backhoe

Abstract

A shovel (100) has a lower traveling body (1), an upper swing body (3) swingably mounted on the lower traveling body (1), a digging attachment (AT) mounted on the upper swing body (3), and a prime mover mounted on the upper swing body (3). The shovel (100) is configured to reduce a rotation speed of the prime mover before starting low-load operation of the digging attachment (AT).

Description

TECHNICAL FIELD

[0001] The present application relates to a shovel. BACKGROUND

[0002] In the past, there has been known a shovel that determines whether a bucket rod closing operation is a high-load operation in a digging work or the like or a low-load operation in a grading work or the like, based on a pressure of working oil in a bucket rod cylinder (see Patent Literature 1).

[0003] PRIOR ART DOCUMENT

[0004] PATENT LITERATURE

[0005] Patent Literature 1: International Publication No. 2017 / 164175 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] However, the energy saving at the time of the low-load operation is not mentioned in Patent Literature 1.

[0008] Therefore, it is desirable to reduce the energy wasted at the time of the low-load operation.

[0009] MEANS FOR SOLVING THE PROBLEMS

[0010] A shovel according to an embodiment of the present application includes a lower traveling body, an upper swing body swingably mounted on the lower traveling body, an attachment mounted on the upper swing body, and an engine mounted on the upper swing body, and the engine is reduced in rotation speed before starting a low-load operation of the attachment.

[0011] EFFECT OF THE INVENTION

[0012] The above-described shovel can reduce the energy wasted at the time of the low-load operation. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a side view of a shovel according to an embodiment of the present application.

[0014] Figure 2 is a diagram showing a configuration example of a hydraulic system of the shovel according to Figure 1

[0015] Figure 3 is a flowchart of an example of a rotation speed reduction process.

[0016] Figure 4 is a diagram showing changes over time of a target rotation speed of the engine, a boom raising pilot pressure, and a boom lowering pilot pressure at the time of execution of the rotation speed reduction process according to Figure 3

[0017] ​​Figure 5 is a flowchart of another example of the rotational speed reduction process.

[0018] Figure 6 is a graph showing changes over time in the target rotational speed of the engine, the boom raising pilot pressure, and the boom lowering pilot pressure when the rotational speed reduction process of Figure 5 is executed.

[0019] Figure 7 is a graph showing an example of the structure of an electrically operated system.

[0020] Figure 8 is a schematic diagram showing an example of a construction system. DETAILED DESCRIPTION

[0021] First, with reference to Figure 1 , an excavator 100 as an embodiment of the present application will be described. Figure 1 is a side view of the excavator 100.

[0022] In the present embodiment, the lower traveling body 1 of the excavator 100 includes tracks 1C. The tracks 1C are driven by traveling hydraulic motors 2M as traveling actuators mounted on the lower traveling body 1. Specifically, the tracks 1C include left and right tracks 1CL and 1CR (not visible in the figure). The left track 1CL is driven by a left traveling hydraulic motor 2ML, and the right track is driven by a right traveling hydraulic motor 2MR (not visible in the figure). Figure 1 Figure 1 In the present embodiment, the lower traveling body 1 of the excavator 100 includes tracks 1C. The tracks 1C are driven by traveling hydraulic motors 2M as traveling actuators mounted on the lower traveling body 1. Specifically, the tracks 1C include left and right tracks 1CL and 1CR (not visible in the figure). The left track 1CL is driven by a left traveling hydraulic motor 2ML, and the right track is driven by a right traveling hydraulic motor 2MR (not visible in the figure).

[0023] The upper swing body 3 is swingably mounted on the lower traveling body 1 via a swing mechanism 2. The swing mechanism 2 is driven by a swing hydraulic motor 2A as a swing actuator mounted on the upper swing body 3.

[0024] A boom 4 is mounted on the upper swing body 3. A stick 5 is mounted on the front end of the boom 4, and a bucket 6 as a terminal attachment is mounted on the front end of the stick 5. The boom 4, the stick 5, and the bucket 6 constitute an excavating attachment AT as an example of an attachment. Also, the boom 4 is driven by a boom cylinder 7, the stick 5 is driven by a stick cylinder 8, and the bucket 6 is driven by a bucket cylinder 9. The boom cylinder 7, the stick cylinder 8, and the bucket cylinder 9 constitute an attachment actuator.

[0025] The boom 4 is supported on the upper swing body 3 so as to be able to turn up and down. Also, a boom angle sensor S1 is mounted on the boom 4. The boom angle sensor S1 is able to detect a boom angle θ1 as a turning angle of the boom 4. The boom angle θ1 is, for example, a raising angle from a state in which the boom 4 is completely lowered. Therefore, the boom angle θ1 becomes the largest when the boom 4 is completely raised.

[0026] ​The arm boom 4 is rotatably supported to the lower frame 2. Further, an arm boom angle sensor S1 is installed in the arm boom 4. The arm boom angle sensor S1 is capable of detecting an arm boom angle θ1 as a rotational angle of the arm boom 4. The arm boom angle θ1 is an opening angle from a state in which the arm boom 4 is completely closed. Therefore, the arm boom angle θ1 becomes maximum when the arm boom 4 is completely opened.

[0027] The bucket 6 is rotatably supported to the arm boom 5. Further, a bucket angle sensor S3 is installed in the bucket 6. The bucket angle sensor S3 is capable of detecting a bucket angle θ3 as a rotational angle of the bucket 6. The bucket angle θ3 is an opening angle from a state in which the bucket 6 is completely closed. Therefore, the bucket angle θ3 becomes maximum when the bucket 6 is completely opened.

[0028] Figure 1 In the embodiment of the present application, each of the arm boom angle sensor S1, the arm lever angle sensor S2, and the bucket angle sensor S3 is constituted by a combination of an acceleration sensor and a gyro sensor. However, each of the arm boom angle sensor S1, the arm lever angle sensor S2, and the bucket angle sensor S3 can be constituted by only an acceleration sensor. Further, the arm boom angle sensor S1 can be a stroke sensor installed in the arm boom cylinder 7, or can be a rotary encoder, a potentiometer, an inertial measurement device, or the like. The same applies to the arm lever angle sensor S2 and the bucket angle sensor S3.

[0029] The posture of the excavating attachment AT is detected, for example, based on the outputs of the arm boom angle sensor S1, the arm lever angle sensor S2, and the bucket angle sensor S3.

[0030] In the upper swing body 3, a cab 10 as a driver's cabin is provided, and a power source (prime mover) such as an engine 11 is mounted. The engine 11 as an example of the prime mover is, for example, an internal combustion engine such as a diesel engine, a gasoline engine, or a hydrogen engine. In the illustrated example, the engine 11 is a diesel engine. Alternatively, the engine 11 can be replaced with another prime mover such as an electric motor (electric motor) using electric power generated by a fuel cell or an electric motor (electric motor) using electric power stored in a battery such as a lithium ion battery, or can be a combination of two or more prime movers such as a combination of an internal combustion engine and an electric motor. Further, in the upper swing body 3, a space recognition device 70, a direction detection device 71, a position measurement device 73, a body inclination sensor S4, a swing angular velocity sensor S5, and the like are installed. Inside the cab 10, an operation device 26, a controller 30, an information input device 72, a display device D1, a sound output device D2, and the like are provided. In the present specification, for convenience, the side of the upper swing body 3 in which the excavating attachment AT is installed is set as the front side, and the side in which the counterweight is installed is set as the rear side.

[0031] The space recognition device 70 is configured to recognize an object existing in a three-dimensional space around the shovel 100. Also, the space recognition device 70 is configured to calculate a distance between the space recognition device 70 or the shovel 100 and the recognized object. The space recognition device 70 includes, 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 includes a front sensor 70F installed at a front end of an upper surface of the cab 10, a rear sensor 70B installed at a rear end of the upper surface of the upper swing body 3, a left sensor 70L installed at a left end of the upper surface of the upper swing body 3, and a right sensor 70R installed at a right end of the upper surface of the upper swing body 3. Figure 1 An upper sensor that recognizes an object existing in a space above the upper swing body 3 can also be installed in the shovel 100.

[0032] The orientation detection device 71 is configured to detect information about a relative relationship between an orientation of the upper swing body 3 and an orientation of the lower traveling body 1. The orientation detection device 71 can be configured, for example, by a combination of a geomagnetic sensor installed in the lower traveling body 1 and a geomagnetic sensor installed in the upper swing body 3. Alternatively, the orientation detection device 71 can be configured by a combination of a GNSS receiver installed in the lower traveling body 1 and a GNSS receiver installed in the upper swing body 3. The orientation detection device 71 can also be a rotary encoder, a rotary position sensor, or the like. In a structure in which the upper swing body 3 is swing-driven by a swing motor generator, the orientation detection device 71 can be configured by a resolver. The orientation detection device 71 can be installed, for example, at a center joint provided in association with the swing mechanism 2 that realizes relative rotation between the lower traveling body 1 and the upper swing body 3.

[0033] The orientation detection device 71 can also be configured by the space recognition device 70 (e.g., a camera) installed in the upper swing body 3. At this time, the orientation detection device 71 detects an image of the lower traveling body 1 included in an input image by performing known image processing on the image captured by the camera installed in the upper swing body 3. Also, the orientation detection device 71 determines a length direction of the lower traveling body 1 by detecting the image of the lower traveling body 1 using a known image recognition technique. Also, an angle formed between a direction of a front-rear axis of the upper swing body 3 and the length direction of the lower traveling body 1 is derived. The direction of the front-rear axis of the upper swing body 3 is derived from a mounting position of the camera. In particular, the track 1C protrudes from the upper swing body 3, so the orientation detection device 71 can determine the length direction of the lower traveling body 1 by detecting an image of the track 1C. At this time, the orientation detection device 71 can be integrated in the controller 30.

[0034] The information input device 72 is configured to enable an operator of the shovel to input information to the controller 30. In the present embodiment, the information input device 72 is a switch panel provided near a display portion of the display device Dl. However, the information input device 72 can be a touch panel provided on the display portion of the display device Dl, or a sound input device such as a microphone provided in the cab 10. Also, the information input device 72 can be a communication device. In this case, the operator can input information to the controller 30 via a communication terminal such as a smartphone.

