Work Machine

Abstract

Provided is a work machine that precisely calculates the weight of a load.　A work machine comprising a lower traveling body, an upper turning body installed on the lower traveling body via a turning mechanism, at attachment having at least a boom and attached to the upper turning body, a boom cylinder that drives the boom, a work tool attached to the attachment, and a control unit, wherein the control unit has a weight calculation unit that measures the weight of a load to be carried with the work tool on the basis of the boom cylinder pressure of the boom cylinder, and a vibration suppression control unit that generates a command for suppressing the vibration of the attachment.

Description

[Technical field]

[0001] The present disclosure relates to a work machine equipped with a work implement at its tip. [Background technology]

[0002] Patent Document 1 discloses a load measuring device for a work machine having a lifting magnet that attracts scrap, the load measuring device having a load measuring means for measuring the load of scrap, and also discloses that when the actual overturning moment exceeds the overturning moment defined by the rated load curve, further expansion of the working radius is restricted. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-201678 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a work machine equipped with a lifting magnet, when a load (carried object) such as scrap iron is attracted and lifted by the lifting magnet, vibrations may occur in the attachment (boom) of the work machine. This is because the weight of the lifting magnet and the load provided at the tip of the attachment are heavy, and vibrations occur in the attachment (boom). In addition, in the work of a work machine equipped with a lifting magnet, a load may be lifted and transported at a position away from the upper rotating body. In this case, vibrations occur in the attachment (boom) because the load is lifted with the attachment in an extended position. In this way, vibrations occurring in the attachment (boom) cause the boom cylinder pressure to vibrate. For this reason, when detecting the weight of the load based on the boom cylinder pressure, the weight of the load may not be measured appropriately.

[0005] In view of the above-mentioned problems, an object of the present invention is to provide a work machine that can accurately calculate the weight of a transported object. [Means for solving the problem]

[0006] In order to achieve the above object, one embodiment of the present invention provides a lifting device that includes a lower traveling body, an upper rotating body mounted on the lower traveling body via a rotating mechanism, an attachment having at least a boom and attached to the upper rotating body, a boom cylinder that drives the boom, and a lifting device that is attached to the attachment. Lifting Magnet and, A power control device that controls a supply voltage for exciting the lifting magnet; A control unit is provided for controlling the boom cylinder pressure based on the boom cylinder pressure. Lifting Magnet a weight calculation unit that measures the weight of the transported object transported by the attachment; and a vibration suppression control unit that generates a command to suppress vibration of the attachment. The vibration suppression control unit generates a command to the power control device to control the supply voltage. A work machine is provided. Effect of the Invention

[0007] According to the above-described embodiment, a work machine that can calculate the weight of a transported object with high accuracy can be provided. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a side view of a work machine according to an embodiment of the present invention. [Diagram 2] 2 is a block diagram showing an example of the configuration of a drive system mounted on the work machine shown in FIG. 1. [Diagram 3] 2 is a schematic diagram showing a state in which the work machine according to the present embodiment suspends a load. FIG. [Figure 4] FIG. 2 is a diagram illustrating a hydraulic circuit of a boom cylinder in the work machine according to the first embodiment. [Diagram 5] FIG. 4 is a diagram illustrating a hydraulic circuit of another boom cylinder in the work machine according to the first embodiment. [Figure 6] FIG. 11 is a diagram illustrating a hydraulic circuit of a boom cylinder in a work machine according to a second embodiment. [Figure 7] FIG. 11 is a diagram showing an example of the configuration of an electric operation system in a work machine according to a second embodiment. [Figure 8] FIG. 11 is a diagram showing an example of the configuration of another electric operation system in the work machine according to the second embodiment. [Figure 9] FIG. 11 is an explanatory diagram for explaining switching of the supply voltage to a lifting magnet in a work machine according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the invention will be described with reference to the drawings.

[0010] <Overview of the work machine> FIG. 1 is a side view of a work machine 100 according to this embodiment. An upper rotating body 3 is mounted on a lower travel unit 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 (work tool). The boom 4 and the 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. In this embodiment, the work tool (transport mechanism) that is attached to the tip of the attachment and can be used to transport the transported object is the lifting magnet 6, but other work tools such as a bucket for digging and transporting earth and sand, a grapple, a demolition fork, a harvester including a chainsaw, etc. may be attached depending on the type of work.

[0011] 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 body inclination sensor S4, and a turning angular velocity sensor S5 are attached to the upper rotating body 3.

[0012] The boom angle sensor S1 is configured to detect a boom angle which is a 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 which detects the rotation angle of the boom 4 around a boom foot pin, a cylinder stroke sensor which detects the stroke amount (boom stroke amount) of the boom cylinder 7, or an inclination (acceleration) sensor which 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 which detects the arm angle which is the rotation angle of the arm 5 relative to the boom 4, and the lifting magnet angle sensor S3 which detects the lifting magnet angle which is the rotation angle of the lifting magnet 6 relative to the arm 5.

[0013] The machine body inclination sensor S4 is configured to detect the inclination (machine body inclination angle) of the upper rotating body 3 with respect to a horizontal plane. In this embodiment, the machine body inclination sensor S4 is an acceleration sensor that detects the inclination angles around the front-rear axis and the left-right axis of the upper rotating body 3. The front-rear axis and the left-right axis of the upper rotating body 3 are, for example, perpendicular to each other and pass through the machine center point, which is a point on the rotation axis of the work machine 100.

[0014] 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, but it may be a resolver, a rotary encoder, or the like.

[0015] 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.

[0016] 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, a number of signals (laser light, etc.) may be transmitted to the object and the reflected signals may be received, thereby detecting the distance and direction of the object from the reflected signals.

[0017] The spatial recognition device 80 is configured to detect objects present around the work machine 100. The objects are, for example, dump trucks, terrain shapes (slope, holes, etc.), electric wires, utility poles, people, animals, vehicles, construction machines, buildings, walls, helmets, safety vests, work clothes, or predetermined marks on helmets. In this manner, the spatial recognition device 80 may be configured to be able to identify at least one of the type, position, shape, etc. of an object. For example, the spatial recognition device 80 may be configured to be able to distinguish between a person and an object other than a person.

