Work machine

Abstract

To provide technology capable of acquiring a highly precise cylinder angle.SOLUTION: A work machine 100 includes: an end attachment EA; an end attachment cylinder 9; a cylinder angle sensor S3 for detecting a cylinder angle; a pressure sensor S9 for detecting cylinder pressure; and a controller 30. The controller 30 calculates an angle using the cylinder pressure detected with the pressure sensor S9 within a preset angle range of the cylinder angle detected with the cylinder angle sensor S3.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to work machines. [Background technology]

[0002] Patent Document 1 discloses a shovel (working machine) that measures the weight of soil and sand that is to be transported while it is stored in a bucket. This shovel measures the weight of the transported object using the detection results of multiple attitude sensors of the attachment, including a bucket angle sensor that detects the rotation angle of the bucket (bucket angle), and the detection results of a strain sensor that detects the distortion of the attachment.

[0003] Incidentally, a work machine is not limited to a configuration in which the bucket angle is detected by a bucket angle sensor, but may also have a cylinder angle sensor that detects the angle (cylinder angle) of a cylinder mechanism that operates the bucket, and the bucket angle can be estimated from this cylinder angle. However, in a configuration in which the cylinder angle is detected, there are some points where the cylinder angle does not change even if the cylinder mechanism is extended or retracted, and a dead angle range occurs in the detection information of the cylinder angle sensor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-166232 A Summary of the Invention [Problem to be solved by the invention]

[0005] Conventionally, when a dead zone occurs in the detection of the cylinder angle of a work machine, the weight of the transported object is calculated using, for example, a preset fixed value. In other words, when the weight of the transported object is calculated in the dead zone, the calculation accuracy decreases.

[0006] In particular, in addition to shovels, there are application machines having end attachments such as lifting magnets that attract and transport objects, and grapples that clamp and transport objects. Since application machines may hold objects and measure their weight by rotating the end attachments at various angles, if the cylinder angle sensor has a dead band angle range, errors are likely to occur in the measurement of the weight of the object.

[0007] The present disclosure provides a technique for stably obtaining a highly accurate cylinder angle. [Means for solving the problem]

[0008] According to one aspect of the present disclosure, there is provided a work machine including an end attachment, an end attachment cylinder that operates the end attachment, a cylinder angle sensor that detects a cylinder angle that changes with the operation of the end attachment cylinder, a pressure sensor that detects the cylinder pressure of the end attachment cylinder, and a processing unit that processes a signal from the cylinder angle sensor and a signal from the pressure sensor, wherein the processing unit calculates an angle using the cylinder pressure detected by the pressure sensor within a set angle range of the cylinder angle detected by the cylinder angle sensor. Effect of the Invention

[0009] According to one aspect, a highly accurate cylinder angle can be stably obtained. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a side view of a work machine according to an embodiment. [Diagram 2] 1 is a diagram showing an example of the configuration of a drive system mounted on a work machine. [Diagram 3] 4 is a graph illustrating an example of a cylinder angle detected by a cylinder angle sensor. [Figure 4]5 is a graph showing the relationship between the angle range of the dead band of a cylinder angle sensor and the cylinder pressure. [Diagram 5] FIG. 4 is a block diagram showing functional blocks of a controller when calculating weight. [Figure 6] Fig. 6(A) is a side view showing a work machine according to a first modified example, and Fig. 6(B) is a side view showing a work machine according to a second modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and duplicated descriptions may be omitted.

[0012] Fig. 1 is a side view of a work machine 100 according to an embodiment. As shown in Fig. 1, the work machine 100 includes a lower traveling body 1, an upper rotating body 3 mounted on the lower traveling body 1 via a rotating mechanism 2, and an attachment AT attached to the upper rotating body 3.

[0013] The lower traveling body 1 has a pair of left and right crawlers 1C. Each crawler 1C is driven by a traveling hydraulic motor (a left-side traveling hydraulic motor and a right-side traveling hydraulic motor) mounted on the lower traveling body 1. The turning mechanism 2 is driven by a turning hydraulic motor mounted on the lower traveling body 1 or the upper turning body 3. Each crawler 1C and the turning mechanism 2 may be driven by an electric actuator.

[0014] The upper rotating body 3 is provided with a cabin 10 at the front and left side (to the left of the boom 4) for an operator to ride in and operate the work machine 100. The upper rotating body 3 also has a counterweight at the rear, and various devices for operating the work machine 100 are provided therein.

[0015] The work machine 100 according to the embodiment is configured as an application machine that holds scrap such as iron scraps as an object to be transported and transports it from one position to another. For this reason, the attachment AT of the work machine 100 has a boom 4 that is attached to the upper rotating body 3 so as to be able to move up and down, an arm 5 that is rotatably attached to the tip of the boom 4, and a lifting magnet 6 that is rotatably attached to the tip of the arm 5. The lifting magnet 6 is an end attachment EA other than the bucket that attracts and holds the object to be transported in the attachment AT.

[0016] The boom 4 is driven by a boom cylinder 7. The arm 5 is driven by an arm cylinder 8. The lifting magnet 6 is driven by an end attachment cylinder 9. The boom cylinder 7, the arm cylinder 8 and the end attachment cylinder 9 constitute an attachment actuator (cylinder mechanism).