[0035] The position measuring device 73 is configured to measure a current position. In the present embodiment, the position measuring device 73 is a GNSS receiver that detects the position of the upper revolving body 3 and outputs the detected value to the controller 30. The position measuring device 73 can be a GNSS compass. In this case, the position measuring device 73 can detect the position and orientation of the upper revolving body 3.

[0036] The body tilt sensor S4 is configured to detect the tilt of the upper revolving body 3 with respect to a prescribed plane. In the present embodiment, the body tilt sensor S4 is an acceleration sensor that detects the tilt angle of the upper revolving body 3 about the fore-aft axis and the tilt angle about the right-left axis with respect to the horizontal plane. The fore-aft axis and the right-left axis of the upper revolving body 3 are, for example, orthogonal to each other and pass through the center point of the shovel, which is a point on the turning axis of the shovel 100.

[0037] The turning angular velocity sensor S5 is configured to detect the turning angular velocity of the upper revolving body 3. In the present embodiment, the turning angular velocity sensor S5 is a gyro sensor. The turning angular velocity sensor S5 can also be a resolver or a rotary encoder. The turning angular velocity sensor S5 can detect the turning speed. The turning speed can be calculated from the turning angular velocity.

[0038] The display device Dl is a device that displays information. In the present embodiment, the display device Dl is a liquid crystal display provided in the cab 10. However, the display device Dl can also be the display of a communication terminal such as a smartphone.

[0039] The sound output device D2 is a device that outputs sound. The sound output device D2 includes at least one of a device that outputs sound to the operator in the cab 10 and a device that outputs sound to a worker outside the cab 10. The sound output device D2 can also be a speaker attached to a communication terminal.

[0040] The operation device 26 is a device used by an operator for the operation of an actuator. In the present embodiment, the operation device 26 is provided in the cab 10 so as to be operable by an operator seated on the driver's seat.

[0041] The controller 30 is a control device (electronic circuit) that can execute various controls. In the present embodiment, the controller 30 is a computer equipped with a CPU, a RAM, an NVRAM, a ROM, and the like, and is configured to control the shovel 100. Also, the controller 30 reads a program corresponding to one or a plurality of functions from the ROM and loads it into the RAM, and causes the CPU to execute processing corresponding to each function. In this way, each function is realized by software. However, at least one of the functions can be realized by hardware, or can be realized by a combination of software and hardware.

[0042] Next, with reference to Figure 2 , a configuration example of a hydraulic system mounted on the shovel 100 will be described. Figure 2 is a view that shows a configuration example of a hydraulic system mounted on the shovel 100. Figure 2 The mechanical power transmission system, the working oil line, the pilot line, and the electrical control system are respectively indicated by double lines, solid lines, broken lines, and dotted lines.

[0043] The hydraulic system of the shovel 100 mainly includes the engine 11, the regulator 13, the main pump 14, the pilot pump 15, the control valve unit 17, the operation device 26, the discharge pressure sensor 28, the operation pressure sensor 29, the controller 30, the dial 75, the ECO button 76, and the like.

[0044] Figure 2 In the present embodiment, the hydraulic system is configured to be able to circulate the working oil from the main pump 14 driven by the engine 11 to the working oil tank through the intermediate bypass line 40 or the parallel line 42.

[0045] The engine 11 is a driving source of the shovel 100. In the present embodiment, the engine 11 is, for example, a diesel engine that operates in such a manner as to maintain a prescribed rotational speed. An output shaft of the engine 11 is linked to input shafts of the main pump 14 and the pilot pump 15, respectively.

[0046] The main pump 14 is configured to be able to supply the working oil to the control valve unit 17 via the working oil line. In the present embodiment, the main pump 14 is a swash plate type variable displacement hydraulic pump.

[0047] The regulator 13 is configured to be able to control the discharge amount of the main pump 14. In the present embodiment, the regulator 13 controls the discharge amount of the main pump 14 by adjusting the swash plate deflection angle of the main pump 14 in accordance with a control command from the controller 30.

[0048] The pilot pump 15 is configured to be able to supply hydraulic oil to the hydraulic control apparatus including the operating device 26 via the pilot line. In the present embodiment, the pilot pump 15 is a fixed displacement type hydraulic pump. The pilot pump 15 can be omitted. In this case, the function of the pilot pump 15 can also be implemented by the main pump 14. That is, the main pump 14 can have a function of supplying hydraulic oil to the operating device 26 or the like after the pressure of the hydraulic oil is reduced by a throttle or the like in addition to a function of supplying hydraulic oil to the control valve unit 17.

[0049] The control valve unit 17 is a hydraulic control device that controls a hydraulic system in the shovel 100. In the present embodiment, the control valve unit 17 includes the switching valves 171 to 176. The switching valve 175 includes the switching valve 175L and the switching valve 175R, and the switching valve 176 includes the switching valve 176L and the switching valve 176R. The control valve unit 17 is configured to be able to selectively supply the hydraulic oil discharged from the main pump 14 to one or a plurality of hydraulic actuators by the switching valves 171 to 176. The switching valves 171 to 176, for example, control the flow rate of the hydraulic oil flowing from the main pump 14 to the hydraulic actuators and the flow rate of the hydraulic oil flowing from the hydraulic actuators to the hydraulic oil tank. The hydraulic actuators include the boom cylinder 7, the stick cylinder 8, the bucket cylinder 9, the left travel hydraulic motor 2ML, the right travel hydraulic motor, and the swing hydraulic motor 2A.

[0050] The operating device 26 is a device used by an operator for the operation of an actuator. The actuator includes at least one of a hydraulic actuator and an electric actuator. In the present embodiment, the operating device 26 is configured to be able to supply the hydraulic oil discharged from the pilot pump 15 to the pilot port of the switching valve corresponding in the control valve unit 17 via the pilot line. The pressure (pilot pressure) of the hydraulic oil supplied to each pilot port is a pressure corresponding to the operation direction and the operation amount of the operating device 26 corresponding to each hydraulic actuator. However, the operating device 26 can be a solenoid pilot type rather than a hydraulic pilot type as described above. Alternatively, the switching valves in the control valve unit 17 can be solenoid type spool valves.

[0051] The discharge pressure sensor 28 is configured to be able to detect the discharge pressure of the main pump 14. In the present embodiment, the discharge pressure sensor 28 outputs the detected value to the controller 30.

[0052] The operation pressure sensor 29 is configured to be able to detect the operation content of the operating device 26 by the operator. In the present embodiment, the operation pressure sensor 29 detects the operation direction and the operation amount of the operating device 26 corresponding to each of the actuators in the form of pressure (operation pressure) and outputs the detected value to the controller 30. The operation content of the operating device 26 can be detected using other sensors or devices than the operation pressure sensor such as a potentiometer.

[0053] The main pumps 14 include a left main pump 14L and a right main pump 14R. Also, the left main pump 14L circulates the working oil to the working oil tank through the left intermediate bypass line 40L or the left parallel line 42L, and the right main pump 14R circulates the working oil to the working oil tank through the right intermediate bypass line 40R or the right parallel line 42R.

[0054] The left intermediate bypass line 40L is a working oil line through the switching valves 171, 173, 175L, and 176L provided in the control valve unit 17. The right intermediate bypass line 40R is a working oil line through the switching valves 172, 174, 175R, and 176R provided in the control valve unit 17.

[0055] The switching valve 171 is a spool valve that switches the flow of the working oil in order to supply the working oil discharged from the left main pump 14L to the left travel hydraulic motor 2ML and discharge the working oil discharged from the left travel hydraulic motor 2ML to the working oil tank.

[0056] The switching valve 172 is a spool valve that switches the flow of the working oil in order to supply the working oil discharged from the right main pump 14R to the right travel hydraulic motor and discharge the working oil discharged from the right travel hydraulic motor to the working oil tank.

[0057] The switching valve 173 is a spool valve that switches the flow of the working oil in order to supply the working oil discharged from the left main pump 14L to the swing hydraulic motor 2A and discharge the working oil discharged from the swing hydraulic motor 2A to the working oil tank.

[0058] The switching valve 174 is a spool valve that switches the flow of the working oil in order to supply the working oil discharged from the right main pump 14R to the bucket cylinder 9 and discharge the working oil in the bucket cylinder 9 to the working oil tank.

[0059] The switching valve 175L is a spool valve that switches the flow of the working oil in order to supply the working oil discharged from the left main pump 14L to the boom cylinder 7. The switching valve 175R is a spool valve that switches the flow of the working oil in order to supply the working oil discharged from the right main pump 14R to the boom cylinder 7 and discharge the working oil in the boom cylinder 7 to the working oil tank.

[0060] The switching valve 176L is a spool valve that switches the flow of the working oil in order to supply the working oil discharged from the left main pump 14L to the stick cylinder 8 and discharge the working oil in the stick cylinder 8 to the working oil tank.

[0061] The switching valve 176R is a spool valve that switches the flow of the working oil in order to supply the working oil discharged from the right main pump 14R to the stick cylinder 8 and discharge the working oil in the stick cylinder 8 to the working oil tank.

[0062] The left parallel line 42L is a hydraulic oil line parallel to the left intermediate bypass line 40L. The left parallel line 42L is able to supply hydraulic oil to a more downstream directional control valve in a case where the flow of hydraulic oil through the left intermediate bypass line 40L is restricted or cut off by one of the directional control valves 171, 173, 175L. The right parallel line 42R is a hydraulic oil line parallel to the right intermediate bypass line 40R. The right parallel line 42R is able to supply hydraulic oil to a more downstream directional control valve in a case where the flow of hydraulic oil through the right intermediate bypass line 40R is restricted or cut off by one of the directional control valves 172, 174, 175R.

[0063] The regulator 13 includes a left regulator 13L and a right regulator 13R. The left regulator 13L controls the discharge amount of the left main pump 14L by regulating the swash plate deflection angle of the left main pump 14L in accordance with the discharge pressure of the left main pump 14L. Specifically, the left regulator 13L, for example, regulates the swash plate deflection angle of the left main pump 14L so as to reduce the discharge amount in accordance with an increase in the discharge pressure of the left main pump 14L. The same applies to the right regulator 13R. This is to prevent the absorbed power (e.g., 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 power (e.g., output horsepower) of the engine 11.

