JP7463162B2 - Work Machine - Google Patents

Description

This disclosure relates to a work machine equipped with a lifting magnet.

Patent Document 1 discloses a load measuring device for a work machine that has a load measuring means for measuring the load of scrap in a work machine equipped with a lifting magnet that attracts scrap. It also discloses that if the actual tipping moment exceeds the tipping moment specified by the rated load curve, further expansion of the working radius is restricted.

JP 2011-201678 A

However, when a work machine equipped with a lifting magnet is used to attract and transport a load such as scrap iron, if a large amount of load is lifted by the lifting magnet, the position of the work machine's body may become unstable.

Therefore, the present invention aims to provide a work machine that improves stability.

A work machine in one embodiment is a work machine comprising a lower running body, an upper rotating body mounted on the lower running body via a rotating mechanism, an attachment attached to the upper rotating body, a lifting magnet attached to the attachment, and a control device, wherein the control device has a limit value setting unit that sets a limit value for the weight of an object to be attracted by the lifting magnet based on the posture of the work machine or the posture of the attachment, a weight calculation unit that calculates the weight of the object attracted by the lifting magnet, and a power control unit that controls the power supplied to the lifting magnet, wherein the power control unit controls the current supplied to the lifting magnet based on the working radius of the lifting magnet when the object is attracted by the lifting magnet before ground cutting, so that the larger the working radius, the smaller the current supplied to the lifting magnet, and controls the power supplied to the lifting magnet after ground cutting based on the weight of the object.

The present invention provides a work machine with improved stability.

FIG. 1 is a side view of a work machine according to an embodiment of the present invention. 2 is a block diagram showing an example of the configuration of a drive system mounted on the work machine shown in FIG. 1 . FIG. 4 is a block diagram illustrating current compensation for a lifting magnet. FIG. 4 is a diagram showing an example of the configuration of a main screen. 5 is a flowchart illustrating control of a work machine in a first operation example. FIG. 11 is a schematic diagram illustrating control of a work machine in a second operation example. 13 is an example of a graph illustrating the relationship between the working radius during attraction (before ground breaking) and the current supplied to the lifting magnet 6.

Figure 1 is a side view of a work machine 100 according to this embodiment. An upper rotating body 3 is mounted on a lower traveling body 1 of the work machine 100 via a rotating mechanism 2. A boom 4 is attached to the upper rotating body 3. An arm 5 is attached to the tip of the boom 4, and a lifting magnet 6 is attached to the tip of the arm 5 as an end attachment. The boom 4 and arm 5 constitute a work 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 lifting magnet 6 is driven by a lifting magnet cylinder 9.

A boom angle sensor S1 is attached to the boom 4, an arm angle sensor S2 is attached to the arm 5, and a lifting magnet angle sensor S3 is attached to the lifting magnet 6. A controller 30, a display device 40, a spatial recognition device 80, a machine tilt sensor S4, and a rotation angular velocity sensor S5 are attached to the upper rotating body 3.

The boom angle sensor S1 is configured 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 the boom foot pin, a cylinder stroke sensor that detects the stroke amount (boom stroke amount) of the boom cylinder 7, or an inclination (acceleration) sensor that detects the inclination angle of the boom 4, or may be a combination of an acceleration sensor and a gyro sensor. The same is true for the arm angle sensor S2 that detects the arm angle that is the rotation angle of the arm 5 relative to the boom 4, and the lifting magnet angle sensor S3 that detects the lifting magnet angle that is the rotation angle of the lifting magnet 6 relative to the arm 5.

The machine body inclination sensor S4 is configured to detect the inclination (machine body inclination angle) of the upper rotating body 3 relative to the horizontal plane. In this embodiment, the machine body inclination sensor S4 is an acceleration sensor that detects the inclination angle around the fore-aft axis and the lateral axis of the upper rotating body 3. The fore-aft axis and the lateral axis of the upper rotating body 3 are, for example, perpendicular to each other and pass through the machine center point, which is a point on the rotation axis of the work machine 100.

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, etc.

The spatial recognition device 80 is configured to capture images of the surroundings of the work machine 100. The spatial recognition device 80 is, for example, a monocular camera, a stereo camera, a distance imaging camera, an infrared camera, or a LIDAR. In the example of FIG. 1, the spatial recognition device 80 includes a front camera 80F attached to the front end of the upper surface of the upper rotating body 3, 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 (not visible in FIG. 1) attached to the right end of the upper surface of the upper rotating body 3.

The spatial recognition device 80 is, for example, a monocular camera having an imaging element such as a CCD or CMOS, and outputs the captured image to the display device 40. The spatial recognition device 80 may also be configured to calculate the distance from the spatial recognition device 80 or the work machine 100 to the recognized object. In addition to using the captured image, when a millimeter wave radar, ultrasonic sensor, laser radar, or the like is used as the spatial recognition device 80, multiple signals (laser light, etc.) may be transmitted to the object, and the reflected signals may be received, and the distance and direction of the object may be detected from the reflected signals.

