Excavator

Abstract

To facilitate determination of an erroneous operation.SOLUTION: A shovel comprises a detection unit that detects a physical quantity that varies according to the content of an operation on an operating device that operates an actuator, and a determination unit that determines whether the operation is an erroneous operation according to whether the physical quantity has continuously increased or decreased.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] In a conventional work vehicle, a technique is known in which, when the operation of an operating member is determined to be an erroneous operation, the operation of a hydraulic actuator by the operating member is locked. For example, a conventional technique is known in which, when the time elapsed since the release state that allows the supply of pilot pressure to the actuator control valve is entered is less than a predetermined time, and the pilot pressure reaches or exceeds a predetermined pressure, the operation of the operating member is determined to be an erroneous operation and the operation of the hydraulic actuator is locked (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5467176 Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional technology described above, it is necessary to set a threshold value for the elapsed time after the release state, which allows the supply of pilot pressure, and a threshold value for the pilot pressure. However, the way in which the pilot pressure increases is affected by the viscosity of the hydraulic oil, which in turn is affected by factors such as the outside air temperature. Therefore, in the past, these threshold values ​​had to be appropriately set depending on the environment in which the work vehicle was used, making it difficult to easily identify erroneous operation. Furthermore, to completely lock out erroneous lever operation, it was necessary to set a low threshold value for the pilot pressure and a long threshold value for the elapsed time. However, this would result in locking even when the user intended to operate the lever, making the machine less user-friendly. Therefore, these threshold values ​​had to be set appropriately, making it difficult to easily identify erroneous operation.

[0005] In view of the above circumstances, an object of the present invention is to make it easier to determine whether an operation error has occurred. [Means for solving the problem]

[0006] The shovel according to the embodiment of the present invention changes depending on the operation of the operating device that operates the actuator. Pilot Pressure a detection unit for detecting a control valve that sets a pilot line connecting the operating device and the pilot pump in a connected state or a cut-off state; a switching unit that uses the control valve to switch the pilot line from a connected state to a cut-off state, or from a cut-off state to a connected state; and a control unit that, when the pilot pressure becomes equal to or greater than a predetermined value within a predetermined time after the pilot line is switched from the cut-off state to the connected state and further increases multiple times consecutively, The above operation is an error That is A determination unit that determines The switching unit repeatedly switches the pilot line from a communication state to a disconnection state when the erroneous operation is determined. . [Effects of the Invention]

[0007] This makes it easier to determine whether an operation has been erroneous. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a side view of a shovel according to an embodiment of the present invention. [Figure 2] FIG. 1 is a top view of a shovel according to an embodiment of the present invention. [Figure 3] FIG. 1 is a diagram illustrating an example of the configuration of a basic system mounted on a shovel. [Figure 4] FIG. 1 is a diagram illustrating an example of the configuration of a hydraulic system mounted on a shovel. [Figure 5] FIG. 2 is a diagram showing an example of an electric circuit diagram illustrating the relationship between a control valve and a controller. [Figure 6] 1 is a first flowchart illustrating the operation of a shovel according to an embodiment. [Figure 7] 4 is a diagram illustrating the relationship between a negative control pressure, an operation signal, and a control signal. FIG. [Figure 8] 10 is a second flowchart illustrating the operation of the shovel according to the embodiment. [Figure 9] FIG. 4 is a diagram illustrating the relationship between a pilot pressure, an operation signal, and a control signal. [Figure 10] FIG. 10 is a diagram showing another example of the configuration of a hydraulic system mounted on a shovel. [Figure 11] 5A and 5B are diagrams illustrating the relationship between the discharge pressure of the backup pump, an operation signal, and a control signal. DETAILED DESCRIPTION OF THE INVENTION

[0009] (Embodiment) First, a shovel 100 as an excavator according to an embodiment of the present invention will be described with reference to Figures 1 and 2. Figure 1 is a side view of the shovel 100, and Figure 2 is a top view of the shovel 100.

[0010] In this embodiment, the undercarriage 1 of the excavator 100 includes crawlers 1C as driven bodies. The crawlers 1C are driven by a traveling hydraulic motor 2M mounted on the undercarriage 1. However, the traveling hydraulic motor 2M may be a traveling motor-generator serving as an electric actuator. 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. The undercarriage 1 functions as a driven body because it is driven by the crawlers 1C.

[0011] An upper rotating body 3 is rotatably mounted on the lower traveling body 1 via a rotating mechanism 2. The rotating mechanism 2, which serves as a driven body, is driven by a rotating hydraulic motor 2A mounted on the upper rotating body 3. However, the rotating hydraulic motor 2A may also be a rotating motor-generator serving as an electric actuator. The upper rotating body 3 is driven by the rotating mechanism 2 and therefore functions as a driven body.

[0012] A boom 4 serving as a driven body is attached to the upper rotating body 3. An arm 5 serving as a driven body is attached to the tip of the boom 4, and a bucket 6 serving as a driven body and an end attachment is attached to the tip of the arm 5. The boom 4, arm 5, and bucket 6 constitute an excavation attachment, 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.

[0013] A boom angle sensor S1 is attached to the boom 4, an arm angle sensor S2 is attached to the arm 5, and a bucket angle sensor S3 is attached to the bucket 6.

[0014] The boom angle sensor S1 detects the rotation angle of the boom 4. In this embodiment, the boom angle sensor S1 is an acceleration sensor, and can detect the boom angle, which is the rotation angle of the boom 4 relative to the upper rotating body 3. For example, the boom angle is at its minimum when the boom 4 is lowered to the lowest position, and increases as the boom 4 is raised.

[0015] The arm angle sensor S2 detects the rotation angle of the arm 5. In this embodiment, the arm angle sensor S2 is an acceleration sensor, and can detect the arm angle, which is the rotation angle of the arm 5 relative to the boom 4. For example, the arm angle is at its smallest when the arm 5 is fully closed, and increases as the arm 5 opens.

[0016] The bucket angle sensor S3 detects the rotation angle of the bucket 6. In this embodiment, the bucket angle sensor S3 is an acceleration sensor, and can detect the bucket angle, which is the rotation angle of the bucket 6 with respect to the arm 5. For example, the bucket angle is at its smallest when the bucket 6 is fully closed, and increases as the bucket 6 opens.

[0017] The boom angle sensor S1, arm angle sensor S2, and bucket angle sensor S3 may each be a potentiometer using a variable resistor, a stroke sensor that detects the stroke amount of the corresponding hydraulic cylinder, a rotary encoder that detects the rotation angle around the connecting pin, a gyro sensor, a combination of an acceleration sensor and a gyro sensor, or the like.

[0018] The upper rotating body 3 is provided with a cabin 10 as a driver's cab, and is equipped with an engine 11 as a prime mover of the excavator 100, etc. The upper rotating body 3 is also equipped with a controller 30, an object detection device 70, an imaging device 80, a direction detection device 85, a machine body inclination sensor S4, a swing angular velocity sensor S5, etc. An operation device 26, etc. is provided inside the cabin 10. For convenience, in this specification, the side of the upper rotating body 3 to which the boom 4 is attached is referred to as the front, and the side to which the counterweight is attached is referred to as the rear.

[0019] In this embodiment, an electric motor may be used as the prime mover instead of the engine 11. In this case, a power storage device is also installed to supply power to the electric motor. The power storage device is a device for storing power, and is, for example, an electric double layer capacitor, a lithium ion battery, or a nickel-metal hydride battery. By controlling the electric motor using an inverter, the main pump 14 is rotated and driven by the power stored in the power storage device.

[0020] The controller 30 is a control device for controlling the shovel 100. In this embodiment, the controller 30 is configured as a computer including a CPU, RAM, NVRAM, ROM, etc. The controller 30 reads out programs corresponding to each functional element from the ROM, loads them into the RAM, and causes the CPU to execute the corresponding processing.

[0021] The object detection device 70 is configured to detect objects present around the shovel 100. The object detection device 70 may also be configured to calculate the distance from the object detection device 70 or the shovel 100 to the recognized object. The object includes, for example, a person, an animal, a vehicle, a construction machine, a building, a hole, etc. The object detection device 70 includes, for example, an ultrasonic sensor, a millimeter-wave radar, a stereo camera, a LIDAR, a range image sensor, an infrared sensor, etc. In this embodiment, the object detection device 70 includes a forward sensor 70F attached to the front end of the top surface of the cabin 10, a rear sensor 70B attached to the rear end of the top surface of the upper rotating body 3, a left sensor 70L attached to the left end of the top surface of the upper rotating body 3, and a right sensor 70R attached to the right end of the top surface of the upper rotating body 3.

[0022] The object detection device 70 may be configured to detect a predetermined object within a predetermined area set around the shovel 100. For example, the object detection device 70 may be configured to be able to distinguish between a person and an object other than a person.