[0017] A boom angle sensor S1 is attached to the boom 4 to detect the boom angle, which is the rotation angle of the boom 4 relative to the upper rotating body 3. The boom angle sensor S1 may be, for example, a rotation angle sensor that detects the rotation angle of the boom 4 around a boom foot pin. In this case, a potentiometer may be used as the rotation angle sensor. The boom angle sensor S1 may be, for example, a cylinder stroke sensor that detects the stroke amount of the boom cylinder 7, an inclination (acceleration) sensor that detects the inclination angle of the boom 4, or an inertial measurement unit (IMU) equipped with an acceleration sensor and a gyro sensor. Alternatively, the boom angle sensor S1 may be configured to detect the boom angle with high accuracy by combining the multiple sensors listed above (for example, a rotation angle sensor and an inertial measurement unit).

[0018] An arm angle sensor S2 is attached to the arm 5 to detect the arm angle, which is the rotation angle of the arm 5 relative to the boom 4. The arm angle sensor S2 may be, for example, a rotation angle sensor (such as a potentiometer) that detects the rotation angle of the arm 5 around an arm foot pin. The arm angle sensor S2 may also be a cylinder stroke sensor that detects the stroke amount of the arm cylinder 8, an inclination (acceleration) sensor that detects the inclination angle of the arm 5, or an inertial measurement unit (IMU) equipped with an acceleration sensor and a gyro sensor. Furthermore, the arm angle sensor S2 may be configured to detect the arm angle with high accuracy by combining multiple sensors listed above (for example, a rotation angle sensor and an inertial measurement unit).

[0019] A cylinder angle sensor S3 that detects the angle (cylinder angle) of the end attachment cylinder 9 is provided between the arm 5 and the lifting magnet 6. The controller 30 calculates the end attachment angle, which is the rotation angle of the lifting magnet 6 relative to the arm 5, using the detection result (cylinder angle) of the cylinder angle sensor S3.

[0020] Here, the attachment AT of the working machine 100 is configured to be replaceable with various end attachments EA other than the lifting magnet 6. Applying a sensor for detecting the end attachment angle to each end attachment EA itself would lead to increased costs and reduced work efficiency due to adjustment and calibration of the sensor. In addition, since the lifting magnet 6 attracts the transported object with a strong magnetic force, providing a sensor on the lifting magnet 6 may cause inconveniences such as an effect on detection or a decrease in durability. For this reason, the working machine 100 according to the embodiment is configured to calculate the end attachment angle based on the cylinder angle detected by the cylinder angle sensor S3. This allows the working machine 100 to obtain the end attachment angle stably at low cost.

[0021] Specifically, the end attachment cylinder 9 of the work machine 100 includes a cylinder body 91 rotatably mounted on the arm 5, and a rod 92 that advances and retreats relative to the cylinder body 91 based on the pressure of a pressure medium. The end attachment cylinder 9 also includes a support frame 93 that extends from the arm 5 and supports the tip of the rod 92, and a transmission frame 94 that connects the rod 92 and the support frame 93 to the lifting magnet 6. The tip of the end attachment cylinder 9, the support frame 93, and the transmission frame 94 are rotatably connected to one another via a link 95.

[0022] The cylinder angle sensor S3 is provided, for example, at a connection point between the arm 5 and the support frame 93, and detects the rotation angle of the support frame 93 relative to the arm 5. The cylinder angle sensor S3 is not particularly limited, but for example, a potentiometer may be used. The potentiometer detects the rotation angle of the support frame 93 by voltage or resistance value, and transmits the detection information to the controller 30.

[0023] Furthermore, the work machine 100 is equipped on the upper rotating body 3 with an external recognition sensor S4, a machine body inclination sensor S5, a rotation angular velocity sensor S6, etc. in addition to the above-mentioned attitude sensors (boom angle sensor S1, arm angle sensor S2, cylinder angle sensor S3).

[0024] The external environment recognition sensor S4 is configured by, for example, one or a combination of a monocular camera, a stereo camera, a distance image camera, an infrared camera, a LIDAR, etc., and acquires information on the external environment of the work machine 100 and outputs the information to the controller 30. The controller 30 extracts an object based on the information on the external environment detected by the external environment recognition sensor S4. The controller 30 may also calculate the distance and direction to the extracted object. Examples of the information on the external environment include dump trucks, terrain shapes (slope, holes, etc.), electric wires, electric poles, people, animals, vehicles, construction machinery, buildings, walls, helmets, safety vests, work clothes, and predetermined marks on helmets.

[0025] The vehicle body tilt sensor S5 detects the tilt (vehicle body tilt angle) of the upper rotating body 3 with respect to the horizontal plane. The vehicle body tilt sensor S5 according to the embodiment is an acceleration sensor that detects the tilt angles around the front-rear axis and the left-right axis of the upper rotating body 3. The turning angular velocity sensor S6 is a gyro sensor, a resolver, a rotary encoder, or the like, and detects the turning angular velocity of the upper rotating body 3.

[0026] The end attachment cylinder 9 is provided with a pressure sensor S9 that detects the pressure inside the cylinder body 91 (cylinder pressure: hydraulic pressure) and transmits the detection information to the controller 30. For example, the pressure sensor S9 is configured by combining a rod pressure sensor S9a that detects the pressure in a rod-side oil chamber and a bottom pressure sensor S9b that detects the pressure in a bottom-side oil chamber. Furthermore, the boom cylinder 7 is provided with a pressure sensor S7 that detects the pressure of the boom cylinder 7, and the arm cylinder 8 is provided with a pressure sensor S8 that detects the pressure of the arm cylinder 8. The pressure sensors S7 and S8 can have a configuration similar to that of the pressure sensor S9 of the end attachment cylinder 9.

