic actuators. Each pilot port is supplied with hydraulic oil having a pressure corresponding to the operating direction and operating amount of the corresponding operating lever 26.

In the present embodiment, the operation lever 26 is a boom operation lever. When the operator operates the operation lever 26, the boom cylinder 7 (see FIG. 3 described later) can be hydraulically driven to operate the boom 4. In addition to the operation lever 26, the excavator PS includes an arm operation lever that can operate the arm 5 by hydraulically driving the arm cylinder 8, a bucket operation lever that can operate the bucket 6 by hydraulically driving the bucket cylinder 9, and for traveling. An operating lever for driving the hydraulic motors 1L, 1R, etc., an operating lever for hydraulically driving the swivel hydraulic motor 2A of the swivel mechanism 2 to swivel the upper swivel body 3, an operating pedal, and the like may be provided.

The pressure sensors 15a and 15b detect the pilot pressure sent to the control valve 17 when the operating lever 26 is operated, and send data indicating the detected pilot pressure to the controller 30. The operation lever 26 is provided with a switch button 27. The operator can send a command signal to the controller 30 by operating the switch button 27 while operating the operation lever 26.

Further, the operation lever 26 may be an electric type that outputs an electric signal (hereinafter, “operation signal”) corresponding to the operation content, instead of the hydraulic pilot type that outputs the pilot pressure. In this case, the electric signal from the operation lever 26 is input to the controller 30, and the controller 30 controls each control valve 171 to 176 in the control valve 17 according to the input electric signal, whereby the operation lever The operation of various hydraulic actuators may be realized according to the operation content with respect to 26. For example, the control valves 171 to 176 in the control valve 17 may be electromagnetic solenoid type spool valves driven by a command from the controller 30. Further, for example, a hydraulic control valve (hereinafter, "operation control valve") that operates in response to an electric signal from the controller 30 is arranged between the pilot pump 15 and the pilot ports of the control valves 171 to 176. You may. The operation control valve may be, for example, a proportional valve, and the shuttle valve is omitted. In this case, when a manual operation using the electric operation lever 26 is performed, the controller 30 controls the operation hydraulic control valve by the electric signal corresponding to the operation amount (for example, the lever operation amount) to control the pilot pressure. Increase or decrease. As a result, the controller 30 can operate each of the control valves 171 to 176 according to the operation content for the operation lever 26. Hereinafter, the description of the operation control valve will proceed on the assumption that it is a proportional valve (pressure reducing valve).

The controller 30 acquires various data. The data acquired by the controller 30 is stored in the storage unit 30a.

The display device 40 displays an image including work information and the like supplied from the controller 30. The display device 40 is connected to the controller 30 via, for example, a communication network such as CAN (Controller Area Network) or LIN (Local Interconnect Network), a dedicated line, or the like. Further, the display device 40 includes a conversion processing unit 40a for generating an image to be displayed on the image display unit 41, and a switch panel 42 as an input unit.

The conversion processing unit 40a generates an image including a captured image to be displayed on the image display unit 41 based on data such as image data obtained from the space recognition device 70. Data such as image data is input to the display device 40 from each of the front sensor 70F, the rear sensor 70B, the left sensor 70L, and the right sensor 70R. Further, the conversion processing unit 40a converts the data to be displayed on the image display unit 41 among the various data input from the controller 30 to the display device 40 into an image signal. The data input from the controller 30 to the display device 40 includes, for example, data indicating the temperature of the engine cooling water, data indicating the temperature of the hydraulic oil, data indicating the remaining amount of urea water, data indicating the remaining amount of fuel, and the like. include. The conversion processing unit 40a outputs the converted image signal to the image display unit 41, and causes the image display unit 41 to display the captured image and the image generated based on various data. The conversion processing unit 40a may be provided not in the display device 40 but in, for example, the controller 30.

The switch panel 42 is a panel including various hardware switches. The switch panel 42 includes a light switch 42a, a wiper switch 42b, and a window washer switch 42c.

The light switch 42a is a switch for switching on / off of a light attached to the outside of the cabin 10. The wiper switch 42b is a switch for switching the operation / stop of the wiper. The window washer switch 42c is a switch for injecting the window washer liquid.

