Work machine

Abstract

To provide a work machine which improves operationality.SOLUTION: A work machine comprises an operation device, a hydraulic pump for supplying hydraulic oil, a hydraulic actuator, a directional control valve for controlling hydraulic oil flowing from the hydraulic pump to the hydraulic actuator, and a control device for controlling the directional control valve based on an operation amount of the operation device. The control device has a reference operation characteristic which serves as a reference for an operation characteristic of an operation amount of the operation device with a working speed of the hydraulic actuator, and the control device changes an operation characteristic of an operation amount of the operation device with the control of the directional control valve so that the operation characteristic approximates the reference operation characteristic.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present disclosure relates to a working machine.

Background Art

[0002] A working machine including a lower traveling body, an upper revolving body rotatable with respect to the lower traveling body, an attachment attached to the upper revolving body, a swing hydraulic motor for revolving the upper revolving body, and a hydraulic actuator for driving the attachment is known (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, for example, the circuit pressure of the hydraulic circuit during a single swing operation is different from the circuit pressure of the hydraulic circuit during a combined operation of the swing operation and the attachment operation. For this reason, even if the operation amount of the swing lever is the same, the flow rate of the hydraulic oil flowing into the swing hydraulic motor during a single swing operation is different from that during a combined operation, and the swing speed of the upper revolving body is different.

[0005] Therefore, an object of the present invention is to provide a working machine that improves operability.

Means for Solving the Problems

[0006] A working machine according to an embodiment of the present invention includes an operation device, a hydraulic pump that supplies hydraulic oil, a hydraulic actuator, a direction switching valve that controls the hydraulic oil flowing from the hydraulic pump to the hydraulic actuator, and a control device that controls the direction switching valve based on an operation amount of the operation device. The control device It has a reference operating characteristic that serves as a reference for the operating characteristics of the operation amount of the operation device and the operating speed of the hydraulic actuator, It has a plurality of operation characteristics between the operation amount of the operation device and the spool stroke amount of the direction switching valve, and based on the differential pressure between the discharge pressure of the hydraulic pump and the load pressure of the hydraulic actuator, so that the operating characteristic approaches the reference operating characteristic, the operation characteristics are changed.

Advantages of the Invention

[0007] According to the present invention, it is possible to provide a working machine that improves operability.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In each drawing, the same or corresponding components are denoted by the same or corresponding reference numerals, and the description thereof will be omitted.

[0010] First, with reference to FIGS. 1 and 2, a hydraulic excavator (working machine) 100 as an excavator according to an embodiment of the present invention will be described. FIG. 1 is a side view of the hydraulic excavator 100, and FIG. 2 is a top view of the hydraulic excavator 100.

[0011] In this embodiment, the lower traveling body 1 of the excavator 100 includes crawlers 1C. The crawlers 1C are driven by a traveling hydraulic motor 2M as a traveling actuator mounted on the lower traveling body 1. Specifically, the crawlers 1C include a left crawler 1CL and a right crawler 1CR. The left crawler 1CL is driven by a left traveling hydraulic motor 2ML, and the right crawler 1CR is driven by a right traveling hydraulic motor 2MR.

[0012] An upper slewing body 3 is mounted on the lower traveling body 1 via a slewing mechanism 2 so as to be slewing capable. The slewing mechanism 2 is driven by a slewing hydraulic motor 2A as a slewing actuator mounted on the upper slewing body 3.

[0013] A boom 4 is attached to the upper slewing body 3. An arm 5 is attached to the tip of the boom 4, and a bucket 6 as an end attachment is attached to the tip of the arm 5. The boom 4, the arm 5, and the bucket 6 constitute an excavation attachment AT which is an example of an attachment. The boom 4 is driven by a boom cylinder 7, the arm 5 is driven by an arm cylinder 8, and the bucket 6 is driven by a bucket cylinder 9. The boom cylinder 7, the arm cylinder 8, and the bucket cylinder 9 constitute an attachment actuator.

[0014] The boom 4 is supported by the upper slewing body 3 so as to be rotatable up and down. A boom angle sensor S1 is attached to the boom 4. The boom angle sensor S1 can detect a boom angle θ1 which is the rotation angle of the boom 4. The boom angle θ1 is, for example, the rising angle from the state where the boom 4 is lowered most. Therefore, the boom angle θ1 becomes maximum when the boom 4 is raised most.

[0015] The arm 5 is rotatably supported with respect to the boom 4. An arm angle sensor S2 is attached to the arm 5. The arm angle sensor S2 can detect the arm angle θ2 which is the rotation angle of the arm 5. The arm angle θ2 is, for example, the opening angle of the arm 5 from the most closed state. Therefore, the arm angle θ2 becomes maximum when the arm 5 is fully opened.

[0016] The bucket 6 is rotatably supported with respect to the arm 5. A bucket angle sensor S3 is attached to the bucket 6. The bucket angle sensor S3 can detect the bucket angle θ3 which is the rotation angle of the bucket 6. The bucket angle θ3 is, for example, the opening angle of the bucket 6 from the most closed state. Therefore, the bucket angle θ3 becomes maximum when the bucket 6 is fully opened.

[0017] In the embodiment of FIG. 1, each of the boom angle sensor S1, the arm angle sensor S2, and the bucket angle sensor S3 is composed of a combination of an acceleration sensor and a gyro sensor. However, it may be composed of only an acceleration sensor. Further, the boom angle sensor S1 may be a stroke sensor attached to the boom cylinder 7, or may be a rotary encoder, a potentiometer, an inertial measurement unit, or the like. The same applies to the arm angle sensor S2 and the bucket angle sensor S3.

[0018] The upper swing body 3 is provided with a cabin 10 as a driver's cab, and a power source such as an engine 11 is mounted thereon. Further, a space recognition device 70, an orientation detection device 71, a positioning device 73, a machine body tilt sensor S4, a swing angular velocity sensor S5, etc. are attached to the upper swing body 3. Inside the cabin 10, an operation device 26, a controller 30, an information input device 72, a display device D1, a voice output device D2, etc. are provided. In this document, for convenience, the side where the excavation attachment AT is attached to the upper swing body 3 is defined as the front, and the side where the counterweight is attached is defined as the rear.

[0019] The space recognition device 70 is configured to recognize objects existing in the three-dimensional space around the excavator 100. Further, the space recognition device 70 is configured to calculate the distance to the object recognized from the space recognition device 70 or the excavator 100. The space recognition device 70 is, for example, an ultrasonic sensor, a millimeter-wave radar, a monocular camera, a stereo camera, LIDAR, a distance image sensor, an infrared sensor, or the like. In the example shown in FIGS. 1 and 2, the space recognition device 70 includes a front sensor 70F attached to the front end of the upper surface of the cab 10, a rear sensor 70B attached to the rear end of the upper surface of the upper swing body 3, a left sensor 70L attached to the left end of the upper surface of the upper swing body 3, and a right sensor 70R attached to the right end of the upper surface of the upper swing body 3. An upper sensor for recognizing an object existing in the space above the upper swing body 3 may be attached to the excavator 100.