[0027] Fig. 2 is a diagram showing an example of the configuration of a drive system mounted on the work machine 100. In Fig. 2, a mechanical power transmission system is indicated by a double line, a hydraulic oil line is indicated by a thick solid line, a pilot line is indicated by a dashed line, an electric control system is indicated by a dashed line, and an electric drive system is indicated by a thick dotted line.

[0028] The drive system of the work machine 100 is mainly composed of the engine 11, the main pump 14, the hydraulic pump 14G, the pilot pump 15, the control valve 17, the operation device 26, the controller 30 and the engine control device 74.

[0029] The engine 11 is a power source of the work machine 100 and is, for example, a diesel engine that rotates at a target rotation speed. The output shaft of the engine 11 is connected to the input shafts of the alternator 11a, the main pump 14, the hydraulic pump 14G, and the pilot pump 15, respectively.

[0030] The main pump 14 supplies hydraulic oil to a control valve 17 via a hydraulic oil line 16. In this embodiment, the main pump 14 is a swash plate type variable displacement hydraulic pump.

[0031] The regulator 14a controls the discharge amount of the main pump 14. In this embodiment, the regulator 14a 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 signal from the controller 30 or the like.

[0032] The pilot pump 15 supplies hydraulic oil to various hydraulic control devices including an operating device 26 via a pilot line 25. In this embodiment, the pilot pump 15 is a fixed displacement hydraulic pump.

[0033] The control valve 17 is a hydraulic control device that controls the hydraulic system in the work machine 100. The control valve 17 selectively supplies hydraulic oil to, for example, one or more of the boom cylinder 7, arm cylinder 8, end attachment cylinder 9, left-side traveling hydraulic motor 1L, right-side traveling hydraulic motor 1R, and swing hydraulic motor 2A. Note that in the following description, the boom cylinder 7, arm cylinder 8, end attachment cylinder 9, left-side traveling hydraulic motor 1L, right-side traveling hydraulic motor 1R, and swing hydraulic motor 2A may be referred to as "hydraulic actuators."

[0034] The operating device 26 is a device used by an operator to operate the hydraulic actuator. In this embodiment, the operating device 26 generates pilot pressure by supplying hydraulic oil from the pilot pump 15 to a pilot port of a corresponding flow control valve in the control valve 17. Specifically, the operating device 26 includes a left operating lever for swing operation and arm operation, a right operating lever for boom operation and lifting magnet operation, a traveling pedal, and a traveling lever (all not shown). The pilot pressure changes depending on the operation content of the operating device 26 (for example, the operation direction and operation amount).

[0035] The operating pressure sensor 29 detects the pilot pressure generated by the operating device 26, and outputs the detected value to the controller 30. The controller 30 recognizes the operation content of each of the operating devices 26 based on the output of the operating pressure sensor 29.

[0036] The controller 30 is configured by a computer equipped with one or more processors, memory (volatile memory, non-volatile memory), etc., and is a processing unit that processes various types of information and controls the work machine 100 based on the processed information. The one or more processors read out from the memory and execute programs for each function that controls the work machine 100.

[0037] The hydraulic pump 14G supplies hydraulic oil to the hydraulic motor 60 via a hydraulic oil line 16. In this embodiment, the hydraulic pump 14G is a fixed displacement hydraulic pump, and supplies hydraulic oil to the hydraulic motor 60 via a switching valve 61.

[0038] The switching valve 61 switches the flow of hydraulic oil discharged by the hydraulic pump 14G. In this embodiment, the switching valve 61 is a solenoid valve whose valve position is switched in response to a control command from the controller 30. The switching valve 61 has a first valve position that communicates between the hydraulic pump 14G and the hydraulic motor 60, and a second valve position that cuts off communication between the hydraulic pump 14G and the hydraulic motor 60.

[0039] When the mode changeover switch 62 is operated to change the operation mode of the work machine 100 to the lifting magnet mode, the controller 30 outputs a control signal to the switching valve 61 to change the switching valve 61 to the first valve position. Also, when the mode changeover switch 62 is operated to change the operation mode of the work machine 100 to a mode other than the lifting magnet mode (such as a grapple mode), the controller 30 outputs a control signal to the switching valve 61 to change the switching valve 61 to the second valve position. Figure 2 shows a state in which the switching valve 61 is in the second valve position.

[0040] The mode changeover switch 62 is a switch that changes the operation mode of the work machine 100. In this embodiment, it is a rocker switch installed inside the cabin 10. The operator operates the mode changeover switch 62 to change between a lifting magnet mode, a grapple mode, etc. The lifting magnet mode is a mode in which an attachment AT having a lifting magnet 6 is operated. The grapple mode is a mode in which an attachment AT having a grapple is operated. The grapple mode is selected, for example, when a grapple is attached to the tip of the arm 5 instead of the lifting magnet 6. The controller 30 may automatically change the operation mode of the work machine 100 based on the outputs of various sensors.

[0041] When the lifting magnet mode is selected, the switching valve 61 is set to the first valve position, and the hydraulic oil discharged by the hydraulic pump 14G is caused to flow into the hydraulic motor 60. On the other hand, when the grapple mode is selected, the switching valve 61 is set to the second valve position, and the hydraulic oil discharged by the hydraulic pump 14G is caused to flow out to the hydraulic oil tank without flowing into the hydraulic motor 60.