The display device 40 operates by receiving electric power from the storage battery 80. The storage battery 80 is charged with the electric power generated by the alternator 11a (generator) of the engine 11. The electric power of the storage battery 80 is also supplied to the electrical components 72 of the excavator PS other than the controller 30 and the display device 40. Further, the starter 11b of the engine 11 is driven by the electric power from the storage battery 80 to start the engine 11.

An engine speed adjusting dial 75 is provided in the cabin 10 of the excavator PS. The engine speed adjustment dial 75 is a dial for adjusting the engine speed, and for example, the engine speed can be switched stepwise. In the present embodiment, the engine speed adjustment dial 75 is provided so that the engine speed can be switched in four stages of SP mode, H mode, A mode, and idling (IDLE) mode. The engine speed adjustment dial 75 sends data indicating the setting state of the engine speed to the controller 30. Note that FIG. 2 shows a state in which the H mode is selected by the engine speed adjustment dial 75.

The SP mode is a rotation speed mode selected when it is desired to prioritize the amount of work, and uses the highest engine speed. The H mode is a rotation speed mode selected when it is desired to achieve both work load and fuel consumption, and uses the second highest engine speed. The A mode is a rotation speed mode selected when it is desired to operate the excavator PS with low noise while giving priority to fuel consumption, and uses the third highest engine speed. The idling mode is a rotation speed mode selected when the engine is desired to be in an idling state, and the lowest engine speed is used. The engine 11 is controlled to a constant rotation speed by the engine rotation speed in the rotation speed mode set by the engine rotation speed adjustment dial 75.

Next, with reference to FIG. 3, the details of the hydraulic system mounted on the excavator PS will be described. FIG. 3 is a schematic view showing a configuration example of a hydraulic system mounted on the excavator PS of FIG. In FIG. 3, the mechanical power system, the high-pressure hydraulic line, the pilot line, and the electric control system are shown by double lines, thick solid lines, broken lines, and dotted lines, respectively.

In FIG. 3, the hydraulic system circulates hydraulic oil from the main pumps 14L and 14R driven by the engine 11 to the hydraulic oil tank via the center bypass pipelines 50L and 50R and the parallel pipelines 52L and 52R. The main pumps 14L and 14R correspond to the main pump 14 of FIG.

The center bypass pipeline 50L is a high-pressure hydraulic line that passes through control valves 171L to 175L arranged in the control valve 17. The center bypass pipeline 50R is a high-pressure hydraulic line that passes through the control valves 171R to 175R arranged in the control valve 17.

The control valve 171L supplies the hydraulic oil discharged by the main pump 14L to the left-side traveling hydraulic motor 1L, and discharges the hydraulic oil discharged by the left-side traveling hydraulic motor 1L to the hydraulic oil tank. It is a spool valve that switches between.

The control valve 171R is a spool valve as a traveling straight valve. The control valve 171R switches the flow of hydraulic oil so that hydraulic oil is supplied from the main pump 14L to each of the left-side traveling hydraulic motor 1L and the right-side traveling hydraulic motor 1R in order to improve the straightness of the lower traveling body 1. Specifically, when the left-side traveling hydraulic motor 1L and the right-side traveling hydraulic motor 1R and any other hydraulic actuator are operated at the same time, the main pump 14L is the left-side traveling hydraulic motor 1L and the right-side traveling hydraulic pressure. The hydraulic oil is supplied to both of the motors 1R. When none of the other hydraulic actuators is operated, the main pump 14L supplies the hydraulic oil to the left side traveling hydraulic motor 1L, and the main pump 14R supplies the hydraulic oil to the right side traveling hydraulic motor 1R.

The control valve 172L is a spool valve that supplies the hydraulic oil discharged by the main pump 14L to the optional hydraulic actuator and switches the flow of the hydraulic oil in order to discharge the hydraulic oil discharged by the optional hydraulic actuator to the hydraulic oil tank. Is. The optional hydraulic actuator is, for example, a grapple opening / closing cylinder.

The control valve 172R supplies the hydraulic oil discharged by the main pump 14R to the right-side traveling hydraulic motor 1R, and discharges the hydraulic oil discharged by the right-side traveling hydraulic motor 1R to the hydraulic oil tank. It is a spool valve that switches between.