[0064] The operation device 26 includes a left operation lever 26L, a right operation lever 26R, and a travel lever 26D as operation levers. The travel lever 26D includes a left travel lever 26DL and a right travel lever 26DR.

[0065] The left operation lever 26L is used for swing operation and operation of the arm 5. If the left operation lever 26L is operated in the front-rear direction, a control pressure corresponding to the lever operation amount is applied to the pilot port of the directional control valve 176 using hydraulic oil discharged by the pilot pump 15. Also, if the left operation lever 26L is operated in the left-right direction, a control pressure corresponding to the lever operation amount is applied to the pilot port of the directional control valve 173 using hydraulic oil discharged by the pilot pump 15.

[0066] Specifically, the left operation lever 26L, in the case of operation in the arm closing direction, causes hydraulic oil to flow into the right side pilot port of the directional control valve 176L and causes hydraulic oil to flow into the left side pilot port of the directional control valve 176R. Also, the left operation lever 26L, in the case of operation in the arm opening direction, causes hydraulic oil to flow into the left side pilot port of the directional control valve 176L and causes hydraulic oil to flow into the right side pilot port of the directional control valve 176R. Also, the left operation lever 26L, in the case of operation in the left swing direction, causes hydraulic oil to flow into the left side pilot port of the directional control valve 173, and, in the case of operation in the right swing direction, causes hydraulic oil to flow into the right side pilot port of the directional control valve 173.

[0067] The right operation lever 26R is used for operation of the boom 4 and operation of the bucket 6. If the right operation lever 26R is operated in the front-rear direction, a control pressure corresponding to the lever operation amount is applied to the pilot port of the directional valve 175 using the working oil discharged by the pilot pump 15. Also, if the right operation lever 26R is operated in the left-right direction, a control pressure corresponding to the lever operation amount is applied to the pilot port of the directional valve 174 using the working oil discharged by the pilot pump 15.

[0068] Specifically, the right operation lever 26R, in the case of operation in the boom lowering direction, causes working oil to flow into the left pilot port of the directional valve 175R. Also, the right operation lever 26R, in the case of operation in the boom raising direction, causes working oil to flow into the right pilot port of the directional valve 175L, and causes working oil to flow into the left pilot port of the directional valve 175R. Also, the right operation lever 26R, in the case of operation in the bucket closing direction, causes working oil to flow into the right pilot port of the directional valve 174, and, in the case of operation in the bucket opening direction, causes working oil to flow into the left pilot port of the directional valve 174.

[0069] The travel lever 26D is used for operation of the track 1C. Specifically, the left travel lever 26DL is used for operation of the left track 1CL. The left travel lever 26DL can be configured to be linked to the left travel pedal. If the left travel lever 26DL is operated in the front-rear direction, a control pressure corresponding to the lever operation amount is applied to the pilot port of the directional valve 171 using the working oil discharged by the pilot pump 15. The right travel lever 26DR is used for operation of the right track. The right travel lever 26DR can be configured to be linked to the right travel pedal. If the right travel lever 26DR is operated in the front-rear direction, a control pressure corresponding to the lever operation amount is applied to the pilot port of the directional valve 172 using the working oil discharged by the pilot pump 15.

[0070] The discharge pressure sensor 28 includes a discharge pressure sensor 28L and a discharge pressure sensor 28R. The discharge pressure sensor 28L detects the discharge pressure of the left main pump 14L and outputs the detected value to the controller 30. The same applies to the discharge pressure sensor 28R.

[0071] The operation pressure sensor 29 includes operation pressure sensors 29LA, 29LB, 29RA, 29RB, 29DL, and 29DR. The operation pressure sensor 29LA detects, in the form of pressure, the operation content by the operator with respect to the left operation lever 26L in the front-rear direction and outputs the detected value to the controller 30. The operation content is, for example, the lever operation direction and the lever operation amount (lever operation angle), and the like.

[0072] Similarly, the operation pressure sensor 29LB detects the content of the operation on the left operating lever 26L in the left-right direction by the operator in the form of pressure and outputs the detected value to the controller 30. The operation pressure sensor 29RA detects the content of the operation on the right operating lever 26R in the front-rear direction by the operator in the form of pressure and outputs the detected value to the controller 30. The operation pressure sensor 29RB detects the content of the operation on the right operating lever 26R in the left-right direction by the operator in the form of pressure and outputs the detected value to the controller 30. The operation pressure sensor 29DL detects the content of the operation on the left traveling lever 26DL in the front-rear direction by the operator in the form of pressure and outputs the detected value to the controller 30. The operation pressure sensor 29DR detects the content of the operation on the right traveling lever 26DR in the front-rear direction by the operator in the form of pressure and outputs the detected value to the controller 30.

[0073] The controller 30 receives the output of the operation pressure sensors 29 and outputs a control command to the regulator 13 as necessary to change the discharge amount of the main pump 14. Also, the controller 30 receives the output of the control pressure sensors 19 provided upstream of the regulators 18 and outputs a control command to the regulator 13 as necessary to change the discharge amount of the main pump 14. The regulators 18 include the left regulator 18L and the right regulator 18R, and the control pressure sensors 19 include the left control pressure sensor 19L and the right control pressure sensor 19R.

[0074] In the left intermediate bypass passage 40L, the left regulator 18L is provided between the changeover valve 176L at the most downstream and the working oil tank. Therefore, the flow of the working oil discharged from the left main pump 14L is restricted by the left regulator 18L. Also, the left regulator 18L generates a control pressure for controlling the left regulator 13L. The left control pressure sensor 19L is a sensor for detecting this control pressure and outputs the detected value to the controller 30. The controller 30 controls the discharge amount of the left main pump 14L by adjusting the swash plate deflection angle of the left main pump 14L in accordance with the control pressure. The controller 30 controls such that the greater the control pressure, the smaller the discharge amount of the left main pump 14L, and the smaller the control pressure, the greater the discharge amount of the left main pump 14L. The discharge amount of the right main pump 14R is also controlled in the same manner.

[0075] Specifically, as Figure 2In the standby state in which none of the hydraulic actuators in the shovel 100 is operated, the working oil discharged from the left main pump 14L reaches the left regulator 18L through the left intermediate bypass line 40L as shown in FIG. 1. And, the flow of the working oil discharged from the left main pump 14L increases the control pressure generated upstream of the left regulator 18L. As a result, the controller 30 reduces the discharge amount of the left main pump 14L to the minimum discharge amount allowed, and suppresses the pressure loss (suction loss) when the discharged working oil passes through the left intermediate bypass line 40L. On the other hand, in the case where a certain hydraulic actuator is operated, the working oil discharged from the left main pump 14L flows into the operated hydraulic actuator via the switching valve corresponding to the operated hydraulic actuator. And, the flow of the working oil discharged from the left main pump 14L reduces or eliminates the amount of reaching the left regulator 18L, and reduces the control pressure generated upstream of the left regulator 18L. As a result, the controller 30 increases the discharge amount of the left main pump 14L, and circulates sufficient working oil in the operated hydraulic actuator, thereby ensuring the drive of the operated hydraulic actuator. In addition, the controller 30 also controls the discharge amount of the right main pump 14R in the same manner.

[0076] With the above-described structure, Figure 2 The hydraulic system according to the present embodiment can suppress unnecessary energy consumption in the main pumps 14 in the standby state. The unnecessary energy consumption includes the suction loss generated in the intermediate bypass line 40 by the working oil discharged from the main pumps 14. And, in the case where the hydraulic actuators are operated, Figure 2 The hydraulic system according to the present embodiment can reliably supply sufficient working oil from the main pumps 14 to the operated hydraulic actuators.

[0077] The dial 75 is configured to enable the operator to manually adjust the target rotation speed of the engine 11. Specifically, the dial 75 is configured to be able to transmit information indicating the set state of the target rotation speed of the engine 11 to the controller 30. In the present embodiment, the dial 75 is configured to be able to switch the target rotation speed in ten stages from the 1st stage (a stage corresponding to the highest target rotation speed) to the 10th stage (a stage corresponding to the lowest target rotation speed). The actual rotation speed of the engine 11 is controlled so as to become the target rotation speed selected by the dial 75.

[0078] The ECO button 76 is an example of an operation tool for switching the on / off of the ECO mode. The ECO mode is one of the working modes of the shovel 100, and is a working mode in which a function for suppressing energy (fuel) consumption is executed. The working modes of the shovel 100 can include a crane mode used when the crane is operated, and the like. In the present embodiment, the working modes of the shovel 100 are configured to be switched between the ECO mode and a normal mode each time the ECO button 76 is pressed. The normal mode is one of the working modes of the shovel 100, and is a working mode in which the function for suppressing fuel consumption is not executed. The function executed in the ECO mode includes, for example, a function of slowing down the attachment operation. If the function of slowing down the attachment operation is executed, the extension / contraction acceleration of each of the boom cylinder 7, the stick cylinder 8, and the bucket cylinder 9 when the operation lever is moved away from the neutral position is limited to be below a predetermined value. In the present embodiment, the maximum extension / contraction speed is not limited, but the maximum extension / contraction speed can also be limited. Also, in the present embodiment, the extension / contraction acceleration when the operation lever is returned to the neutral position is not limited, but the extension / contraction acceleration when the operation lever is returned to the neutral position can also be limited. This function is realized, for example, by limiting the stroke acceleration (rate of increase of the pilot pressure) of the directional control valves 174 to 176. By using the ECO button 76, the operator of the shovel 100 can suppress the consumption of fuel as needed. Therefore, the shovel 100 can, for example, correspond to a case where the operator wants to suppress the fuel consumption even if the operability of the shovel 100 is limited.

[0079] Next, the information acquisition section 30a and the control section 30b, which are functions of the controller 30, will be described. Figure 2 In the present embodiment, the information acquisition section 30a and the control section 30b are distinguished for convenience of explanation, but need not be physically distinguished, and can be constituted by software components or hardware components common to the whole or a part, or a combination thereof.