[0042] The rotating shaft of the hydraulic motor 60 is mechanically connected to the rotating shaft of a generator 63. The generator 63 generates electric power for exciting the lifting magnet 6. In this embodiment, the generator 63 is an AC generator that operates in response to a control command from a power control device 64.

[0043] The power control device 64 controls the supply and cut-off of power for exciting the lifting magnet 6. In this embodiment, the power control device 64 controls the start and stop of AC power generation by the generator 63 in response to a power generation start command and a power generation stop command from the controller 30. The power control device 64 also converts the AC power generated by the generator 63 into DC power and supplies it to the lifting magnet 6. The power control device 64 can also control the magnitude of the voltage applied to the lifting magnet 6 and the magnitude of the current flowing through the lifting magnet 6.

[0044] When the lifting magnet switch 65 is turned on and put into the on state, the controller 30 outputs an attraction command to the power control device 64. The power control device 64 that has received the attraction command converts the AC power generated by the generator 63 into DC power and supplies it to the lifting magnet 6, thereby exciting the lifting magnet 6. The excited lifting magnet 6 is brought into an attraction state in which it can attract an object (magnetic material).

[0045] Furthermore, when the lifting magnet switch 65 is turned off and put into the off state, the controller 30 outputs an attraction release command to the power control device 64. Upon receiving the attraction release command, the power control device 64 stops power generation by the generator 63 and puts the lifting magnet 6, which was in an attracted state, into a non-attracted state. The attraction release state of the lifting magnet 6 means a state in which the supply of power to the lifting magnet 6 is stopped and the electromagnetic force generated by the lifting magnet 6 disappears.

[0046] The lifting magnet switch 65 is a switch that switches between attraction and release of attraction of the lifting magnet 6. The lifting magnet switch 65 includes a weak excitation button 65A and a strong excitation button 65B as push button switches provided at the top of the left operation lever 26L, and a non-excitation button 65C as a push button switch provided at the top of the right operation lever 26R.

[0047] The weak excitation button 65A is an example of an input device for applying a predetermined voltage to the lifting magnet 6 to bring the lifting magnet 6 into an adsorption state (weak adsorption state). The predetermined voltage is, for example, a voltage set via the magnetic force adjustment dial 66.

[0048] The strong excitation button 65B is an example of an input device for applying the maximum allowable voltage to the lifting magnet 6 to bring the lifting magnet 6 into an attracted state (strongly attracted state).

[0049] The de-energization button 65C is an example of an input device for putting the lifting magnet 6 into an attraction release state.

[0050] The magnetic force adjustment dial 66 is a dial for adjusting the magnetic force (attractive force) of the lifting magnet 6. In this embodiment, the magnetic force adjustment dial 66 is installed inside the cabin 10, and is configured so that the magnetic force (attractive force) of the lifting magnet 6 can be switched between four levels when the weak excitation button 65A is pressed. Specifically, the magnetic force adjustment dial 66 is configured so that the magnetic force (attractive force) of the lifting magnet 6 can be switched between four levels, from a first level to a fourth level.

[0051] The lifting magnet 6 is controlled so as to generate a magnetic force (attractive force) of a level set by a magnetic force adjustment dial 66. The magnetic force adjustment dial 66 outputs data indicating the level of the magnetic force (attractive force) to the controller 30.

[0052] With this configuration, the operator can use his / her fingers to attract and release an object (magnetic material) by the lifting magnet 6 while operating the left operation lever 26L with the left hand and the right operation lever 26R with the right hand to operate the work attachment. Typically, the operator presses the weak excitation button 65A while the lifting magnet 6 is in contact with an object (e.g., scrap iron, etc.) to attract the scrap iron to the lifting magnet 6. After that, the operator gently raises the boom 4, lifts up the lifting magnet 6 that has attracted the scrap iron, and then presses the strong excitation button 65B to increase the magnetic force (attraction force) of the lifting magnet 6. This is to prevent the scrap iron from falling off the lifting magnet 6 during the transportation of the scrap iron by the attachment operation (operation including at least one of the boom operation, arm operation, and bucket operation) or the swing operation.

[0053] Furthermore, the operator can sort objects by adjusting the magnetic force (attractive force) of the lifting magnet 6 with the magnetic force adjustment dial 66. For example, the operator can separate relatively light objects from relatively heavy objects by selectively lifting and moving relatively light objects from a pile of scrap iron using a relatively weak level of magnetic force (attractive force). This is because using a relatively weak level of magnetic force (attractive force) can prevent the work machine 100 from lifting relatively heavy objects.

[0054] When the weak excitation button 65A or the strong excitation button 65B is pressed, the work machine 100 may automatically switch the operation mode to the speed limited mode. The speed limited mode is an operation mode in which the swing speed and the drive speed of the attachment are limited in the lifting magnet mode, for example.

[0055] Furthermore, when a predetermined operation is performed or a predetermined state is reached after the weak excitation button 65A is pressed, the work machine 100 may automatically transition the state of the lifting magnet 6 to the strong attraction state, which is the state when the strong excitation button 65B is pressed. The predetermined operation is, for example, a turning operation. The predetermined state is, for example, a state in which the attachment is in a predetermined posture, specifically, a state in which the boom angle is at a predetermined angle. In this case, when the lifting magnet 6 in the weak attraction state is lifted by the boom 4 and then a turning operation is performed, the work machine 100 can automatically transition the lifting magnet 6 to the strong attraction state even if the strong excitation button 65B is not pressed.