[0020] The orientation detection device 71 is configured to detect information regarding the relative relationship between the orientation of the upper swing body 3 and the orientation of the lower traveling body 1. The orientation detection device 71 may be configured, for example, by a combination of a geomagnetic sensor attached to the lower traveling body 1 and a geomagnetic sensor attached to the upper swing body 3. Alternatively, the orientation detection device 71 may be configured by a combination of a GNSS receiver attached to the lower traveling body 1 and a GNSS receiver attached to the upper swing body 3. The orientation detection device 71 may be a rotary encoder, a rotary position sensor, or the like. In a configuration where the upper swing body 3 is swing-driven by a swing electric generator, the orientation detection device 71 may be configured by a resolver. The orientation detection device 71 may be attached, for example, to a center joint provided in relation to a swing mechanism 2 that realizes relative rotation between the lower traveling body 1 and the upper swing body 3.

[0021] The orientation detection device 71 may be composed of a camera attached to the upper revolving body 3. In this case, the orientation detection device 71 performs known image processing on the image (input image) captured by the camera attached to the upper revolving body 3 to detect the image of the lower traveling body 1 included in the input image. Then, the orientation detection device 71 identifies the longitudinal direction of the lower traveling body 1 by detecting the image of the lower traveling body 1 using known image recognition technology. And it derives the angle formed between the direction of the front-rear axis of the upper revolving body 3 and the longitudinal direction of the lower traveling body 1. The direction of the front-rear axis of the upper revolving body 3 is derived from the attachment position of the camera. Since the crawler 1C protrudes from the upper revolving body 3, the orientation detection device 71 can identify the longitudinal direction of the lower traveling body 1 by detecting the image of the crawler 1C. In this case, the orientation detection device 71 may be integrated with the controller 30.

[0022] The information input device 72 is configured so that the operator of the excavator can input information to the controller 30. In this embodiment, the information input device 72 is a switch panel installed close to the display unit of the display device D1. However, the information input device 72 may be a touch panel arranged on the display unit of the display device D1, or may be a voice input device such as a microphone arranged in the cabin 10. Also, the information input device 72 may be a communication device. In this case, the operator can input information to the controller 30 via a communication terminal such as a smartphone.

[0023] The positioning device 73 is configured to measure the current position. In this embodiment, the positioning device 73 is a GNSS receiver, which detects the position of the upper revolving body 3 and outputs the detected value to the controller 30. The positioning device 73 may be a GNSS compass. In this case, the positioning device 73 can detect the position and orientation of the upper revolving body 3.

[0024] The body tilt sensor S4 is configured to detect the tilt of the upper swing body 3 with respect to a predetermined plane. In the present embodiment, the body tilt sensor S4 is an acceleration sensor that detects the tilt angles of the upper swing body 3 around the longitudinal axis and the lateral axis with respect to the horizontal plane. The longitudinal axis and the lateral axis of the upper swing body 3 pass through, for example, the center point of the excavator, which is a point on the swing axis of the excavator 100 and is orthogonal to each other.

[0025] The swing angular velocity sensor S5 is configured to detect the swing angular velocity of the upper swing body 3. In the present embodiment, the swing angular velocity sensor S5 is a gyro sensor. The swing angular velocity sensor S5 may be a resolver, a rotary encoder, or the like. The swing angular velocity sensor S5 may detect the swing speed. The swing speed may be calculated from the swing angular velocity.

[0026] Hereinafter, at least one of the boom angle sensor S1, the arm angle sensor S2, the bucket angle sensor S3, the body tilt sensor S4, and the swing angular velocity sensor S5 is also referred to as an attitude detection device. The attitude of the excavation attachment AT is detected based on, for example, the respective outputs of the boom angle sensor S1, the arm angle sensor S2, and the bucket angle sensor S3.

[0027] The display device D1 is a device for displaying information. In the present embodiment, the display device D1 is a liquid crystal display installed in the cab 10. However, the display device D1 may be a display of a communication terminal such as a smartphone.

[0028] The audio output device D2 is a device for outputting audio. The audio output device D2 includes at least one of a device for outputting audio to the operator inside the cab 10 and a device for outputting audio to the worker outside the cab 10. The audio output device D2 may be a speaker attached to a communication terminal.

[0029] The operation device 26 is a device used by the operator for operating the actuator. The operation device 26 is installed inside the cab 10 so that it can be used by the operator sitting in the driver's seat.

[0030] The controller 30 is a control device for controlling the excavator 100. In the present embodiment, the controller 30 is composed of a computer including a CPU, a RAM, a NVRAM, a ROM, and the like. Then, the controller 30 reads out a program corresponding to functional elements such as an information acquisition unit 30a and a control unit 30b from the ROM and loads it into the RAM, and causes the CPU to execute processing corresponding to each functional element. In this way, each functional element is realized by software. However, at least one of the functional elements may be realized by hardware or firmware. Note that each functional element is distinguished for convenience of explanation, and it remains a part of the controller 30, and it is not necessary to be physically configured separately.

[0031] Next, referring to FIG. 3, a configuration example of a hydraulic system mounted on the excavator 100 will be described. FIG. 3 is a diagram showing a configuration example of a hydraulic system mounted on the excavator 100. FIG. 3 shows a mechanical power transmission system, a hydraulic oil line, a pilot line, and an electric control system with double lines, solid lines, broken lines, and dotted lines, respectively.

[0032] The hydraulic system of the excavator 100 mainly includes an engine 11, a regulator 13, a main pump 14, a pilot pump 15, a control valve unit 17, an operating device 26, a discharge pressure sensor 28, an operation sensor 29, a controller 30, and the like.

[0033] In FIG. 3, the hydraulic system is configured such that hydraulic oil can be circulated from the main pump 14 driven by the engine 11 to the hydraulic oil tank through the center bypass pipeline 40 or the parallel pipeline 42.

[0034] The engine 11 is a drive source of the excavator 100. In the present embodiment, the engine 11 is, for example, a diesel engine that operates to maintain a predetermined rotational speed. The output shaft of the engine 11 is connected to the input shafts of the main pump 14 and the pilot pump 15, respectively.

[0035] The main pump 14 is configured to be able to supply hydraulic oil to the control valve unit 17 via a hydraulic oil line. In the present embodiment, the main pump 14 is a swash plate type variable displacement hydraulic pump.

[0036] 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 tilt angle of the main pump 14 in response to a control command from the controller 30.

[0037] The pilot pump 15 is configured to be able to supply hydraulic oil to hydraulic control devices (for example, the pilot ports of the direction switching valves 171 to 176 described later) via a pilot line 25 (see FIG. 4 described later). In the present embodiment, the pilot pump 15 is a fixed displacement hydraulic pump. The pilot pump 15 may be omitted. In this case, the function that the pilot pump 15 has may be realized by the main pump 14. That is, the main pump 14 may have a function of supplying hydraulic oil to the hydraulic control devices after reducing the pressure of the hydraulic oil by a throttle or the like, in addition to the function of supplying hydraulic oil to the control valve unit 17.

[0038] The control valve unit 17 is a hydraulic control device that controls the hydraulic system in the excavator 100. In the present embodiment, the control valve unit 17 includes direction control valves 171 to 176. The direction control valve 175 includes a direction control valve 175L and a direction control valve 175R, and the direction control valve 176 includes a direction control valve 176L and a direction control valve 176R. The control valve unit 17 is configured to selectively supply the hydraulic oil discharged from the main pump 14 to one or a plurality of hydraulic actuators through the direction control valves 171 to 176. The direction control valves 171 to 176 control, for example, the flow rate of the hydraulic oil flowing from the main pump 14 to the hydraulic actuator and the flow rate of the hydraulic oil flowing from the hydraulic actuator to the hydraulic oil tank. The hydraulic actuators include a boom cylinder 7, an arm cylinder 8, a bucket cylinder 9, a left traveling hydraulic motor 2ML, a right traveling hydraulic motor 2MR, and a swing hydraulic motor 2A.