[0080] The information acquisition section 30a is configured to acquire information relating to the shovel 100. In the present embodiment, the information acquisition section 30a is configured to acquire information from at least one of the boom angle sensor S1, the stick angle sensor S2, the bucket angle sensor S3, the body inclination sensor S4, the swing angular velocity sensor S5, a cylinder pressure sensor, a swing pressure sensor, a travel pressure sensor, a boom cylinder stroke sensor, a stick cylinder stroke sensor, a bucket cylinder stroke sensor, the discharge pressure sensor 28, the operation pressure sensor 29, the space recognition device 70, the orientation detection device 71, the information input device 72, the position measurement device 73, a communication device, and the like. The cylinder pressure sensor includes, for example, at least one of a boom rod pressure sensor, a boom bottom pressure sensor, a stick rod pressure sensor, a stick bottom pressure sensor, a bucket rod pressure sensor, a bucket bottom pressure sensor, and the like.

[0081] The information acquisition unit 30a acquires, for example, at least one of the swing boom angle, the arm angle, the bucket angle, the body tilt angle, the swing angular velocity, the boom rod pressure, the boom bottom pressure, the arm rod pressure, the arm bottom pressure, the bucket rod pressure, the bucket bottom pressure, the swing pressure, the travel pressure, the boom stroke amount, the arm stroke amount, the bucket stroke amount, the discharge pressure of the main pump 14, the operation pressure of the operation device 26, information related to an object existing in the three-dimensional space around the shovel 100, information related to the relative relationship between the orientation of the upper swing body 3 and the orientation of the lower travel body 1, information input to the controller 30, and information related to the current position, as information related to the work content of the shovel 100. At least one of the boom rod pressure, the boom bottom pressure, the arm rod pressure, the arm bottom pressure, the bucket rod pressure, and the bucket bottom pressure is also referred to as a cylinder pressure.

[0082] The control unit 30b is configured to be able to determine whether a specific work or a specific action is being performed, depending on the information related to the work content of the shovel 100.

[0083] For example, the control unit 30b is able to determine whether excavation is being performed, depending on the posture of the excavating attachment AT and the pressure of the working oil in the boom cylinder 7. Specifically, the control unit 30b is able to determine whether excavation is being performed, depending on the posture of the excavating attachment AT derived from the swing boom angle and the arm angle and the boom bottom pressure.

[0084] Also, the control unit 30b is able to determine whether the boom raising action is being performed, depending on the output of the operation pressure sensor 29RA. Specifically, the control unit 30b is able to determine whether the boom raising action is being performed, depending on the pilot pressure (hereinafter referred to as "boom raising pilot pressure") acting on the pilot port of the directional valve 175 when the right operation lever 26R is operated in the boom raising direction.

[0085] Also, the control unit 30b is able to determine whether the boom lowering action is being performed, depending on the output of the operation pressure sensor 29RA. Specifically, the control unit 30b is able to determine whether the boom lowering action is being performed, depending on the pilot pressure (hereinafter referred to as "boom lowering pilot pressure") acting on the pilot port of the directional valve 175 when the right operation lever 26R is operated in the boom lowering direction.

[0086] Also, the control unit 30b is configured to be able to control the action of the shovel 100, depending on the information related to the work content of the shovel 100. In the present embodiment, the control unit 30b is configured to reduce the rotation speed of the engine 11 before starting a low-load action of the excavating attachment AT when the implementation of the low-load action of the excavating attachment AT is expected.

[0087] This is because, in a case where the same rotation speed as that of the engine 11 at the time of performing the high-load operation of the excavating attachment AT is utilized in order to perform the low-load operation of the excavating attachment AT, fuel is consumed more than necessary. Therefore, the control section 30b is configured to reduce the rotation speed of the engine 11 before the low-load operation is started, in order to suppress unnecessary consumption of fuel.

[0088] The low-load operation of the excavating attachment AT is, for example, a boom lowering and swing operation, a boom lowering and sole operation, or an operation in a dumping procedure. The boom lowering and swing operation is typically a compound operation based on a combination of a boom lowering operation and a swing operation. However, the boom lowering and swing operation can also be a compound operation based on a combination of a boom lowering operation, a swing operation, and a bucket opening operation. The operation in the dumping procedure is typically a compound operation based on a combination of an aerial boom lowering operation, a stick opening operation, and a bucket opening operation. However, the operation in the dumping procedure can be a compound operation based on a combination of a stick opening operation and a bucket opening operation, or a bucket closing sole operation. The high-load operation of the excavating attachment AT is, for example, a boom raising and swing operation, a boom raising sole operation, or a stick closing operation in a digging procedure. The boom raising and swing operation is a compound operation based on a combination of a boom raising operation and a swing operation.

[0089] The "before the low-load operation is started" is, for example, before the boom lowering and swing operation is started. At this time, "before the boom lowering and swing operation is started" is preferably before the right operating lever 26R is tilted in the boom lowering direction. This is because the earlier the timing at which the rotation speed of the engine 11 is reduced, the more the amount of fuel that is wasted when the low-load operation is actually performed can be reduced.

[0090] For example, "before the boom lowering and swing operation is started" can be when the boom raising operation is about to end. That is, the control section 30b can be configured to reduce the rotation speed of the engine 11 when it is determined that the boom lowering and swing operation is to be performed during the boom raising operation, in other words, before the boom raising operation is ended.

[0091] However, "before the boom lowering and swing operation is started" can be when the right operating lever 26R is tilted in the boom lowering direction, or can be before the boom cylinder 7 is actually contracted after the right operating lever 26R is tilted in the boom lowering direction.

[0092] Alternatively, "before the boom lowering and swing operation is started" can be when it is detected that the boom tilt operation is switched from the operation in the maximum tilt angle direction to the operation in the neutral direction. Alternatively, "before the boom lowering and swing operation is started" can be when it is detected that the boom tilt operation is switched from the operation in the maximum tilt angle direction to the operation in the neutral direction at around 80% of the boom tilt. Note that the boom tilt at the maximum tilt angle is set to 100% and the boom tilt at the neutral position is set to 0%.

[0093] Here, for reference Figure 3 An example of the process by which the control unit 30b of the controller 30 reduces the speed of the engine 11 before the start of low-load operation (hereinafter referred to as "speed reduction process") will be described. Figure 3 This is a flowchart illustrating an example of speed reduction processing during excavation and loading operations. The excavation and loading operation is divided into an excavation phase, a boom raising and slewing phase, a dumping phase, and a boom lowering and slewing phase. The low-load operation is an action within the dumping phase. The excavation phase consists of at least one of the following: a boom raising action, a stick closing action, and a bucket closing action. The dumping phase consists of at least one of the following: a boom lowering action, a stick opening action, and a bucket opening action. The control unit 30b repeatedly executes this speed reduction processing at a predetermined control cycle until the engine speed 11 is actually reduced. Figure 3 In the example shown, the control unit 30b is configured to perform speed reduction processing when ECO mode is on, and not to perform speed reduction processing when ECO mode is off. However, the control unit 30b can be configured to perform speed reduction processing regardless of whether ECO mode is on or off.

[0094] First, the control unit 30b determines whether the excavation process has started (step ST1). Figure 3 In the example shown, the control unit 30b determines whether digging has been performed within a specified period (e.g., 1 second) including the current moment, based on information related to the work content of the excavator 100 acquired by the information acquisition unit 30a, and thus determines whether the digging process has started. Specifically, the control unit 30b determines whether digging has been performed within the specified period based on the posture of the digging attachment AT derived from the boom angle and stick angle acquired within that specified period, and the boom bottom pressure acquired within that specified period. Furthermore, the posture of the digging attachment AT can be derived from the boom angle, stick angle, and bucket angle.

[0095] Alternatively, control unit 30b can determine whether digging has occurred based on stick pressure, stick bottom pressure, stick pilot pressure, and bucket pilot pressure. Stick pilot pressure is the pilot pressure acting on the pilot port of directional valve 176. Bucket pilot pressure is the pilot pressure acting on the pilot port of directional valve 174.

[0096] Alternatively, the control unit 30b can determine whether digging has been performed based on the bucket closing pilot pressure, the boom raising pilot pressure, and the discharge pressure of the main pump 14, or based on the bucket closing pilot pressure, the stick closing pilot pressure, and the discharge pressure of the main pump 14. The bucket closing pilot pressure is the pilot pressure applied to the pilot port of the directional valve 174 when the right operating lever 26R is operated in the bucket closing direction. The stick closing pilot pressure is the pilot pressure applied to the pilot port of the directional valve 176 when the left operating lever 26L is operated in the stick closing direction.

[0097] In a case where it is determined that the excavating operation has not started (NO in step ST1), the control section 30b determines that there is no excavating operation, and thus ends the present rotational speed reduction processing. This is because implementation of the low-load operation is not expected. Specifically, this is because the control section 30b can determine that, since there is no sand or the like in the bucket 6, operation in the dumping operation as the low-load operation will not be performed.

[0098] In a case where it is determined that the excavating operation has started (YES in step ST1), the control section 30b determines whether the excavating operation has ended (step ST2). Figure 3 In the illustrated example, the control section 30b determines whether the excavating operation has ended, based on at least one of the operation pressure and the cylinder pressure acquired by the information acquisition section 30a.

[0099] In a case where it is determined that the excavating operation has not ended (NO in step ST2), the control section 30b ends the present rotational speed reduction processing. This is because implementation of the low-load operation is not expected. Specifically, this is because the control section 30b can determine that, since the excavating operation has not ended, operation in the dumping operation as the low-load operation will not be performed.

[0100] In a case where it is determined that the excavating operation has ended (YES in step ST2), it is determined that the excavating operation has ended, and the control section 30b determines whether the swing-up operation of the boom has started. Specifically, the control section 30b determines whether the swing-up operation of the boom has started (step ST3). Figure 3 In the illustrated example, the control section 30b determines whether the swing-up operation of the boom is being performed, based on the boom swing-up pilot pressure acquired by the information acquisition section 30a, and thus determines whether the swing-up operation of the boom has started. Specifically, the control section 30b determines that the swing-up operation of the boom is being performed (boom swing-up operation) in a case where the boom swing-up pilot pressure exceeds the first prescribed pressure (for example, 2.0 MPa).

[0101] In a case where it is determined that the swing-up operation of the boom has not started (NO in step ST3), the control section 30b ends the present rotational speed reduction processing. This is because implementation of the low-load operation is not expected. Specifically, this is because the control section 30b can determine that, since the swing-up operation of the boom has not been performed, the boom-down-only operation or the boom-down-while-swinging operation as the low-load operation will not be performed.