[0018] The boom cylinder 7 may be provided with a boom rod pressure sensor S6a, a boom bottom pressure sensor S6b, and a boom cylinder stroke sensor S7 as pressure sensors for the boom cylinder 7. The arm cylinder 8 may be provided with an arm rod pressure sensor S6c, an arm bottom pressure sensor S6d, and an arm cylinder stroke sensor S8 as pressure sensors for the arm cylinder 8. The lifting magnet cylinder 9 may be provided with a lifting magnet rod pressure sensor S6e, a lifting magnet bottom pressure sensor S6f, and a lifting magnet cylinder stroke sensor S9 as pressure sensors for the lifting magnet cylinder 9.

[0019] 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").

[0020] The upper rotating body 3 is provided with a cab 10 serving as an operator's room, and is equipped with a power source such as an engine 11.

[0021] A cab 10 is provided on the upper rotating body 3 so as to be movable up and down via a cab lifting device 90. Hereinafter, such a cab that can be raised and lowered may be referred to as an "elevator cab." Note that Fig. 1 shows a state in which the cab 10 has been raised to the highest position by the cab lifting device 90. The cab 10 is also disposed to the side of the boom 4 (usually on the left side).

[0022] 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.

[0023] The drive system of the work machine 100 is mainly made up 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.

[0024] The engine 11 is a 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, respectively.

[0025] 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.

[0026] The regulator 13 controls the discharge amount of the main pump 14. In this embodiment, the regulator 13 controls the discharge amount of the main pump 14 by adjusting the swash plate tilt angle of the main pump 14 in response to a control signal from the controller 30 or the like.

[0027] 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.

[0028] 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 the "hydraulic actuator."

[0029] 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 (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).

[0030] 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.

[0031] The controller 30 is a control device that executes various calculations. In this embodiment, the controller 30 is a microcomputer equipped with a CPU, a volatile storage device, and a non-volatile storage device. For example, the controller 30 reads out programs corresponding to various functions from the non-volatile storage device, loads them into the volatile storage device, and causes the CPU to execute processes corresponding to each of the programs.

[0032] The hydraulic pump 14G supplies hydraulic oil through a hydraulic oil line 16a to a hydraulic motor 60. 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.

[0033] 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 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.

[0034] When the mode changeover switch 62 is operated to switch 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 switch the switching valve 61 to the first valve position. Also, when the mode changeover switch 62 is operated to switch the operation 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 a state in which the switching valve 61 is in the second valve position.

[0035] The mode changeover switch 62 is a switch for changing the operation mode of the work machine 100. In this embodiment, it is a rocker switch installed in the cab 10. The operator operates the mode changeover switch 62 to alternatively switch between the shovel mode and the lifting magnet mode. The shovel mode is an operation 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 operation mode of the work machine 100 based on the outputs of various sensors.

[0036] 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 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 caused to flow out to the hydraulic oil tank without flowing into the hydraulic motor 60.

[0037] 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.

[0038] 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.

[0039] 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).

[0040] Furthermore, when the lifting magnet switch 65 is turned off and put into 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-attached state (released state). The released 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.

[0041] 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 operation lever 26L, and a release button 65C as a push button switch provided at the top of the right operation lever 26R.

[0042] 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.

[0043] 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).

[0044] The release button 65C is an example of an input device for putting the lifting magnet 6 into a released state.

[0045] 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 cab 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. FIG. 2 shows a state in which the third level is selected with the magnetic force adjustment dial 66.

[0046] 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.

[0047] With this configuration, the operator can operate the left operation lever 26L with the left hand and the right operation lever 26R with the right hand to operate the work attachment, while using his fingers to cause the lifting magnet 6 to attract and release an object (magnetic body). 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.

[0048] Also, 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 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).

[0049] 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 swing speed and the drive speed of the attachment are limited in the lifting magnet mode, for example.

[0050] 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 adsorption 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, the work machine 100 can automatically transition the state of the lifting magnet 6 to the strong adsorption state even if the strong excitation button 65B is not pressed, when, for example, the lifting magnet 6 that is in the weak adsorption state due to the weak excitation button 65A being pressed is lifted in response to a boom raising operation and then a turning operation is performed.

[0051] 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 cab 10 in which the driver's seat is provided. As shown in FIG. 2 , the display device 40 can provide information related to the work machine 100 to the operator by displaying the information 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.

[0052] 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 on / off a light attached to the exterior of the cab 10. The wiper switch 42b is a switch for switching on / off the operation of the wipers. The window washer switch 42c is a switch for spraying window washer fluid.

[0053] The display device 40 operates by receiving power from a storage battery 70. The storage battery 70 is charged with power generated by an 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 power from the storage battery 70 to start the engine 11.

[0054] 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 configured as an integrated entity. For example, the engine control device 74 may be integrated into the controller 30.

[0055] 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 cab 10, and is configured to be able to switch the engine speed in four stages. Specifically, the engine speed adjustment dial 75 is configured to be able to switch the engine speed in four stages: SP mode, H mode, A mode, and idling mode. Fig. 2 shows a state in which the H mode is selected with the engine speed adjustment dial 75.

[0056] The SP mode is a rotation speed mode selected when prioritizing the amount of work, and uses the highest engine rotation speed. The H mode is a rotation speed mode selected when prioritizing both the amount of work and fuel economy, and uses the second highest engine rotation speed. The A mode is a rotation speed mode selected when prioritizing fuel economy while operating the work machine with low noise, and uses the third highest engine rotation speed. The idling mode is a rotation speed mode selected when operating the engine in an idling state, and uses the lowest engine rotation speed (idling rotation speed).

[0057] The engine 11 is controlled so as to maintain an 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 setting state of the engine speed to the controller 30.

[0058] 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, a remaining weight calculation unit 36, and a vibration suppression control unit 37.

[0059] 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 an operator, may be set based on the remaining weight in the remaining weight calculation unit 36 ​​described later, or may be set in advance.

[0060] 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 (measured values ​​of the boom rod pressure sensor S6a and the boom bottom pressure sensor S6b) 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.

[0061] The attraction force control section 33 controls the current command value of the current supplied to the lifting magnet 6 to control the attraction force of the lifting magnet 6 .

[0062] 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, for example, an operator, or may be determined based on an image of the dump truck captured by the spatial recognition device 80 as to the type of vehicle (size, etc.) of the dump truck, and the maximum load capacity may be set based on the determined type of vehicle (size, etc.).

[0063] The accumulated weight calculation unit 35 calculates the accumulated weight of the objects loaded onto the bed of the dump truck.

[0064] The remaining weight calculation unit 36 ​​calculates the remaining weight, which is the difference between the maximum load amount and the accumulated weight.

[0065] The vibration suppression control unit 37 generates and outputs a command to suppress vibration of the attachment.