[0039] The operating device 26 is a device used by the operator for operating the actuator. The operating device 26 includes, for example, an operating lever and an operating pedal. The actuator includes at least one of a hydraulic actuator and an electric actuator. In the present embodiment, an electric operating system including an electric operating lever can be used. The lever operation amount of the electric operating lever is input to the controller 30 as an electric signal. Further, solenoid valves (hydraulic control valves 31X1 and 31X2 described later in FIG. 4) are arranged between the pilot pump 15 and the pilot ports of the respective control valves. The solenoid valves are configured to operate according to an electric signal from the controller 30. With this configuration, when a manual operation using the electric operating lever is performed, the controller 30 can control the solenoid valves with an electric signal corresponding to the lever operation amount to increase or decrease the pilot pressure, thereby moving each control valve within the control valve unit 17. Note that each control valve may be configured by an electromagnetic spool valve. In this case, the electromagnetic spool valve operates according to an electric signal from the controller 30 corresponding to the lever operation amount of the electric operating lever.

[0040] The discharge pressure sensor 28 is configured 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.

[0041] The operation sensor 29 is configured to detect the content of the operation of the operation device 26 by the operator. In the present embodiment, the operation sensor 29 detects the operation direction and operation amount of the operation device 26 corresponding to each actuator, and outputs the detected value to the controller 30. For example, the operation sensor 29 is an angle sensor that detects the operation angle of the operation lever. The content of the operation of the operation device 26 may be detected using other sensors other than the angle sensor.

[0042] The main pump 14 includes a left main pump 14L and a right main pump 14R. The left main pump 14L circulates the hydraulic oil to the hydraulic oil tank through the left center bypass pipeline 40L or the left parallel pipeline 42L, and the right main pump 14R circulates the hydraulic oil to the hydraulic oil tank through the right center bypass pipeline 40R or the right parallel pipeline 42R.

[0043] The left center bypass pipeline 40L is a hydraulic oil line that passes through the direction switching valves 171, 173, 175L, and 176L arranged in the control valve unit 17. The right center bypass pipeline 40R is a hydraulic oil line that passes through the direction switching valves 172, 174, 175R, and 176R arranged in the control valve unit 17.

[0044] The direction switching valve 171 is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged from the left main pump 14L to the left travel hydraulic motor 2ML and to discharge the hydraulic oil discharged from the left travel hydraulic motor 2ML to the hydraulic oil tank.

[0045] The direction switching valve 172 is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged from the right main pump 14R to the right travel hydraulic motor 2MR and to discharge the hydraulic oil discharged from the right travel hydraulic motor 2MR to the hydraulic oil tank.

[0046] The direction change valve 173 is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged from the left main pump 14L to the swing hydraulic motor 2A and to discharge the hydraulic oil discharged from the swing hydraulic motor 2A to the hydraulic oil tank.

[0047] The direction change valve 174 is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged from the right main pump 14R to the bucket cylinder 9 and to discharge the hydraulic oil in the bucket cylinder 9 to the hydraulic oil tank.

[0048] The direction change valve 175L is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged from the left main pump 14L to the boom cylinder 7. The direction change valve 175R is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged from the right main pump 14R to the boom cylinder 7 and to discharge the hydraulic oil in the boom cylinder 7 to the hydraulic oil tank.

[0049] The direction change valve 176L is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged from the left main pump 14L to the arm cylinder 8 and to discharge the hydraulic oil in the arm cylinder 8 to the hydraulic oil tank.

[0050] The direction change valve 176R is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged from the right main pump 14R to the arm cylinder 8 and to discharge the hydraulic oil in the arm cylinder 8 to the hydraulic oil tank.

[0051] The left parallel pipeline 42L is a hydraulic oil line parallel to the left center bypass pipeline 40L. The left parallel pipeline 42L is configured to supply hydraulic oil to a more downstream direction switching valve when the flow of hydraulic oil through the left center bypass pipeline 40L is restricted or blocked by any one of the direction switching valves 171, 173, and 175L. The right parallel pipeline 42R is a hydraulic oil line parallel to the right center bypass pipeline 40R. The right parallel pipeline 42R is configured to supply hydraulic oil to a more downstream direction switching valve when the flow of hydraulic oil through the right center bypass pipeline 40R is restricted or blocked by any one of the direction switching valves 172, 174, and 175R.

[0052] The regulator 13 includes a left regulator 13L and a right regulator 13R. The left regulator 13L controls the discharge amount of the left main pump 14L by adjusting the swash plate tilt angle of the left main pump 14L according to the discharge pressure of the left main pump 14L. Specifically, for example, the left regulator 13L adjusts the swash plate tilt angle of the left main pump 14L in response to an increase in the discharge pressure of the left main pump 14L to decrease the discharge amount. The same applies to the right regulator 13R. This is to ensure that the absorption power (e.g., absorption horsepower) of the main pump 14, which is represented by the product of the discharge pressure and the discharge amount, does not exceed the output power (e.g., output horsepower) of the engine 11.

[0053] The operating device 26 includes a left operating lever 26L, a right operating lever 26R, and a traveling lever 26D. The traveling lever 26D includes a left traveling lever 26DL and a right traveling lever 26DR.

[0054] The left operating lever 26L is used for turning operation and operation of the arm 5. When the left operating lever 26L is operated in the front-rear direction, it utilizes the hydraulic oil discharged by the pilot pump 15 and applies a control pressure corresponding to the lever operation amount to the pilot port of the direction switching valve 176. When the left operating lever 26L is operated in the left-right direction, it utilizes the hydraulic oil discharged by the pilot pump 15 and applies a control pressure corresponding to the lever operation amount to the pilot port of the direction switching valve 173.

[0055] Specifically, when the left operation lever 26L is operated in the arm closing direction, hydraulic oil is introduced into the right pilot port of the direction switching valve 176L and also into the left pilot port of the direction switching valve 176R. Further, when the left operation lever 26L is operated in the arm opening direction, hydraulic oil is introduced into the left pilot port of the direction switching valve 176L and also into the right pilot port of the direction switching valve 176R. Also, when the left operation lever 26L is operated in the left turning direction, hydraulic oil is introduced into the left pilot port of the direction switching valve 173, and when it is operated in the right turning direction, hydraulic oil is introduced into the right pilot port of the direction switching valve 173.

[0056] The right operation lever 26R is used for the operation of the boom 4 and the operation of the bucket 6. When the right operation lever 26R is operated in the front-rear direction, it uses the hydraulic oil discharged by the pilot pump 15 and applies a control pressure corresponding to the lever operation amount to the pilot port of the direction switching valve 175. Also, when it is operated in the left-right direction, it uses the hydraulic oil discharged by the pilot pump 15 and applies a control pressure corresponding to the lever operation amount to the pilot port of the direction switching valve 174.

[0057] Specifically, when the right operation lever 26R is operated in the boom lowering direction, hydraulic oil is introduced into the left pilot port of the direction switching valve 175R. Further, when the right operation lever 26R is operated in the boom raising direction, hydraulic oil is introduced into the right pilot port of the direction switching valve 175L and also into the left pilot port of the direction switching valve 175R. Also, when the right operation lever 26R is operated in the bucket closing direction, hydraulic oil is introduced into the right pilot port of the direction switching valve 174, and when it is operated in the bucket opening direction, hydraulic oil is introduced into the left pilot port of the direction switching valve 174.