The control valve 173L supplies the hydraulic oil discharged by the main pump 14L to the swivel hydraulic motor 2A, and switches the flow of the hydraulic oil in order to discharge the hydraulic oil discharged by the swivel hydraulic motor 2A to the hydraulic oil tank. It is a spool valve.

The swivel hydraulic motor 2A can swivel the upper swivel body 3. The port 21L of the swivel hydraulic motor 2A is connected to the hydraulic oil tank via a relief valve 22L. The port 21R of the swivel hydraulic motor 2A is connected to the hydraulic oil tank via the relief valve 22R. The relief valve 22L opens when the pressure on the port 21L side reaches a predetermined relief pressure, and discharges the hydraulic oil on the port 21L side to the hydraulic oil tank. The relief valve 22R opens when the pressure on the port 21R side reaches a predetermined relief pressure, and discharges the hydraulic oil on the port 21R side to the hydraulic oil tank.

The control valve 173R is a spool valve for supplying the hydraulic oil discharged by the main pump 14R to the bucket cylinder 9 and discharging the hydraulic oil in the bucket cylinder 9 to the hydraulic oil tank.

The control valves 174L and 174R are spools that supply the hydraulic oil discharged by the main pumps 14L and 14R to the boom cylinder 7 and switch the flow of the hydraulic oil in order to discharge the hydraulic oil in the boom cylinder 7 to the hydraulic oil tank. It is a valve. In this embodiment, the control valve 174L operates only when the boom 4 is raised, and does not operate when the boom 4 is lowered.

The control valves 175L and 175R are spools that supply the hydraulic oil discharged by the main pumps 14L and 14R to the arm cylinder 8 and switch the flow of the hydraulic oil in order to discharge the hydraulic oil in the arm cylinder 8 to the hydraulic oil tank. It is a valve.

The parallel line 52L is a high-pressure hydraulic line parallel to the center bypass line 50L. The parallel pipeline 52L can supply the hydraulic oil to the control valve further downstream when the flow of the hydraulic oil through the center bypass pipeline 50L is restricted or blocked by any of the control valves 171L to 174L. The parallel line 52R is a high-pressure hydraulic line parallel to the center bypass line 50R. The parallel pipeline 52R can supply the hydraulic oil to the control valve further downstream when the flow of the hydraulic oil through the center bypass pipeline 50R is restricted or blocked by any of the control valves 172R to 174R.

The regulators 14aL and 14aR control the discharge amount of the main pumps 14L and 14R by adjusting the swash plate tilt angle of the main pumps 14L and 14R according to the discharge pressure of the main pumps 14L and 14R. The regulators 14aL and 14aR correspond to the regulator 14a of FIG. The regulators 14aL and 14aR, for example, adjust the swash plate tilt angle of the main pumps 14L and 14R to reduce the discharge amount when the discharge pressures of the main pumps 14L and 14R become equal to or higher than a predetermined value. This is to prevent the absorbed horsepower of the main pump 14, which is represented by the product of the discharge pressure and the discharge amount, from exceeding the output horsepower of the engine 11.

The discharge pressure sensors 14bL and 14bR are sensors for detecting the discharge pressures of the main pumps 14L and 14R, and output the detected values to the controller 30. The discharge pressure sensors 14bL and 14bR correspond to the discharge pressure sensor 14b of FIG.

The operating lever 26 uses the hydraulic oil discharged from the pilot pump 15 to apply a pilot pressure according to the lever operating amount to the pilot ports of the control valves 174L and 174R. Specifically, when the operating lever 26 is operated in the boom raising direction, the operating lever 26 exerts a pilot pressure on the right side pilot port of the control valve 174L and the left side pilot port of the control valve 174R. On the other hand, when the operating lever 26 is operated in the boom lowering direction, the pilot pressure is applied to the right pilot port of the control valve 174R.

The pressure reducing valves 25L and 25R increase / decrease the pilot pressure according to the command current from the controller 30. The pressure reducing valve 25L reduces the pilot pressure generated when the operating lever 26 is operated in the boom raising direction and acts on the right side pilot port of the control valve 174L and the left side pilot port of the control valve 174R. The pressure reducing valve 25R reduces the pilot pressure generated when the operating lever 26 is operated in the boom lowering direction and acts on the right pilot port of the control valve 174R.