[0056] The display device 40 is a device that displays various types of information, and is fixed to a pillar at the front right part of the cabin 10. As shown in Fig. 2, the display device 40 displays information related to the work machine 100 on an image display unit 41 to provide the information to the operator. The display device 40 also includes a switch panel 42 as an input device. The operator can input various commands to the controller 30 using the switch panel 42. The switch panel 42 is a panel that includes various switches (light switch, wiper switch, window washer switch).

[0057] The storage battery 70 is charged with power generated by the alternator 11a. The power of the storage battery 70 is also supplied to electrical components 72 and the like other than the controller 30 and the display device 40. The starter 11b of the engine 11 is driven by the power from the storage battery 70 to start the engine 11.

[0058] The engine control device 74 controls the engine 11. In this embodiment, the engine control device 74 collects various data indicating the state of the engine 11 and transmits the collected data to the controller 30. The engine control device 74 and the controller 30 are configured as separate entities, but may be an integrated device. For example, the engine control device 74 may be integrated into the controller 30.

[0059] The engine speed adjustment dial 75 is a dial for adjusting the engine speed. The engine 11 is controlled by the engine control device 74 so as to maintain the engine speed corresponding to the speed mode set by the engine speed adjustment dial 75. In addition, the engine speed adjustment dial 75 outputs data indicating the setting state of the engine speed to the controller 30.

[0060] Furthermore, when the lifting magnet mode is implemented, the controller 30 calculates the weight of the transported object (e.g., iron scraps) attracted by the lifting magnet 6, and displays it on the display device 40. Note that the processing unit that measures the weight of the transported object may be an information processing device such as a computer that is provided outside the work machine 100 and configured to be able to communicate with the work machine 100.

[0061] Returning to FIG. 1, the weight of the transported object by the work machine 100 is calculated using the balance of torque around the base of the boom 4. When the lifting magnet 6 attracts the transported object, the thrust of the boom cylinder 7 is increased by the transported object, and the torque around the base of the boom 4 calculated from the thrust of the boom cylinder 7 increases. This torque increase matches the weight of the transported object and the torque calculated from the center of gravity of the transported object. Therefore, the controller 30 can calculate the weight of the object based on the torque of the boom cylinder 7 and the center of gravity of the object.

[0062] The thrust of the boom cylinder 7 can be obtained based on the detection information of the pressure sensor S7 of the boom cylinder 7 when the boom 4 is raised. Meanwhile, the center of gravity of the object can be calculated based on the attitude of the attachment AT (the length of the boom 4, the length of the arm 5, the length of the lifting magnet 6, the boom angle, the arm angle, and the end attachment angle). The length of the boom 4, the length of the arm 5, and the length of the lifting magnet 6 are preset fixed values ​​and can be stored in the controller 30. Meanwhile, the boom angle can be obtained from the detection information of the boom angle sensor S1, and the arm angle can be obtained from the detection information of the arm angle sensor S2.

[0063] As described above, the end attachment angle can be calculated based on the detection information of the cylinder angle sensor S3 (the cylinder angle of the end attachment cylinder 9). However, when the cylinder angle sensor S3 is used, there is a dead angle range in which it is difficult to detect the cylinder angle. The dead angle range of the cylinder angle sensor S3 will be described below with reference to FIG. 3.

[0064] Fig. 3 is a graph showing an example of the cylinder angle detected by the cylinder angle sensor S3. The horizontal axis of the graph is the theoretical cylinder angle, and the vertical axis of the graph is the cylinder angle (detection information) detected by the cylinder angle sensor S3. The two-dot chain line in Fig. 3 shows the cylinder angle that changes linearly for comparison.

[0065] When the cylinder angle is detected by the cylinder angle sensor S3, the detected information is slightly deviated from the ideal cylinder angle. The linear deviation of the detected information can be eliminated by performing an appropriate correction in the controller 30.

[0066] On the other hand, when the cylinder angle is in the range of 36° to 86°, the detection information of the cylinder angle sensor S3 changes slowly and deviates significantly from the actual change in the cylinder angle. That is, even if the attachment AT changes the rotation angle of the lifting magnet 6 by the extension and contraction of the end attachment cylinder 9, there is a portion where the support frame 93 detected by the cylinder angle sensor S3 hardly moves (the angle does not change). For example, this portion is in the range of the detection information of 36° to 86°, and since the cylinder angle hardly changes, the controller 30 cannot correctly calculate the end attachment angle, which is the angle of the lifting magnet 6.

[0067] For example, a conventional controller performs processing using a fixed value of 86.5° (perpendicular to the ground or the value closest to perpendicular within the dead zone) in the angle range of the dead zone of the cylinder angle sensor S3. That is, in a posture within the angle range of the dead zone, the controller 30 considers that the lifting magnet 6 of the attachment AT is conveying downward, thereby allowing the conveyance of the conveyed object to continue.

[0068] However, the attachment AT having the lifting magnet 6 will adsorb the transported object in various positions depending on the operator. For example, when measuring the weight of the transported object using the thrust of the boom 4 when the boom 4 is raised after adsorbing the transported object, the position of the lifting magnet 6 may be within the angle range of the dead zone of the cylinder angle sensor S3. If a fixed value close to vertical is used for the angle range of the dead zone, the calculation accuracy of the weight of the transported object will decrease.