[0066] An example of the operation of the work machine 100 according to this embodiment will be described below.

[0067] First, the target weight setting unit 31 of the controller 30 sets a target weight of an object to be attracted by the lifting magnet 6. In addition, the maximum load setting unit 34 sets the maximum load of a dump truck onto which the object is to be loaded.

[0068] Next, the operator operates the operating device 26 to move the lifting magnet 6 above the object to be attracted.

[0069] Next, the operator operates the weak excitation button 65A to generate a magnetic force (adhesive force) in the lifting magnet 6. As a result, the object is attracted to the lifting magnet 6. At this time, the adhesive force control section 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 such that the weight of 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.

[0070] Next, the operator operates the operating device 26 to raise the lifting magnet 6 to a predetermined height. As a result, the object attracted to the lifting magnet 6 is lifted together with the lifting magnet 6. This also triggers the controller 30 to start compensation control, which will be described later. Whether the lifting magnet 6 has risen to a predetermined height may be determined based on the position of the lifting magnet 6, or may be determined based on the posture of the attachment, the positions of each connecting pin of the attachment, the elapsed time since the lifting magnet 6 started to rise, the operation state of the attraction switch, etc.

[0071] 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.

[0072] Next, when the current weight is heavier than the target weight, the attractive force control section 33 of the controller 30 performs compensation control of the current supplied to the lifting magnet 6. For example, the attractive force control section 33 adjusts the current command value to decrease. This reduces the magnetic force (attractive 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.

[0073] Thereafter, in the compensation control, the controller 30 repeats the calculation of the weight (current weight) of the object attracted to the lifting magnet 6 and the adjustment (decrease) of the current command value until the current weight reaches the target weight. Note that the current command value when the current weight reaches the target weight is set as the second current command value.

[0074] Next, the attraction 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 larger than the second current command value. This prevents the object that has reached the target weight from falling off the lifting magnet 6.

[0075] Next, when the current weight reaches the target weight, the controller 30 notifies the operator. Note that the notification method may be, for example, a display on the display device 40 or a voice notification.

[0076] Next, the operator who has been notified operates the strong excitation button 65B to bring the lifting magnet 6 into an adsorption state (strong adsorption state). Next, the operator operates the operation 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 brings the lifting magnet 6 into a release state. As a result, an object of the target weight is loaded onto the bed of the dump truck.

[0077] 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.

[0078] By repeating these operations, a desired cumulative weight of objects can be loaded onto the bed of the dump truck.

[0079] After the lifting magnet 6 is raised 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 reaches the target weight (while the calculation of the current weight and the adjustment of the current are repeated). This makes it possible to prevent objects from falling and scattering around when adjusting the current weight to the target weight.

[0080] Although the above description is given taking loading onto a dump truck as an example, the present invention is not limited to this. Similarly, when unloading an object, an object of a desired target weight can be unloaded from a dump truck.

[0081] Here, vibration of the attachment will be described with reference to Fig. 3. Fig. 3 is a schematic diagram showing the state when the work machine 100 according to this embodiment suspends a load.

[0082] When a load is lifted by the lifting magnet 6, the attachment lowers the boom 4, opens the arm 5, and lifts the load in a closed position with the lifting magnet 6. The attachment is supported by a cantilever on the upper rotating body 3 at the foot pin side of the boom 4. A heavy lifting magnet 6 is provided at the tip side of the attachment. For this reason, the lifting magnet 6 causes vibrations in the boom 4 when the boom is raised. The vibrations in the boom 4 also cause vibrations in the pressure of the boom cylinder 7 (detection value of the sensors S6a and S6b). For this reason, when the weight calculation unit 32 detects the weight of the load based on the pressure of the boom cylinder 7, it may not be possible to suitably calculate the weight of the load.

[0083] <First Example> Next, the operation of suppressing vibration of the boom 4 in the work machine 100 according to the first embodiment will be described with reference to Figures 4 and 5. Here, in the work machine 100 according to the first embodiment, the controller 30 controls the operating pressure of the boom cylinder 7 to suppress vibration of the boom 4.

[0084] FIG. 4 is a diagram illustrating a hydraulic circuit of the boom cylinder 7 in the work machine 100 according to the first embodiment.

[0085] In this example, the boom 4, i.e., the boom cylinder 7, is operated by the boom operation lever 26A. Also, the pilot line that transmits the secondary pilot pressure from the boom operation lever 26A to the port of the boom control valve 175 that supplies hydraulic oil to the boom cylinder 7 in the control valve 17 is called the pilot line 27A.

[0086] As shown in FIG. 4, in this example, bypass oil passages 271, 272 are provided which branch off from between the boom control valve 175 in the control valve 17 and the rod side oil chamber and bottom side oil chamber of the boom cylinder 7 and discharge the hydraulic oil into the tank T.

[0087] In the bypass oil passage 271, an electromagnetic relief valve 201 for discharging the hydraulic oil in the rod side oil chamber of the boom cylinder 7 to the tank T is provided.

[0088] In the bypass oil passage 272, an electromagnetic relief valve 202 for discharging the hydraulic oil in the bottom side oil chamber of the boom cylinder 7 to the tank T is provided.

[0089] The bypass oil passages 271 and 272 and the electromagnetic relief valves 201 and 202 may be provided either inside or outside the control valve 17.

[0090] The controller 30 detects the rod pressure P of the boom cylinder 7 detected by the boom rod pressure sensor S6a. R The controller 30 receives the bottom pressure P of the boom cylinder 7 detected by the boom bottom pressure sensor S6b. B is entered.

[0091] The controller 30 detects the rod pressure P based on the output signals input from the boom rod pressure sensor S6a and the boom bottom pressure sensor S6b. R and bottom pressure P B In addition, controller 30 outputs a current command value to electromagnetic relief valves 201, 202 as appropriate to forcibly discharge the hydraulic oil in the rod-side oil chamber or the bottom-side oil chamber of boom cylinder 7 into tank T, thereby suppressing excessive pressure in boom cylinder 7.