The pressure sensor 15ab corresponds to the pressure sensors 15a and 15b of FIG. The pressure sensor 15ab detects the operation content of the operator with respect to the operation lever 26 in the form of pressure, and outputs the detected value to the controller 30. The operation contents are, for example, a lever operation direction, a lever operation amount (lever operation angle), and the like.

Here, the negative control control (hereinafter referred to as “negative control control”) adopted in the hydraulic system of FIG. 3 will be described.

The center bypass pipelines 50L and 50R are provided with negative control throttles 18L and 18R between the most downstream control valves 175L and 175R and the hydraulic oil tank, respectively. The flow of hydraulic oil discharged by the main pumps 14L and 14R is limited by the negative control throttles 18L and 18R. Then, the negative control diaphragms 18L and 18R generate a control pressure for controlling the regulators 14aL and 14aR (hereinafter, referred to as "negative control pressure").

The negative control pressure sensors 19L and 19R are sensors that detect the negative control pressure generated upstream of the negative control diaphragms 18L and 18R. In this embodiment, the negative control pressure sensors 19L and 19R output the detected values to the controller 30.

The controller 30 outputs a command according to the negative control pressure to the regulators 14aL and 14aR. The regulators 14aL and 14aR control the discharge amount of the main pumps 14L and 14R by adjusting the swash plate tilt angle of the main pumps 14L and 14R in response to a command. Specifically, the regulators 14aL and 14aR decrease the discharge amounts of the main pumps 14L and 14R as the negative control pressure increases, and increase the discharge amounts of the main pumps 14L and 14R as the negative control pressure decreases.

When none of the hydraulic actuators are operated (hereinafter referred to as "standby mode"), the hydraulic oil discharged by the main pumps 14L and 14R passes through the center bypass pipelines 50L and 50R and the negative control throttles 18L and 18R. To. The flow of hydraulic oil discharged by the main pumps 14L and 14R increases the negative pressure generated upstream of the negative control throttles 18L and 18R. As a result, the regulators 14aL and 14aR reduce the discharge amount of the main pumps 14L and 14R to the allowable minimum discharge amount, and reduce the pressure loss (pumping loss) when the discharged hydraulic oil passes through the center bypass pipelines 50L and 50R. Suppress.

On the other hand, when any of the hydraulic actuators is operated, the hydraulic oil discharged from the main pumps 14L and 14R flows into the operation target hydraulic actuator via the control valve corresponding to the operation target hydraulic actuator. Then, the flow of the hydraulic oil discharged by the main pumps 14L and 14R reduces or eliminates the amount reaching the negative control throttles 18L and 18R, and lowers the negative control pressure generated upstream of the negative control throttles 18L and 18R. As a result, the regulators 14aL and 14aR increase the discharge amount of the main pumps 14L and 14R, circulate sufficient hydraulic oil to the operation target hydraulic actuator, and ensure the drive of the operation target hydraulic actuator.

With the above configuration, the hydraulic system of FIG. 3 can suppress wasteful energy consumption in the main pumps 14L and 14R in the standby mode. The wasteful energy consumption includes a pumping loss generated by the hydraulic oil discharged from the main pumps 14L and 14R in the center bypass pipelines 50L and 50R.

Further, the hydraulic system of FIG. 3 ensures that necessary and sufficient hydraulic oil can be supplied from the main pumps 14L and 14R to the hydraulic actuator to be operated when the hydraulic actuator is operated.

Next, returning to FIG. 2, the functional configuration of the controller 30 will be described. As shown in FIG. 2, the controller 30 includes a control level estimation unit 31, a boom lowering limit setting unit 32, and an operation control unit 33.

The control level estimation unit 31 estimates a control level indicating the magnitude of the impact applied to the bucket 6 by a work object such as earth and sand when performing excavation work described later, for example. The control level is an index indicating the magnitude of the impact, and in the following description, it will be described that the larger the impact, the higher the value of the control level. The control level estimation unit 31 estimates the control level based on the hardness of the work object.