The spatial recognition device 80 is configured to detect objects present around the work machine 100. The objects are, for example, dump trucks, terrain features (slope, holes, etc.), electric wires, utility poles, people, animals, vehicles, construction machinery, buildings, walls, helmets, safety vests, work clothes, or specific marks on helmets. In this way, the spatial recognition device 80 may be configured to identify at least one of the type, position, and shape of an object. For example, the spatial recognition device 80 may be configured to distinguish between people and non-human objects.

The boom cylinder 7 may be equipped with a boom rod pressure sensor S6a, a boom bottom pressure sensor S6b, and a boom cylinder stroke sensor S7. The arm cylinder 8 may be equipped with an arm rod pressure sensor S6c, an arm bottom pressure sensor S6d, and an arm cylinder stroke sensor S8. The lifting magnet cylinder 9 may be equipped with a lifting magnet rod pressure sensor S6e, a lifting magnet bottom pressure sensor S6f, and a lifting magnet cylinder stroke sensor S9.

The boom rod pressure sensor S6a detects the pressure in the rod side oil chamber of the boom cylinder 7 (hereinafter referred to as the "boom rod pressure"), and the boom bottom pressure sensor S6b detects the pressure in the bottom side oil chamber of the boom cylinder 7 (hereinafter referred to as the "boom bottom pressure"). The arm rod pressure sensor S6c detects the pressure in the rod side oil chamber of the arm cylinder 8 (hereinafter referred to as the "arm rod pressure"), and the arm bottom pressure sensor S6d detects the pressure in the bottom side oil chamber of the arm cylinder 8 (hereinafter referred to as the "arm bottom pressure"). The lifting magnet rod pressure sensor S6e detects the pressure in the rod side oil chamber of the lifting magnet cylinder 9 (hereinafter referred to as the "lifting magnet rod pressure"), and the lifting magnet bottom pressure sensor S6f detects the pressure in the bottom side oil chamber of the lifting magnet cylinder 9 (hereinafter referred to as the "lifting magnet bottom pressure").

The upper rotating body 3 is provided with a cabin 10 as a driver's cab and is equipped with a power source such as an engine 11.

Figure 2 is a diagram showing an example of the configuration of a drive system mounted on the work machine 100. In Figure 2, the mechanical power transmission system is shown by a double line, the hydraulic oil line is shown by a thick solid line, the pilot line is shown by a dashed line, the electrical control system is shown by a dashed line, and the electrical drive system is shown by a thick dotted line.

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 operating device 26, the controller 30, and the engine control device 74.

The engine 11 is the power source of the work machine 100, and is, for example, a diesel engine that operates to maintain a predetermined 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.

The main pump 14 supplies hydraulic oil to the 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.

The regulator 14a controls the discharge volume of the main pump 14. In this embodiment, the regulator 14a controls the discharge volume 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, etc.

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

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 discharged from the main pump 14 to, for example, one or more of the boom cylinder 7, arm cylinder 8, lifting magnet cylinder 9, left-side traveling hydraulic motor 1L, right-side traveling hydraulic motor 1R, and swing hydraulic motor 2A. In the following description, the boom cylinder 7, arm cylinder 8, lifting magnet cylinder 9, left-side traveling hydraulic motor 1L, right-side traveling hydraulic motor 1R, and swing hydraulic motor 2A are collectively referred to as "hydraulic actuators."

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 the pilot port of the corresponding flow control valve in the control valve 17. Specifically, the operating device 26 includes a left operating lever for rotation and arm operation, a right operating lever for boom operation and lifting magnet operation, a travel pedal, and a travel lever (none of which are shown). The pilot pressure changes depending on the operation content of the operating device 26 (including, for example, the operation direction and operation amount).

The operating pressure sensor 29 detects the pilot pressure generated by the operating device 26. In this embodiment, 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 grasps the operation content of each of the operating devices 26 based on the output of the operating pressure sensor 29.

The controller 30 is a control device that executes various calculations. In this embodiment, the controller 30 is a microcomputer that includes a CPU, a volatile storage device, and a non-volatile storage device. For example, the controller 30 reads programs corresponding to various functions from the non-volatile storage device, loads them into the volatile storage device, and causes the CPU to execute the processes corresponding to each of these programs.

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

The switching valve 61 is configured to switch the flow of hydraulic oil discharged by the hydraulic pump 14G. In this embodiment, the switching valve 61 is an electromagnetic 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 connects the hydraulic pump 14G and the hydraulic motor 60, and a second valve position that blocks communication between the hydraulic pump 14G and the hydraulic motor 60.

When the mode changeover switch 62 is operated to switch the operating mode of the work machine 100 to the lifting magnet mode, the controller 30 outputs a control signal to the switching valve 61 to switch the switching valve 61 to the first valve position. Also, when the mode changeover switch 62 is operated to switch the operating mode of the work machine 100 to a mode other than the lifting magnet mode, the controller 30 outputs a control signal to the switching valve 61 to switch the switching valve 61 to the second valve position. Figure 2 shows the state in which the switching valve 61 is in the second valve position.