[0092] Here, the vibration suppression control section 37 of the controller 30 detects the rod pressure P of the boom cylinder 7 detected by the boom rod pressure sensor S6a and the boom bottom pressure sensor S6b. R and bottom pressure P BThe occurrence of vibration is detected based on a change in the pressure of the boom rod pressure sensor S6a and the boom bottom pressure sensor S6b. Thereafter, the electromagnetic relief valves 201, 202 are controlled using the detection values ​​of the boom rod pressure sensor S6a and the boom bottom pressure sensor S6b. That is, the hydraulic oil pressure of the boom cylinder 7 is controlled. Specifically, the vibration suppression control section 37 of the controller 30 controls the electromagnetic relief valves 201, 202 so as to suppress a sudden change in pressure of the boom cylinder 7. This makes it possible to suppress vibration of the boom 4 (see FIG. 3). Furthermore, the weight calculation section 32 can suitably calculate the weight of the suspended load based on the pressure of the boom cylinder 7 (detection values ​​of the sensors S6a, S6b). The occurrence of vibration may be detected using an acceleration sensor (machine body tilt sensor S4, etc.).

[0093] The controller 30 may control the electromagnetic relief valves 201, 202 based on the angular velocity of the boom 4 detected by the boom angle sensor S1. This makes it possible to suppress vibration of the boom 4.

[0094] Furthermore, by suppressing the vibration of the boom 4, the weight calculation unit 32 can suitably calculate the weight of the suspended load based on the pressure (detection values ​​of the sensors S6a and S6b) of the boom cylinder 7. The angular velocity of the boom 4 may be detected by the boom cylinder stroke sensor S7.

[0095] 5 is a diagram illustrating the hydraulic circuit of another boom cylinder 7 in the work machine 100 according to the first embodiment. In the following, two boom cylinders 7 are shown in the figure, but the fact that a control valve 17 and a pressure retention circuit 50, which will be described later, are interposed between the main pump 14 and the boom cylinder 7 is the same for all boom cylinders 7, so the hydraulic circuit for one boom cylinder 7 (the boom cylinder 7 on the right side in the figure) will be mainly described.

[0096] An electromagnetic relief valve 201 for discharging hydraulic oil from the rod-side oil chamber to tank T is provided in an oil passage branching off from between control valve 17 and the rod-side oil chamber of boom cylinder 7.

[0097] As shown in FIG. 5, the work machine 100 of this example is provided with a pressure retention circuit 50 that keeps the hydraulic oil in the bottom oil chamber of the boom cylinder 7 from being discharged even if, for example, the hydraulic hose is damaged due to bursting or the like.

[0098] The pressure maintaining circuit 50 is disposed in an oil passage that connects the control valve 17 and the bottom-side oil chamber of the boom cylinder 7. The pressure maintaining circuit 50 mainly includes a maintaining valve 52 and a spool valve 54.

[0099] The holding valve 52 supplies the hydraulic oil supplied from the control valve 17 via the oil passage 321 to the bottom side oil chamber of the boom cylinder 7 regardless of the state of the spool valve 54 .

[0100] Furthermore, when the spool valve 54 is in a non-communicating state (the spool state at the left end in the figure), the retention valve 52 holds the hydraulic oil in the bottom-side oil chamber of the boom cylinder 7 so that it is not discharged to the downstream side of the pressure retention circuit 50. On the other hand, when the spool valve 54 is in a communicating state (the spool state at the right end in the figure), the retention valve 52 allows the hydraulic oil in the bottom-side oil chamber of the boom cylinder 7 to be discharged to the downstream side of the pressure retention circuit 50 via the oil passage 322.

[0101] The spool valve 54 is controlled in its connected / disconnected state according to the pilot pressure input to the port from the boom-lowering remote control valve 26Aa, which is included in the operating device 26 for operating the boom cylinder 7 and outputs a pilot pressure corresponding to the lowering operation of the boom 4 (boom-lowering operation). Specifically, when the pilot pressure indicating that the boom-lowering operation is being performed is input from the boom-lowering remote control valve 26Aa, the spool valve 54 is set to a spool state corresponding to the connected state (the spool state at the right end in the figure). On the other hand, when the pilot pressure indicating that the boom-lowering operation is not being performed is input from the boom-lowering remote control valve 26Aa, the spool valve 54 is set to a spool state corresponding to the disconnected state (the spool state at the left end in the figure). As a result, even if the hydraulic hose downstream of the pressure holding circuit 50 is damaged or the like when the boom-lowering operation is not being performed, the hydraulic oil (bottom pressure) in the bottom-side oil chamber of the boom cylinder 7 is held, so that the boom 4 can be prevented from falling.

[0102] The pressure maintaining circuit 50 also includes an electromagnetic relief valve 203 .

[0103] The electromagnetic relief valve 203 is provided in an oil passage 324 that branches off from an oil passage 323 between the holding valve 52 in the pressure holding circuit 50 and the bottom-side oil chamber of the boom cylinder 7, and is connected to the tank T. That is, the electromagnetic relief valve 203 relieves the hydraulic oil from the oil passage 323 upstream of the holding valve, i.e., on the boom cylinder 7 side, to the tank T. Therefore, the electromagnetic relief valve 203 can discharge the hydraulic oil in the bottom-side oil chamber of the boom cylinder 7 to the tank T regardless of the operating state of the pressure holding circuit 50, specifically, the connected / disconnected state of the spool valve 54. That is, the hydraulic oil in the bottom-side oil chamber of the boom cylinder 7 can be discharged to the tank T regardless of the presence or absence of a boom lowering operation, thereby suppressing excessive bottom pressure, while preventing the boom 4 from falling due to the function of the pressure holding circuit 50 of holding the hydraulic oil in the bottom-side oil chamber of the boom cylinder 7.

[0104] The controller 30 can monitor the rod pressure PR and the bottom pressure PB based on the output signals input from the boom rod pressure sensor S6a and the boom bottom pressure sensor S6b. Furthermore, the controller 30 can forcibly discharge the hydraulic oil in the rod side oil chamber or the bottom side oil chamber of the boom cylinder 7 to the tank T and suppress excessive pressure in the boom cylinder 7 by appropriately outputting a current command value to the electromagnetic relief valves 201, 203, regardless of whether the boom lowering operation is performed or not.

[0105] Here, the vibration suppression control unit 37 of the controller 30 controls the electromagnetic relief valves 201, 203 based on the rod pressure PR and bottom pressure PB of the boom cylinder 7 detected by the boom rod pressure sensor S6a and the boom bottom pressure sensor S6b. That is, it controls the hydraulic pressure of the boom cylinder 7. Specifically, the vibration suppression control unit 37 of the controller 30 controls the electromagnetic relief valves 201, 203 so as to suppress a sudden pressure change in the boom cylinder 7. This makes it possible to suppress vibration of the boom 4 (see FIG. 3). Also, the weight calculation unit 32 can suitably calculate the weight of the suspended load based on the pressure of the boom cylinder 7 (detection values ​​of the sensors S6a, S6b).