For example, the control level estimation unit 31 estimates the hardness of the work object based on the amount of subduction into the work object when a predetermined pressure is applied to the work object by the bucket 6 in a predetermined posture. To estimate the control level. The amount of sinking into the work object can be obtained based on, for example, the detection value of the posture sensor of the excavator PS and the information on the work object recognized by the space recognition device 70. Specifically, the amount of subduction into the work object can be obtained based on the posture change of the shovel PS calculated from the detection value of the posture sensor of the shovel PS. The amount of subduction into the work object is based on the distance from the space recognition device 70 or the excavator PS recognized by the space recognition device 70 to the work object, the image of the work object captured by the space recognition device 70, and the like. You can ask.

Further, for example, the control level estimation unit 31 estimates the control level by estimating the hardness of the work object based on the past work history. The control level estimation unit 31 estimates the formation state of the work object from the position information of the excavator PS by the GPS device P1, the operation history of each part of the excavator PS by various sensors S1 to S6, and the like. Here, as the formation state of the work object, for example, the embankment with the excavated earth and sand etc. piled up, the foundation compacted for the excavator PS to work on, and the unexcavated ground (from the beginning). Ground surface shape) etc. For example, the state of soil is acquired from the pressure waveform of the cylinder pressure of various cylinders 7 to 9 at the time of excavation, the detected value of the strain gauge, and the like. Further, based on the locus of the excavator PS, the locus of the bucket 6, and the like, it is estimated whether the work object is an embankment or a base. Further, a construction drawing is input as terrain information in the storage unit 30a of the controller 30, and the control level estimation unit 31 may acquire information on the ground from the terrain information. Then, the control level estimation unit 31 estimates the hardness of the work object based on the estimated formation state of the work object (filling, foundation, ground, etc.) and determines the control level. As for the work history used by the control level estimation unit 31, not only the work history of the own excavator PS but also the work history of the other excavator PS is acquired via the transmission device T1 to obtain the hardness of the work object. It may be used for the estimation of.

Further, for example, the control level estimation unit 31 estimates the control level by estimating the hardness of a work object such as earth and sand that comes into contact with the space recognition device 70 based on the image captured by the space recognition device 70. Detected values of various cylinders 7 to 9 and strain gauges may be used for estimating the hardness. Further, for the estimation of hardness, rock quality information such as propagation velocity and water absorption rate and geological information such as geological information such as water veins may be used. The control level estimation unit 31 acquires an image of the work object through the display device 40, and forms the work object from the shape, surface condition, etc. of the work object (filling, foundation, ground, etc.). To estimate. As a method of estimating the formation state of the work object from the image, AI technology such as pattern learning may be used. An image and a load (detected values of various cylinders, etc.) may be combined for pattern learning. Then, the control level estimation unit 31 estimates the hardness of the work object based on the estimated formation state (fill, foundation, ground, etc.) of the work object, and estimates the control level. Here, the formation state of the work object can be determined based on the work content of the excavator PS. The work content can be obtained based on the detected values of the space recognition device 70, the posture sensor of the excavator PS, the boom cylinder 7, the arm cylinder 8, the pressure sensor of the bucket cylinder 9, and the like. The image used by the control level estimation unit 31 is not only an image captured by the space recognition device 70 of its own excavator PS, but also an image captured by the space recognition device 70 of another excavator PS via the transmission device T1. It may be acquired and used for estimating hardness.

By the way, when the attachments (boom 4, arm 5, bucket 6) of the excavator 100 load the excavated object onto the dump truck, fatigue damage is accumulated due to the weight of the loaded object. Here, the life of the attachment is proportional to the cube of the reciprocal of the stress acting on the attachment. That is, when the stress acting on the attachment is halved, the life of the attachment is halved. In addition, the stress acting on the attachment is proportional to the weight of the load. Further, it does not necessarily have to be the 3.0th power, and the 3.5th power may be determined as a guideline for the life calculation.

The boom lowering limit setting unit 32 sets the limit value of the boom 4 based on the control level estimated by the control level estimation unit 31. FIG. 4 is an example of a table included in the boom lowering limit setting unit 32. The boom lowering limit setting unit 32 has a table of limit values as shown in FIG. In the table, a limit value of the moving speed of the toe of the bucket 6 (bucket toe lowering speed) when performing the boom lowering operation is set with respect to the control level. Specifically, the higher the control level, in other words, the harder the work object is, the smaller the limit value is set. The boom lowering limit setting unit 32 sets the limit value of the bucket toe lowering speed based on the table of the control level and the limit value estimated by the control level estimation unit 31.