The mode change switch 62 is a switch that changes the operating mode of the work machine 100. In this embodiment, it is a rocker switch installed in the cabin 10. The operator operates the mode change switch 62 to alternate between the shovel mode and the lifting magnet mode. The shovel mode is an operating mode when the work machine 100 is operated as an excavator (shovel), and is selected, for example, when a bucket is attached to the tip of the arm 5 instead of the lifting magnet 6. The lifting magnet mode is a mode when the work machine 100 is operated as a work machine with a lifting magnet, and is selected when the lifting magnet 6 is attached to the tip of the arm 5. The controller 30 may automatically switch the operating mode of the work machine 100 based on the output of various sensors.

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 allowed to flow into the hydraulic motor 60. On the other hand, when an operating mode other than the lifting magnet 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 allowed to flow out to the hydraulic oil tank without flowing into the hydraulic motor 60.

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

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.

When the lifting magnet switch 65 is turned on and enters the on state, the controller 30 outputs an attraction command to the power control device 64. Upon receiving the attraction command, the power control device 64 converts the AC power generated by the generator 63 into DC power and supplies it to the lifting magnet 6, exciting the lifting magnet 6. The excited lifting magnet 6 enters an attraction state in which it can attract an object (magnetic material).

When the lifting magnet switch 65 is turned off and enters the off state, the controller 30 outputs a release command to the power control device 64. Upon receiving the release command, the power control device 64 stops power generation by the generator 63 and puts the lifting magnet 6, which is in an attracted state, into a non-attracted state (released state). The released state of the lifting magnet 6 means that the supply of power to the lifting magnet 6 has been stopped and the electromagnetic force generated by the lifting magnet 6 has disappeared.

The lifting magnet switch 65 is a switch that switches between attraction and release of the lifting magnet 6. In this embodiment, 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 operating lever 26L, and a release button 65C as a push button switch provided at the top of the right operating lever 26R.

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

The strong excitation button 65B is an example of an input device for applying the maximum allowable voltage to the lifting magnet 6 to place the lifting magnet 6 in an adsorption state (strong adsorption state).

The release button 65C is an example of an input device for putting the lifting magnet 6 into a released state.

The magnetic force adjustment dial 66 is a dial for adjusting the magnetic force (adhesive 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 (adhesive 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 (adhesive force) of the lifting magnet 6 can be switched between four levels, from a first level to a fourth level. Figure 2 shows the state in which the third level is selected with the magnetic force adjustment dial 66.

The lifting magnet 6 is controlled to generate a level of magnetic force (adhesive force) set by the magnetic force adjustment dial 66. The magnetic force adjustment dial 66 outputs data indicating the level of magnetic force (adhesive force) to the controller 30.

With this configuration, the operator can use his fingers to attract and release an object (magnetic material) with the lifting magnet 6 while operating the left operating lever 26L with his left hand and the right operating lever 26R with his 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. The operator then gently raises the boom 4, lifts up the lifting magnet 6 that has attracted the scrap iron, and 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 attachment operation (operation including at least one of boom operation, arm operation, and bucket operation) or swing operation.

The operator can also 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 the pile of scraps using a relatively weak level of magnetic force (attractive force). This is because the operator can prevent himself from lifting relatively heavy objects by using a relatively weak level of magnetic force (attractive force).

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

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 adhesion state, which is the state when the strong excitation button 65B is pressed. The predetermined operation is, for example, a rotation 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, the work machine 100 can automatically transition the state of the lifting magnet 6 to the strong adhesion state even if the strong excitation button 65B is not pressed, for example, when the lifting magnet 6, which is in a weak adhesion state due to the weak excitation button 65A being pressed, is lifted in response to a boom-up operation and then a rotation operation is performed.

The display device 40 is a device that displays various types of information. In this embodiment, the display device 40 is fixed to a pillar (not shown) at the right front of the cabin 10 in which the driver's seat is provided. As shown in FIG. 2, the display device 40 can provide information to the operator by displaying information related to the work machine 100 on an image display unit 41. 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 including various switches. In this embodiment, the switch panel 42 includes a light switch 42a, a wiper switch 42b, and a window washer switch 42c as hardware buttons. The light switch 42a is a switch for switching the lights attached to the exterior of the cabin 10 on and off. The wiper switch 42b is a switch for switching the wipers on and off. The window washer switch 42c is a switch for spraying window washer fluid.

The display device 40 operates by receiving power from the storage battery 70. 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 equipment 72 other than the controller 30 and the display device 40. The starter 11b of the engine 11 is driven by power from the storage battery 70 to start the engine 11.

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 also be configured as an integrated entity. For example, the engine control device 74 may be integrated into the controller 30.