[0106] Also, the vibration suppression control section 37 of the controller 30 may determine the occurrence of vibration in the attachment (boom 4). For example, when the vibration suppression control section 37 detects pulsation in the pressure value of the boom cylinder 7 within a predetermined period, the vibration suppression control section 37 may determine that vibration has occurred in the attachment (boom 4). Furthermore, the vibration suppression control section 37 may determine that vibration has occurred in the attachment (boom 4) when, for example, the pressure value of the boom cylinder 7 increases or decreases rapidly within a predetermined period and the amount of increase or decrease in the pressure value exceeds a predetermined value. In this manner, the vibration suppression control section 37 of the controller 30 may determine the occurrence of vibration.

[0107] The controller 30 may control the electromagnetic relief valves 201, 203 based on the angular velocity of the boom 4 detected by the boom angle sensor S1. This makes it possible to suppress vibration of the boom 4. The weight calculation unit 32 can suitably calculate the weight of the suspended load based on the pressure of the boom cylinder 7 (the detection value of the sensors S6a, S6b). The angular velocity of the boom 4 may be detected by the boom cylinder stroke sensor S7.

[0108] The controller 30 may control only the bottom side electromagnetic relief valve 203, or may control both the bottom side electromagnetic relief valve 203 and the rod side electromagnetic relief valve 201.

[0109] <Second Example> Next, the operation of suppressing vibration of the boom 4 in the work machine 100 according to the second embodiment will be described with reference to Figures 6 to 8. Here, in the work machine 100 according to the second embodiment, the controller 30 suppresses vibration of the boom 4 by controlling the control valve 17 (control valve 175).

[0110] Figure 6 is a diagram illustrating the hydraulic circuit of the boom cylinder 7 in a work machine 100 according to a second embodiment. Here, the operating lever of the work machine is a hydraulic operating lever, and the controller 30 suppresses vibration of the boom 4 by controlling the pilot pressure to a control valve 17 (control valve 175). Note that in Figure 6, mechanical power transmission lines, hydraulic oil lines, pilot lines and electrical control lines are indicated by double lines, solid lines, dashed lines and dotted lines, respectively.

[0111] The hydraulic system circulates hydraulic oil from the left main pump 14L driven by the engine 11 to a hydraulic oil tank via a left center bypass line 40L or a left parallel line 42L, and also circulates hydraulic oil from the right main pump 14R driven by the engine 11 to a hydraulic oil tank via a right center bypass line 40R or a right parallel line 42R. The left main pump 14L and the right main pump 14R correspond to the main pump 14 in FIG. 2.

[0112] 2. The left center bypass line 40L is a hydraulic oil line that passes through control valves 171, 173, 175L, and 176L arranged in the control valve 17. The right center bypass line 40R is a hydraulic oil line that passes through control valves 172, 174, 175R, and 176R arranged in the control valve 17. The control valves 175L and 175R correspond to the control valve 175 in FIG. 2. The control valves 176L and 176R correspond to the control valve 176 in FIG. 2.

[0113] The control valve 171 is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged by the left main pump 14L to the left-side traveling hydraulic motor 1L and to discharge the hydraulic oil discharged by the left-side traveling hydraulic motor 1L to the hydraulic oil tank.

[0114] The control valve 172 is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged by the right main pump 14R to the right-side traveling hydraulic motor 1R and to discharge the hydraulic oil discharged by the right-side traveling hydraulic motor 1R to the hydraulic oil tank.

[0115] The control valve 173 is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged by the left main pump 14L to the swing hydraulic motor 2A and to discharge the hydraulic oil discharged by the swing hydraulic motor 2A to the hydraulic oil tank.

[0116] The control valve 174 is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged by the right main pump 14R to the lifting magnet cylinder 9 and to discharge the hydraulic oil in the lifting magnet cylinder 9 to the hydraulic oil tank.

[0117] The control valve 175L is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged from the left main pump 14L to the boom cylinder 7.

[0118] The control valve 175R is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged by the right main pump 14R to the boom cylinder 7 and to discharge the hydraulic oil in the boom cylinder 7 to the hydraulic oil tank.

[0119] The control valve 176L is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged by the left main pump 14L to the arm cylinder 8 and to discharge the hydraulic oil in the arm cylinder 8 to the hydraulic oil tank.

[0120] The control valve 176R is a spool valve that switches the flow of hydraulic oil to supply the hydraulic oil discharged by the right main pump 14R to the arm cylinder 8 and to discharge the hydraulic oil in the arm cylinder 8 to the hydraulic oil tank.

[0121] The left parallel conduit 42L is a hydraulic oil line that runs parallel to the left center bypass conduit 40L. When the flow of hydraulic oil through the left center bypass conduit 40L is restricted or blocked by any of the control valves 171, 173, 175L, the left parallel conduit 42L can supply hydraulic oil to a more downstream control valve. The right parallel conduit 42R is a hydraulic oil line that runs parallel to the right center bypass conduit 40R. When the flow of hydraulic oil through the right center bypass conduit 40R is restricted or blocked by any of the control valves 172, 174, 175R, the right parallel conduit 42R can supply hydraulic oil to a more downstream control valve.

[0122] The left regulator 13L is configured to be able to control the discharge amount of the left main pump 14L. In this embodiment, the left regulator 13L controls the discharge amount of the left main pump 14L, for example, by adjusting the swash plate tilt angle of the left main pump 14L according to the discharge pressure of the left main pump 14L. The right regulator 13R is configured to be able to control the discharge amount of the right main pump 14R. In this embodiment, the right regulator 13R controls the discharge amount of the right main pump 14R, for example, by adjusting the swash plate tilt angle of the right main pump 14R according to the discharge pressure of the right main pump 14R. The left regulator 13L and the right regulator 13R correspond to the regulator 13 in FIG. 2. The left regulator 13L reduces the discharge amount by adjusting the swash plate tilt angle of the left main pump 14L, for example, according to an increase in the discharge pressure of the left main pump 14L. The same applies to the right regulator 13R. This is to prevent the absorption horsepower of the main pump 14, which is expressed by the product of the discharge pressure and the discharge amount, from exceeding the output horsepower of the engine 11.

[0123] The left discharge pressure sensor 28L is an example of a discharge pressure sensor 28, and detects the discharge pressure of the left main pump 14L and outputs the detected value to the controller 30. The same applies to the right discharge pressure sensor 28R.