[0023] The imaging device 80 is configured to capture images of the surroundings of the excavator 100. In this embodiment, the imaging device 80 includes a rear camera 80B attached to the rear end of the upper surface of the upper rotating body 3, a left camera 80L attached to the left end of the upper surface of the upper rotating body 3, and a right camera 80R attached to the right end of the upper surface of the upper rotating body 3. The imaging device 80 may also include a front camera.

[0024] The rear camera 80B is disposed adjacent to the rear sensor 70B, the left camera 80L is disposed adjacent to the left sensor 70L, and the right camera 80R is disposed adjacent to the right sensor 70R. The front camera may be disposed adjacent to the front sensor 70F.

[0025] The images captured by the imaging device 80 are displayed on a display device DS installed inside the cabin 10. The imaging device 80 may be configured to display viewpoint-converted images such as overhead images on the display device DS. The overhead image is generated by, for example, combining images output by the rear camera 80B, the left camera 80L, and the right camera 80R.

[0026] The imaging device 80 may function as an object detection device, in which case the object detection device 70 may be omitted.

[0027] With this configuration, the shovel 100 can display on the display device DS an image of an object detected by the object detection device 70. Therefore, when the operation of the driven body is restricted or prohibited, the operator of the shovel 100 can immediately identify the object that caused this by looking at the image displayed on the display device DS.

[0028] The orientation detection device 85 is configured to detect information (hereinafter referred to as "orientation-related information") regarding the relative relationship between the orientation of the upper rotating body 3 and the orientation of the lower traveling body 1. For example, the orientation detection device 85 may be configured by a combination of a geomagnetic sensor attached to the lower traveling body 1 and a geomagnetic sensor attached to the upper rotating body 3.

[0029] Alternatively, the orientation detection device 85 may be configured by a combination of a GNSS receiver attached to the undercarriage 1 and a GNSS receiver attached to the upper rotating body 3. In a configuration in which the upper rotating body 3 is driven to rotate by a rotation motor-generator, the orientation detection device 85 may be configured by a resolver. The orientation detection device 85 may be disposed, for example, in a center joint provided in association with the rotation mechanism 2 that realizes relative rotation between the undercarriage 1 and the upper rotating body 3.

[0030] The machine body tilt sensor S4 detects the tilt of the shovel 100 relative to a predetermined plane. In this embodiment, the machine body tilt sensor S4 is an acceleration sensor that detects the tilt angle of the front-rear axis and the left-right axis of the upper rotating body 3 relative to a horizontal plane. The sensor may be configured as a combination of an acceleration sensor and a gyro sensor. The front-rear axis and the left-right axis of the upper rotating body 3 are, for example, perpendicular to each other and pass through the shovel center point, which is a point on the rotation axis of the shovel 100.

[0031] The rotation angular velocity sensor S5 detects the rotation angular velocity of the upper rotating body 3. In this embodiment, it is a gyro sensor. It may also be a resolver, a rotary encoder, or the like. The rotation angular velocity sensor S5 may also detect the rotation speed. The rotation speed may be calculated from the rotation angular velocity.

[0032] Hereinafter, any combination of the boom angle sensor S1, arm angle sensor S2, bucket angle sensor S3, machine body tilt sensor S4 and turning angular velocity sensor S5 will also be collectively referred to as an attitude sensor.

[0033] Next, the basic system mounted on the shovel 100 will be described with reference to Fig. 3. Fig. 3 shows an example of the configuration of the basic system mounted on the shovel 100. In Fig. 3, mechanical power transmission lines are indicated by double lines, hydraulic oil lines by thick solid lines, pilot lines by dashed lines, and power lines by thin solid lines.

[0034] The basic system mainly includes an engine 11, a main pump 14, a pilot pump 15, a control valve 17, an operating device 26, an operating pressure sensor 29, a controller 30, an alarm device 49, a control valve 60, an object detection device 70, an engine control unit (ECU 74), an engine speed adjustment dial 75, and an imaging device 80.

[0035] The engine 11 is a diesel engine that employs isochronous control to maintain a constant engine speed regardless of load fluctuations. The fuel injection amount, fuel injection timing, boost pressure, etc. of the engine 11 are controlled by an ECU 74. The engine 11 is connected to a main pump 14 and a pilot pump 15, which serve as hydraulic pumps. The main pump 14 is connected to a control valve 17 via a hydraulic oil line.

[0036] The control valve 17 is a hydraulic control device that controls the hydraulic system of the excavator 100. The control valve 17 is connected to hydraulic actuators such as the left traveling hydraulic motor 2ML, the right traveling hydraulic motor 2MR, the boom cylinder 7, the arm cylinder 8, the bucket cylinder 9, and the swing hydraulic motor.

[0037] Specifically, the control valve 17 includes multiple spool valves corresponding to the respective hydraulic actuators. Each spool valve is configured to be displaceable in response to the pilot pressure so that the opening area of ​​the PC port and the opening area of ​​the CT port can be increased or decreased. The PC port is a port that connects the main pump 14 to the hydraulic actuators. The CT port is a port that connects the hydraulic actuators to the hydraulic oil tank.

[0038] The operating device 26 is a device used by an operator to operate the actuator. The actuator includes at least one of a hydraulic actuator and an electric actuator. In this embodiment, the operating device 26 is a hydraulic operating device, and supplies hydraulic oil discharged from the pilot pump 15 to the pilot port of the corresponding spool valve in the control valve 17 via a pilot line.

[0039] The pressure of the hydraulic oil (pilot pressure) supplied to each pilot port corresponds to the operation direction and operation amount of the operation device 26 corresponding to each hydraulic actuator. The operation device 26 includes, for example, a left operation lever, a right operation lever, and a travel operation device.

[0040] The discharge pressure sensor 28 detects the discharge pressure of the main pump 14. In this embodiment, the discharge pressure sensor 28 outputs the detected value to the controller 30.

[0041] The operation pressure sensor 29 detects the operation of the operation device 26 by the operator. In this embodiment, the operation pressure sensor 29 detects the operation direction and operation amount of the operation device 26 corresponding to each actuator in the form of pressure (operation pressure), and outputs the detected value to the controller 30. The operation of the operation device 26 may be detected using a sensor other than the operation pressure sensor.

[0042] The alarm device 49 is configured to be able to call the attention of people involved in work with the excavator 100. The alarm device 49 may be configured, for example, as a combination of an indoor alarm device and an outdoor alarm device.

[0043] The indoor alarm device is configured to attract the attention of the operator of the excavator 100 inside the cabin 10. The indoor alarm device includes, for example, at least one of a sound output device, a vibration generator, and a light emitting device provided inside the cabin 10. The indoor alarm device may be a display device DS.

[0044] The outdoor alarm device is configured to attract the attention of workers working around the excavator 100. The outdoor alarm device includes, for example, at least one of an audio output device and a light-emitting device provided outside the cabin 10. The audio output device as the outdoor alarm device may be, for example, a traveling alarm device attached to the bottom surface of the upper rotating body 3. The outdoor alarm device may be a light-emitting device provided on the upper rotating body 3. However, the outdoor alarm device may be omitted. For example, when the object detection device 70 detects an object, the alarm device 49 may notify people involved in work with the excavator 100 of that fact.

[0045] The control valve 60 is configured to be able to switch between an enabled state and an disabled state of the operating device 26. The enabled state of the operating device 26 is a state in which the operator can operate the hydraulic actuator using the operating device 26. The disabled state of the operating device 26 is a state in which the operator cannot operate the hydraulic actuator using the operating device 26.

[0046] In this embodiment, the control valve 60 includes a gate lock valve configured to operate in response to a command from the controller 30. Specifically, the control valve 60 is disposed in a pilot line connecting the pilot pump 15 and the operating device 26, and is configured to be able to switch between disconnection and communication of the pilot line in response to a command from the controller 30.

[0047] The operating device 26 is activated when the gate lock valve is opened, for example, by operating a gate lock lever (not shown). When the gate lock valve is open, the pilot line is connected by the gate lock valve. In the following description, the state in which the gate lock valve is open may be referred to as the connected state.

[0048] Furthermore, the operating device 26 is disabled when the gate lock valve is closed by operating the gate lock lever. When the gate lock valve is closed, the pilot line is blocked by the gate lock valve. In the following explanation, the state in which the gate lock valve is open may be referred to as the blocked state.

[0049] The ECU 74 outputs data relating to the state of the engine 11, such as the coolant temperature, to the controller 30. The regulator 13 of the main pump 14 outputs data relating to the swash plate tilt angle to the controller 30. The discharge pressure sensor 28 outputs data relating to the discharge pressure of the main pump 14 to the controller 30. The oil temperature sensor 14c provided in the line between the hydraulic oil tank and the main pump 14 outputs data relating to the temperature of the hydraulic oil flowing through that line to the controller 30. The operating pressure sensor 29 outputs data relating to the pilot pressure generated when the operating device 26 is operated to the controller 30. The controller 30 stores this data in a temporary storage unit (memory) and can output it to the display device DS when necessary.