The engine speed adjustment dial 75 is a dial for adjusting the engine speed. In this embodiment, the engine speed adjustment dial 75 is installed inside the cabin 10 and is configured to allow the engine speed to be switched between four stages. Specifically, the engine speed adjustment dial 75 is configured to allow the engine speed to be switched between four stages: SP mode, H mode, A mode, and idling mode. Figure 2 shows the state in which the H mode is selected with the engine speed adjustment dial 75.

SP mode is the rotation speed mode selected when prioritizing the amount of work, and uses the highest engine rotation speed. H mode is the rotation speed mode selected when prioritizing both the amount of work and fuel economy, and uses the second highest engine rotation speed. A mode is the rotation speed mode selected when prioritizing fuel economy while operating the work machine with low noise, and uses the third highest engine rotation speed. Idling mode is the rotation speed mode selected when operating the engine in an idling state, and uses the lowest engine rotation speed (idling rotation speed).

The engine 11 is controlled so as to maintain the engine speed corresponding to the speed mode set by the engine speed adjustment dial 75. The engine speed adjustment dial 75 outputs data indicating the engine speed setting state to the controller 30.

The controller 30 also has a target weight setting unit 31, a weight calculation unit 32, an adhesive force control unit 33, a maximum load amount setting unit 34, an accumulated weight calculation unit 35, and a remaining weight calculation unit 36.

The target weight setting unit 31 acquires the target weight of the object to be attracted by the lifting magnet 6. The target weight may be input by the operator, may be set based on the remaining weight of the remaining weight calculation unit 36 described later, or may be set in advance.

The weight calculation unit 32 calculates the weight (current weight) of the object attracted to the lifting magnet 6. The current weight is calculated, for example, by balancing the torque around the base of the boom 4. Specifically, the thrust of the boom cylinder 7 increases due to the object attracted to the lifting magnet 6, and the torque around the base of the boom 4 calculated from the thrust of the boom cylinder 7 also increases. The increase in torque matches the torque calculated from the weight of the object and the center of gravity of the object. In this way, the weight calculation unit 32 can calculate the weight of the object based on the thrust of the boom cylinder 7 (measurement value of the boom rod pressure sensor S7R and the boom bottom pressure sensor S7B) and the center of gravity of the object. The center of gravity of the object is, for example, experimentally obtained in advance and stored in the controller 30. The method of calculating the weight of the object is not limited to this, and various methods can be applied.

The adhesive force control unit 33 controls the current command value of the current supplied to the lifting magnet 6 to control the adhesive force of the lifting magnet 6.

The maximum load capacity setting unit 34 sets the maximum load capacity of the dump truck on which the object is to be loaded. The maximum load capacity may be input by an operator, for example, or the vehicle type (size, etc.) of the dump truck may be determined based on an image of the dump truck captured by the spatial recognition device 80, and the maximum load capacity may be set based on the determined vehicle type (size, etc.).

The cumulative weight calculation unit 35 calculates the cumulative weight of objects loaded onto the bed of the dump truck.

The remaining weight calculation unit 36 calculates the remaining weight, which is the difference between the maximum load capacity and the accumulated weight.

The following describes an example of the operation of the work machine 100 according to this embodiment.

First, the target weight setting unit 31 of the controller 30 sets the target weight of the object to be attracted by the lifting magnet 6. In addition, the maximum load setting unit 34 sets the maximum load of the dump truck onto which the object is to be loaded.

Next, the operator operates the operating device 26 to move the lifting magnet 6 above the object to be attracted.

Next, the operator operates the weak excitation button 65A to generate a magnetic force (adhesive force) in the lifting magnet 6. This causes the object to be attracted to the lifting magnet 6. At this time, the adhesive force control unit 33 of the controller 30 commands a first current command value as a current command value. The first current command value is set to a sufficient current value so that the object attracted to the lifting magnet 6 is equal to or greater than the target weight. The power control device 64 controls the current supplied to the lifting magnet 6 based on the current command value.

Next, the operator operates the operating device 26 to raise the lifting magnet 6 to a predetermined height. This causes the object attracted to the lifting magnet 6 to be lifted together with the lifting magnet 6. This also triggers the controller 30 to start compensation control, which will be described later. Note that whether the lifting magnet 6 has risen to the predetermined height may be determined from the position of the lifting magnet 6, or may be determined based on the posture of the attachment, the position of each connecting pin of the attachment, the time elapsed since the lifting magnet 6 began to rise, the operation state of the suction switch, etc.

Next, the weight calculation unit 32 of the controller 30 calculates the weight (current weight) of the object attracted (suspended) by the lifting magnet 6.

Next, when the current weight is heavier than the target weight, the adhesive force control unit 33 of the controller 30 performs compensation control of the current supplied to the lifting magnet 6. For example, the adhesive force control unit 33 adjusts the current command value to decrease. This reduces the magnetic force (adhesive force) of the lifting magnet 6, causing part of the object attracted to the lifting magnet 6 to fall. In other words, the weight of the object attracted to the lifting magnet 6 decreases.