[0124] Here, the negative control employed in the hydraulic system of FIG. 6 will be described.

[0125] In the left center bypass pipe 40L, a left throttle 18L is disposed between the most downstream control valve 176L and the hydraulic oil tank. The flow of hydraulic oil discharged by the left main pump 14L is restricted by the left throttle 18L. The left throttle 18L generates a control pressure for controlling the left regulator 13L. The left control pressure sensor 19L is a sensor for detecting the control pressure, and outputs the detected value to the controller 30. In the right center bypass pipe 40R, a right throttle 18R is disposed between the most downstream control valve 176R and the hydraulic oil tank. The flow of hydraulic oil discharged by the right main pump 14R is restricted by the right throttle 18R. The right throttle 18R generates a control pressure for controlling the right regulator 13R. The right control pressure sensor 19R is a sensor for detecting the control pressure, and outputs the detected value to the controller 30.

[0126] The controller 30 controls the discharge rate of the left main pump 14L by adjusting the swash plate tilt angle of the left main pump 14L in response to the control pressure. The controller 30 decreases the discharge rate of the left main pump 14L as the control pressure increases, and increases the discharge rate of the left main pump 14L as the control pressure decreases. The discharge rate of the right main pump 14R is controlled in a similar manner.

[0127] Specifically, as shown in FIG. 6, in the case of a standby state in which none of the hydraulic actuators in the work machine 100 are operated, the hydraulic oil discharged by the left main pump 14L passes through the left center bypass pipe 40L and reaches the left throttle 18L. Then, the flow of the hydraulic oil discharged by the left main pump 14L increases the control pressure generated upstream of the left throttle 18L. As a result, the controller 30 reduces the discharge amount of the left main pump 14L to the allowable minimum discharge amount, suppressing the pressure loss (pumping loss) when the discharged hydraulic oil passes through the left center bypass pipe 40L. On the other hand, when any of the hydraulic actuators is operated, the hydraulic oil discharged by the left main pump 14L flows into the hydraulic actuator to be operated via the control valve corresponding to the hydraulic actuator to be operated. Then, the flow of the hydraulic oil discharged by the left main pump 14L reduces or eliminates the amount of hydraulic oil reaching the left throttle 18L, lowering the control pressure generated upstream of the left throttle 18L. As a result, the controller 30 increases the discharge rate of the left main pump 14L to circulate sufficient hydraulic oil to the hydraulic actuator to be operated, and ensures the drive of the hydraulic actuator to be operated. The same applies to the hydraulic oil discharged by the right main pump 14R.

[0128] With the above-mentioned configuration, the hydraulic system of Fig. 6 can suppress unnecessary energy consumption in each of the left main pump 14L and the right main pump 14R in a standby state. The unnecessary energy consumption includes pumping loss caused in the left center bypass line 40L by the hydraulic oil discharged from the left main pump 14L and pumping loss caused in the right center bypass line 40R by the hydraulic oil discharged from the right main pump 14R. Furthermore, when operating a hydraulic actuator, the hydraulic system of Fig. 6 can supply necessary and sufficient hydraulic oil from each of the left main pump 14L and the right main pump 14R to the hydraulic actuator to be operated.

[0129] Further, pressure reducing valves 204 and 205 are provided in a pilot pressure circuit that connects the remote control valve 26Aa to the control valves 175 (175L and 175R).

[0130] The work machine 100 applies a current to the lifting magnet 6 based on an operation command to attract the load (carried object) to the lifting magnet 6, and then performs a boom-up operation. Then, it performs a rotation operation and an arm-opening operation to transport the load to the release position. However, if the vibration of the attachment (boom 4) generated during attraction or boom-up operation is large, the vibration continues during the rotation operation, and the load of the load cannot be measured accurately. Therefore, the vibration suppression control unit 37 of the controller 30 controls the pressure reducing valves 204, 205 based on the rod pressure PR and bottom pressure PB of the boom cylinder 7 detected by the boom rod pressure sensor S6a and the boom bottom pressure sensor S6b. That is, it controls the pilot pressure of the control valve 17 (control valve 175). Specifically, the vibration suppression control unit 37 of the controller 30 controls the pressure reducing valves 204, 205 to suppress a sudden pressure change of the boom cylinder 7. This makes it possible to suppress vibration of the boom 4 (see FIG. 3) from suction (grasping in the case of a grapple) to release. Then, the weight calculation unit 32 calculates the weight calculated when the vibration of the boom 4 is equal to or less than a predetermined threshold as the weight of the current suspended load. In this way, the weight calculation unit 32 can also preferably calculate the weight of the suspended load based on the pressure of the boom cylinder 7 (detection values ​​of sensors S6a, S6b).

[0131] The controller 30 may control the pressure reducing valves 204, 205 based on the angular velocity of the boom 4 detected by the boom angle sensor S1. This makes it possible to suppress vibration of the boom 4. The weight calculation unit 32 can suitably calculate the weight of the load based on the pressure of the boom cylinder 7 (the detection value of the sensors S6a, S6b). The angular velocity of the boom 4 may be detected by the boom cylinder stroke sensor S7.

[0132] 7 is a diagram showing an example of the configuration of an electric operation system in a work machine 100 according to a second embodiment. Here, the operation lever of the work machine is an electromagnetic operation lever, and the controller 30 suppresses vibration of the boom 4 by controlling the pilot pressure to the control valve 17 (control valve 175).

[0133] When an electric operation system equipped with an electric operation lever is employed, the controller 30 can easily execute the autonomous control function compared to when a hydraulic operation system equipped with a hydraulic operation lever is employed. Specifically, the electric operation system in Fig. 7 is an example of a boom operation system, and is mainly composed of a pilot pressure operated control valve 17, a boom operation lever 26A as an electric operation lever, a controller 30, a solenoid valve 160 for boom-raising operation, and a solenoid valve 162 for boom-lowering operation. The electric operation system in Fig. 7 can also be applied to an arm operation system, a bucket operation system, and the like.

[0134] The pilot pressure operated control valve 17 includes a control valve 175 (see FIG. 6) for the boom cylinder 7, a control valve 176 (see FIG. 6) for the arm cylinder 8, and a control valve 174 (see FIG. 6) for the lifting magnet cylinder 9. The solenoid valve 160 is configured to be able to adjust the flow path area of ​​the pipe connecting the pilot pump 15 and the up-side pilot port of the control valve 175. The solenoid valve 162 is configured to be able to adjust the flow path area of ​​the pipe connecting the pilot pump 15 and the down-side pilot port of the control valve 175.