[0050] The engine speed adjustment dial 75 is a dial for adjusting the speed of the engine 11. The engine speed adjustment dial 75 outputs data relating to the setting state of the engine speed to the controller 30. The engine speed adjustment dial 75 is configured to be able to switch the engine speed among four stages: SP mode, H mode, A mode, and idling mode.

[0051] The SP mode is a rotation speed mode selected when priority is given to the amount of work, and uses the highest engine rotation speed. The H mode is a rotation speed mode selected when priority is given to both the amount of work and fuel economy, and uses the second highest engine rotation speed. The A mode is a rotation speed mode selected when priority is given to fuel economy while operating the excavator 100 with low noise, and uses the third highest engine rotation speed. The idling mode is a rotation speed mode selected when the engine 11 is to be in an idling state, and uses the lowest engine rotation speed. The engine 11 is controlled to maintain a constant engine rotation speed corresponding to the rotation speed mode set with the engine rotation speed adjustment dial 75. The rotation speed mode is not limited to that in this embodiment, and may be set to five or more stages.

[0052] The display device DS has a control unit DSa, an image display unit DS1, and a switch panel DS2 as an input unit. The control unit DSa is configured to control the image displayed on the image display unit DS1. In this embodiment, the control unit DSa is configured as a computer equipped with a CPU, RAM, NVRAM, ROM, etc. In this case, the control unit DSa reads out programs corresponding to each functional element from the ROM, loads them into the RAM, and causes the CPU to execute the corresponding processing. However, each functional element may be configured as hardware, or as a combination of software and hardware. Furthermore, the image displayed on the image display unit DS1 may be controlled by the controller 30 or the imaging device 80.

[0053] The switch panel DS2 is a panel including hardware switches. The switch panel DS2 may be a touch panel. The display device DS operates by receiving power from the storage battery BT. The storage battery BT is charged with electricity generated by, for example, an alternator 11a. The power of the storage battery BT may be supplied to the controller 30 or the like. The starter 11b of the engine 11 is driven by, for example, power from the storage battery BT to start the engine 11.

[0054] The lever button LB is a button provided on the operating device 26. In this embodiment, the lever button LB is a button provided on the tip of an operating lever serving as the operating device 26. The operator of the shovel 100 can operate the lever button LB while operating the operating lever. For example, the operator can press the lever button LB with his thumb while holding the operating lever in his hand.

[0055] Next, a description will be given of the functions of the controller 30 of this embodiment. The controller 30 of this embodiment realizes the functions of each unit described below by the CPU executing a program stored in the ROM or the like.

[0056] The controller 30 of this embodiment has a switching unit 31, a detection unit 32, and a determination unit 33. The switching unit 31 outputs a control signal for controlling the state of the control valve 60 (gate lock valve) in response to a switching instruction from the determination unit 33. Specifically, the switching unit 31 receives a control valve switching instruction from the determination unit 33 and switches the control valve 60 from a communicating state to a blocked state.

[0057] Furthermore, the switching unit 31 may switch the control valve 60 from a shut-off state to a communicating state, or from a communicating state to a shut-off state, in response to an operation on a gate lock lever (not shown).

[0058] The detection unit 32 detects physical quantities detected in the shovel 100. The physical quantities in this embodiment specifically include, for example, the pressure of the hydraulic oil (pilot pressure) detected by the operating pressure sensor 29, and the control pressure (negative control pressure) detected by the control pressure sensor 19 described below. In other words, the physical quantities in this embodiment are values ​​that change depending on the amount of lever operation (contents of operation) for the operating device 26 of the shovel 100, and are values ​​that are detected depending on the content of the operation for the operating device 26.

[0059] When the control valve 60 is in a communicating state, the judgment unit 33 judges whether the operation of the operating device 26 is an erroneous operation depending on whether the physical quantity detected by the detection unit 32 decreases or increases multiple times consecutively within a predetermined time from when the switch 51 is switched to the ON state and becomes less than or greater than a predetermined value.

[0060] In this embodiment, the determination unit 33 determines the physical quantity as the control pressure (negative control pressure) detected by the control pressure sensor 19, and determines whether the negative control pressure has decreased multiple times consecutively within a predetermined time from when the switch 51 is switched to the ON state, and whether the negative control pressure is equal to or less than a predetermined value. Note that the predetermined time from when the switch 51 is switched to the ON state and the predetermined value here are preset values, which are specified values ​​that are set independently of the environment of the work site of the excavator 100, etc.

[0061] If the negative control pressure decreases multiple times consecutively within a predetermined time from when the switch 51 is switched to the ON state, the judgment unit 33 judges that the operation on the operating device 26 at that time was an erroneous operation, and notifies the switching unit 31 of an instruction to switch the gate lock valve from a communicating state to a blocked state.

[0062] The determining unit 33 of this embodiment may determine, for example, whether the control valve 60 is in a communicating state or a blocked state.

[0063] Next, a configuration example of a hydraulic system mounted on the shovel 100 will be described with reference to Fig. 4. Fig. 4 is a diagram showing a configuration example of a hydraulic system mounted on the shovel 100. In Fig. 4, a mechanical power transmission system, a hydraulic oil line, a pilot line, and an electrical control system are indicated by double lines, solid lines, dashed lines, and dotted lines, respectively.

[0064] 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 17, an operating device 26, a discharge pressure sensor 28, an operating pressure sensor 29, a controller 30, a control valve 60, and the like.

[0065] In FIG. 4, the hydraulic system circulates hydraulic oil from a main pump 14 driven by an engine 11 through a center bypass line 40 or a parallel line 42 to a hydraulic oil tank.

[0066] The engine 11 is a drive source of the excavator 100. In this embodiment, the engine 11 is, for example, a diesel engine that operates to maintain a predetermined rotation speed. An output shaft of the engine 11 is connected to the input shafts of the main pump 14 and the pilot pump 15.

[0067] The main pump 14 supplies hydraulic oil through a hydraulic oil line to the control valve 17. In this embodiment, the main pump 14 is a swash plate type variable displacement hydraulic pump.

[0068] The regulator 13 controls the discharge amount of the main pump 14. In this embodiment, the regulator 13 controls the discharge amount of the main pump 14 by adjusting the tilt angle of the swash plate of the main pump 14 in response to a control command from the controller 30.

[0069] The pilot pump 15 supplies hydraulic oil via a pilot line to hydraulic control devices including an operating device 26. In this embodiment, the pilot pump 15 is a fixed displacement hydraulic pump.

[0070] The control valve 17 is a hydraulic control device that controls the hydraulic system in the excavator 100. In this embodiment, the control valve 17 includes control valves 171 to 176. The control valve 175 includes a control valve 175L and a control valve 175R, and the control valve 176 includes a control valve 176L and a control valve 176R. The control valve 17 can selectively supply hydraulic oil discharged from the main pump 14 to one or more hydraulic actuators via the control valves 171 to 176. The control valves 171 to 176 control the flow rate of hydraulic oil flowing from the main pump 14 to the hydraulic actuators and the flow rate of hydraulic oil flowing from the hydraulic actuators to a hydraulic oil tank. The hydraulic actuators include a boom cylinder 7, an arm cylinder 8, a bucket cylinder 9, a left traveling hydraulic motor 2ML, a right traveling hydraulic motor 2MR, and a swing hydraulic motor 2A.

[0071] The main pump 14 includes a left main pump 14L and a right main pump 14R. The left main pump 14L circulates hydraulic oil to the hydraulic oil tank via a left center bypass line 40L or a left parallel line 42L, and the right main pump 14R circulates hydraulic oil to the hydraulic oil tank via a right center bypass line 40R or a right parallel line 42R.

[0072] The left center bypass line 40L is a hydraulic oil line that passes through control valves 171, 173, 175L, and 176L arranged within the control valve 17. The right center bypass line 40R is a hydraulic oil line that passes through control valves 172, 174, 175R, and 176R arranged within the control valve 17.

[0073] The control valve 171 is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged by the left main pump 14L to the left traveling hydraulic motor 2ML and to discharge the hydraulic oil discharged by the left traveling hydraulic motor 2ML to the hydraulic oil tank.

[0074] The control valve 172 is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged by the right main pump 14R to the right traveling hydraulic motor 2MR and to discharge the hydraulic oil discharged by the right traveling hydraulic motor 2MR to the hydraulic oil tank.

[0075] The control valve 173 is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged by the left main pump 14L to the swing hydraulic motor 2A and to discharge the hydraulic oil discharged by the swing hydraulic motor 2A to the hydraulic oil tank.

[0076] The control valve 174 is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged by the right main pump 14R to the bucket cylinder 9 and to discharge the hydraulic oil in the bucket cylinder 9 to the hydraulic oil tank.

[0077] The control valve 175L is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged by the left main pump 14L to the boom cylinder 7. The control valve 175R is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged by the right main pump 14R to the boom cylinder 7 and to discharge the hydraulic oil in the boom cylinder 7 to the hydraulic oil tank.