Then, in the compensation control, the controller 30 repeatedly calculates the weight (current weight) of the object attracted to the lifting magnet 6 and adjusts (decreases) the current command value until the current weight becomes the target weight. The current command value when the current weight becomes the target weight is set as the second current command value.

Next, the adhesive force control unit 33 of the controller 30 sets the current command value to a third current command value. The third current command value is a current command value greater than the second current command value. This prevents the object that has reached the target weight from falling off the lifting magnet 6.

Next, when the current weight reaches the target weight, the controller 30 notifies the operator. The notification method may be, for example, a display on the display device 40 or an audio notification.

Next, the operator who has been notified operates the strong excitation button 65B to put the lifting magnet 6 into an adsorption state (strong adsorption state). Next, the operator operates the operating device 26 to move the upper rotating body 3 and the work attachment (boom 4, arm 5) and move the lifting magnet 6 onto the bed of the dump truck. Next, the operator operates the release button 65C, which puts the lifting magnet 6 into a released state. This causes an object of the target weight to be loaded onto the bed of the dump truck.

The accumulated weight calculation unit 35 updates the accumulated weight by adding the current target weight to the accumulated weight up to the previous time. The remaining weight calculation unit 36 calculates the remaining weight based on the updated accumulated weight.

By repeating these operations, a desired cumulative weight of objects can be loaded onto the dump truck bed.

After raising the lifting magnet 6 to a predetermined height, the controller 30 may prohibit or limit the rotation of the upper rotating body 3 to a predetermined angle range until the current weight becomes the target weight (while the calculation of the current weight and the current adjustment are repeated). This makes it possible to prevent objects from falling and scattering around when adjusting the current weight to the target weight.

Note that while the example described above is loading onto a dump truck, this is not limited to this, and when unloading, an object of the desired target weight can be unloaded from the dump truck in the same manner.

Next, an example of a block diagram of the work machine 100 is shown using FIG. 3. FIG. 3 is a block diagram explaining current compensation of the lifting magnet 6. As shown in FIG. 3, the work machine 100 has an adsorption start determination unit 101, a compensator 102, and a weight detection unit 103.

The adsorption start determination unit 101 has the function of switching the target weight to be input to the compensator 102. For example, when the weak excitation button 65A is operated, the adsorption start determination unit 101 switches so that Wref+ΔW is input to the compensator 102 as the target weight. Also, for example, when the lifting magnet 6 is raised to a predetermined height, the adsorption start determination unit 101 switches so that Wref is input to the compensator 102 as the target weight. In this way, the target weight is processed to be larger during the period from when the weak excitation button 65A is operated until the lifting magnet 6 is raised to the predetermined height.

After the lifting magnet 6 is raised to a predetermined height, the compensator 102 compensates the current supplied to the lifting magnet 6 based on the difference between the target weight Wref and the current weight detected by the weight detection unit 103. Here, the current compensation may be performed not only after an object is suspended from the lifting magnet 6, but also to compensate for the current corresponding to the target flow rate Wref calculated before the object is suspended.

The weight detection unit 103 detects the weight of the object attracted by the lifting magnet 6.

In this way, the weight of the object attracted to the lifting magnet 6 can be set to the target weight by compensating the current supplied to the lifting magnet 6 based on the target weight Wref and the current weight.

Next, referring to FIG. 4, an example of the configuration of the main screen 41V displayed on the display device 40 will be described. The main screen 41V in FIG. 4 is displayed on the image display unit 41, for example, when the operation mode is the lifting magnet mode.

The main screen 41V includes a date and time display area 41a, a driving mode display area 41b, an attachment display area 41c, a fuel consumption display area 41d, an engine control status display area 41e, an engine operating time display area 41f, a coolant temperature display area 41g, a remaining fuel amount display area 41h, an RPM mode display area 41i, a remaining urea water amount display area 41j, a hydraulic oil temperature display area 41k, a camera image display area 41m, a current weight display area 41p, a cumulative weight display area 41q, a reset button 41r, a remaining weight display area 41s, and a target weight display area 41t.

The travel mode display area 41b, the attachment display area 41c, the engine control status display area 41e, and the rotation speed mode display area 41i are areas that display setting status information, which is information related to the setting status of the work machine 100. The fuel consumption display area 41d, the engine operating time display area 41f, the cooling water temperature display area 41g, the remaining fuel amount display area 41h, the remaining urea water amount display area 41j, the hydraulic oil temperature display area 41k, the current weight display area 41p, and the accumulated weight display area 41q are areas that display operating status information, which is information related to the operating status of the work machine 100.

Specifically, the date and time display area 41a is an area that displays the current date and time. The driving mode display area 41b is an area that displays the current driving mode. The attachment display area 41c is an area that displays an image that represents the currently attached end attachment. Figure 4 shows the state in which an image that represents the lifting magnet 6 is displayed.