[0069] Therefore, the work machine 100 according to this embodiment compensates for the angle within the dead zone angle range of the cylinder angle sensor S3 by using the cylinder pressure of the end attachment cylinder 9. This enables the work machine 100 to obtain an appropriate end attachment angle even within the dead zone angle range of the cylinder angle sensor S3.

[0070] Fig. 4 is a graph showing the relationship between the angle range of the dead band of the cylinder angle sensor S3 and the cylinder pressure. In Fig. 4, the horizontal axis represents the time when the lifting magnet 6 is rotated, and the vertical axis represents the angle of the cylinder angle sensor S3 and the cylinder pressure. The dotted line in the graph represents the conventional recognition value in the angle range of the dead band of the cylinder angle sensor S3, and the thin line in the graph represents the detection value of the cylinder pressure of the pressure sensor S9 of the end attachment cylinder 9. The solid line in the graph is an example of a cylinder angle that compensates for the angle range of the dead band of the cylinder angle sensor S3.

[0071] As shown in Fig. 4, when the end attachment cylinder 9 rotates the lifting magnet 6 in the first direction, the cylinder angle sensor S3 detects a gradually increasing cylinder angle. However, in the range where the cylinder angle increases from 36° to 86°, there is a dead zone where the detection information of the cylinder angle sensor S3 is deviated. Conventionally, in this dead zone angle range, the controller recognized a sudden increase in the cylinder angle as shown by the dotted line in Fig. 4.

[0072] In addition, when the end attachment cylinder 9 rotates the lifting magnet 6 in the second direction (opposite to the first direction), the cylinder angle sensor S3 detects a gradual decrease in the cylinder angle. However, in the range where the cylinder angle decreases from 86° to 36°, there is a dead zone where the detection information of the cylinder angle sensor S3 is deviated. Conventionally, in this dead zone angle range, the controller recognized a sudden decrease in the cylinder angle as shown by the dotted line in FIG. 4.

[0073] In contrast, the controller 30 according to the embodiment calculates the cylinder angle using the cylinder pressure of the end attachment cylinder 9 in the angle range of the dead band of the cylinder angle sensor S3. That is, when the lifting magnet 6 is rotated in the first direction, the cylinder pressure of the end attachment cylinder 9 shows a gradually decreasing change. As shown by the fact that the cylinder angle in FIG. 4 is generally in a mountain shape, while the change in the cylinder pressure is generally in a valley shape, the change in the cylinder pressure has a correlation with the change in the cylinder angle. Therefore, within the angle range of the dead band of the cylinder angle, it is possible to substitute the change in the cylinder angle for the change in the cylinder pressure.

[0074] For example, when the cylinder angle (plunging angle) immediately before entering the dead zone is A and the cylinder pressure of the end attachment cylinder 9 is P, the controller 30 can calculate the compensation value C of the cylinder angle by the following formula [1].

[0075] C = A + (αP + β) …[1]

[0076] The plunge angle A at which the cylinder enters the dead zone is obtained from the detection information of the cylinder angle sensor S3. For example, in the example of FIG. 4, the plunge angle A is 36° when the cylinder angle is rising, and 86° when the cylinder angle is falling. On the other hand, the cylinder pressure is obtained from the detection information of the pressure sensor S9, and the controller 30 uses the detection value of the pressure sensor S9 from the timing immediately before the cylinder enters the dead zone to the timing when the dead zone ends. In addition, α and β in the formula [1] are arbitrary constants and are set in advance according to the end attachment EA (the model of the lifting magnet 6, etc.). α is a value for converting the cylinder pressure to a cylinder angle, and the αP term in the formula [1] corresponds to an angle conversion value. For example, α has a negative value to change a decrease in the cylinder pressure to an increase in the cylinder angle. In addition, β is a constant for correcting the amount of deviation of the angle conversion value based on the cylinder pressure from the plunge angle A.

[0077] The controller 30 can obtain a gradually increasing or decreasing cylinder angle by compensating the cylinder angle by the formula [1] based on the cylinder pressure in the angle range of the dead band of the cylinder angle sensor S3. The detected value of the cylinder pressure of the pressure sensor S9 may repeat amplitude in a short period of time due to vibration of the work machine 100 or the attachment AT. For this reason, when using the cylinder pressure of the pressure sensor S9, the controller 30 preferably performs a filter process (applies a filter) to reduce the amplitude of the detected value of the pressure sensor S9. This filter process is not particularly limited, and a well-known calculation that smooths the amplitude of the signal can be applied. As a result, as shown in the lower diagram of FIG. 4, the cylinder pressure changes smoothly, and the cylinder angle calculated based on this cylinder pressure also changes smoothly.

[0078] Fig. 5 is a block diagram showing the functional blocks of the controller 30 when calculating the weight. In order to perform the above processing, when calculating the weight of the transported object, the controller 30 constructs the functional blocks as shown in Fig. 5. Specifically, the controller 30 includes a torque acquisition unit 31, a posture information acquisition unit 32, and a weight calculation unit 33.

[0079] The torque acquisition unit 31 is configured to acquire the thrust of the boom 4 and calculate the torque from the thrust in order to calculate the weight of the transported object. The thrust of the boom 4 can be obtained based on the detection information of the pressure sensor S7 of the boom cylinder 7, as described above.

[0080] The posture information acquisition unit 32 acquires information on the posture of the attachment AT in order to obtain the position of the center of gravity for calculating the weight of the transported object. Specifically, the posture information acquisition unit 32 includes a boom angle acquisition unit 321, an arm angle acquisition unit 322, a cylinder angle acquisition unit 323, a cylinder pressure acquisition unit 324, and an end attachment angle calculation unit 335.