[0058] The travel lever 26D is used for the operation of the crawler 1C. Specifically, the left travel lever 26DL is used for the operation of the left crawler 1CL. The left travel lever 26DL may be configured to be interlocked with the left travel pedal. When the left travel lever 26DL is operated in the front-rear direction, it utilizes the hydraulic oil discharged from the pilot pump 15 and applies a control pressure corresponding to the lever operation amount to the pilot port of the direction change valve 171. The right travel lever 26DR is used for the operation of the right crawler 1CR. The right travel lever 26DR may be configured to be interlocked with the right travel pedal. When the right travel lever 26DR is operated in the front-rear direction, it utilizes the hydraulic oil discharged from the pilot pump 15 and applies a control pressure corresponding to the lever operation amount to the pilot port of the direction change valve 172.

[0059] 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.

[0060] The operation sensor 29 includes operation sensors 29LA, 29LB, 29RA, 29RB, 29DL, and 29DR. The operation sensor 29LA detects the content of the front-rear direction operation on the left operation lever 26L by the operator and outputs the detected value to the controller 30. The content of the operation is, for example, the lever operation direction and the lever operation amount (lever operation angle), etc.

[0061] Similarly, the operation sensor 29LB detects the content of the left-right direction operation on the left operation lever 26L by the operator, and outputs the detected value to the controller 30. The operation sensor 29RA detects the content of the front-rear direction operation on the right operation lever 26R by the operator, and outputs the detected value to the controller 30. The operation sensor 29RB detects the content of the left-right direction operation on the right operation lever 26R by the operator, and outputs the detected value to the controller 30. The operation sensor 29DL detects the content of the front-rear direction operation on the left travel lever 26DL by the operator, and outputs the detected value to the controller 30. The operation sensor 29DR detects the content of the front-rear direction operation on the right travel lever 26DR by the operator, and outputs the detected value to the controller 30.

[0062] The controller 30 receives the output of the operation sensor 29, outputs a control command to the regulator 13 as necessary, and changes the discharge amount of the main pump 14. Further, the controller 30 receives the output of the control pressure sensor 19 provided upstream of the throttle 18, outputs a control command to the regulator 13 as necessary, and changes the discharge amount of the main pump 14. The throttle 18 includes a left throttle 18L and a right throttle 18R, and the control pressure sensor 19 includes a left control pressure sensor 19L and a right control pressure sensor 19R.

[0063] In the left center bypass pipeline 40L, a left throttle valve 18L is arranged between the most downstream direction switching valve 176L and the hydraulic oil tank. Therefore, the flow of the hydraulic oil discharged by the left main pump 14L is restricted by the left throttle valve 18L. And the left throttle valve 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 tilting angle of the left main pump 14L according to this control pressure. The controller 30 decreases the discharge amount of the left main pump 14L as this control pressure increases, and increases the discharge amount of the left main pump 14L as this control pressure decreases. The discharge amount of the right main pump 14R is controlled in the same way.

[0064] Specifically, when the hydraulic system is in a standby state where none of the hydraulic actuators in the excavator 100 shown in FIG. 3 are operated, the hydraulic oil discharged by the left main pump 14L reaches the left throttle valve 18L through the left center bypass pipeline 40L. And the flow of the hydraulic oil discharged by the left main pump 14L increases the control pressure generated upstream of the left throttle valve 18L. As a result, the controller 30 decreases the discharge amount of the left main pump 14L to the allowable minimum discharge amount, and suppresses the pressure loss (pumping loss) when the hydraulic oil discharged by the left main pump 14L passes through the left center bypass pipeline 40L. On the other hand, when any of the hydraulic actuators is operated, the hydraulic oil discharged by the left main pump 14L flows into the operated hydraulic actuator through the direction switching valve corresponding to the operated hydraulic actuator. And the flow of the hydraulic oil discharged by the left main pump 14L decreases or disappears the amount reaching the left throttle valve 18L, and decreases the control pressure generated upstream of the left throttle valve 18L. As a result, the controller 30 increases the discharge amount of the left main pump 14L, circulates sufficient hydraulic oil to the operated hydraulic actuator, and ensures the driving of the operated hydraulic actuator. Note that the controller 30 controls the discharge amount of the right main pump 14R in the same way.

[0065] With the above configuration, in the standby state, the hydraulic system of FIG. 3 can suppress wasteful energy consumption in the main pump 14. The wasteful energy consumption includes the pumping loss generated by the hydraulic oil discharged from the main pump 14 in the center bypass pipeline 40. Further, when operating the hydraulic actuator, the hydraulic system of FIG. 3 can reliably supply sufficient hydraulic oil from the main pump 14 to the hydraulic actuator to be operated.

[0066] Next, the information acquisition unit 30a and the control unit 30b, which are functional elements of the controller 30, will be described. The information acquisition unit 30a is configured to acquire information about the excavator 100. In the present embodiment, the information acquisition unit 30a acquires information about the excavator 100 from at least one of a boom angle sensor S1, an arm angle sensor S2, a bucket angle sensor S3, a machine body inclination sensor S4, a swing angular velocity sensor S5, a cylinder pressure sensor, a swing pressure sensor (swing pressure sensors 27X1 and 27X2 described later in FIG. 4), a traveling pressure sensor, a boom cylinder stroke sensor, an arm cylinder stroke sensor, a bucket cylinder stroke sensor, a discharge pressure sensor 28, an operation sensor 29, a space recognition device 70, an orientation detection device 71, an information input device 72, a positioning device 73, and a communication device. The cylinder pressure sensor includes at least one of, for example, a boom rod pressure sensor, a boom bottom pressure sensor, an arm rod pressure sensor, an arm bottom pressure sensor, a bucket rod pressure sensor, and a bucket bottom pressure sensor.

[0067] The information acquisition unit 30a acquires at least one of, for example, as information regarding the excavator 100, boom angle, arm angle, bucket angle, machine body tilt angle, swing angular velocity, boom rod pressure, boom bottom pressure, arm rod pressure, arm bottom pressure, bucket rod pressure, bucket bottom pressure, swing pressure, travel pressure, boom stroke amount, arm stroke amount, bucket stroke amount, discharge pressure of the main pump 14, operation pressure of the operation device 26, information regarding an object existing in the three-dimensional space around the excavator 100, information regarding 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 regarding the current position.

[0068] Further, the information acquisition unit 30a acquires information regarding the operation of the excavator 100 based on the information regarding the excavator 100 that has been acquired. The information regarding the operation of the excavator 100 includes, for example, information regarding the operation that the excavator 100 is performing. The operations that the excavator 100 is performing include, for example, a swing-alone operation of swinging the upper swing body 3, a boom-raising swing composite operation of swinging the upper swing body 3 while raising the boom 4, a boom-lowering swing composite operation of swinging the upper swing body 3 while lowering the boom 4, an arm-opening swing composite operation of swinging the upper swing body 3 while opening the arm 5, an arm-closing swing composite operation of swinging the upper swing body 3 while closing the arm 5, a bucket-opening swing composite operation of swinging the upper swing body 3 while opening the bucket 6, a bucket-closing swing composite operation of swinging the upper swing body 3 while closing the bucket 6, and the like.

[0069] The control unit 30b is configured to be able to control the movement of the excavator 100 based on the information acquired by the information acquisition unit 30a.