[0078] The control valve 176L is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged by the left main pump 14L to the arm cylinder 8 and to discharge the hydraulic oil in the arm cylinder 8 to the hydraulic oil tank.

[0079] The control valve 176R is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged by the right main pump 14R to the arm cylinder 8 and to discharge the hydraulic oil in the arm cylinder 8 to the hydraulic oil tank.

[0080] The left parallel conduit 42L is a hydraulic oil line that runs parallel to the left center bypass conduit 40L. When the flow of hydraulic oil through the left center bypass conduit 40L is restricted or blocked by any of the control valves 171, 173, and 175L, the left parallel conduit 42L can supply hydraulic oil to a downstream control valve. The right parallel conduit 42R is a hydraulic oil line that runs parallel to the right center bypass conduit 40R. When the flow of hydraulic oil through the right center bypass conduit 40R is restricted or blocked by any of the control valves 172, 174, and 175R, the right parallel conduit 42R can supply hydraulic oil to a downstream control valve.

[0081] The regulator 13 includes a left regulator 13L and a right regulator 13R. The left regulator 13L controls the discharge rate of the left main pump 14L by adjusting the tilt angle of the swash plate of the left main pump 14L in accordance with the discharge pressure of the left main pump 14L. Specifically, the left regulator 13L adjusts the tilt angle of the swash plate of the left main pump 14L in accordance with an increase in the discharge pressure of the left main pump 14L to reduce the discharge rate. The same applies to the right regulator 13R. This is to prevent the absorption horsepower of the main pump 14, which is expressed as the product of the discharge pressure and the discharge rate, from exceeding the output horsepower of the engine 11.

[0082] The operating device 26 includes a left operating lever 26L, a right operating lever 26R, and a travel lever 26D. The travel lever 26D includes a left traveling lever 26DL and a right traveling lever 26DR.

[0083] The left operating lever 26L is used for swing operation and operation of the arm 5. When the left operating lever 26L is operated in the forward / backward direction, it uses the hydraulic oil discharged from the pilot pump 15 to introduce a control pressure corresponding to the amount of lever operation into the pilot port of the control valve 176. When it is operated in the left / right direction, it uses the hydraulic oil discharged from the pilot pump 15 to introduce a control pressure corresponding to the amount of lever operation into the pilot port of the control valve 173.

[0084] Specifically, when the left operating lever 26L is operated in the arm closing direction, it introduces hydraulic oil into the right pilot port of the control valve 176L and into the left pilot port of the control valve 176R. When the left operating lever 26L is operated in the arm opening direction, it introduces hydraulic oil into the left pilot port of the control valve 176L and into the right pilot port of the control valve 176R. When the left operating lever 26L is operated in the left turning direction, it introduces hydraulic oil into the left pilot port of the control valve 173, and when operated in the right turning direction, it introduces hydraulic oil into the right pilot port of the control valve 173.

[0085] The right operating lever 26R is used to operate the boom 4 and the bucket 6. When the right operating lever 26R is operated in the forward / backward direction, it uses the hydraulic oil discharged by the pilot pump 15 to introduce a control pressure corresponding to the amount of lever operation into the pilot port of the control valve 175. When it is operated in the left / right direction, it uses the hydraulic oil discharged by the pilot pump 15 to introduce a control pressure corresponding to the amount of lever operation into the pilot port of the control valve 174.

[0086] Specifically, when the right operating lever 26R is operated in the boom-lowering direction, it introduces hydraulic oil to the left pilot port of the control valve 175R. When the right operating lever 26R is operated in the boom-raising direction, it introduces hydraulic oil to the right pilot port of the control valve 175L and also introduces hydraulic oil to the left pilot port of the control valve 175R. When the right operating lever 26R is operated in the bucket-closing direction, it introduces hydraulic oil to the right pilot port of the control valve 174, and when operated in the bucket-opening direction, it introduces hydraulic oil to the left pilot port of the control valve 174.

[0087] The travel lever 26D is used to operate the crawler 1C. Specifically, the left travel lever 26DL is used to operate the left crawler 1CL. It may be configured to operate in conjunction with the left travel pedal. When the left travel lever 26DL is operated in the forward / backward direction, it uses hydraulic oil discharged from the pilot pump 15 to introduce a control pressure corresponding to the amount of lever operation into the pilot port of the control valve 171. The right travel lever 26DR is used to operate the right crawler 1CR. It may be configured to operate in conjunction with the right travel pedal. When the right travel lever 26DR is operated in the forward / backward direction, it uses hydraulic oil discharged from the pilot pump 15 to introduce a control pressure corresponding to the amount of lever operation into the pilot port of the control valve 172.

[0088] 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.

[0089] The operation pressure sensor 29 includes operation pressure sensors 29LA, 29LB, 29RA, 29RB, 29DL, and 29DR. The operation pressure sensor 29LA detects the operation of the left operation lever 26L by the operator in the forward / backward direction in the form of pressure, and outputs the detected value to the controller 30. The operation content includes, for example, the lever operation direction, the lever operation amount (lever operation angle), etc.

[0090] Similarly, the operating pressure sensor 29LB detects the operation of the left operating lever 26L by the operator in the left-right direction in the form of pressure, and outputs the detected value to the controller 30. The operating pressure sensor 29RA detects the operation of the right operating lever 26R by the operator in the forward-backward direction in the form of pressure, and outputs the detected value to the controller 30.

[0091] The operating pressure sensor 29RB detects the operation of the right operating lever 26R by the operator in the left-right direction in the form of pressure, and outputs the detected value to the controller 30. The operating pressure sensor 29DL detects the operation of the left traveling lever 26DL by the operator in the forward-backward direction in the form of pressure, and outputs the detected value to the controller 30. The operating pressure sensor 29DR detects the operation of the right traveling lever 26DR by the operator in the forward-backward direction in the form of pressure, and outputs the detected value to the controller 30.

[0092] The controller 30 receives the output of the operating pressure sensor 29, and outputs a control command to the regulator 13 as necessary to change the discharge rate of the main pump 14.

[0093] Here, a description will be given of negative control using the throttle 18 and the control pressure sensor 19. 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.

[0094] A left throttle 18L is disposed in the left center bypass pipe 40L between the most downstream control valve 176L and the hydraulic oil tank. Therefore, the flow of hydraulic oil discharged by the left main pump 14L is restricted by the left throttle 18L. The left throttle 18L generates a control pressure (negative 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.

[0095] The value detected by the control pressure sensor 19 is a negative control pressure that changes as the hydraulic oil discharged from the main pump 14 flows into the hydraulic actuator due to the movement of the control valves 171 to 176 corresponding to the lever operation amount of the operating device 26.

[0096] The controller 30 controls the discharge rate of the left main pump 14L by adjusting the swash plate tilt angle of the left main pump 14L in accordance with this control pressure. The controller 30 decreases the discharge rate of the left main pump 14L as this control pressure increases, and increases the discharge rate of the left main pump 14L as this control pressure decreases. The discharge rate of the right main pump 14R is controlled in a similar manner.

[0097] Specifically, as shown in Fig. 4, when the excavator 100 is in a standby state in which none of the hydraulic actuators are operated, the hydraulic oil discharged from the left main pump 14L passes through the left center bypass pipe 40L and reaches the left throttle 18L. Then, the flow of the hydraulic oil discharged from the left main pump 14L increases the control pressure generated upstream of the left throttle 18L.

[0098] As a result, the controller 30 reduces the discharge rate of the left main pump 14L to the allowable minimum discharge rate, thereby suppressing pressure loss (pumping loss) when the discharged hydraulic oil passes through the left center bypass pipe 40L. On the other hand, when any of the hydraulic actuators is operated, the hydraulic oil discharged from the left main pump 14L flows into the hydraulic actuator to be operated via the control valve corresponding to the hydraulic actuator to be operated.

[0099] The flow of hydraulic oil discharged from the left main pump 14L reduces or eliminates the amount of hydraulic oil reaching the left throttle 18L, lowering the control pressure generated upstream of the left throttle 18L. As a result, the controller 30 increases the discharge rate of the left main pump 14L, circulating sufficient hydraulic oil to the hydraulic actuator to be operated and ensuring reliable drive of the hydraulic actuator. The controller 30 also controls the discharge rate of the right main pump 14R in a similar manner.

[0100] With the above-described configuration, the hydraulic system of Fig. 4 can suppress unnecessary energy consumption in the main pump 14 in a standby state. The unnecessary energy consumption includes pumping loss caused by the hydraulic oil discharged from the main pump 14 in the center bypass pipe 40. Furthermore, when operating a hydraulic actuator, the hydraulic system of Fig. 4 can reliably supply necessary and sufficient hydraulic oil from the main pump 14 to the hydraulic actuator to be operated.

[0101] The control valve 60 is configured to switch between an enabled state and an disabled state of the operating device 26. In this embodiment, the control valve 60 is a spool-type solenoid valve, and is configured to operate in response to a current command from the controller 30.