[0102] In a case where it is determined that the swing-up operation of the boom has started (YES in step ST3), it is determined that the swing-up operation of the boom has started, and the control section 30b determines whether the swing-up operation of the boom is about to end (step ST4). Also, Figure 3In the example shown, the control section 30b is configured to omit the determinations of steps ST1, ST2, and ST3 and perform the determination of step ST4 when repeatedly performing the rotation speed reduction process after determining that the boom is being raised.

[0103] Specifically, the control section 30b determines whether the boom raising is about to end based on the boom raising pilot pressure acquired by the information acquisition section 30a, and thereby determines whether the boom raising swing process is about to end. More specifically, the control section 30b determines that the boom raising is about to end when the boom raising pilot pressure that exceeds the first prescribed pressure is lower than a second prescribed pressure (e.g., 1.5 MPa). The second prescribed pressure is typically a pressure lower than the first prescribed pressure. However, the second prescribed pressure can be equal to or higher than the first prescribed pressure.

[0104] The control section 30b can determine that the boom raising is about to end when the boom raising pilot pressure that exceeds the first prescribed pressure continuously decreases within a prescribed time.

[0105] Alternatively, the control section 30b can determine that the boom raising is about to end when the boom raising pilot pressure that exceeds the first prescribed pressure continuously decreases within a prescribed time.

[0106] When it is determined that the boom raising swing process is not about to end (NO in step ST4), the control section 30b ends the present rotation speed reduction process. This is because the control section 30b can determine that the low-load operation will not be performed immediately at the present time because the boom raising is being continued.

[0107] When it is determined that the boom raising swing process is about to end (YES in step ST4), it is determined that the low-load operation (the dumping process) will be started before the boom lowering is performed, and the control section 30b reduces the rotation speed of the engine 11 (step ST5). This is because the control section 30b can determine that the boom lowering alone operation or the boom lowering swing operation as the low-load operation is highly likely to be performed within a prescribed time thereafter.

[0108] Specifically, the control section 30b reduces the actual rotation speed of the engine 11 by reducing the target rotation speed of the engine 11. Figure 3 In the example shown, the control section 30b adopts a value obtained by subtracting a prescribed value (a prescribed reduction amount) from a value of the current target rotation speed (hereinafter referred to as "first target rotation speed") as a value of a new target rotation speed (hereinafter referred to as "second target rotation speed"). Figure 3In the example shown, the prescribed reduction amount is a value that is set in advance for each level of the first target engine speed. At this time, for example, the value of the second target engine speed set when the first level is selected as the first target engine speed is different from the value of the second target engine speed set when the second level is selected as the first target engine speed. However, the control section 30b can also adopt a value that is set in advance as the value of the second target engine speed regardless of the first target engine speed. At this time, for example, the value of the second target engine speed set when the first level is selected as the first target engine speed can be the same as the value of the second target engine speed set when the second level is selected as the first target engine speed. The same applies to the relationship between the first level and the second level and other levels.

[0109] Next, with reference to Figure 4 , the execution Figure 3 of the engine speed reduction process shown will be described. Figure 4 The changes in the target engine speed N, the boom raising pilot pressure Pu, and the boom lowering pilot pressure Pd over time are shown. Specifically, Figure 4 (A) of FIG. 10 shows the change in the target engine speed N over time, Figure 4 (B) of FIG. 10 shows the change in the boom raising pilot pressure Pu over time, Figure 4 (C) of FIG. 10 shows the change in the boom lowering pilot pressure Pd over time. Also, Figure 4 In the example shown, the target engine speed is maintained at the value N0 at the time of idling until the time ts. Also, the operator of the shovel 100 ends the digging work at the time t0, and then successively performs the boom raising operation, the right turning operation, and the boom lowering operation, and wants to perform the dumping work. However, the following description also applies to the case where the right turning operation and the boom lowering operation are performed at the same time, i.e., the case where the boom lowering turning action is performed.

[0110] Specifically, Figure 4 In the example shown, the operator of the shovel 100 starts the operation of the right operation lever 26R in the boom raising direction at the time t1. At this time, as shown in Figure 4 (A) of FIG. 11, the target engine speed N of the engine 11 is set to the value N1 of the first target engine speed. Also, as shown in Figure 4 (B) of FIG. 11, the boom raising pilot pressure Pu becomes the value Pu0 that indicates that the right operation lever 26R is positioned at the neutral position.

[0111] Then, if the boom raising pilot pressure Pu exceeds the value Pu1 at the time t2, the control section 30b of the controller 30 determines that the boom raising is being performed. The value Pu1 is a value that is set in advance in the control section 30b of the controller 30. Figure 4The threshold value used in step ST3 is the boom lifting pilot pressure Pu when the right control lever 26R is tilted about 80% in the boom lifting direction.

[0112] Then, at time t3, the operator of excavator 100 begins to return the right control lever 26R, which operates in the boom lifting direction, to the neutral position. At this time, as... Figure 3 As shown in (A), the target speed N of engine 11 is set to a value N1. Value N1 can, for example, be the value of the rated engine speed. That is, Figure 4 In the example shown, during boom raising, the engine speed of engine 11 can be controlled to be the rated engine speed. However, during boom raising, the engine speed of engine 11 can be controlled to be a speed higher than the rated engine speed. Furthermore, as... Figure 4 As shown in (B), the boom lifting pilot pressure Pu is Pu2, which indicates that the right operating lever 26R is tilted to the maximum extent in the boom lifting direction.

[0113] Then, if the boom lifting pilot pressure Pu is lower than the value Pu3 at time t4, the control unit 30b of the controller 30 determines that the boom lifting is about to end. The value Pu3 is... Figure 4 The threshold used in step ST4 is the decision.

[0114] If the control unit 30b determines that the boom raising is about to end, it reduces the target speed N of the engine 11 from the current value N1 (the first target speed) to a preset value N2, which is the value for the second target speed. Therefore, as Figure 3 As shown in (A), the target rotational speed N changes from value N1 to value N2 at time t4.

[0115] Then, at time t5, the operator of excavator 100 returns the right operating lever 26R, which operates in the boom raising direction, to the neutral position. Then, at time t6, the operator begins operating the right operating lever 26R in the boom lowering direction. Figure 4 In the example shown, when the control unit 30b determines that the boom lowering operation has begun, it continues to maintain the target speed N of the engine 11 at a value of N2. Therefore, as Figure 4 As shown in (A), the target speed N of engine 11 is maintained at the value N2. Furthermore, as... Figure 4 As shown in (C), the boom lowering pilot pressure Pd becomes the value Pd0, which indicates that the right operating lever 26R is in the neutral position.

[0116] Then, as Figure 4 As shown in (C), the boom lowering pilot pressure Pd reaches value Pd1 at time t7. Value Pd1 represents the value indicating that the right operating lever 26R is tilted to its maximum extent in the boom lowering direction.

[0117] Then, the operator of the shovel 100 starts returning the right operating lever 26R, which is operated in the boom lowering direction, to the neutral position at time t8. Then, as shown in (C) of FIG. 10, the boom lowering pilot pressure Pd reaches the value PdO at time t9. As shown in (A) of FIG. 10, the target engine speed N of the engine 11 is maintained at the value N2 during the period from time t6 to time t9, that is, during the entire period in which the right operating lever 26R is operated in the boom lowering direction. Figure 4 Figure 4

[0118] Thus, the control section 30b can reduce the engine speed of the engine 11 when the boom lowering sole operation, which is a low load operation, is performed. Therefore, the control section 30b can suppress unnecessary consumption of energy (fuel).

[0119] Further, the control section 30b can reduce the engine speed of the engine 11 before starting the boom lowering sole operation. Therefore, the control section 30b can reduce the engine speed of the engine 11 during a period longer than the period in which the boom lowering sole operation is actually performed. As a result, the control section 30b can further suppress unnecessary consumption of fuel compared to the case in which the engine speed of the engine 11 is reduced after the boom lowering sole operation has started.

[0120] In addition, in the example shown in FIG. 10, if operation of the right operating lever 26R in the boom raising direction is started at a later time t10, the control section 30b restores (increases) the target engine speed N of the engine 11 from the current value N2 to the value Nl of the original target engine speed. Therefore, as shown in (A) of FIG. 10, the target engine speed N is changed from the value N2 to the value Nl at time t10. In addition, the control section 30b can restore (increase) the target engine speed N of the engine 11 from the current value N2 to the value Nl of the original target engine speed when the boom raising swing operation or the like, which is a composite operation, has started. Figure 4 Figure 4

[0121] Alternatively, the control section 30b can restore (increase) the target engine speed N of the engine 11 from the current value N2 to the value Nl of the original target engine speed when it is determined that the boom lowering operation has ended, that is, at time t9.

[0122] Further, the control section 30b can restore (increase) the target engine speed N of the engine 11 from the current value N2 to the value Nl of the original target engine speed in stages.

[0123] Next, another example of the engine speed reduction process will be described with reference to FIG. 11. Figure 5 Figure 5 ​​​​​is a flowchart of another example of the rotational speed reduction process. The control section 30b repeatedly executes this rotational speed reduction process at a prescribed control cycle until the rotational speed of the engine 11 is actually reduced. Also, Figure 5 In the example shown, the control section 30b is configured to execute the rotational speed reduction process when the ECO mode is on, and not to execute the rotational speed reduction process when the ECO mode is off. However, the control section 30b can be configured to execute the rotational speed reduction process regardless of whether the ECO mode is on or off.

[0124] Figure 5 The steps ST1 to ST5 in the flowchart shown are the same as the steps ST1 to ST5 in the flowchart shown in FIG. 7. Therefore, hereinafter, the description relating to the steps ST1 to ST5 will be omitted, and the steps ST6 and ST7 that follow will be described in detail. Figure 3 The steps ST1 to ST5 in the flowchart shown are the same as the steps ST1 to ST5 in the flowchart shown in FIG. 7. Therefore, hereinafter, the description relating to the steps ST1 to ST5 will be omitted, and the steps ST6 and ST7 that follow will be described in detail.