[0070] Next, the operation system of the excavator 100 will be described with reference to FIG. 4. FIG. 4 is a diagram showing a configuration example of an electric operation system. Specifically, the electric operation system in FIG. 4 is an example of a swing operation system. Note that the electric operation system in FIG. 4 can be similarly applied to a boom operation system, an arm operation system, a bucket operation system, a travel operation system, and the like.

[0071] The electric operation system mainly consists of a direction switching valve 173 (also see Fig. 3) of a pilot pressure actuated control valve unit 17, an operating device 26 as an electric operation lever, a hydraulic control valve 31X1 for left turning operation, a hydraulic control valve 31X2 for right turning operation, a pressure sensor 32X1, a pressure sensor 32X2, and a controller 30.

[0072] The direction switching valve 173 controls the flow rate of the hydraulic oil flowing from the main pump 14 to the swing hydraulic motor 2A which is a hydraulic actuator. Specifically, the direction switching valve 173 has pilot ports P1 and P2, and moves the spool by supplying hydraulic oil (pilot pressure) to the pilot ports P1 and P2.

[0073] The operating device 26 as an electric operation lever has an operation sensor 29 that detects the content (operation direction, operation amount) of the operation of the operating device 26 by the operator and outputs the detected value to the controller 30.

[0074] The hydraulic control valve 31X1 as an electro-hydraulic proportional valve is provided on a pilot line 25 connecting the pilot pump 15 and the pilot port P1 of the direction switching valve 173, and supplies hydraulic oil (pilot pressure) to the pilot port P1 of the direction switching valve 173. Thereby, the hydraulic control valve 31X1 moves the spool of the direction switching valve 173 from the neutral position to one end side (right side in Fig. 4) in the axial direction. The hydraulic oil supplied from the main pump 14 is supplied to the left port of the swing hydraulic motor 2A, and the upper swing body 3 can be turned left.

[0075] The hydraulic control valve 31X2 as an electromagnetic proportional valve is provided on the pilot line 25 that connects the pilot pump 15 and the pilot port P2 of the direction switching valve 173, and supplies hydraulic oil (pilot pressure) to the pilot port P2 of the direction switching valve 173. Thereby, the hydraulic control valve 31X1 moves the spool of the direction switching valve 173 from the neutral position axially to the other end side (the left side in FIG. 4). The hydraulic oil supplied from the main pump 14 is supplied to the right port of the slewing hydraulic motor 2A, and the upper slewing body 3 can be slewed to the right.

[0076] The pressure sensor 32X1 detects the pressure of the hydraulic oil on the secondary side of the hydraulic control valve 31X1. The pressure sensor 32X1 outputs the detected value to the controller 30.

[0077] The pressure sensor 32X2 detects the pressure of the hydraulic oil on the secondary side of the hydraulic control valve 31X2. The pressure sensor 32X2 outputs the detected value to the controller 30.

[0078] The slewing pressure sensor 27X1 detects the pressure of the hydraulic oil (load pressure during left slewing) at the left port of the slewing hydraulic motor 2A which is a hydraulic actuator. The slewing pressure sensor 27X1 outputs the detected value to the controller 30.

[0079] The slewing pressure sensor 27X2 detects the pressure of the hydraulic oil (load pressure during right slewing) at the right port of the slewing hydraulic motor 2A which is a hydraulic actuator. The slewing pressure sensor 27X2 outputs the detected value to the controller 30.

[0080] The discharge pressure sensor 28 detects the discharge pressure of the main pump 14. The discharge pressure sensor 28 outputs the detected value to the controller 30.

[0081] Based on the output of the operation sensor 29LB that detects the lever operation amount of the turning operation lever (operation in the left-turning direction of the left operation lever 26L), the controller 30 can control the pilot pressure supplied to the port P1 of the direction switching valve 173 by controlling the hydraulic control valve 31X1. At this time, the controller 30 monitors the output of the pressure sensor 32X1 that detects the pressure of the hydraulic oil on the secondary side of the hydraulic control valve 31X1 while controlling the hydraulic control valve 31X1. Also, based on the output of the operation sensor 29LB that detects the lever operation amount of the turning operation lever (operation in the right-turning direction of the left operation lever 26L), the controller 30 can control the pilot pressure supplied to the port P2 of the direction switching valve 173 by controlling the hydraulic control valve 31X2. At this time, the controller 30 monitors the output of the pressure sensor 32X2 that detects the pressure of the hydraulic oil on the secondary side of the hydraulic control valve 31X2 while controlling the hydraulic control valve 31X2. That is, the controller 30 is configured to be able to control the spool stroke amount of the direction switching valve 173 by controlling the hydraulic control valves 31X1 and 31X2.

[0082] Based on the content of the operation of the operating device 26 (operation direction, operation amount) detected by the operation sensor 29, the controller 30 controls the hydraulic control valves 31X1 and 31X2 to control the spool stroke amount of the direction switching valve 173. Also, based on the content of the operation of the operating device 26 (operation direction, operation amount) detected by the operation sensor 29 and the discharge pressure of the main pump 14 detected by the discharge pressure sensor 28, the controller 30 controls the hydraulic control valves 31X1 and 31X2 to control the spool stroke amount of the direction switching valve 173. Further, based on the content of the operation of the operating device 26 (operation direction, operation amount) detected by the operation sensor 29, the discharge pressure of the main pump 14 detected by the discharge pressure sensor 28, and the differential pressure between the discharge pressure of the main pump 14 and the load pressure of the hydraulic actuator, the controller 30 controls the hydraulic control valves 31X1 and 31X2 to control the spool stroke amount of the direction switching valve 173.

[0083] Next, the characteristics of the lever operation amount and the opening area of the direction switching valve will be described with reference to FIG. 5. FIG. 5 is a graph showing the characteristics of the lever operation amount and the opening area of the direction switching valve. In FIG. 5, the horizontal axis represents the lever operation amount, and the vertical axis represents the PT opening area of the direction switching valve (the opening area between the port connected to the main pump 14 and the port connected to the hydraulic oil tank). Also, the opening characteristics (swing opening characteristics) 510 of the lever operation amount of the swing operation lever (the left-right operation of the left operation lever 26L) and the PT opening area of the direction switching valve 173 that controls the swing hydraulic motor 2A are shown by a solid line. Further, the opening characteristics (boom opening characteristics) 520 of the lever operation amount of the boom operation lever (the operation of the right operation lever 26R in the boom raising direction) and the PT opening area of the direction switching valve 175 that controls the boom cylinder 7 are shown by a broken line.

[0084] As shown in FIG. 5, the swing opening characteristics 510 and the boom opening characteristics 520 are different. Specifically, the swing opening characteristics 510 are represented by a curve in which the PT opening area decreases with respect to the lever operation amount. On the other hand, the boom opening characteristics 520 have an opening characteristic 521 in which the PT opening area rapidly (with a large slope) decreases with respect to the lever operation amount and an opening characteristic 522 in which the PT opening area gradually (with a small slope) decreases with respect to the lever operation amount. Therefore, as shown in FIG. 5, the rate of decrease of the PT opening area with respect to the lever operation amount is larger for the boom opening characteristics 520 than for the swing opening characteristics 510.