[0102] The enabled state of the operating device 26 is a state in which the operator can move the associated driven body by operating the operating device 26, and the disabled state of the operating device 26 is a state in which the operator cannot move the associated driven body even if he or she operates the operating device 26. In other words, when the control valve 60 is in a communicating state, the operating device 26 is in an enabled state, and when the control valve 60 is in a shutoff state, operation of the hydraulic actuator by the operating device 26 is in an disabled state.

[0103] In this embodiment, the control valve 60 is a solenoid valve that can switch between a connected state and a cut-off state of a pilot line CD1 that connects the pilot pump 15 and the operating device 26. Specifically, the control valve 60 is configured to switch between a connected state and a cut-off state of the pilot line CD1 in response to a command from the controller 30. More specifically, the control valve 60 connects the pilot line CD1 in a first valve position and cuts off the pilot line CD1 in a second valve position. Figure 4 shows that the control valve 60 is in the first valve position and that the pilot line CD1 is connected.

[0104] The control valve 60 may be configured to operate in conjunction with a gate lock lever (not shown). Specifically, the control valve 60 may be configured to block the pilot line CD1 when the gate lock lever is pushed down and to open the pilot line CD1 when the gate lock lever is pulled up. The control valve 60 may also be configured to be able to individually switch each of the multiple operating devices 26 between an enabled state and an disabled state.

[0105] Using the above-described hydraulic system, the controller 30 may be configured to automatically brake the drive unit of the shovel 100 as needed. Automatically braking the drive unit may include, for example, forcibly slowing down or stopping the movement of the drive unit even if the operating device 26 related to the drive unit is being operated.

[0106] The controller 30 may be configured to automatically brake the drive unit when the object detection device 70 detects an object, for example. In this case, the drive unit may include, for example, at least one of the swing hydraulic motor 2A and the traveling hydraulic motor 2M. Braking of the drive unit is achieved, for example, by switching the pilot line CD1 from a connected state to a blocked state using the control valve 60 while the operation device 26 is being operated. This is because the control valve corresponding to the operation device 26 that is being operated returns to the neutral valve position. Braking of the drive unit may include at least one of reducing the operating speed of the drive unit and stopping the movement of the drive unit.

[0107] "When braking the drive unit" may include, for example, when the operating speed of the drive unit is reduced, when the movement of the drive unit is stopped, and when the drive unit is kept stopped.

[0108] Note that such a hydraulic system may employ an electric control lever equipped with an electric pilot circuit, instead of a hydraulic control lever. In this case, the lever operation amount of the electric control lever is input to the controller 30 as, for example, an electric signal. Also, a solenoid valve is disposed between the pilot pump 15 and the pilot port of each control valve. The solenoid valve is configured to operate in response to an electric signal from the controller 30. With this configuration, when manual operation is performed using the electric control lever, the controller 30 controls the solenoid valve with an electric signal corresponding to the lever operation amount, thereby increasing or decreasing the pilot pressure and moving each control valve.

[0109] Next, the relationship between the control valve 60 and the controller 30 will be described with reference to Fig. 5. Fig. 5 is a diagram showing an example of an electric circuit diagram illustrating the relationship between the control valve and the controller.

[0110] The controller 30 of this embodiment is connected to a switch 51 and a relay 52. ​​One end of the switch 51 is connected to an ignition power supply 55, and the other end is connected to the controller 30 and one input terminal of the relay 52. ​​The relay 52 is connected between the switch 51 and the control valve 60.

[0111] The switch 51 is turned on (conductive) or off (cut-off) depending on the operation of the gate lock lever.

[0112] In this embodiment, when the switch 51 is turned on by operating the gate lock lever, the control valve 60 and the ignition power supply 55 are electrically connected via the relay 52, power is supplied to the control valve 60, and the control valve 60 is brought into a communicating state. At this time, the relay 52 is in the ON state (conducting).

[0113] Furthermore, when the switch 51 is turned on, a high-level (hereinafter referred to as H-level) signal is input from the ignition power supply 55 to the controller 30 via the switch 51. The controller 30 detects from this signal that the control valve 60 has entered a communicating state.

[0114] In addition, in this embodiment, when the switch 51 is turned OFF by operating the gate lock lever, the control valve 60 and the ignition power supply 55 are cut off, the supply of power to the control valve 60 is stopped, and the control valve 60 is turned off.

[0115] Furthermore, when the switch 51 is turned OFF, the H-level signal input from the ignition power supply 55 to the controller 30 is inverted to a low level (hereinafter referred to as L-level). The controller 30 detects from this L-level signal that the control valve 60 has entered a shutoff state.

[0116] In this way, the switch 51 of this embodiment switches the state of the control valve 60 from a communicating state to a blocking state, or from a blocking state to a communicating state, in response to the operation of the gate lock lever.

[0117] The relay 52 controls the connection and disconnection between the switch 51 and the control valve 60 in response to a control signal output from the switching unit 31 of the controller 30 .

[0118] More specifically, when the judgment unit 33 determines that the operation of the operating device 26 is an erroneous operation based on a change in the physical quantity detected by the detection unit 32 of the controller 30, the relay 52 disconnects the switch 51 and the control valve 60, thereby bringing the control valve 60 into a disconnected state.

[0119] The case where the physical quantity changes due to the operation of the operating device 26 means that the operating device 26 is in an effective state, and the control valve 60 is in a communicating state.

[0120] That is, the switching of the state of the control valve 60 using the relay 52 of this embodiment is applied when the control valve 60 is in the communicating state by the switch 51.

[0121] One input terminal of the relay 52 is connected to the other end of the switch 51, and the other input terminal is connected to the controller 30. In addition, the output terminal of the relay 52 is connected to the control valve 60.

[0122] In this embodiment, when the switch 51 is in the ON state and the switch 51 and the control valve 60 are electrically connected via the relay 52, the control valve 60 is in a communicating state. In other words, the operating device 26 is in an enabled state.

[0123] Furthermore, when the connection between the switch 51 and the control valve 60 is interrupted by the relay 52, even if the switch 51 is in the ON state, power is not supplied to the control valve 60, and the control valve 60 is in the interrupted state. In other words, the operating device 26 is in the disabled state.

[0124] In this manner, in this embodiment, even if the control valve 60 has been placed in the open state by the gate lock lever, if the controller 30 determines that the operation of the operating device 26 is an erroneous operation, the controller 30 can place the control valve 60 in the closed state. Therefore, according to this embodiment, safety can be improved compared to when the state of the control valve 60 is controlled only by the gate lock lever.

[0125] Next, the operation of the shovel 100 of this embodiment will be described with reference to Fig. 6. Fig. 6 is a first flowchart illustrating the operation of the shovel of this embodiment.

[0126] The controller 30 of the excavator 100 executes the processing of FIG. 6 when the control valve (gate lock valve) 60 is in the shutoff state and the engine is ON.

[0127] In this embodiment, for example, when an operator inserts a key into the key cylinder of the shovel 100 and turns the key to a first position, the power of the shovel 100 is turned on and the controller 30 is started. After that, even if the key is further turned to a second position, if the control valve 60 is in a communicating state, the engine 11 is not turned on, and the engine 11 is turned on only if the control valve 60 is in a shutoff state.

[0128] In this embodiment, this control makes it possible to prevent the shovel 100 from suddenly operating, for example, even if an erroneous operation occurs on the operating device 26 immediately after the engine 11 is turned on.

[0129] During work, it is expected that the operator may temporarily suspend operation inside the cabin 10. For example, this may occur when making a phone call or waiting for the next dump truck to arrive. In this state, the operator keeps the engine 11 in the ON state (the state in which the engine 11 is rotating) and shuts off the control valve 60 by operating the gate lock. By shutting off the control valve 60 in this way, even if the operator accidentally tilts the lever while waiting, application of pilot pressure to the control valves 171 to 176 can be prevented, and the hydraulic actuators will not malfunction.

[0130] In this manner, in a state where the operator has placed the control valve 60 in a closed state by operating the gate lock lever while maintaining the engine 11 in an ON state (a state where the operation is temporarily suspended), the controller 30 determines whether or not the control valve 60 has been switched from a closed state to a connected state by operating the gate lock lever (step S601). In other words, the controller 30 determines whether or not the switch 51 has been set to an ON state. In step S601, if the control valve 60 is not in a connected state, the controller 30 waits until the control valve 60 is set to a connected state.

[0131] When the control valve 60 is set to the open state in step S601, the controller 30 starts detecting the control pressure (negative control pressure) detected by the control pressure sensor 19 using the detection unit 32 (step S602). In this state, the lever included in the operation device 26 is not tilted, so the high-pressure hydraulic oil discharged from the main pump 14 does not flow into any hydraulic actuators but is returned to the tank T via the orifice 18. Because the return oil to the tank T is limited by the orifice 18, the negative control pressure detected by the control pressure sensor 19 is high. In this state, the determination unit 33 continues to detect the state of the switch 51 and the state of the negative control pressure.