The operation control unit 33 limits the bucket toe lowering speed during the lowering operation of the boom 4 based on the limit value set by the boom lowering limit setting unit 32. Specifically, the controller 30 controls the pilot pressure of the control valve 174R by controlling the pressure reducing valve 25R shown in FIG. 3 to control the hydraulic oil flowing into the rod-side oil chamber of the boom cylinder 7. , Limit the lowering speed of the boom 4 (bucket toe lowering speed).

Next, an example of the excavation operation performed by the excavator PS of the present embodiment will be described with reference to FIG. FIG. 5 is a side view for explaining the movement of the bucket 6 in the excavation operation. In FIG. 5, the positions of the arm 5 and the bucket 6 when the toe of the bucket 6 comes into contact with the ground, which is an example of a work object, are shown by a solid line, and the arm 5 and the bucket 6 immediately before the toe of the bucket 6 comes into contact with the ground are shown. The position of is indicated by a broken line.

As shown in FIG. 5, in the excavation operation, the boom 4, the arm 5, and the bucket 6 are operated to bring the toes of the bucket 6 into contact with the ground to be excavated in front of and below the excavator PS. Then, even after the toes of the bucket 6 come into contact with the ground, the toes of the bucket 6 are moved downward to allow the bucket 6 to enter the ground and excavate the ground. At this time, each time the bucket 6 comes into contact with the ground, the excavation attachment receives an impact load, which shortens the life of the excavation attachment. In particular, the harder the ground, the greater the impact load received by the excavation attachment, and the shorter the life of the excavation attachment becomes. Further, when the ground is hard, the toes of the bucket 6 are also easily damaged.

Therefore, in order to reduce such damage to the excavation attachment, a skilled excavator PS operator performs excavation operation while finely adjusting the moving speed and toe angle of the bucket 6 when the toe of the bucket 6 comes into contact with the ground. It is carried out. However, the excavation operation while making fine adjustments is a burden on the operator of the excavator PS. Further, it is difficult for an unskilled excavator PS operator to make fine adjustments performed by a skilled excavator PS operator.

Therefore, in the present embodiment, the controller 30 limits and controls the attachment so as to reduce the bucket speed before the bucket 6 comes into contact with the work object based on the hardness information of the work object. As a result, damage to the attachment can be suppressed and the burden on the operator of the excavator PS can be reduced.

Further, the controller 30 may continue or release the attachment restriction control after the bucket 6 comes into contact with the work object. When releasing the restriction control of the attachment, it is preferable to release it gently after the bucket 6 comes into contact with the work object. As a result, the discomfort felt by the operator of the excavator PS can be reduced.

In addition to the attachment restriction control, the controller 30 may adjust the bucket angle and the posture of the excavator PS when the bucket 6 comes into contact with the work object based on the hardness information of the work object.

Next, with reference to FIG. 6, an example of a process in which the controller 30 supports the excavation operation by the excavation attachment (hereinafter referred to as “excavation support process”) will be described. FIG. 6 is a flowchart showing an example of excavation support processing.

In step ST1, the motion control unit 33 determines whether or not the current bucket toe lowering speed is equal to or higher than the threshold speed. Here, the threshold speed may be, for example, a limit value of the bucket toe lowering speed set by the boom lowering limit setting unit 32. If the current bucket toe lowering speed is equal to or higher than the threshold speed, the process proceeds to step ST2. On the other hand, if the current bucket toe lowering speed is less than the threshold speed, the process proceeds to step ST4.

In step ST2, the motion control unit 33 determines whether or not the distance from the bucket 6 (for example, the toe of the bucket 6) to the work object is equal to or less than the threshold distance. The distance from the bucket 6 to the work object is detected by, for example, the space recognition device 70. If the distance from the bucket 6 to the work object is equal to or less than the threshold value, the process proceeds to step ST3. On the other hand, if the distance from the bucket 6 to the work object is less than the threshold value, the process proceeds to step ST4.

In step ST3, the operation control unit 33 limits and controls the bucket toe lowering speed based on the limit value set by the boom lowering limit setting unit 32. Then, the process ends.

On the other hand, in step ST4, the motion control unit 33 determines that the bucket toe lowering speed is not limited. Then, the process ends.