[0085] Here, as shown in FIG. 3, the direction switching valve 173 and the direction switching valve 175 are arranged on the center bypass pipeline 40. Also, as shown in FIG. 5, the rate of decrease of the PT opening area with respect to the lever operation amount is larger during the boom operation than during the swing operation. Thereby, for example, when the lever operation amount of the boom operation is input, the PT opening area of the direction switching valve 175 rapidly decreases along the opening characteristics 520, and the circuit pressure (the discharge pressure of the main pump 14 detected by the discharge pressure sensor 28) rises. Therefore, the circuit pressure in the combined operation of the boom operation and the swing operation is higher than the circuit pressure in the swing-only operation.

[0086] Therefore, even when the operation amount of the swing operation lever is the same (in other words, when the PT opening area of the direction switching valve 173 is equal), the circuit pressure is higher during the boom swing combined operation than during the swing-alone operation, and the flow rate of the hydraulic oil flowing into the swing hydraulic motor 2A increases. That is, even when the operation amount of the swing operation lever is the same, the swing speed of the upper swing body 3 is higher during the boom swing combined operation than during the swing-alone operation.

[0087] On the other hand, the operator of the excavator 100 adjusts, for example, the operation amount of the swing operation lever to be smaller during the boom swing combined operation to adjust the swing speed of the upper swing body 3. In addition, since the operator of the excavator 100 needs to adjust the lever operation amount, there is a risk of leading to operator fatigue.

[0088] FIG. 6 is a diagram for explaining the control in the excavator according to the reference example.

[0089] FIG. 6(a) is a graph showing the lever operation characteristics 610 of the lever operation amount of the swing operation lever and the spool stroke amount of the direction switching valve 173. In FIG. 6(a), the horizontal axis represents the lever operation amount of the swing operation lever, and the vertical axis represents the spool stroke amount of the direction switching valve 173. In the excavator according to the reference example, regardless of the differential pressure between the circuit pressure and the load pressure described later, the spool stroke amount is controlled by one lever operation characteristic 610 with respect to the lever operation amount.

[0090] FIG. 6(b) is a graph showing the characteristics of the lever operation amount of the swing operation lever and the flow rate of the hydraulic oil supplied to the swing hydraulic motor 2A. In FIG. 6(b), the horizontal axis represents the lever operation amount of the swing operation lever, and the vertical axis represents the flow rate of the hydraulic oil supplied to the swing hydraulic motor 2A. Here, the flow rate of the hydraulic oil supplied to the swing hydraulic motor 2A corresponds to the rotation speed of the swing hydraulic motor 2A and the swing speed of the upper swing body 3. That is, the flow rate characteristics shown in FIG. 6(b) correspond to the operation characteristics of the swing hydraulic motor 2A.

[0091] Also, regarding the differential pressure between the circuit pressure (the discharge pressure of the main pump 14 detected by the discharge pressure sensor 28) and the load pressure of the hydraulic actuator (in the example of FIG. 4, the swing hydraulic motor 2A), specifically, the pressure of the hydraulic oil in the left port of the swing hydraulic motor 2A detected by the swing pressure sensor 27X1), the flow rate characteristics 621 of the lever operation amount and the flow rate when the differential pressure is in the normal state (for example, during swing-alone operation) are shown by a solid line.

[0092] Also, for example, during the boom swing combined operation, the circuit pressure becomes higher compared to the swing-alone operation, and the differential pressure between the circuit pressure and the load pressure also increases. When such a differential pressure becomes larger than the normal state (for example, during the boom swing combined operation), the flow rate characteristics 622 of the lever operation amount and the flow rate are shown by a dashed line. As shown by contrasting the flow rate characteristics 621 with the normal differential pressure and the flow rate characteristics 622 with a large differential pressure, even when the operation amount of the swing operation lever is the same, in the state with a large differential pressure, compared to the normal state, the flow rate of the hydraulic oil flowing into the swing hydraulic motor 2A increases, and the swing speed of the upper swing body 3 becomes faster.

[0093] Also, for example, during the arm swing combined operation, since the hydraulic oil flows into the arm cylinder 8 with a smaller load than the swing hydraulic motor 2A, the circuit pressure becomes lower compared to the swing-alone operation, and the differential pressure between the circuit pressure and the load pressure also decreases. When such a differential pressure becomes smaller than the normal state (for example, during the arm swing combined operation), the flow rate characteristics 623 of the lever operation amount and the flow rate are shown by a dash-dotted line. As shown by contrasting the flow rate characteristics 621 with the normal differential pressure and the flow rate characteristics 623 with a small differential pressure, even when the operation amount of the swing operation lever is the same, in the state with a small differential pressure, compared to the normal state, the flow rate of the hydraulic oil flowing into the swing hydraulic motor 2A decreases, and the swing speed of the upper swing body 3 becomes slower.

[0094] Thus, even when the operation amount of the swing operation lever is the same, the swing speed of the upper swing body 3 changes due to the difference in circuit pressure. In other words, even when the operation amount of the swing operation lever is the same, the swing speed of the upper swing body 3 changes due to the difference in the differential pressure between the circuit pressure and the load pressure. Further in other words, the swing speed of the upper swing body 3 changes due to the difference in the operation of the excavator (such as swing-alone operation, boom-swing combined operation, arm-swing combined operation, etc.). For this reason, there is a possibility of giving a sense of discomfort to the excavator operator.

[0095] FIG. 6(c) is a schematic diagram showing an example of the operation range of the operation lever. The arrow indicates the operable range of the operation lever. Here, an example of the operation position 631 of the operation lever where the spool stroke amount becomes maximum is shown. In the excavator according to the reference example, the operation position 631 is set to coincide with the operable range of the operation lever. That is, when the operation lever is operated to the maximum of the operable range, the spool stroke amount becomes maximum.

[0096] FIG. 7 is a diagram for explaining the control in the excavator 100 according to the present embodiment.

[0097] FIG. 7(a) is a graph showing the characteristics of the lever operation amount of the swing operation lever and the spool stroke amount of the direction switching valve 173. In FIG. 7(a), the horizontal axis indicates the lever operation amount of the swing operation lever, and the vertical axis indicates the spool stroke amount of the direction switching valve 173. In the excavator 100 according to the present embodiment, according to the differential pressure between the circuit pressure and the load pressure, the lever operation characteristics 711 to 713 of the spool stroke amount with respect to the lever operation amount are controlled to be different.

[0098] The lever operation characteristic 711 of the lever operation amount and the spool stroke amount when the differential pressure between the circuit pressure and the load pressure is in the normal state (for example, during swing-alone operation) is shown by a solid line.

[0099] When the differential pressure between the circuit pressure and the load pressure is greater than the normal state (for example, during the combined boom slewing operation), the lever operation characteristics 712 of the lever operation amount and the spool stroke amount are indicated by a broken line. Also, the greater the differential pressure, the smaller the spool stroke amount with respect to the lever operation amount.

[0100] When the differential pressure between the circuit pressure and the load pressure is smaller than the normal state (for example, during the combined arm slewing operation), the lever operation characteristics 713 of the lever operation amount and the spool stroke amount are indicated by a one-dot chain line. Also, the smaller the differential pressure, the larger the spool stroke amount with respect to the lever operation amount.

[0101] Figure 7(b) is a graph showing the characteristics of the lever operation amount of the slewing operation lever and the flow rate of the hydraulic oil supplied to the slewing hydraulic motor 2A. In Figure 7(b), the horizontal axis represents the lever operation amount of the slewing operation lever, and the vertical axis represents the flow rate of the hydraulic oil supplied to the slewing hydraulic motor 2A. Here, the flow rate of the hydraulic oil supplied to the slewing hydraulic motor 2A corresponds to the rotational speed of the slewing hydraulic motor 2A and the slewing speed of the upper slewing body 3. That is, the flow rate characteristics shown in Figure 7(b) correspond to the operating characteristics of the slewing hydraulic motor 2A.