[0135] When manual operation is performed, the controller 30 generates a boom-raising operation signal (electrical signal) or a boom-lowering operation signal (electrical signal) in response to an operation signal (electrical signal) output by an operation signal generating section of the boom operation lever 26A. The operation signal output by the operation signal generating section of the boom operation lever 26A is an electric signal that changes in response to the amount and direction of operation of the boom operation lever 26A.

[0136] Specifically, when boom operation lever 26A is operated in the boom-raising direction, controller 30 outputs a boom-raising operation signal (electrical signal) corresponding to the lever operation amount to solenoid valve 160. Solenoid valve 160 adjusts the flow path area according to the boom-raising operation signal (electrical signal) and controls the pilot pressure acting on the raising-side pilot port of control valve 175 as a boom-raising operation signal (pressure signal). Similarly, when boom operation lever 26A is operated in the boom-lowering direction, controller 30 outputs a boom-lowering operation signal (electrical signal) corresponding to the lever operation amount to solenoid valve 162. Solenoid valve 162 adjusts the flow path area according to the boom-lowering operation signal (electrical signal) and controls the pilot pressure acting on the lowering-side pilot port of control valve 175 as a boom-lowering operation signal (pressure signal).

[0137] When executing the autonomous control, the controller 30 generates a boom-raising operation signal (electrical signal) or a boom-lowering operation signal (electrical signal) in response to a corrective operation signal (electrical signal) instead of in response to an operation signal (electrical signal) output by an operation signal generating unit of the boom operation lever 26A. The corrective operation signal may be an electric signal generated by the controller 30, or may be an electric signal generated by an external control device other than the controller 30.

[0138] Here, the vibration suppression control section 37 of the controller 30 controls the solenoid valves 160, 162 based on the rod pressure PR and bottom pressure PB of the boom cylinder 7 detected by the boom rod pressure sensor S6a and the boom bottom pressure sensor S6b. That is, it controls the pilot pressure of the control valve 17 (control valve 175). Specifically, the vibration suppression control section 37 of the controller 30 controls the solenoid valves 160, 162 so as to suppress a sudden pressure change of the boom cylinder 7. This makes it possible to suppress vibration of the boom 4 (see FIG. 3). Also, the weight calculation section 32 can suitably calculate the weight of the suspended load based on the pressure of the boom cylinder 7 (detection values ​​of the sensors S6a, S6b).

[0139] The controller 30 may control the solenoid valves 160, 162 based on the angular velocity of the boom 4 detected by the boom angle sensor S1. This makes it possible to suppress vibration of the boom 4. The weight calculation unit 32 can suitably calculate the weight of the load based on the pressure of the boom cylinder 7 (the detection value of the sensors S6a, S6b). The angular velocity of the boom 4 may be detected by the boom cylinder stroke sensor S7.

[0140] 8 is a diagram showing an example of the configuration of another electric operation system in the work machine 100 according to the second embodiment. Here, the operation lever of the work machine is an electromagnetic operation lever, the control valve 17 (control valve 175) is a solenoid valve, and the controller 30 suppresses vibration of the boom 4 by controlling the electrical signal to the control valve 17 (control valve 175).

[0141] The control valve 17 is an electromagnetic valve, and is controlled by an operation signal (electrical signal) from a controller 30.

[0142] Here, the vibration suppression control section 37 of the controller 30 directly controls the control valve 17 based on the rod pressure PR and bottom pressure PB of the boom cylinder 7 detected by the boom rod pressure sensor S6a and the boom bottom pressure sensor S6b. Specifically, the vibration suppression control section 37 of the controller 30 controls the control valve 17 so as to suppress abrupt pressure changes in the boom cylinder 7. This makes it possible to suppress vibrations of the boom 4 (see FIG. 3). Also, the weight calculation section 32 can suitably calculate the weight of the suspended load based on the pressure of the boom cylinder 7 (detection values ​​of the sensors S6a, S6b).

[0143] The controller 30 may directly control the control valve 17 based on the angular velocity of the boom 4 detected by the boom angle sensor S1. This makes it possible to suppress vibration of the boom 4. The weight calculation unit 32 can suitably calculate the weight of the suspended load based on the pressure of the boom cylinder 7 (the detection value of the sensors S6a and S6b). The angular velocity of the boom 4 may be detected by the boom cylinder stroke sensor S7.

[0144] <Third Example> Next, an operation for suppressing vibration of the boom 4 in the work machine 100 according to the third embodiment will be described with reference to FIG.

[0145] Fig. 9 is an explanatory diagram for explaining switching of the supply voltage (adhesive force, magnetic force) of the lifting magnet 6 in the work machine 100 according to the third embodiment. The horizontal axis of Fig. 9 indicates elapsed time, and the vertical axis indicates the voltage supplied to the lifting magnet 6. Moreover, the supply voltage according to the reference example is shown by a dashed line, and the supply voltage according to this embodiment is shown by a solid line.

[0146] As shown in Fig. 9, the supply voltage in the reference example rises in a step shape. Therefore, there is a risk that the transported object such as iron scraps attracted by the magnetic force will collide with the lifting magnet 6, causing the boom 4 to vibrate.

[0147] In contrast, the supply voltage in this embodiment rises smoothly, which reduces vibration of the boom 4 caused by collision of the lifting magnet 6 with the transported objects such as iron scraps attracted by magnetic force.

[0148] The controller 30 may detect a change in the boom cylinder pressure and a change in the angular velocity (each acceleration) of the boom 4 to control the voltage supplied to the lifting magnet 6.

[0149] The suppression of vibration of the boom 4 by controlling the supply voltage of the lifting magnet 6 in the third embodiment may be applied to the work machine 100 according to the first and second embodiments.

[0150] In the above-described embodiment, as shown in Figures 4, 5, etc., a form in which the vibration of the attachment (boom 4) is suppressed by discharging the hydraulic oil in the boom cylinder 7 into the hydraulic oil tank T has been shown, but the present invention is not necessarily limited to this form.

[0151] For example, the hydraulic oil of the boom cylinder 7 may be supplied to the arm cylinder 8 to suppress vibration of the attachment (boom 4) that occurs during boom operation.