[0132] Next, the controller 30 monitors the switching of the switch 51 to ON using the judgment unit 33, and judges whether the negative control pressure has decreased below a predetermined value multiple times consecutively within a predetermined time from the switching of the switch 51 to the ON state (step S603).

[0133] Here, for example, while the operator is operating the gate lock lever to resume operation, the operator's arm may come into contact with the lever. If the lever is already tilted due to a malfunction while the gate lock lever is being operated, pilot pressure will be applied to the control valve corresponding to the tilted lever immediately after the control valve 60 switches to the communicating state.

[0134] As a result, hydraulic oil flows into the hydraulic actuator through the control valve to which pilot pressure is applied, causing the hydraulic actuator to operate suddenly. As hydraulic oil flows into the hydraulic actuator, the amount of return oil flowing into the throttle 18 decreases, and so the negative control pressure also decreases.

[0135] As a result, in step S603, if the negative control pressure decreases consecutively below a predetermined value within a predetermined time from when the switch 51 is switched to the ON state, the controller 30 determines that this is an erroneous operation, shuts off the control valve 60 (step S604), and terminates the processing.

[0136] Thus, in step S604, the controller 30 determines that an operation error has occurred when the negative control pressure, at or below a predetermined value, decreases multiple times consecutively within a predetermined time from when the switch 51 is switched to the ON state. The determination unit 33 then notifies the switching unit 31 of a switching instruction for the relay 52. ​​Alternatively, the determination unit 33 may determine that an operation error has occurred based only on multiple consecutive decreases in the negative control pressure within a predetermined time.

[0137] Upon receiving this notification, the switching unit 31 outputs a control signal to the relay 52 to switch the control valve 60 from a connected state to a cut-off state. Based on this control signal, the relay 52 cuts off the connection between the switch 51 and the control valve 60. This operation stops the supply of power to the control valve 60, switches the control valve 60 from a connected state to a cut-off state, and disables the operating device 26.

[0138] In step S603, if the negative control pressure does not decrease multiple times consecutively within a predetermined time below a predetermined value, the controller 30 determines that this operation is normal, maintains the control valve 60 in a connected state (step S605), and terminates the processing.

[0139] In this embodiment, by operating the gate lock lever to switch the control valve 60 from a shutoff state to a communicating state, the entrance to the cabin 10 is blocked, making it difficult for people such as operators to enter or exit the cabin 10. Therefore, in this embodiment, it is possible to prevent people from getting in or out of the cabin 10 when the operating device 26 is in an active state.

[0140] In addition, in this embodiment, the entrance to the cabin 10 is opened by operating the gate lock lever to switch the control valve 60 from a communicating state to a blocking state. Therefore, in this embodiment, when the operating device 26 is disabled, people such as operators can easily enter and exit the cabin 10.

[0141] In this embodiment, after the control valve 60 is shut off in step S604, the controller 30 may control the regulator 13 so that the discharge rate of the main pump 14 is minimized.

[0142] Furthermore, in this embodiment, the controller 30 may reduce the rotation speed of the engine 11 after bringing the control valve 60 into the shutoff state in step S604.

[0143] In this embodiment, after outputting an ON signal to the switch 51 to switch the control valve 60 into a communicating state, the controller 30 determines whether an erroneous operation has occurred based on a continuous decrease in the negative control pressure within a predetermined time. This makes it possible to reduce judgment errors due to viscosity, even if the viscosity of the hydraulic oil changes due to changes in the outside air temperature, for example. By performing this type of control, the amount of hydraulic oil supplied to the hydraulic actuator that operates in response to the erroneously operated lever can be reduced after the control valve 60 is shut off, thereby shortening the time required to completely stop the operation of the excavator 100.

[0144] The operation of the shovel 100 will be specifically described below with reference to Fig. 7. Fig. 7 is a diagram illustrating the relationship between the negative control pressure, the operation signal, and the control signal. Fig. 7(A) is a diagram showing the waveform of the negative control pressure, and Fig. 7(B) is a diagram showing the waveform of the signal related to the determination of an erroneous operation.

[0145] In the example of FIG. 7, the predetermined time is set to a predetermined time ΔT from when the switch 51 is switched to the ON state. In this case, the predetermined time is the time from timing T1 to timing T5. At timing T1, the switch 51 is turned ON and a high-level (hereinafter referred to as H level) operation signal SG1 is input, and the controller 30 detects that the control valve 60 is in a communicating state. In the example of FIG. 7(A), negative control pressure is detected at timings T1, T2, and T3.

[0146] In Figure 7(A), if the lever is already tilted at time T1, the negative control pressure will then decrease continuously. In Figure 7(A), the negative control pressure at time T1 is N1 (standby pressure), and the negative control pressure detected at time T2 is N2, which is lower than N1. The negative control pressure detected at time T3 is N3, which is lower than N2.

[0147] Even during standby, the negative control pressure fluctuates because the hydraulic oil is under high pressure. To prevent the judgment unit 33 from judging fluctuations in the negative control pressure during standby as multiple consecutive decreases, a threshold value (predetermined value) Nth for preventing erroneous judgment is set to a pressure value slightly lower than the negative control pressure N1 during standby. This allows the judgment unit 33 to judge that fluctuations in the negative control pressure higher than the predetermine value Nth are normal fluctuations during standby. Furthermore, the threshold value (predetermined value) Nth for preventing erroneous judgment does not necessarily have to be set.

[0148] In the example of FIG. 7(A), after the operation signal SG1 corresponding to the lever operation amount to the operation device 26 is input, the negative control pressure is decreased several times in succession.

[0149] In addition, in the example of Figure 7(A), the period from timing T1 to timing T3 is within the predetermined time until timing T5, and furthermore, the detected value of the negative control pressure (N2, N3) shows a state in which it has decreased to below the threshold value (predetermined value) Nth for preventing erroneous judgment.

[0150] Therefore, at timing T3, the controller 30 determines that an erroneous operation occurred when operating the gate lock lever at timing T1, and as shown in Figure 7(B), the switching unit 31 immediately inverts the control signal SG2 from low level (hereinafter referred to as L level) to H level at timing T3.

[0151] In this embodiment, when the control signal SG2 is inverted from L level to H level, the relay 52 switches to the cut-off position, and the connection between the switch 51 and the control valve 60 is cut off. This switches the control valve 60 from a connected state to a cut-off state. In other words, the operating device 26 becomes inactive. At this time, the switch 51 remains in the ON state, so the operating signal SG1 maintains the H level.

[0152] Therefore, in this embodiment, the control signal SG2 can be switched to the H level at timing T3, which is earlier than timing T5, from timing T1 when the control valve 60 is in the open state. As a result, the control valve 60 is in the closed state, and the generation of pilot pressure to the control valves 171 to 176 can be suppressed. As a result, all of the hydraulic oil discharged from the main pump 14 passes through the throttle 18, and the negative control pressure is also restored at timing T4.

[0153] In this way, in this embodiment, it is determined whether or not an operation on the operating device 26 is an erroneous operation based on whether or not the detected physical quantity changes continuously. Therefore, in this embodiment, in determining an erroneous operation, it is not necessary to set a threshold value that depends on the environment of the work site of the shovel 100, and it is possible to easily determine an erroneous operation.

[0154] Furthermore, in this embodiment, whether or not an operation has been erroneous is determined based on how the physical quantity has changed, so that an erroneous operation can be determined in a short time.

[0155] 7, the control signal SG2 output by the controller 30 to the relay 52 is a signal that is at L level when the control valve 60 is in the open state and at H level when the control valve 60 is in the closed state, but is not limited to this. The control signal SG2 may be a signal that is at H level when the control valve 60 is in the open state and at L level when the control valve 60 is in the closed state. In other words, the control signal SG2 may be any signal whose level changes depending on the state of the control valve 60.

[0156] In the example of FIG. 7, the values ​​of the negative control pressures N1, N2, and N3 are physical quantities, but the present invention is not limited to this.

[0157] The physical quantity may be, for example, a value indicating the difference between the negative control pressure N1 and the negative control pressure N2. In other words, the differential value (gradient) of the negative control pressure may be used as the physical quantity. In this case, the more the physical quantity decreases continuously, the more rapidly the negative control pressure decreases. Therefore, when the change in the negative control pressure is used as the physical quantity, the determination unit 33 may determine that an erroneous operation has occurred when the physical quantity decreases continuously.

[0158] Alternatively, the physical quantity may be the integral of the negative control pressure. In this case, the increase in the integral at each timing is calculated, and if the increase in the integral at timing T1 decreases continuously to the increase in the integral at timing T2, and the increase in the integral at timing T2 decreases continuously to the increase in the integral at timing T3, it can be said that the negative control pressure is decreasing rapidly.