The fuel efficiency display area 41d is an area that displays fuel efficiency information calculated by the controller 30. The fuel efficiency display area 41d includes an average fuel efficiency display area 41d1 that displays the lifetime average fuel efficiency or the section average fuel efficiency, and an instantaneous fuel efficiency display area 41d2 that displays the instantaneous fuel efficiency.

The engine control status display area 41e is an area that displays the control status of the engine 11. The engine operating time display area 41f is an area that displays the cumulative operating time of the engine 11. The coolant temperature display area 41g is an area that displays the current temperature state of the engine coolant. The remaining fuel amount display area 41h is an area that displays the remaining amount of fuel stored in the fuel tank. The rotation speed mode display area 41i is an area that displays the current rotation speed mode set by the engine rotation speed adjustment dial 75. The urea water remaining amount display area 41j is an area that displays the remaining amount of urea water stored in the urea water tank. The hydraulic oil temperature display area 41k is an area that displays the temperature state of the hydraulic oil in the hydraulic oil tank.

The camera image display area 41m is an area that displays an image captured by the spatial recognition device 80. In the example of FIG. 4, the camera image display area 41m displays a rear camera image captured by the rear camera 80B. The rear camera image is a rear image that shows the space behind the work machine 100, and includes an image 3a of the counterweight.

The current weight display area 41p is an area that displays the weight (current weight) of the object currently being lifted by the lifting magnet 6. Figure 4 shows that the current weight is 550 kg.

The controller 30 calculates the current weight based on, for example, the attitude of the work attachment, the boom bottom pressure, and the specifications of the work attachment registered in advance (weight, center of gravity position, etc.). Specifically, the controller 30 calculates the current weight based on the output of information acquisition devices such as the boom angle sensor S1, the arm angle sensor S2, the lifting magnet angle sensor S3, and the boom bottom pressure sensor S6b.

The accumulated weight display area 41q is an area that displays the cumulative weight of objects lifted by the lifting magnet 6 during a specified period (hereinafter referred to as the "accumulated weight"). Figure 4 shows that the accumulated weight is 9,500 kg.

The specified period is, for example, the period that begins when the reset button 41r is pressed. For example, when the operator is loading scrap iron onto the bed of a dump truck, the operator presses the reset button 41r to reset the accumulated weight every time the target dump truck is changed. This is to make it easy to grasp the total weight of scrap iron loaded onto each dump truck.

With this configuration, the work machine 100 can prevent scrap iron from being loaded onto the bed of the dump truck in excess of the maximum load weight of the dump truck. When weight measurement at the platform gauge detects that scrap iron has been loaded in excess of the maximum load weight, the driver of the dump truck must return to the loading yard and unload some of the scrap iron that has been loaded onto the bed. The work machine 100 can prevent this type of load weight adjustment work from occurring.

The specified period may be, for example, the period from the start of a day's work to the end of that day's work. This is to allow the operator or manager to easily recognize the total weight of scrap iron transported during a day's work.

The reset button 41r is a software button for resetting the accumulated weight. The reset button 41r may be a hardware button located on the switch panel 42, the left operating lever 26L, the right operating lever 26R, etc.

The controller 30 may be configured to automatically recognize the change of dump trucks and automatically reset the cumulative weight. In this case, the controller 30 may recognize the change of dump trucks using an image captured by the spatial recognition device 80, or may recognize the change of dump trucks using a communication device.

The controller 30 may be configured to recognize that the scrap iron lifted by the lifting magnet 6 has been loaded onto the bed of the dump truck based on the image captured by the spatial recognition device 80, and then calculate the current weight. This is to prevent scrap iron that has been moved to a location other than the bed of the dump truck from being calculated as scrap iron that has been loaded onto the dump truck.

The controller 30 may determine whether the scrap iron lifted by the lifting magnet 6 has been loaded onto the bed of the dump truck based on the posture of the work attachment. Specifically, the controller 30 may determine that the scrap iron has been loaded onto the bed of the dump truck when, for example, the height of the lifting magnet 6 exceeds a predetermined value (e.g., the height of the bed of the dump truck) and the release button 65C is pressed.

The controller 30 may be configured to output an alarm when it is determined that the current weight exceeds a predetermined value. The predetermined value is, for example, a value based on the rated lifting weight. The alarm may be a visual alarm, an audible alarm, or a tactile alarm. With this configuration, the controller 30 can inform the operator that the current weight has exceeded the predetermined value or is at risk of exceeding it.

When lifting relatively small scrap such as iron scraps, the volume of scrap that can be attracted to the lifting magnet 6 is limited, so the working machine 100 does not excessively increase the current weight. However, when lifting relatively large objects such as iron plates or iron blocks, the working machine 100 may lift an object that is so heavy that the stability SV of the working machine 100 falls below a predetermined value (e.g., 1.0). The stability SV of the working machine 100 is expressed as SV = (W2 x L2) / (W1 x L1). W1 is the weight of the working attachment (including the weight of the lifted object), and L1 is the horizontal distance from the tipping fulcrum to the center of gravity of the working attachment. W2 is the weight of the body of the working machine 100 (excluding the weight of the working attachment), and L2 is the horizontal distance from the tipping fulcrum to the center of gravity of the body.