[0125] After the rotational speed of the engine 11 is reduced in the step ST5, the control section 30b of the controller 30 determines whether the earth removal work has started (step ST6). Figure 5 In the example shown, the control section 30b determines whether the boom lowering has started, based on the boom lowering pilot pressure acquired by the information acquisition section 30a, thereby determining whether the earth removal work has started. Specifically, the control section 30b determines that the boom lowering has started (boom lowering operation) when the boom lowering pilot pressure exceeds the third prescribed pressure.

[0126] When it is determined that the earth removal work has not started (NO in the step ST6), the control section 30b ends the present rotational speed reduction process. This is because the control section 30b can determine that the low-load operation is unlikely to be performed. Specifically, this is because the control section 30b can determine that the boom lowering-only operation or the boom lowering-rotation operation, which are the low-load operations, is unlikely to be performed.

[0127] When it is determined that the earth removal work has started (YES in the step ST6), the control section 30b reduces the rotational speed of the engine 11 (step ST7). This is because the control section 30b can determine that the boom lowering-only operation or the boom lowering-rotation operation, which are the low-load operations, is actually performed.

[0128] Specifically, the control section 30b further reduces the actual rotational speed of the engine 11 by further reducing the target rotational speed of the engine 11. Figure 5 In the example shown, the control section 30b adopts, as the value of the new target rotational speed (hereinafter, referred to as "third target rotational speed"), the value obtained by subtracting a prescribed value (second reduction amount) from the value of the second target rotational speed. The value of the second target rotational speed is the value obtained by subtracting a prescribed value (first reduction amount) from the value of the first target rotational speed. Therefore, the third target rotational speed is also a value dependent on the value of the first target rotational speed.Figure 5 In the example shown, both the first reduction magnitude and the second reduction magnitude are preset values ​​for each level of the first target speed. However, the control unit 30b may also use preset values ​​as the value of the third target speed, regardless of the first target speed.

[0129] Next, refer to Figure 6 , for execution Figure 5 The changes in the target speed N of engine 11, boom lifting pilot pressure Pu, and boom lowering pilot pressure Pd over time during the speed reduction process are explained. Figure 6 This represents the time-varying changes in target rotational speed N, boom lifting pilot pressure Pu, and boom lowering pilot pressure Pd. Specifically, Figure 6 (A) represents the change of the target rotational speed N over time. Figure 6 (B) represents the change of boom lifting pilot pressure Pu over time. Figure 6 (C) represents the time-varying pilot pressure Pd during boom descent. Additionally, regarding... Figure 6 The target rotational speed N shown in (A) changes with time up to time t6a. Figure 4 The target rotational speed N shown in (A) changes with time in the same way. Furthermore, Figure 6 The change of boom lifting pilot pressure Pu over time shown in (B) is related to... Figure 4 The change of boom lifting pilot pressure Pu over time is the same as shown in (B). Figure 6 The time variation of the boom descent pilot pressure Pd shown in (C) is compared with... Figure 4 The change of the boom lowering pilot pressure Pd over time is the same as shown in (C). Therefore, the change of the target rotational speed N over time after time t6a will be explained in detail below.

[0130] In addition, with Figure 4 Similarly, the operator of the excavator 100 finishes the excavation process at time t0, and then sequentially performs the boom raising operation, the right slewing operation, and the boom lowering operation, and performs the soil removal operation. However, the following explanation also applies when the right slewing operation and the boom lowering operation are performed simultaneously, that is, when the boom lowering and slewing action is performed.

[0131] At time t6, the operator begins operating the right control lever 26R in the boom-lowering direction. At this time, as... Figure 6 As shown in (A), the target speed N of engine 11 is set to the value N2. Furthermore, as... Figure 6 As shown in (C), the boom lowering pilot pressure Pd becomes the value Pd0, which indicates that the right operating lever 26R is in the neutral position.

[0132] Then, as Figure 6the boom lowering pilot pressure Pd reaches a value Pdt at time t6a. The value Pdt is a value indicating that the right operating lever 26R is in a state of being tilted to the boom lowering direction by the maximum degree. The value Pdt is set in advance as a value of the target engine speed N at the time of the boom lowering operation. Figure 5 the threshold value utilized in the determination of step ST6.

[0133] If the boom lowering pilot pressure Pd exceeds the value Pdt at time t6a, the control portion 30b of the controller 30 determines that the boom lowering has started. Also, if the control portion 30b determines that the boom lowering has started, the control portion 30b reduces the target engine speed N of the engine 11 from the current value N2 to a value N3 which is set in advance as a third target engine speed. Thus, as shown in (A) of FIG. 10, the target engine speed N is changed from the value N2 to the value N3 at time t6a. Figure 6

[0134] Then, as shown in (C) of FIG. 10, the boom lowering pilot pressure Pd reaches a value Pdl at time t7. The value Pdl is a value indicating that the right operating lever 26R is in a state of being tilted to the boom lowering direction by the maximum degree. Figure 6

[0135] Then, the operator of the shovel 100 starts returning the right operating lever 26R operated to the boom lowering direction to the neutral position at time t8. Then, as shown in (C) of FIG. 10, the boom lowering pilot pressure Pd reaches a value Pdo at time t9. As shown in (A) of FIG. 10, the target engine speed N of the engine 11 is maintained at the value N3 during the period from time t7 to time t9, that is, during almost the entire period during which the right operating lever 26R is operated to the boom lowering direction. Figure 6 Figure 6

[0136] Thus, compared with the case of Figure 4 , the control portion 30b of the controller 30 can further reduce the engine speed of the engine 11 at the time of the boom lowering independent operation which is the low load operation. Thus, the control portion 30b can further suppress the unnecessary consumption of energy (fuel).

[0137] ​​​​Further, the control section 30b can lower the engine speed of the engine 11 before starting the boom lowering individual action, and can further lower the engine speed of the engine 11 after starting the boom lowering individual action. Therefore, the control section 30b can lower the engine speed of the engine 11 for a longer period than the period during which the boom lowering individual action is actually performed. Also, the control section 30b can further lower the engine speed of the engine 11 for almost the entire period during which the boom lowering individual action is actually performed. As a result, the control section 30b can further suppress the consumption of unnecessary energy (fuel) compared to the case where the engine speed of the engine 11 is lowered after starting the boom lowering individual action. Also, the control section 30b can further suppress the consumption of unnecessary energy (fuel) compared to the case where the engine speed of the engine 11 is lowered before starting the boom lowering individual action and is maintained until ending the boom lowering individual action.

[0138] Further, the control section 30b can prevent the engine speed of the engine 11 from being excessively lowered in the case where the high-load action is performed without the anticipated low-load action being performed. This is because the control section 30b can lower the engine speed of the engine 11 in stages. For example, assume the case where, after the value of the target engine speed of the engine 11 is lowered to the value N3 of the third target engine speed instead of the value N2 of the second target engine speed at time t4, the boom raising action as the high-load action is started instead of the boom lowering action as the low-load action at time t6. At this time, the control section 30b wants to restore the engine speed of the engine 11 to increase the output power of the engine 11 at the time when the boom raising action has started, in order to smoothly perform the boom raising action. However, the actual engine speed of the engine 11 does not sharply increase, and therefore the control section 30b can not be able to smoothly raise the boom 4. In contrast, when the value of the target engine speed of the engine 11 is set to the value N2 of the second target engine speed at time t4, the control section 30b can restore the engine speed of the engine 11 early even after the boom raising action has started, and can smoothly raise the boom 4.

[0139] In addition, Figure 6 In the example shown, if the right operating lever 26R is returned to the neutral position at time t9, the control section 30b increases the target engine speed N of the engine 11 from the current value N3 to the value Nl of the original target engine speed. Therefore, as shown in (A) of Fig. 10, the target engine speed N is changed from the value N3 to the value Nl at time t9. Figure 6

[0140] Alternatively, the control section 30b can also restore (increase) the target engine speed N of the engine 11 from the current value N3 to the value Nl of the original target engine speed at time t10 when the right operating lever 26R has started the operation in the boom raising direction.

[0141] ​Also, the control section 30b can cause the target engine speed N of the engine 11 to be gradually restored (increased) from the current value N3 to the value Nl of the original target engine speed.

[0142] As described above, the excavator 100 according to an embodiment of the present application has: a lower traveling body 1; an upper swing body 3 swingably mounted on the lower traveling body 1; an attachment (excavating attachment AT) mounted on the upper swing body 3; and an engine 11 mounted on the upper swing body 3. Also, the excavator 100 is configured to reduce the engine speed of the engine 11 before starting low-load operation of the excavating attachment AT.

[0143] The "before starting low-load operation of the excavating attachment AT" can be, for example, immediately before the time point at which the boom lowering individual operation is started in the case of Figure 4 and Figure 6 This time, the "before starting low-load operation of the excavating attachment AT" can include the period from after the boom raising pilot pressure Pu becomes the value PuO at the time point t5 to before the boom lowering pilot pressure Pd becomes higher than the value PdO at the time point t6.

[0144] For example, the excavator 100 is shifted to a state in which the engine speed of the engine 11 is reduced in the case where the operation content of the operation lever and the operation state of the excavator 100 satisfy predetermined conditions. The operation state of the excavator 100 includes, for example, a state in which the ECO mode is on and a state in which the ECO mode is off, and the like. Also, the excavator 100 is shifted to a state in which the engine speed of the engine 11 is reduced before the boom lowering operation is performed. Also, the excavator 100 determines how much the engine speed of the engine 11 is reduced in accordance with the level of the selected target engine speed.

[0145] Also, the reduced engine speed of the engine 11 is preferably lower than the engine speed of the engine 11 in the excavating process (from the start of the excavating to the end of the excavating). For example, Figure 4 In the example shown in FIG. 8, the reduced engine speed of the engine 11, i.e., the engine speed when the target engine speed N is set to the value N2, is lower than the engine speed of the engine 11 in the excavating process, i.e., the engine speed when the target engine speed N is set to the value Nl. Note that the value Nl and the value N2 are values that vary in accordance with the level selected by the dial 75.

[0146] Also, the timing at which the engine speed of the engine 11 is reduced can be determined independently of the discharge pressure of the main pump 14. For example, as shown in FIG. 9, the timing at which the engine speed of the engine 11 is reduced can be determined in accordance with the operation content of the right operation lever 26R independently of the discharge pressure of the main pump 14. Figure 5

[0147] ​This structure allows the excavator 100 to reduce energy wasted during low-load operations. This is because it enables the engine 11 to operate at speeds appropriate for low-load operations, and reduces the amount of fuel wasted in the engine 11. In other words, if low-load operations were performed while maintaining the engine 11 speed appropriate for high-load operations, fuel would be wasted.