[0159] (Another embodiment) Another embodiment will be described below with reference to Fig. 8. In this embodiment, the physical quantity is the pilot pressure, and an erroneous operation when the operation of the shovel 100 is restarted is determined.

[0160] Specifically, in this embodiment, the detection unit 32 of the controller 30 detects the pressure of the hydraulic oil (pilot pressure) detected by the operating pressure sensor 29. Furthermore, the determination unit 33 determines that the operation of the operating device 26 is an erroneous operation when the pilot pressure increases multiple times consecutively to a predetermined value or more within a predetermined time period after the switch 51 is switched to the ON state.

[0161] Figure 8 is a second flowchart illustrating the operation of the shovel according to the embodiment. The state of the shovel 100 when the processing shown in Figure 8 is executed is the same as the state when the processing in Figure 6 is executed, and the processing in step S801 in Figure 8 is the same as the processing in step S601 in Figure 6, so a description thereof will be omitted.

[0162] Following step S801, the controller 30 causes the detection unit 32 to start detecting the pilot pressure using the operating pressure sensor 29 (step S802).

[0163] Next, the controller 30 determines, by the determination unit 33, whether or not the pilot pressure has increased multiple times consecutively within a predetermined time period to a value equal to or greater than a predetermined value (step S803).

[0164] In step S803, if the pilot pressure increases multiple times consecutively within a predetermined time to a value equal to or greater than the predetermined value, the controller 30 proceeds to step S804. In addition, in step S803, if the pilot pressure does not increase multiple times consecutively within a predetermined time to a value equal to or greater than the predetermined value, the controller 30 proceeds to step S805. In addition, the determination unit 33 may determine that an operation has occurred erroneously based only on multiple consecutive increases in the pilot pressure within a predetermined time.

[0165] The processing in steps S804 and S805 is similar to the processing in steps S604 and S605 in FIG. 6, and therefore a description thereof will be omitted.

[0166] The relationship between the pilot pressure, the operation signal, and the control signal will be described below with reference to Fig. 9. Fig. 9 is a diagram illustrating the relationship between the pilot pressure, the operation signal, and the control signal. Fig. 9(A) is a diagram showing the waveform of the pilot pressure of the shovel 100 to which this embodiment is applied, and Fig. 9(B) is a diagram showing the waveform of a signal related to the determination of an erroneous operation in the shovel 100 to which this embodiment is applied. Also, Fig. 9(C) is a diagram showing the waveform of the pilot pressure in the shovel of the comparative example, and Fig. 9(D) is a diagram showing the waveform of a signal related to the determination of an erroneous operation in the shovel of the comparative example.

[0167] As shown in FIG. 9A, at timing T11, when the switch 51 is turned on and an H-level operation signal SG11 is input, the controller 30 detects that the control valve 60 has entered a communication state, and the determination unit 33 starts periodic detection of the pilot pressure. In the example of FIG. 9A, the pilot pressure is detected at timings T11, T12, and T13. The predetermined time is set to a predetermined time ΔT from when the switch 51 is switched to the ON state. In this case, the predetermined time is the time from timing T11 to timing T15.

[0168] 9A, the value of the pilot pressure at time T11 is P1, the value of the pilot pressure detected at time T12 is P2, which is higher than P1, and the value of the pilot pressure detected at time T13 is P3, which is higher than P2.

[0169] The pilot pressure also fluctuates during standby. To prevent the determination unit 33 from determining that small fluctuations in the pilot pressure during standby are multiple consecutive decreases, a threshold value (predetermined value) Pth for preventing erroneous determination is set to a pressure value slightly higher than the pilot pressure P1 during standby. This allows the determination unit 33 to determine that fluctuations in the pilot pressure lower than the predetermined value are normal fluctuations during standby. Furthermore, the threshold value (predetermined value) Pth for preventing erroneous determination does not necessarily have to be set.

[0170] Therefore, in the example of FIG. 9(A), after the operation signal SG11 corresponding to the lever operation amount to the operation device 26 is input, the pilot pressure increases multiple times in succession.

[0171] In the example of FIG. 9(A), the period from timing T11 to timing T13 is within a predetermined time, and furthermore, the pilot pressure P3 is equal to or greater than a predetermined value.

[0172] 9B, at timing T13, the controller 30 determines that the operation started at timing T11 is an erroneous operation, and causes the switching unit 31 to invert the control signal SG12 from L level to H level, switching the control valve 60 from the open state to the closed state. As a result, in this embodiment, the control signal SG12 can be switched from timing T11, when the control valve 60 is in the open state, to timing T13, which is earlier than timing T15, to H level. As a result, the control valve 60 is in the closed state, and the generation of pilot pressure to the control valves 171 to 176 can be suppressed. As a result, the hydraulic oil is blocked between the pilot pump 15 and the operating device 26, and the pilot pressure also decreases at timing T14.

[0173] Therefore, in this embodiment, the period from timing T11 when the control valve 60 is opened to timing T13 when the control signal SG12 becomes H level is the determination time required to determine whether an erroneous operation has occurred.

[0174] In contrast, as shown in Figure 9(C), in the comparative example, at timing Ta, when switch 51 is turned on and an H-level signal SG21 is input, controller 30 determines whether the pilot pressure becomes equal to or greater than threshold value TH within a certain period of time.

[0175] In the example of Figure 9(C), at time Tb, which is within a certain time from time Ta, the pilot pressure exceeds the threshold value TH, so this operation is determined to be an erroneous operation, and a signal SG22 is output to shut off the gate lock valve, as shown in Figure 9(D).

[0176] In this comparative example, it is necessary to set a certain time (a time threshold for determining an erroneous operation) in consideration of the viscosity of the hydraulic oil, which changes depending on the temperature.

[0177] Specifically, for example, if the work site of the shovel 100 is in a cold region or the like, the outside air temperature will be low and the viscosity of the hydraulic oil will be high. Also, if the work site of the shovel 100 is in a warm region or the like, the outside air temperature will be higher than in cold regions and the viscosity of the hydraulic oil will be lower than in cold regions.

[0178] In such a case, even if the same erroneous operation is performed on the excavator 100, if the viscosity of the hydraulic oil is high, it will take longer for the pilot pressure to reach the threshold value TH than if the viscosity of the hydraulic oil is low.

[0179] Therefore, when the viscosity of the hydraulic oil is high, the threshold time for determining whether an operation has been erroneous must be set longer than when the viscosity of the hydraulic oil is low. As such, in the method of the comparative example, the threshold for determining whether an operation has been erroneous must be set according to the environment, and it is difficult to set an appropriate threshold.

[0180] Furthermore, in the comparative example, an erroneous operation is determined when the hydraulic oil level reaches the threshold value TH, and therefore, it takes a long time to determine the erroneous operation. In the example of Fig. 9, the determination time for determining an erroneous operation in Fig. 9(B) is the period from timing T11 to timing T13. In contrast, the determination time for determining an erroneous operation in Fig. 9(D) is the period from timing Ta to timing Tb, which is longer than that in Fig. 9(B).

[0181] In this way, in this embodiment, it is possible to quickly and easily determine whether the shovel 100 is operating erroneously, regardless of the environment of the work site where the shovel 100 is being used.

[0182] (Yet another embodiment) In this embodiment, the physical quantity includes the discharge pressure of a pump provided separately from the main pump 14.

[0183] Fig. 10 is a diagram showing another example of the configuration of a hydraulic system mounted on an excavator. The hydraulic system shown in Fig. 10 includes a pump 14A in addition to the main pump 14. The pump 14A is, for example, a spare pump that is added to ensure a flow rate when operating an actuator other than the actuators (bucket, boom, arm, travel, and swing) driven by the hydraulic oil discharged by the main pump 14. The other actuator may be, for example, a rotation drive unit of a tiltrotator, a compactor, or the like.

[0184] The pump 14A supplies hydraulic oil to a control valve 17A via a hydraulic oil line. The control valve 17A includes a control valve 177 corresponding to another actuator (hereinafter, referred to as a cylinder) 9A. The control valve 177 is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged by the pump 14A to the cylinder 9A and to discharge the hydraulic oil in the cylinder 9A to a hydraulic oil tank.

[0185] The discharge pressure sensor 28A detects the discharge pressure of the pump 14A. In this embodiment, the discharge pressure sensor 28A outputs the detected value to the controller 30. In the following description, the discharge pressure of the pump 14A may be referred to as a preliminary pump pressure.

[0186] In the shovel 100 of this embodiment, the operating device 26A is one of the operating devices 26 and may be used to operate another actuator. The operating device 26A is, for example, a proportional switch provided on an operating lever, an operating pedal, or the like.

[0187] The operating device 26A generates a pilot pressure acting on a right pilot port of the control valve 177 (hereinafter referred to as right pilot pressure) and a pilot pressure acting on a left pilot port of the control valve 177 (hereinafter referred to as left pilot pressure). The right pilot pressure of the control valve 177 is, for example, a pilot pressure for extending or retracting the cylinder 9A, and the left pilot pressure of the control valve 177 is, for example, a pilot pressure for retracting or extending the cylinder 9A.