In the present embodiment, it has been described that when the operator operates the bucket, the controller 30 calculates the distance between the bucket 6 and the object to limit the speed, but the bucket 6 is set based on a preset target trajectory. It can also be applied to controlled semi-automatic excavators and autonomous excavators.

Next, an operation example of the excavation support process will be described with reference to FIG. 7. In FIG. 7, the waveform when the excavation support process is performed (Example) is shown by a solid line, and the waveform when the excavation support process is not performed (reference example) is shown by a broken line.

First, the case of a reference example will be described. At time t0, when the operating lever 26 is operated as shown in FIG. 7A, the bucket toe lowering speed also increases and becomes constant at a predetermined speed as shown in FIG. 7B. .. Then, at time t1, the bucket 6 comes into contact with the work object. At this time, as shown in FIG. 7C, a large stress is generated in the reference example. Therefore, the excavation attachment receives a large impact load. Then, the bucket 6 excavates the work object while stress is generated.

On the other hand, in the embodiment, when the operation lever 26 is operated as shown in FIG. 7 (a) at time t0, the bucket toe lowering speed also increases as shown in FIG. 7 (b). It becomes constant at a predetermined speed. Then, by satisfying the conditions (step ST1: YES and step ST2: YES), the motion control unit 33 limits the bucket toe lowering speed before coming into contact with the work object. Then, at time t3, the bucket 6 comes into contact with the work object. At this time, as shown in FIG. 7 (c), the stress at the time of contact is smaller than that of the reference example. Thereby, the control of the embodiment can reduce the impact at the time of contact and reduce the damage of the excavation attachment as compared with the reference example.

As described above, according to the excavator PS of the present embodiment, the controller 30 reduces the bucket speed before the bucket 6 comes into contact with the work object based on the hardness information of the work object. Limit control of excavation attachments. As a result, the impact when the bucket 6 comes into contact with the work object can be reduced, and damage to the excavation attachment can be reduced. In addition, the burden on the operator of the excavator PS can be reduced.

Further, the controller 30 sets the limit value of the excavation operation based on the control level indicating the magnitude of the impact applied to the bucket 6 by the work object. As a result, it is possible to prevent the restriction from becoming excessive and the operability from being lowered.

Further, the controller 30 is based on the amount of sinking into the work object when a predetermined pressure is applied to the work object by the bucket 6 in a predetermined posture, the image captured by the space recognition device 70, and the work history of the excavator PS. To estimate the control level. As a result, the excavator PS can be suitably controlled regardless of the skill level of the operator of the excavator PS.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications and substitutions are made to the above-described embodiments without departing from the scope of the present invention. be able to.

In the above embodiment, in the configuration in which the control valves 174L and 174R are operated by the pilot pressure, the controller 30 controls the pressure reducing valves 25L and 25R to limit the operation of the excavation attachment. It is not limited to such a configuration. For example, the same can be applied to a configuration in which the controller 30 electrically operates the control valves 174L and 174R.

PS Excavator 1 Lower traveling body 3 Upper rotating body 4 Boom 5 Arm 6 Bucket 31 Control level estimation unit 32 Boom lowering limit setting unit 33 Motion control unit 70 Space recognition device

Claims (6)

With the lower running body,
An upper swivel body mounted on the lower traveling body so as to be swivel,
An attachment that is attached to the upper swing body and includes a bucket,
A control device that controls the operation of the attachment,
With
Based on the hardness information of the work object, the control device limits and controls the attachment so as to reduce the bucket speed before the bucket abuts on the work object.
Excavator. The hardness information of the work object is input by the operator.
The excavator according to claim 1. The hardness information of the work object is estimated based on the pressure obtained when the bucket is pressed against the work object.
The excavator according to claim 1 or 2. The hardness information of the work object is estimated from an image obtained by capturing the work object.
The excavator according to any one of claims 1 to 3. The hardness information of the work object is estimated based on the past work history.
The excavator according to any one of claims 1 to 4. A method of controlling the operation of an attachment of an excavator including a lower traveling body, an upper rotating body rotatably mounted on the lower traveling body, and an attachment attached to the upper rotating body and including a bucket.
Based on the hardness information of the work object, the attachment is restricted and controlled so as to reduce the bucket speed before the bucket abuts on the work object.
Excavator control method.

Images