[0148] Low-load actions include boom descent and slewing or boom descent alone. Boom descent and slewing and boom descent alone can be accompanied by at least one of stick opening and bucket opening actions, respectively.

[0149] The excavator 100 is preferably configured to determine the timing for reducing the engine speed 11 based on the operation of the control lever. For example, the control unit 30b of the controller 30 can set the timing for reducing the engine speed 11 as the moment when a predetermined operation corresponding to a predetermined action of the excavating attachment AT is performed using a predetermined control lever before performing an operation corresponding to a low-load action of the excavating attachment AT.

[0150] For example, the control unit 30b of the controller 30 can be configured to reduce the speed of the engine 11 when the operating lever tilted in a predetermined direction returns to the neutral position. Specifically, the control unit 30b can determine the time when the right operating lever 26R, which was determined to be operated in the boom lifting direction, returns to the neutral position (see reference). Figure 4 The time t4 is set as the time at which the engine speed of 11 begins to decrease. This time is the time to perform the operation of the right control lever 26R in the boom lowering direction (reference). Figure 4 The moment before t6.

[0151] With this structure, the control unit 30b of the controller 30 can reduce the engine speed of the engine 11 before the low-load operation of the excavating attachment AT begins. Therefore, compared to reducing the engine speed of the engine 11 when the low-load operation of the excavating attachment AT begins, the control unit 30b can extend the period during which the engine speed of the engine 11 is maintained at a reduced speed. That is, the control unit 30b can extend the period during which unnecessary fuel consumption is suppressed.

[0152] The control unit 30b can be configured to further reduce the speed of the engine 11 when the operating lever used to achieve low-load operation has already been operated.

[0153] The control section 30b can also be configured to reduce the engine speed of the engine 11 after the digging and the boom raising. This is to prevent the engine speed of the engine 11 from being reduced although the possibility of the boom lowering swing operation or the boom lowering sole operation as the low load operation is low. For example, the control section 30b can also be configured to be able to reduce the engine speed of the engine 11 when it is determined that the boom raising is to be ended immediately after it is determined that the boom raising is performed within a prescribed period after the digging. This is because the control section 30b can determine that the possibility of the boom lowering swing operation or the boom lowering sole operation is high when the boom raising is performed within the prescribed period after the digging. That is, this is because the control section 30b can determine that the sand or the like enters the bucket 6 when the boom raising is performed within the prescribed period after the digging, and can determine that the operation for discharging the sand is continued thereafter.

[0154] With this configuration, the control section 30b can prevent the engine speed of the engine 11 from being unnecessarily reduced when the possibility of the low load operation is low.

[0155] The control section 30b of the controller 30 is configured to reduce the engine speed of the engine 11 before starting the low load operation of the attachment, but the reduction amount of the engine speed of the engine 11 can be set for each target speed. At this time, the reduction amount of the engine speed of the engine 11 can be variably stored in the NVRAM or the like, for example.

[0156] For example, the reduction amount of the engine speed of the engine 11 can be set to be different for each target speed. For example, the reduction amount of the engine speed of the engine 11 can be set to be smaller when the first stage is selected as the target speed than when the ninth stage is selected as the target speed. This is because the operator of the shovel 100 considers the operability of the shovel 100 to be more important than the energy saving when the first stage is selected, and thus the first stage is selected. Also, this is because the greater the reduction amount of the engine speed of the engine 11, the greater the influence on the operability of the shovel 100. Also, this is because the operator of the shovel 100 considers the energy saving to be more important than the operability of the shovel 100 when the ninth stage is selected, and thus the ninth stage is selected. Also, this is because the greater the reduction amount of the engine speed of the engine 11, the greater the degree of unnecessary fuel can be suppressed.

[0157] Alternatively, the reduction amount of the engine speed of the engine 11 can be set to be different for each work mode. For example, the reduction amount of the engine speed of the engine 11 can be set to be smaller when the normal mode is selected as the work mode of the shovel 100 than when the ECO mode is selected as the work mode of the shovel 100.

[0158] The above describes the preferred embodiments of the present application in detail. However, the present application is not limited to the above-described embodiments. The above-described embodiments can be applied to various modifications, substitutions, and the like without departing from the scope of the present application. Also, the features described separately can be combined as long as no technical contradiction occurs.

[0159] For example, in the above-described embodiments, the hydraulic operating system is mounted in the shovel 100, but an electric operating system can be mounted instead of the hydraulic operating system. Figure 7 An example of the structure of the electric operating system is shown. Specifically, Figure 7 The electric operating system of the above-described embodiment is an example of a boom operating system and mainly includes a pilot pressure operation type control valve unit 17, a right operating lever 26R as an electric operating lever, a controller 30, an electromagnetic valve 65 for boom raising operation, and an electromagnetic valve 66 for boom lowering operation. Figure 7 The electric operating system of the above-described embodiment can also be applied to a swing operating system, a stick operating system, a bucket operating system, and a travel operating system, and the like.

[0160] As shown in Figure 2 The pilot pressure operation type control valve unit 17 includes a changeover valve 171 related to the left travel hydraulic motor 2ML, a changeover valve 172 related to the right travel hydraulic motor 2MR, a changeover valve 173 related to the swing hydraulic motor 2A, a changeover valve 174 related to the bucket cylinder 9, a changeover valve 175 related to the boom cylinder 7, and a changeover valve 176 related to the stick cylinder 8. The electromagnetic valve 65 is configured to be able to adjust the flow passage area of a pipe connecting the boom raising side pilot port of the changeover valve 175 and the pilot pump 15. The electromagnetic valve 66 is configured to be able to adjust the flow passage area of a pipe connecting the boom lowering side pilot port of the changeover valve 175 and the pilot pump 15.

[0161] In the case of manual operation, the controller 30 generates a boom raising operation signal (electric signal) or a boom lowering operation signal (electric signal) based on an operation signal (electric signal) output from an operation signal generating portion of the right operating lever 26R. The operation signal output from the operation signal generating portion of the right operating lever 26R is an electric signal that varies according to the operation direction and the operation amount of the right operating lever 26R.

[0162] Specifically, in a case where the right operating lever 26R is operated in the boom raising direction, the controller 30 outputs a boom raising operation signal (an electric signal) corresponding to the lever operation amount to the electromagnetic valve 65. The electromagnetic valve 65 adjusts the flow passage area in accordance with the boom raising operation signal (the electric signal), and controls the pilot pressure as the boom raising operation signal (a pressure signal) acting on the boom raising side pilot port of the directional control valve 175. Similarly, in a case where the right operating lever 26R is operated in the boom lowering direction, the controller 30 outputs a boom lowering operation signal (an electric signal) corresponding to the lever operation amount to the electromagnetic valve 66. The electromagnetic valve 66 adjusts the flow passage area in accordance with the boom lowering operation signal (the electric signal), and controls the pilot pressure as the boom lowering operation signal (a pressure signal) acting on the boom lowering side pilot port of the directional control valve 175.

[0163] In a case where the autonomous control function is executed, the controller 30 generates the boom raising operation signal (the electric signal) or the boom lowering operation signal (the electric signal) in place of the operation signal (the electric signal) output from the operation signal generating portion of the right operating lever 26R, for example, in accordance with an autonomous control signal (an electric signal). The autonomous control function is a function for autonomously operating the hydraulic actuator regardless of the operation content of the operation device 26 by the operator, for example. The autonomous control signal can be an electric signal generated by the controller 30, or an electric signal generated by an external control device or the like other than the controller 30. In a case where the autonomous control function is executed, the control portion 30b does not need to anticipate whether the low-load operation of the attachment AT is implemented or not in order to determine the timing of reducing the engine speed when reducing the engine speed of the engine 11 before starting the low-load operation. This is because the control portion 30b can grasp at which timing the low-load operation is started in advance. Therefore, the control portion 30b can reduce the engine speed of the engine 11 at the desired timing before starting the low-load operation.

[0164] Also, in the above-described embodiment, the control portion 30b is typically configured to execute the engine speed reduction processing when the ECO mode is on, and not to execute the engine speed reduction processing when the ECO mode is off. Also, the ECO mode is defined as one of the work modes of the shovel 100. However, the ECO mode can be a plurality of selectable ECO modes such as a first ECO mode and a second ECO mode. At this time, Figure 3 The engine speed reduction processing of the above-described embodiment can be executed only when the first ECO mode is on, for example. Also, Figure 5 The engine speed reduction processing of the above-described embodiment can be executed only when the second ECO mode is on, for example.

[0165] Also, regarding the reduction of the engine 11 speed based on the speed reduction processing, it is typically achieved before starting the action in the dumping process when the loading work for loading the sand soil to the dump truck is performed. However, regarding the reduction of the engine 11 speed based on the speed reduction processing, it is not only achieved when the loading work is performed, but also can be achieved when other work is performed.

[0166] Also, in the above-described embodiment, the hydraulic type operation system is employed, and the controller 30 is configured to be able to detect the operation content of the operation device 26 by the operator based on the output of the operation pressure sensor 29. However, in the case where the electric type operation system as shown in Figure 7 Figure 4 Figure 6 Each of the boom up pilot pressure Pu changes is replaced by, for example, the change of the operation signal related to the boom up. The operation signal is, for example, a current value supplied to the solenoid valve 65 or a value of the tilt angle indicating the tilt of the right operation lever 26R, or the like. The same applies to the boom down pilot pressure Pd.

[0167] Also, in the above-described embodiment, the excavator 100 is configured to be operated by the operator who sits on the driver seat in the cab 10. However, the excavator 100 can be a remote operation type excavator. Figure 8 is a schematic diagram showing an example of a construction system SYS including the excavator 100 as a remote operation type excavator. As shown in Figure 8 The construction system SYS includes the excavator 100, the management device 200, and the support device 300. The construction system SYS is configured to be able to support the construction by one or a plurality of excavators 100.