[0152] A switching valve (not shown) is provided between the boom cylinder 7 and the arm cylinder 8, and the vibration suppression control section 37 of the controller 30 controls the switching valve based on the rod pressure PR and bottom pressure PB of the boom cylinder 7 detected by the boom rod pressure sensor S6a and the boom bottom pressure sensor S6b. That is, when a combined operation corresponding to the lifting operation of the boom 4 (boom lifting operation) and the opening operation of the arm 5 (arm opening operation) or the closing operation of the arm 5 (arm closing operation) is performed, the switching valve switches from a blocked state to a communicating state. Specifically, the switching valve switches from a blocked state to a communicating state in response to a pilot pressure supplied from an electromagnetic proportional valve controlled by the controller 30. As a result, the hydraulic control valve 172 can supply the hydraulic oil discharged from the bottom side oil chamber of the boom cylinder 7 to the arm cylinder 8 via the switching valve.

[0153] Also, a regeneration circuit may be formed in control valve 175 of boom cylinder 7 to discharge the hydraulic oil from boom cylinder 7 to hydraulic oil tank T. In this case, there is no need to provide a switching valve between boom cylinder 7 and arm cylinder 8.

[0154] In addition, the hydraulic oil of the boom cylinder 7 does not necessarily have to be supplied to the arm cylinder 8. It may be configured to supply the hydraulic oil of the boom cylinder 7 to the swing hydraulic motor 2A, or may be configured to supply the hydraulic oil to a hydraulic cylinder that drives an end attachment (lifting magnet cylinder 9, bucket cylinder, etc.).

[0155] In this way, by supplying hydraulic oil to other hydraulic actuators that form a combined motion with the boom 4, vibrations can be suppressed.

[0156] Although the preferred embodiments and examples of the working machine of the present invention have been described above, the present invention is not limited to the above-described embodiments or examples. In other words, the present invention can be modified or changed in various ways within the scope of the appended claims.

[0157] This application claims priority based on Japanese Patent Application No. 2020-198907, filed on November 30, 2020, the entire contents of which are incorporated herein by reference. [Explanation of symbols]

[0158] 100 Work Machines 1 Undercarriage 2 Swivel mechanism 3. Upper rotating body 4 Boom (attachment) 5 Arm (attachment) 6 Lifting magnet (working tool, transport mechanism) 7 Boom cylinder 8 Arm Cylinder 9 Lifting Magnet Cylinder 17 Control valve 175 Control valve 30 Controller 32 Weight calculation section 33 Adsorption force control unit (power control unit) 37 Vibration suppression control section

Claims

1. A lower running body; An upper rotating body mounted on the lower traveling body via a rotating mechanism; An attachment having at least a boom and attached to the upper rotating body; A boom cylinder that drives the boom; a lifting magnet attached to the attachment; A power control device that controls a supply voltage for exciting the lifting magnet; A work machine comprising: The control unit is a weight calculation unit that measures a weight of an object transported by the lifting magnet based on a boom cylinder pressure of the boom cylinder; A vibration suppression control unit that generates a command to suppress vibration of the attachment, The vibration suppression control unit generates a command to the power control device to control the supply voltage. Working machinery.

2. A lower running body; An upper rotating body mounted on the lower traveling body via a rotating mechanism; An attachment having at least a boom and attached to the upper rotating body; A boom cylinder that drives the boom; a hydraulic circuit for supplying hydraulic oil to the boom cylinder; A work tool attached to the attachment; and A work machine comprising: The control unit is a weight calculation unit that measures a weight of an object transported by the working tool based on a boom cylinder pressure of the boom cylinder; A vibration suppression control unit that generates a command to suppress vibration of the attachment, The hydraulic circuit includes: a control valve for switching the flow of hydraulic oil supplied to the boom cylinder; a first electromagnetic relief valve provided in a first bypass flow path that discharges hydraulic oil from a rod side oil chamber of the boom cylinder to a hydraulic oil tank; a second electromagnetic relief valve provided in a second bypass flow path for discharging hydraulic oil in a bottom side oil chamber of the boom cylinder to the hydraulic oil tank, the vibration suppression control unit generates a command to the first electromagnetic relief valve and the second electromagnetic relief valve to suppress a pressure change in the boom cylinder. Working machinery.

3. A lower running body; An upper rotating body mounted on the lower traveling body via a rotating mechanism; An attachment having at least a boom and attached to the upper rotating body; A boom cylinder that drives the boom; a control valve for controlling hydraulic oil supplied to the boom cylinder; A work tool attached to the attachment; and A work machine comprising: The control unit is a weight calculation unit that measures a weight of an object transported by the working tool based on a boom cylinder pressure of the boom cylinder; A vibration suppression control unit that generates a command to suppress vibration of the attachment, The control valve is a control valve operated by a pilot pressure, the vibration suppression control unit generates a command to suppress a pressure change in the boom cylinder to a pressure reducing valve provided in a pilot line that inputs a pilot pressure to the control valve, Working machinery.

4. A lower running body; An upper rotating body mounted on the lower traveling body via a rotating mechanism; An attachment having at least a boom and attached to the upper rotating body; A boom cylinder that drives the boom; a control valve for controlling hydraulic oil supplied to the boom cylinder; A work tool attached to the attachment; and A work machine comprising: The control unit is a weight calculation unit that measures a weight of an object transported by the working tool based on a boom cylinder pressure of the boom cylinder; A vibration suppression control unit that generates a command to suppress vibration of the attachment, The control valve is a control valve operated by a pilot pressure, the vibration suppression control unit generates a command to suppress a pressure change in the boom cylinder to a solenoid valve provided in a pilot line that inputs a pilot pressure to the control valve, Working machinery.

5. A lower running body; An upper rotating body mounted on the lower traveling body via a rotating mechanism; An attachment having at least a boom and attached to the upper rotating body; A boom cylinder that drives the boom; a control valve for controlling hydraulic oil supplied to the boom cylinder; A work tool attached to the attachment; and A work machine comprising: The control unit is a weight calculation unit that measures a weight of an object transported by the working tool based on a boom cylinder pressure of the boom cylinder; A vibration suppression control unit that generates a command to suppress vibration of the attachment, The control valve is an electromagnetic control valve, the vibration suppression control unit generates a command to the control valve to suppress a pressure change in the boom cylinder, Working machinery.

6. The vibration suppression control unit suppresses vibrations generated in the attachment during a boom raising operation. A work machine according to any one of claims 2 to 5.

7. The weight calculation unit is Calculating a weight of the transported object when the vibration of the attachment is equal to or less than a predetermined threshold value. A work machine according to any one of claims 1 to 6.

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