[0081] The boom angle acquisition unit 321 acquires detection information of the boom angle from the boom angle sensor S1 and outputs it to the weight calculation unit 33. The arm angle acquisition unit 322 acquires detection information of the arm angle from the arm angle sensor S2 and outputs it to the weight calculation unit 33. The cylinder angle acquisition unit 323 acquires detection information of the cylinder angle from the cylinder angle sensor S3 and outputs it to the end attachment angle calculation unit 335. The cylinder pressure acquisition unit 324 acquires detection information of the cylinder pressure from the pressure sensor S9 and outputs it to the end attachment angle calculation unit 335.

[0082] The end attachment angle calculation unit 335 calculates the end attachment angle using the detection information of the cylinder angle and cylinder pressure, and outputs the calculated end attachment angle to the weight calculation unit 33. The end attachment angle calculation unit 335 calculates the end attachment angle based on the cylinder angle of the cylinder angle sensor S3 outside the angle range of the dead zone of the cylinder angle sensor S3.

[0083] On the other hand, the end attachment angle calculation unit 335 compensates the cylinder angle using the cylinder pressure of the pressure sensor S9 in the angle range of the dead band of the cylinder angle sensor S3, and calculates the end attachment angle based on the compensated cylinder angle. The end attachment angle calculation unit 335 calculates the cylinder angle in the angle range of the dead band using, for example, the above formula [1]. Note that the end attachment angle calculation unit 335 may be configured to directly calculate the end attachment angle from the cylinder pressure of the pressure sensor S9 using an appropriate function in the angle range of the dead band.

[0084] The weight calculation unit 33 calculates the weight of the transported object based on the acquired torque of the boom 4 and the attitude of the attachment AT (boom angle, arm angle, end attachment angle). As described above, the weight calculation unit 33 holds in advance the length of the boom 4, the length of the arm 5, and the length of the lifting magnet 6 required for calculating the weight. Using these parameters, the weight calculation unit 33 can calculate, for example, the distance from the base of the boom 4 to the center of gravity of the transported object, and obtain the weight of the transported object by dividing the torque by this distance.

[0085] The work machine 100 according to the present disclosure is not limited to the above embodiment, and various modifications are possible. For example, the controller 30 may not only calculate the weight of the transported object using the end attachment angle and cylinder angle that have compensated for the angle range of the dead zone, but also use the angle for various controls of the work machine 100. As one example, the controller 30 can control the operation of the attachment AT based on the end attachment angle, and can perform control such as adjusting the orientation of the lifting magnet 6 to an angle that makes it difficult for the transported object to fall, and adjusting the magnetic force.

[0086] Fig. 6(A) is a side view showing a work machine 100A according to a first modified example. As shown in Fig. 6(A), the work machine 100A according to the first modified example differs from the work machine 100 according to the embodiment in that a grapple 6A that clamps and holds an object to be transported is applied as the end attachment EA. Even when the grapple 6A is applied, the work machine 100 detects the cylinder angle of the end attachment cylinder 9 that opens and closes the grapple 6A using a cylinder angle sensor S3, and can obtain the end attachment angle based on the detection information.

[0087] During operation of the grapple 6A, the controller 30 can compensate for the cylinder angle by the cylinder pressure of the pressure sensor S9 in the angle range of the dead zone of the cylinder angle sensor S3. However, the angle range of the dead zone when the grapple 6A is applied is different from the angle range of the dead zone when the lifting magnet 6 is applied. Therefore, the controller 30 may appropriately set the angle range of the dead zone according to the model of the end attachment EA, and compensate for the cylinder angle by using the cylinder pressure in that angle range.

[0088] Fig. 6(B) is a side view showing a work machine 100B according to a second modified example. As shown in Fig. 6(B), the work machine 100B according to the second modified example differs from the work machines 100 and 100B described above in that a bucket 6B for accommodating transported material such as soil and sand is applied as the end attachment EA. Even when the bucket 6B is applied, the work machine 100 detects the cylinder angle of the end attachment cylinder 9 that rotates the bucket 6B by the cylinder angle sensor S3, and can obtain the end attachment angle based on the detection information. In this case as well, when the bucket 6B is in operation, the controller 30 can compensate for the cylinder angle by the cylinder pressure of the pressure sensor S9 within the angle range of the dead band of the cylinder angle sensor S3.

[0089] In short, the type of end attachment EA applied to the work machine 100 is not particularly limited, and in addition to the above, for example, harvesters and grapple saws used in forestry, as well as material hands for gripping various transported objects, can be applied. Even when these end attachments EA are applied, the cylinder pressure can be utilized within the angle range of the dead band of the cylinder angle sensor S3.

[0090] The technical ideas and effects of the present disclosure explained in the above embodiments will be described below.

[0091] A first aspect of the present disclosure is a work machine 100 including an end attachment EA, an end attachment cylinder 9 that operates the end attachment EA, a cylinder angle sensor S3 that detects a cylinder angle that changes with the operation of the end attachment cylinder 9, a pressure sensor S9 that detects the cylinder pressure of the end attachment cylinder 9, and a processing unit (controller 30) that processes signals from the cylinder angle sensor S3 and the pressure sensor S9, and the processing unit calculates an angle using the cylinder pressure detected by the pressure sensor S9 within a set angle range of the cylinder angle detected by the cylinder angle sensor S3.