[0168] The information acquired by the excavator 100 can be shared with the manager and the operators of other excavators, and the like, through the construction system SYS. Each of the excavator 100, the management device 200, and the support device 300 constituting the construction system SYS can be one, or can be a plurality. Figure 8 In the example shown, the construction system SYS includes one excavator 100, one management device 200, and one support device 300.

[0169] The management device 200 is typically a fixed terminal device, for example, a server computer (so-called cloud server) provided at a management center or the like outside the construction site. Also, the management device 200 can also be, for example, an edge server provided at the construction site. Also, the management device 200 can be a mobile terminal device (for example, a laptop computer terminal, a tablet terminal, or a mobile terminal such as a smartphone). ​​

[0170] The support device 300 is typically a mobile terminal device, such as a laptop terminal, a tablet terminal, or a smartphone carried by a worker at a construction site, or the like. The support device 300 can be a mobile terminal carried by an operator of the shovel 100. The support device 300 can also be a stationary terminal device.

[0171] At least one of the management device 200 and the support device 300 can be provided with a monitor and a remote operation operation device. In this case, an operator using the management device 200 or the support device 300 can operate the shovel 100 while using the remote operation operation device. The remote operation operation device is communicably connected to the controller 30 mounted on the shovel 100, for example, through a wireless communication network such as a close proximity wireless communication network, a mobile phone communication network, or a satellite communication network. The remote operation operation device can be configured to be able to directly communicate with the controller 30 mounted on the shovel 100.

[0172] Further, various information images displayed on the display device D1 provided in the cab 10 (for example, image information indicating the state of the surroundings of the shovel 100 or various setting screens, or the like) can be displayed in a display device connected to at least one of the management device 200 and the support device 300. The image information indicating the state of the surroundings of the shovel 100 can be generated from an image captured by a camera (for example, a camera serving as the space recognition device 70). Thereby, the manager using the management device 200 or the worker using the support device 300 or the like can confirm the state of the surroundings of the shovel 100 while performing remote operation of the shovel 100 or performing various settings related to the shovel 100.

[0173] For example, in the construction system SYS, the controller 30 of the shovel 100 can transmit various information to at least one of the management device 200 and the support device 300. In this case, the controller 30 can transmit an image captured by the space recognition device 70 to at least one of the management device 200 and the support device 300. Further, the controller 30 can transmit information on at least one of data related to the content of the action of the shovel 100, data related to the posture of the shovel 100, and data related to the posture of the excavating attachment, to at least one of the management device 200 and the support device 300. Thereby, the manager using the management device 200 or the worker using the support device 300 can acquire information related to the shovel 100.

[0174] As such, the construction system SYS can share information related to the shovel 100 with the manager and the operators of other shovels or the like.

[0175] In addition, as Figure 8As shown, the communication device mounted on the shovel 100 can be configured to transmit and receive information with the communication device T2 provided in the remote operation room RC via wireless communication. Figure 8 In the example shown, the communication device mounted on the shovel 100 and the communication device T2 are configured to transmit and receive information via a 5th generation mobile communication line (5G line), an LTE line, or a satellite line, or the like.

[0176] In the remote operation room RC, a remote controller 30R, a sound output device A2, an indoor camera C2, a display device RP, a communication device T2, and the like are provided. Also, in the remote operation room RC, a driver seat DS where an operator OP who remotely controls the shovel 100 sits is provided.

[0177] The remote controller 30R is an arithmetic device (electronic circuit) that performs various arithmetic operations. Figure 8 In the example shown, the remote controller 30R is configured of a microcomputer including a CPU and a memory, like the controller 30. Also, various functions of the remote controller 30R are realized by the CPU executing a program stored in the memory.

[0178] The sound output device A2 is configured to output sound. Figure 8 In the example shown, the sound output device A2 is a speaker and is configured to reproduce sound collected by a sound collecting device (not shown) mounted on the shovel 100.

[0179] The indoor camera C2 is configured to take an image of the inside of the remote operation room RC. Figure 8 In the example shown, the indoor camera C2 is a camera provided inside the remote operation room RC and is configured to take an image of the operator OP who sits on the driver seat DS.

[0180] The communication device T2 is configured to control wireless communication with the communication device mounted on the shovel 100.

[0181] Figure 8 In the example shown, the driver seat DS has the same structure as a driver seat provided in a driver cabin 10 of a general shovel. Specifically, a left console box is arranged on the left side of the driver seat DS, and a right console box is arranged on the right side of the driver seat DS. Also, a left lever is arranged on the front end of the upper surface of the left console box, and a right lever is arranged on the front end of the upper surface of the right console box. Also, a travel lever and a travel pedal are arranged in front of the driver seat DS. Furthermore, a dial 75 is arranged on the central portion of the upper surface of the right console box. The left lever, the right lever, the travel lever, the travel pedal, and the dial 75 each constitute an operation device 26A.

[0182] An operation sensor 29A for detecting the operation content of the operation device 26A is provided in the operation device 26A. The operation sensor 29A is, for example, a tilt sensor that detects the tilt angle of an operation lever or an angle sensor that detects the swing angle of an operation lever around a swing axis, or the like. The operation sensor 29A can be constituted by a pressure sensor, a current sensor, a voltage sensor, or another sensor such as a distance sensor. The operation sensor 29A outputs information related to the detected operation content of the operation device 26A to the remote controller 30R. The remote controller 30R generates an operation signal in accordance with the received information and transmits the generated operation signal to the shovel 100. The operation sensor 29A can also be configured to generate an operation signal. At this time, the operation sensor 29A can output the operation signal to the communication device T2 without passing through the remote controller 30R.

[0183] The display device RP is configured to display information related to the situation of the surroundings of the shovel 100. Figure 8 In the illustrated example, the display device RP is a multi-monitor constituted by nine monitors of three vertical segments by three horizontal columns and is configured to be able to display the states of the front, left, and right spaces of the shovel 100. Each monitor is a liquid crystal monitor or an organic EL monitor or the like. However, the display device RP can be constituted by one or a plurality of curved monitors or can be constituted by a projector.

[0184] The display device RP can also be a display device that the operator OP can wear. For example, the display device RP can be a head-mounted display and is configured to be able to transmit and receive information between the remote controller 30R through wireless communication. The head-mounted display can be connected to the remote controller by wire. The head-mounted display can be a see-through type head-mounted display or a non-see-through type head-mounted display. The head-mounted display can be a monocular type head-mounted display or a binocular type head-mounted display.

[0185] The display device RP is configured to display an image in which the operator OP in the remote operation room RC can recognize the surroundings of the shovel 100. That is, the display device RP displays an image so that the operator can confirm the situation of the surroundings of the shovel 100 as in the cab 10 of the shovel 100 even though the operator is in the remote operation room RC.

[0186] This application claims priority based on Japanese Patent Application No. 2020-094927 filed on May 29, 2020, the entire contents of which are incorporated herein by reference.

[0187] Explanation of Symbols

[0188] 1 - lower traveling body, 1C - crawler belt, 1CL - left crawler belt, 2 - swing mechanism, 2A - swing hydraulic motor, 2M - traveling hydraulic motor, 2ML - left traveling hydraulic motor, 3 - upper swing body, 4 - boom, 5 - arm, 6 - bucket, 7 - boom cylinder, 8 - arm cylinder, 9 - bucket cylinder, 10 - cab, 11 - engine, 13 - regulator, 14 - main pump, 15 - pilot pump, 17 - control valve unit, 18 - restrictor, 19 - control pressure sensor, 26, 26A - operating device, 26D - traveling lever, 26DL - left traveling lever, 26DR - right traveling lever, 26L - left operating lever, 26R - right operating lever, 28 - discharge pressure sensor, 29, 29DL, 29DR, 29LA, 29LB, 29RA, 29RB - operating pressure sensor, 29A - operation sensor, 30 - controller, 30a - information acquisition section, 30b - control section, 30R - remote controller, 40 - intermediate bypass line, 42 - parallel line, 65, 66 - solenoid valve, 70 - space recognition device, 70F - front sensor, 70B - rear sensor, 70L - left sensor, 100 - shovel, 71 - orientation detection device, 72 - information input device, 73 - positioning device, 75 - dial, 171 to 176 - directional control valve, 200 - management device, 300 - support device, A2 - sound output device, AT - excavating attachment, C2 - indoor camera, D1 - display device, D2 - sound output device, DS - driver seat, OP - operator, RC - remote operation room, RP - display device, S1 - boom angle sensor, S2 - arm angle sensor, S3 - bucket angle sensor, S4 - body inclination sensor, S5 - swing angular velocity sensor, SYS - construction system, T2 - communication device.

Claims

1. An excavator, comprising: Lower driving body; The upper rotating body is rotatably mounted on the lower traveling body; Accessories, installed on the upper rotating body; and The prime mover is mounted on the upper rotating body. Reduce the speed of the prime mover before initiating low-load operation of the accessory. The timing for reducing the speed of the prime mover is determined based on the operation of the control lever. When the operating lever, which has been tilted in the specified direction, returns to the neutral position, and when the operation of the operating lever is in a semi-operation state, the rotational speed of the prime mover is reduced.

2. The excavator according to claim 1, wherein, When the operating lever used to achieve the low-load action is started, the rotational speed of the prime mover is further reduced.

3. The excavator according to claim 1, wherein, After excavation and boom raising, the speed of the prime mover is reduced.

4. The excavator according to claim 1, wherein, The reduction in the speed of the prime mover is set according to each target speed.

5. The excavator according to claim 1, wherein, The reduction in the speed of the prime mover is set according to each level of the target speed.

6. The excavator according to claim 1, wherein, The reduction in the speed of the prime mover is set according to each operating mode.

7. The excavator according to claim 1, wherein, After the high-load operation of the accessory is performed and before the low-load operation of the accessory begins, the speed of the prime mover is reduced.

8. The excavator according to claim 1, wherein, The speed of the prime mover is reduced to a level lower than the speed of the prime mover before the high-load operation of the accessory begins.

9. The excavator according to claim 1, wherein, The speed of the prime mover is reduced to a level lower than the manually set target speed.

10. The excavator according to claim 1, wherein, The higher the manually set target speed, the greater the reduction in the speed of the prime mover.

11. The excavator according to claim 1, wherein, After performing the low-load operation of the accessory, restore the speed of the prime mover.

12. The excavator according to claim 1, wherein, This excavator is a remotely operated excavator.

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