[0102] Also, the flow rate characteristics 721 of the lever operation amount and the flow rate when the differential pressure between the circuit pressure and the load pressure is in the normal state (for example, during the slewing alone operation) are indicated by a solid line. The flow rate characteristics 722 of the lever operation amount and the flow rate when the differential pressure between the circuit pressure and the load pressure is greater than the normal state (for example, during the combined boom slewing operation) are indicated by a broken line. The flow rate characteristics 723 of the lever operation amount and the flow rate when the differential pressure between the circuit pressure and the load pressure is smaller than the normal state (for example, during the combined arm slewing operation) are indicated by a one-dot chain line.

[0103] Thus, when the differential pressure between the circuit pressure and the load pressure is in the normal state (for example, during the slewing alone operation), as shown in Figure 7(a), the controller 30 controls the spool stroke amount of the direction change valve 173 using the lever operation characteristics 711 in the normal state. Thereby, as shown in Figure 7(b), the flow rate characteristics of the lever operation amount and the flow rate of the hydraulic oil supplied to the slewing hydraulic motor 2A become the flow rate characteristics 721 in the normal state.

[0104] Also, when the differential pressure between the circuit pressure and the load pressure is greater than the normal state (for example, during the combined operation of boom swing), as shown in Fig. 7(a), the controller 30 uses a lever operation characteristic 712 in which the spool stroke amount with respect to the lever operation amount is smaller compared to the lever operation characteristic 711 in the normal state, and controls the spool stroke amount of the direction switching valve 173. As a result, as shown in Fig. 7(b), the flow rate characteristic between the lever operation amount and the flow rate of the hydraulic oil supplied to the swing hydraulic motor 2A becomes the flow rate characteristic 722, and can approach the flow rate characteristic 721 in the normal state.

[0105] Also, when the differential pressure between the circuit pressure and the load pressure is smaller than the normal state (for example, during the combined operation of arm swing), as shown in Fig. 7(a), the controller 30 uses a lever operation characteristic 713 in which the spool stroke amount with respect to the lever operation amount is larger compared to the lever operation characteristic 711 in the normal state, and controls the spool stroke amount of the direction switching valve 173. As a result, as shown in Fig. 7(b), the flow rate characteristic between the lever operation amount and the flow rate of the hydraulic oil supplied to the swing hydraulic motor 2A becomes the flow rate characteristic 723, and can approach the flow rate characteristic 721 in the normal state.

[0106] Thus, according to the excavator 100 according to the present embodiment, even during the swing single operation or the combined operation of the swing operation and other operations (boom operation, arm operation), the swing speed of the upper swing body 3 with respect to the operation amount of the swing operation lever can be made substantially equal, so that the operability of the operator is improved.

[0107] Fig. 7(c) is a schematic diagram showing an example of the operation range of the operation lever. The arrow indicates the operable range of the operation lever.

[0108] Here, an example of the operation position 731 of the operation lever at which the spool stroke amount in the normal state of the differential pressure becomes maximum is shown. Here, the operation position 731 is set to coincide with the operable range of the operation lever. That is, when the differential pressure is in the normal state and the operation lever is operated to the maximum of the operable range, the spool stroke amount becomes maximum.

[0109] Further, an example of the operation position 732 of the operation lever at which the spool stroke amount is maximized when the differential pressure is greater than the normal state is shown. Here, the operation position 732 is set outside the operable range of the operation lever. That is, when the differential pressure is greater than the normal state, even if the operation lever is operated to the maximum of the operable range, the spool stroke amount does not reach the maximum.

[0110] Also, an example of the operation position 733 of the operation lever at which the spool stroke amount is maximized when the differential pressure is less than the normal state is shown. Here, the operation position 733 is set inside the operable range of the operation lever. That is, when the differential pressure is less than the normal state, if the operation lever is operated to the operation position 733 before operating the operation lever to the maximum of the operable range, the spool stroke amount becomes the maximum.

[0111] That is, the operation positions (731 to 733) of the operation lever at which the spool stroke amount is maximized move farther away from the neutral position of the operation lever as the differential pressure increases, and closer to the neutral position of the operation lever as the differential pressure decreases.

[0112] Note that although the controller 30 has been described as changing the lever operation characteristics 711 to 713 based on the differential pressure between the circuit pressure and the load pressure, it is not limited to this.

[0113] The controller 30 may change the lever operation characteristics 711 to 713 based on the circuit voltage. That is, when the circuit voltage is in the normal state (for example, during the slewing-alone operation), the controller 30 uses the lever operation characteristics 711 in the normal state to control the spool stroke amount of the direction switching valve 173. Also, when the circuit voltage is greater than the normal state (for example, during the boom slewing combined operation), the controller 30 uses the lever operation characteristics 712 to control the spool stroke amount of the direction switching valve 173. Further, when the circuit voltage is less than the normal state (for example, during the arm slewing combined operation), the controller 30 uses the lever operation characteristics 713 to control the spool stroke amount of the direction switching valve 173. Even with such control, the slewing speed of the upper slewing body 3 with respect to the operation amount of the slewing operation lever can be made substantially equal, so the operability of the operator is improved.

[0114] Also, the controller 30 may change the lever operation characteristics 711 to 713 based on the operation of the excavator 100 (such as slewing-alone operation, boom slewing combined operation, arm slewing combined operation, etc.). That is, the controller 30 determines the operation of the excavator 100 (such as slewing-alone operation, boom slewing combined operation, arm slewing combined operation, etc.) based on the content of the operation of the operating device 26 detected by the operation sensor 29. And when it is determined that the operation of the excavator 100 is the slewing-alone operation, the controller 30 uses the lever operation characteristics 711 to control the spool stroke amount of the direction switching valve 173. Also, when it is determined that the operation of the excavator 100 is the boom slewing combined operation, the controller 30 uses the lever operation characteristics 712 to control the spool stroke amount of the direction switching valve 173. Further, when it is determined that the operation of the excavator 100 is the arm slewing combined operation, the controller 30 uses the lever operation characteristics 713 to control the spool stroke amount of the direction switching valve 173. Even with such control, the slewing speed of the upper slewing body 3 with respect to the operation amount of the slewing operation lever can be made substantially equal, so the operability of the operator is improved.

[0115] Also, the flow rate of the hydraulic oil supplied to the swing hydraulic motor 2A shown in FIG. 7(b) corresponds to the rotational speed of the swing hydraulic motor 2A (the operating speed of the hydraulic actuator). The controller 30 has a reference operating characteristic (e.g., flow rate characteristic 721) as a reference for the operating characteristic (flow rate characteristic) between the lever operation amount and the operating speed of the hydraulic actuator. Then, the controller 30 changes the lever operation characteristics 711 to 713 so that the operating characteristic approaches the reference operating characteristic. Even with such control, the swing speed of the upper swing body 3 with respect to the operation amount of the swing operation lever can be made substantially equal, thus improving the operability of the operator.

[0116] As described above, the embodiment of the excavator 100 has been explained, but the present invention is not limited to the above embodiment, and various modifications and improvements are possible within the scope of the gist of the present invention described in the claims.