If an excessively heavy object is lifted, the controller 30 can sound a buzzer and display on the display device 40 an image indicating that the current weight has exceeded a predetermined value. This can prevent an excessively heavy object from being lifted for an extended period of time without the operator realizing it. As a result, the safety of work performed by the work machine 100 can be improved.

The remaining weight display area 41s is an area that displays the remaining weight. Figure 4 shows that the accumulated weight is 9,500 kg and the remaining weight is 500 kg. In other words, this shows that the maximum load capacity is 10,000 kg. However, the display device 40 may display the maximum load capacity without displaying the remaining weight, or may display the maximum load capacity separately from the remaining weight.

The target weight display area 41t is an area that displays the target weight of the object to be attracted by the lifting magnet 6. The target weight is set to a value that does not exceed the remaining weight.

In the example shown in FIG. 4, the remaining weight is 500 kg, so the target weight is set to 500 kg. Meanwhile, the current weight is 550 kg. Therefore, the controller 30 controls the current of the lifting magnet 6 to decrease until the current weight becomes 500 kg (target weight). This makes it possible to prevent the dump truck from being overloaded.

As described above, with the work machine 100 according to this embodiment, the weight (current weight) of the object lifted by the lifting magnet 6 can be set as the target weight.

It is possible to have a configuration in which a table that associates target weights with target current commands is provided, and a target current command for the current to be supplied to the lifting magnet 6 is generated based on the target weight, thereby bringing the weight of the object lifted by the lifting magnet 6 closer to the target weight. However, if the object to be attracted to the lifting magnet 6 is, for example, an object with varying density, such as scrap iron or steel beams, it is expected that the weight of the object actually attracted to the lifting magnet 6 will deviate from the target weight even if a current value corresponding to the target weight is applied. In contrast, with the work machine 100 according to this embodiment, the weight of the object to be attracted to the lifting magnet can be set as the target weight.

In addition, messages are displayed in the message display area 41m1. For example, if the current weight exceeds the target weight, a message to that effect is displayed. This makes it possible to prevent loading operations from being performed before weight adjustment is completed. A message may also be displayed if the accumulated weight exceeds the maximum load capacity. This makes it possible to prompt the operator to perform loading and unloading operations, and to prevent overloading of the dump truck.

Next, the control for stabilizing the posture of the work machine when the work machine lifts a load will be described with reference to FIG. 5. FIG. 5 is a flowchart illustrating the control of the work machine in the first operation example.

In step S101, the work machine is lifted off the ground. Specifically, first, the operator operates the control device 26 to operate the attachment and place the lifting magnet 6 on the object that is the suspended load. Next, the operator turns on the lifting magnet switch 65. This causes the controller 30 to supply current to the lifting magnet 6. Note that the current value supplied may be the maximum current. Then, the operator operates the control device 26 to operate the attachment and raise the lifting magnet 6. This causes the object suspended by the lifting magnet 6 to leave the ground and be lifted off the ground.

In step S102, the controller 30 (weight detection unit 103) calculates the weight of the object attracted by the lifting magnet 6.

In step S103, the controller 30 determines whether the weight of the object (current weight) calculated in step S102 is equal to or less than the limit value. Here, the limit value may be uniquely determined regardless of the posture of the work machine. The limit value may also differ based on the posture of the work machine (posture of the attachment). For example, the greater the horizontal distance of the object suspended from the lifting magnet 6 from the foot pin of the boom 4, the greater the moment. For this reason, the closer the lifting magnet 6 is, the greater the limit value may be set, and the farther the lifting magnet 6 is, the smaller the limit value may be set.

If the current weight is equal to or less than the limit value (S103, Yes), the processing of the controller 30 shown in FIG. 5 is terminated.

If the current weight is not equal to or less than the limit value (S103: No), the controller 30 proceeds to step S104.

In step S104, the target weight is limited. That is, the current supplied to the lifting magnet 6 is reduced. As a result, as shown in FIG. 3, the current supplied to the lifting magnet 6 is reduced based on the target weight. That is, the attraction force of the lifting magnet 6 is reduced, and the weight of the object attracted to the lifting magnet 6 is reduced. Then, the processing of the controller 30 returns to step S102.

After the process shown in FIG. 5 is completed, the current supplied to the lifting magnet 6 may be set to the maximum value. Since the lifting magnet 6 has been lifted from the ground, the weight of the suspended object can be maintained without increasing even if the current supplied to the lifting magnet 6 is increased. This makes it possible to prevent the object from falling and scattering on the transport path, for example, when the upper rotating body 3 is rotated to transport the object attracted to the lifting magnet 6.