[0092] According to the above, the work machines 100, 100A, 100B can obtain a highly accurate cylinder angle by using the cylinder pressure within a set angle range. As a result, the work machines 100, 100A, 100B can accurately recognize the posture of the attachment AT including the end attachment EA, for example, and can accurately calculate the weight of the transported object held by the attachment AT based on the posture of the attachment AT.

[0093] In addition, the end attachment EA is rotatably connected to the tip of the arm 5, and the processing unit (controller 30) calculates the rotation angle of the end attachment EA relative to the arm 5 based on the cylinder angle. This allows the work machines 100, 100A, 100B to accurately recognize the orientation of the end attachment EA relative to the arm 5, and makes it possible to use this for various controls of the attachment.

[0094] Furthermore, the processing unit (controller 30) calculates the weight of the transported object held by the end attachment EA based on the rotation angle of the end attachment EA. The work machines 100, 100A, 100B can obtain the weight of the transported object with high accuracy through the above processing, and can obtain the effects of being able to properly set the control contents for transporting the transported object and being able to recognize the accumulated weight of the transported objects.

[0095] In addition, the cylinder angle sensor S3 is installed at a position away from the end attachment EA, which makes it possible for the work machines 100, 100A, 100B to reduce sensor failures caused by direct vibrations, magnetic forces, and the like from the end attachment EA, and to increase the durability of the sensor.

[0096] Furthermore, the processing unit (controller 30) calculates the angle based on an angle conversion value obtained by multiplying the cylinder pressure P by a constant α corresponding to the end attachment EA, a plunge angle A when the cylinder angle plunges into a set angle range, and a constant β of the deviation amount from the plunge angle A. This allows the work machines 100, 100A, 100B to more accurately calculate the cylinder angle based on the cylinder pressure.

[0097] Furthermore, the processing unit (controller 30) performs a filter process to reduce the amplitude of the cylinder pressure detected by the pressure sensor S9 before calculating the angle. This allows the work machines 100, 100A, 100B to obtain a cylinder angle with a reduced amplitude, and makes good use of this cylinder angle.

[0098] Furthermore, the work machines 100, 100A are application machines that have an end attachment EA other than the bucket 6B. Application machines have many opportunities to replace the end attachment EA, and if a sensor that detects the angle of the end attachment EA is used, the work efficiency of the replacement will decrease. In contrast, the work machines 100, 100A can prevent a decrease in the work efficiency of the replacement by using the cylinder angle of the cylinder angle sensor S3. Moreover, in the angle range of the dead band of the cylinder angle sensor S3, the cylinder angle can be adequately compensated for by using the cylinder pressure.

[0099] Further, the end attachment EA is a lifting magnet 6 that attracts and holds a transported object by magnetic force. This enables the work machine 100 to obtain the angle of the lifting magnet 6 with high accuracy based on the cylinder angle.

[0100] Further, the end attachment EA is a grapple 6A that clamps and holds the transported object. This enables the work machine 100A to obtain the angle of the grapple 6A with high accuracy based on the cylinder angle.

[0101] The work machines 100, 100A, 100B according to the embodiments disclosed herein are illustrative in all respects and are not restrictive. The embodiments can be modified and improved in various forms without departing from the spirit and scope of the appended claims. The matters described in the above embodiments can be configured in other ways as long as they are not inconsistent, and can be combined as long as they are not inconsistent. [Explanation of symbols]

[0102] 5 Arm 6 Lifting Magnets 6A Grapple 6B Bucket 9 End attachment cylinder 30 Controller 100, 100A, 100B Work Machine EA End Attachment S3 Cylinder Angle Sensor S9 Pressure Sensor

Claims

1. An end attachment; an end attachment cylinder for operating the end attachment; a cylinder angle sensor that detects a cylinder angle that changes with the operation of the end attachment cylinder; a pressure sensor that detects a cylinder pressure of the end attachment cylinder; A processing unit that processes a signal from the cylinder angle sensor and a signal from the pressure sensor, The processing unit calculates an angle by using the cylinder pressure detected by the pressure sensor within a set angle range of the cylinder angle detected by the cylinder angle sensor. Working machinery.

2. The end attachment is rotatably connected to a tip of the arm, The processing unit calculates a rotation angle of the end attachment relative to the arm based on the cylinder angle.

2. The work machine of claim 1.

3. The processing unit calculates a weight of the transported object held by the end attachment based on a rotation angle of the end attachment.

3. A work machine according to claim 2.

4. The cylinder angle sensor is installed at a position away from the end attachment.

3. A work machine according to claim 2.

5. the processing unit calculates the angle based on an angle conversion value obtained by multiplying the cylinder pressure by a constant corresponding to the end attachment, a plunge angle when the cylinder angle plunges into the set angle range, and a constant for a deviation amount for the plunge angle. A work machine according to any one of claims 1 to 4.

6. the processing unit performs a filter process to reduce an amplitude of the cylinder pressure detected by the pressure sensor before calculating the angle. A work machine according to any one of claims 1 to 4.

7. The work machine is an application machine having an end attachment other than a bucket. A work machine according to any one of claims 1 to 4.

8. The end attachment is a lifting magnet that attracts and holds the transported object by magnetic force.

8. A work machine according to claim 7.

9. The end attachment is a grapple that pinches and holds the transported object.

8. A work machine according to claim 7.

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