[0117] In the excavator 100 according to the present embodiment, the case where the lever operation characteristics 712 and 713 are changed so that the swing speed of the upper swing body 3 with respect to the operation amount of the swing operation lever is substantially equal to the swing speed during the single swing operation when the combined operation of the swing operation and other operations (boom operation, arm operation, etc.) is set as the normal state (reference state) during the single swing operation has been described as an example. However, the present invention is not limited to this. For example, the lever operation characteristics may be changed so that the swing speed of the upper swing body 3 with respect to the operation amount of the swing operation lever is substantially equal to the swing speed during the boom swing combined operation when the boom swing combined operation is set as the normal state (reference state) during the single swing operation. Alternatively, the lever operation characteristics may be changed so that the swing speed of the upper swing body 3 with respect to the operation amount of the swing operation lever is substantially equal to the swing speed during the arm swing combined operation when the arm swing combined operation is set as the normal state (reference state) during the single swing operation. Whichever operation is set as the normal state (reference state), as long as the same operating feeling is realized, it does not matter which operation is set as the reference state because it has no relation to the operating feeling.

[0118] In the excavator 100 according to this embodiment, although the case where the lever operation characteristics 711 to 713 of the direction switching valve 173 that controls the swing hydraulic motor 2A are changed in the swing-alone operation or the combined operation of the swing operation and other operations (boom operation, arm operation, etc.) has been described as an example, the present invention is not limited to this.

[0119] For example, in the bucket-alone operation or the combined operation of the bucket operation and other operations (boom operation, arm operation, etc.), a configuration may be adopted in which the lever operation characteristics of the direction switching valve 174 that controls the bucket cylinder 9 are changed. Even when the operation amount of the bucket operation lever is the same operation amount, in the combined operation of the bucket operation and the boom operation, the opening and closing speed of the bucket 6 increases as compared with the case of the bucket-alone operation. Also, even when the operation amount of the bucket operation lever is the same operation amount, in the combined operation of the bucket operation and the arm operation, the opening and closing speed of the bucket 6 decreases as compared with the case of the bucket-alone operation. On the other hand, by changing the lever operation characteristics of the direction switching valve 174 that controls the bucket cylinder 9, the opening and closing speed of the bucket 6 with respect to the operation amount of the bucket operation lever can be made substantially equal, so the operability of the operator is improved.

[0120] Similarly, a configuration may be adopted in which the lever operation characteristics of the direction switching valves 171, 172 that control the travel hydraulic motor 2M, the direction switching valve 175 that controls the boom cylinder 7, and the direction switching valve 176 that controls the arm cylinder 8 are changed.

[0121] Further, it may be applied to the remotely operated excavator 100. In the remotely operated excavator 100, the operator operates the excavator 100, for example, by viewing the video acquired by the space recognition device 70 (for example, a camera). For this reason, the operator cannot feel information of the excavator 100 such as vibration and acceleration. For this reason, if the operating speed of the hydraulic actuator with respect to the operation amount of the operation lever is different, there is a possibility that the operator of the excavator 100 will feel more discomfort. On the other hand, according to the excavator 100 according to this embodiment, the operating speed of the hydraulic actuator with respect to the operation amount of the operation lever can be made substantially equal, so the operability of the operator can be improved.

[0122] During the turning operation alone, the hydraulic oil discharged by the main pump 14 is supplied to the swing hydraulic motor 2A but not to other hydraulic actuators. On the other hand, for example, during the combined operation of raising the boom and turning, the hydraulic oil discharged by the main pump 14 is supplied to each of the swing hydraulic motor 2A and the boom cylinder 7. Therefore, if the discharge pressure of the main pump 14 is the same, the flow rate of the hydraulic oil supplied to the swing hydraulic motor 2A during the turning operation alone is greater than the flow rate of the hydraulic oil supplied to the swing hydraulic motor 2A during the combined operation of raising the boom and turning. This is because during the combined operation of raising the boom and turning, the load pressure of the swing hydraulic motor 2A is lower than the load pressure of the boom cylinder 7 and the discharge pressure of the main pump 14. That is, since the hydraulic oil discharged by the main pump 14 tends to flow to the side with lower pressure, it is more likely to flow into the swing hydraulic motor 2A than into the boom cylinder 7. Also, if the discharge pressure of the main pump 14 is the same, the flow rate of the hydraulic oil supplied to the swing hydraulic motor 2A during the turning operation alone is less than the flow rate of the hydraulic oil supplied to the swing hydraulic motor 2A during the combined operation of closing the arm and turning. This is because during the combined operation of closing the arm and turning, the load pressure of the arm cylinder 8 is lower than the load pressure of the swing hydraulic motor 2A and the discharge pressure of the main pump 14. That is, since the hydraulic oil discharged by the main pump 14 tends to flow to the side with lower pressure, it is more likely to flow into the arm cylinder 8 than into the swing hydraulic motor 2A.

[0123] Therefore, the controller 30 is configured to grasp the amount of hydraulic oil flowing into the swing hydraulic motor 2A based on the differential pressure between the discharge pressure of the main pump 14 and the load pressure of the swing hydraulic motor 2A. Note that the controller 30 may be configured to grasp the amount of hydraulic oil flowing into the swing hydraulic motor 2A based on the operation amount of the operation device 26 instead of the differential pressure. This is because the controller 30 can estimate the differential pressure between the discharge pressure of the main pump 14 and the load pressure of the swing hydraulic motor 2A based on the operation amount of the operation device 26, and furthermore, can estimate the amount of hydraulic oil flowing into the swing hydraulic motor 2A. Note that the operation amount of the operation device 26 is, for example, the operation amount of each of the left operation lever 26L and the right operation lever 26R.

Description of Symbols

[0124] 2A Swing Hydraulic Motor (Hydraulic Actuator) 14 Main Pump (Hydraulic Pump) 26 Operating Device 30 Controller (Control Device) 100 Excavator 171 - 176 Directional Control Valve 510 Swing Opening Characteristic 520 Boom Opening Characteristic 610 Lever Operating Characteristic 621 - 623 Flow Rate Characteristic 631 Operating Position 711 - 713 Lever Operating Characteristic (Operating Characteristic) 721 - 723 Flow Rate Characteristic (Operating Characteristic) 731 - 731 Operating Position

Claims

1. An operating device, a hydraulic pump for supplying hydraulic oil, a hydraulic actuator, a direction switching valve for controlling the hydraulic oil flowing from the hydraulic pump to the hydraulic actuator, and a control device for controlling the direction switching valve based on the operation amount of the operating device, wherein the control device has a reference operating characteristic that serves as a reference for the operating characteristics between the operation amount of the operating device and the operating speed of the hydraulic actuator, has a plurality of operating characteristics between the operation amount of the operating device and the spool stroke amount of the direction switching valve, and changes the operating characteristics so that the operating characteristics approach the reference operating characteristic based on the differential pressure between the discharge pressure of the hydraulic pump and the load pressure of the hydraulic actuator. A working machine.

2. The direction switching valve is a spool valve, and the control device reduces the stroke amount of the spool of the direction switching valve with respect to the operation amount of the operating device as the differential pressure increases. The working machine according to Claim 1.

3. The direction switching valve is a spool valve, and the control device increases the stroke amount of the spool of the direction switching valve with respect to the operation amount of the operating device as the differential pressure decreases. The working machine according to Claim 1 or Claim 2.

4. The control device changes the operating characteristics based on the operation of the operating device. The working machine according to Claim 1.

5. The control device determines the operation of the working machine based on the operation of the operating device, and changes the operating characteristics based on the operation. The working machine according to Claim 4.

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