According to the work machine of the first operation example, the weight of the object suspended by the lifting magnet 6 can be reduced by reducing the current supplied to the lifting magnet 6. This makes it possible to prevent the posture of the work machine from becoming unstable when an object is lifted by the lifting magnet 6. This makes it possible to improve the stability of the work machine.

Next, the work machine according to the second operation example will be described with reference to Figures 6 and 7.

Figure 6 is a schematic diagram explaining the control of the work machine in the second operation example. The horizontal distance from the center of rotation of the upper rotating body 3 of the work machine to the reference position of the lifting magnet 6 is called the working radius. In Figure 6, the case of working radius r2 of the lifting magnet 6 is shown by a solid line, and the cases of working radii r1 and r3 (r1 < r2 < r3) before and after that are shown by dashed lines. Even if the weight of the suspended object is the same, the larger the working radius r, the larger the moment (indicated by the white arrow in Figure 6) that tends to cause the body of the work machine to tip over with point P as the fulcrum.

Figure 7 is an example of a graph that explains the relationship between the working radius during attraction (before ground breaking) and the current supplied to the lifting magnet 6. As shown in the relational expression 701 in Figure 7, the current supplied to the lifting magnet 6 during attraction is limited in advance according to the working radius r. Note that the relational expression between the working radius r and the current I is not limited to the linear relational expression 701, but may be a curve 702.

According to the work machine of the second embodiment, the weight of the object suspended from the lifting magnet 6 can be reduced by reducing the current supplied to the lifting magnet 6 in advance. This makes it possible to prevent the posture of the body of the work machine from becoming unstable due to the load of the suspended object. This makes it possible to improve the stability of the work machine.

In addition, with the work machine of the second embodiment, it is possible to shorten the processing time until the weight of the suspended object stabilizes. In other words, once the object is lifted, the current can be reduced to reduce the number of objects that fall. This makes it possible to prevent objects from scattering around.

The work machine of this embodiment can prevent the work machine from tipping over or the rear of the vehicle body from lifting up, improving the stability of the work machine, without limiting the working radius. Note that with the method of limiting the working radius, as in Patent Document 1, it is necessary to run the work machine and approach the object to be lifted before lifting the object. In contrast, the work machine of this embodiment can transport an object without changing the position of the vehicle body. As a result, even if the object to be lifted by the lifting magnet 6 is placed in a position away from the work machine, the attachment can be extended to attract the object and transport the attracted object, improving workability.

There is also a known control method that reduces the overturning moment of the vehicle body caused by an object suspended from the lifting magnet 6 by releasing pressure from the boom cylinder 7. However, this control method has the problem that the boom 4 is lowered. In contrast, the work machine of this embodiment can reduce the overturning moment without lowering the boom 4.

The above describes the preferred embodiments of the present invention in detail. However, the present invention is not limited to the above-described embodiments. Various modifications, substitutions, etc. may be applied to the above-described embodiments without departing from the scope of the present invention. Furthermore, features described separately may be combined as long as no technical contradiction occurs.

The adhesive force control unit 33 has been described as controlling the current supplied to the lifting magnet 6, but is not limited to this. For example, it may be configured to control the voltage. That is, the adhesive force control unit 33 may control the adhesive force of the lifting magnet 6 by controlling the power supplied to the lifting magnet 6.

100 Work machine 1 Lower travelling body 2 Rotation mechanism 3 Upper rotating body 4 Boom (attachment)
5 Arm (attachment)
6 Lifting magnet 7 Boom cylinder 8 Arm cylinder 9 Lifting magnet cylinder 30 Controller 31 Target weight setting unit 32 Weight calculation unit 33 Adsorption force control unit (power control unit)
34 Maximum load setting unit 35 Accumulated weight calculation unit 36 Remaining weight calculation unit 100 Work machine 101 Suction start determination unit (power control unit)
102 Compensator (power control unit)
103 Weight detection unit

Claims (2)

A lower running body;
An upper rotating body mounted on the lower traveling body via a rotating mechanism;
An attachment attached to the upper rotating body;
a lifting magnet attached to the attachment;
A work machine comprising:
The control device includes:
a limit value setting unit that sets a limit value for the weight of an object that can be attracted by the lifting magnet based on a posture of the work machine or a posture of the attachment;
a weight calculation unit that calculates a weight of an object attracted by the lifting magnet;
A power control unit that controls the power supplied to the lifting magnet,
The power control unit is
When the object is attracted by the lifting magnet before being lifted off the ground, a current supplied to the lifting magnet is controlled based on a working radius of the lifting magnet so that the current is reduced as the working radius is increased,
After the lifting, the power supplied to the lifting magnet is controlled based on the weight of the object and the limit value .
Working machinery. The power control unit sets a target weight based on the posture of the attachment, and reduces the power supplied to the lifting magnet so that the weight of the object approaches the target weight.
2. The work machine of claim 1 .

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