[0188] The proportional valves 65L and 65R are valves that adjust the pilot pressure generated by the pilot pump 15 in accordance with the operation amount of the operating device 26A. The proportional valve 65L receives the left pilot pressure generated by the pilot pump 15 as a primary pressure, and applies the adjusted pilot pressure as a secondary pressure to the left pilot port of the control valve 177 in accordance with the operation amount of the operating device 26A (specifically, the opening degree of the cushion valve). The proportional valve 65R receives the right pilot pressure generated by the pilot pump 15 as a primary pressure, and applies the adjusted pilot pressure as a secondary pressure to the right pilot port of the control valve 177 in accordance with the operation amount of the operating device 26A.

[0189] The controller 30 of this embodiment may determine an erroneous operation of the shovel 100 by using the discharge pressure detected by the discharge pressure sensor 28A instead of the operating pressure detected by the operating pressure sensor 29. Furthermore, in this embodiment, in addition to the operating pressure detected by the operating pressure sensor 29, when making a determination by the determination unit 33, it may also determine whether the discharge pressure detected by the discharge pressure sensor 28A has increased multiple times consecutively within a predetermined time period to a value equal to or greater than a predetermined value.

[0190] Specifically, the judgment unit 33 judges that the operation on the operating device 26 is an erroneous operation when the negative control pressure decreases multiple times consecutively within a specified time period above a specified value, or when the discharge pressure of the pump 14A increases multiple times consecutively above a specified value.

[0191] The relationship between the discharge pressure of the pump 14A, the operation signal, and the control signal will be described below with reference to Fig. 11. Fig. 11 is a diagram illustrating the relationship between the discharge pressure of the backup pump, the operation signal, and the control signal. Fig. 11(A) is a diagram showing the waveform of the discharge pressure of the pump 14A of the shovel 100 to which this embodiment is applied, and Fig. 11(B) is a diagram showing the waveform of a signal related to the determination of an erroneous operation in the shovel 100 to which this embodiment is applied.

[0192] As shown in FIG. 11A, at time T21, when the switch 51 is turned on based on the operation of the gate lock lever by the operator and an H-level operation signal SG31 is input, the controller 30 detects that the control valve 60 has entered a communicating state, and the determination unit 33 starts periodically detecting the discharge pressure of the pump 14A. In the example of FIG. 11A, the discharge pressure of the pump 14A is detected at times T21, T22, and T23. The predetermined time is set to a predetermined time ΔTa from when the switch 51 is switched to the ON state. In this case, the predetermined time is the time from time T21 to time T25.

[0193] 11A, the value of the discharge pressure of the pump 14A at time T21 is P11, and the value of the discharge pressure of the pump 14A detected at time T22 is P21, which is a value higher than P11. Furthermore, the value of the discharge pressure of the pump 14A detected at time T23 is P31, which is a value higher than P21.

[0194] The discharge pressure of the pump 14A also fluctuates during standby. To prevent the determination unit 33 from determining that small fluctuations in the discharge pressure of the pump 14A during standby are multiple consecutive increases, a threshold value (predetermined value) Pth1 for preventing erroneous determination is set to a pressure value slightly higher than the discharge pressure P11 of the pump 14A during standby. This allows the determination unit 33 to determine that fluctuations in the discharge pressure of the pump 14A that are lower than the predetermined value are normal fluctuations during standby. Furthermore, the threshold value (predetermined value) Pth1 for preventing erroneous determination does not necessarily have to be set.

[0195] In the example of FIG. 11(A), after the operation signal SG31 corresponding to the lever operation amount to the operation device 26 is input, the discharge pressure of the pump 14A increases multiple times in succession.

[0196] Thereafter, in the example of FIG. 11(A), the period from timing T21 to timing T23 is within a predetermined time, and furthermore, the pilot pressure P31 is equal to or greater than a predetermined value.

[0197] Therefore, as shown in FIG. 11(B), at timing T23, the controller 30 determines that the operation started at timing T21 is an erroneous operation, and causes the switching unit 31 to invert the control signal SG32 from L level to H level.

[0198] In this embodiment, when the control signal SG32 is inverted from L level to H level, the relay 52 switches to the cut-off position, and the connection between the switch 51 and the control valve 60 is cut off. This cuts off the connection between the relay 52 and the control valve 60, and the control valve 60 switches from a connected state to a cut-off state. In other words, the operating device 26 is in an inactive state.

[0199] As a result, in this embodiment, the control signal SG32 can be switched to the H level at timing T23, which is earlier than timing T25 from timing T21 when the control valve 60 is brought into the communicating state.

[0200] The predetermined value for the negative control pressure and the predetermined value for the discharge pressure of the pump 14A are different values.

[0201] In addition, in this embodiment, the judgment unit 33 judges that the operation on the operating device 26 is an erroneous operation when the pilot pressure increases multiple times consecutively within a predetermined time period above a predetermined value, or when the discharge pressure of the pump 14A increases multiple times consecutively above a predetermined value.

[0202] The predetermined value for the pilot pressure and the predetermined value for the discharge pressure of the pump 14A are different values.

[0203] In this embodiment, if the two types of physical quantities each satisfy the above-mentioned conditions within a predetermined time, it is determined that an operation error has occurred. Therefore, in this embodiment, even if, for example, detection of the negative control pressure or detection of the pilot pressure has failed, it is possible to determine that an operation error has occurred, thereby improving safety.

[0204] Furthermore, the physical quantities may be, for example, integral values ​​or differential values ​​of the negative control pressure, the pilot pressure, the discharge pressure of the pump 14A, and the discharge pressure of the main pump 14.

[0205] Furthermore, in each of the above-described embodiments, when the judgment unit 33 judges that an operation has been erroneous, the controller 30 causes the switching unit 31 to cut off the connection between the control valve 60 and the switch 51, thereby disabling the operating device 26. However, the operating device 26 may also be disabled in cases other than when an operation has been judged to be erroneous.

[0206] Specifically, for example, when the object detection device 70 detects a specified object within a specified area set around the shovel 100, the controller 30 may change the control signal output from the switching unit 31 from L level to H level to shut off the control valve 60 and disable the operating device 26.

[0207] By controlling in this manner, for example, when a person, an animal, or the like is detected within the area around the shovel 100, the operation of the shovel 100 can be automatically stopped.

[0208] Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. [Explanation of symbols]

[0209] 11 Engine 14 Main pump 19 Control pressure sensor 28 Discharge pressure sensor 30 Controllers 31 Switching section 32 Detection unit 33 Judgment section 60 Control valve 100 Shovel

Claims

1. a detection unit that detects a pilot pressure that changes depending on the content of an operation on an operating device that operates the actuator; a control valve that connects a pilot line connecting the operating device and the pilot pump to a communication state or a cut-off state; a switching unit that switches the pilot line from a connected state to a blocked state or from a blocked state to a connected state using the control valve; a determination unit that determines that the operation is an erroneous operation when the pilot pressure becomes equal to or greater than a predetermined value within a predetermined time after the pilot line is switched from a blocked state to a connected state and further increases multiple times consecutively, The switching unit is When the erroneous operation is determined, the pilot line is repeatedly switched from a connected state to a disconnected state.

2. a detection unit that detects a negative control pressure that changes depending on the content of an operation on an operating device that operates the actuator; a control valve that connects a pilot line connecting the operating device and the pilot pump to a communication state or a cut-off state; a switching unit that switches the pilot line from a connected state to a blocked state or from a blocked state to a connected state using the control valve; a determination unit that determines that the operation is an erroneous operation when the negative control pressure becomes equal to or greater than a predetermined value within a predetermined time after the pilot line is switched from a blocked state to a connected state and further decreases multiple times in succession; The switching unit is When the erroneous operation is determined, the pilot line is repeatedly switched from a connected state to a disconnected state.

3. a detection unit that detects the discharge pressure of a pump that supplies hydraulic oil to another actuator, the detection unit being provided separately from the main pump and that changes depending on the content of an operation on an operating device that operates the actuator; a control valve that connects a pilot line connecting the operating device and the pilot pump to a communication state or a cut-off state; a switching unit that switches the pilot line from a connected state to a blocked state or from a blocked state to a connected state using the control valve; a determination unit that determines that the operation is an erroneous operation when the discharge pressure becomes equal to or greater than a predetermined value within a predetermined time after the pilot line is switched from a blocked state to a connected state and further increases multiple times consecutively, The switching unit is When the erroneous operation is determined, the pilot line is repeatedly switched from a connected state to a disconnected state.

4. A shovel as described in claim 1, wherein the predetermined value is the pilot pressure in a standby state where no operation is being performed on the actuator.

5. an object detection unit that detects a predetermined object within a set predetermined area; The switching unit is The shovel according to claim 1 , wherein the pilot line is switched from a connected state to a disconnected state when the object detection unit detects the predetermined object in the predetermined area.

Images