Work machine

Abstract

[Problem] To provide a work machine that is capable of reducing operator fatigue caused by cab vibration while improving the work efficiency of a screening operation. [Solution] A hydraulic shovel comprising a controller 50 that controls the operation of work of a front work device 3 and automatically vibrates the front work device 3, wherein the front work device 3 includes a boom 21, an arm 22, and a bucket 23, and in the control of the automatic vibration, the controller 50 controls a boom cylinder 24 and an arm cylinder 25 such that the simultaneous operations of raising of the boom 21 and dumping of the arm 22 and the simultaneous operations of lowering of the boom 21 and crowding of the arm 22 are alternately and repeatedly executed in a prescribed cycle.

Description

Working Machine

[0001] The present invention relates to a working machine provided with a boom and an arm.

[0002] Patent Document 1 discloses an automatic vibration device for a working implement of a hydraulic excavator, which sets the amplitude and frequency of at least one hydraulic actuator for a boom, an arm and a bucket of the hydraulic excavator in accordance with a work mode, and automatically and repeatedly controls at least one of the boom, the arm and the bucket based on the set amplitude and frequency.

[0003] Japanese Unexamined Patent Publication No. Hei 5-263441

[0004] When a sieving operation is performed by repeatedly vibrating the boom and the arm as in the above-mentioned conventional technology, if the boom and the arm are vibrated with a relatively large angular width to improve work efficiency, the sway of the cab (operator's compartment) on the upper rotating structure that supports the base end of the boom increases, and the physical fatigue of the operator increases. If the boom and the arm are vibrated with a relatively small angular width to reduce the physical fatigue of the operator, the work efficiency of the sieving operation decreases. That is, improving the work efficiency of the sieving operation and reducing the operator's fatigue caused by the sway of the cab are in a trade-off relationship, making it difficult to achieve both. In Patent Document 1, sufficient consideration is not given to such a point.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a working machine capable of reducing operator fatigue caused by cab sway while improving the work efficiency of sieving operations.

[0006] To achieve the above objective, the present invention provides a vehicle body, a front work device provided on the front side of the vehicle body, a hydraulic pump, a plurality of hydraulic actuators for operating the front work device with hydraulic fluid discharged from the hydraulic pump, and a controller that controls the plurality of hydraulic actuators to control the working operation of the front work device and to cause the front work device to vibrate automatically, wherein the front work device includes a boom connected to the vehicle body so as to be able to move up and down, an arm connected to the tip of the boom so as to be able to move up and down, and a bucket connected to the tip of the arm so as to be able to move up and down, wherein the plurality of hydraulic actuators include a boom cylinder for lowering and raising the boom, and an arm cylinder for dumping and clouding the arm, and the controller controls the boom cylinder and the arm cylinder so as to control the automatic vibration, that simultaneous operation of raising the boom and dumping the arm and simultaneous operation of lowering the boom and clouding the arm are repeated alternately at a predetermined period.

[0007] According to the present invention, it is possible to improve the work efficiency of sieving operations while reducing operator fatigue caused by cab vibration.

[0008] This is a left side view showing the structure of a hydraulic excavator in one embodiment of the present invention. This is a perspective view showing the detailed structure of the bucket of the hydraulic excavator in Figure 1. This is a hydraulic circuit diagram showing an example of the hydraulic system installed in the hydraulic excavator in Figure 1. This is a hydraulic circuit diagram showing another example of the hydraulic system installed in the hydraulic excavator in Figure 1. This is an explanatory diagram showing the behavior when the controller automatically vibrates the boom when the sieving switch is pressed. This is an explanatory diagram showing the behavior when the controller automatically vibrates the arm when the sieving switch is pressed. This is a schematic diagram showing the behavior of the pilot pressure in the pilot pipeline related to the supply of pressurized oil to the bottom and rod sides of the boom cylinder and arm cylinder. This is a graph and explanatory diagram conceptually showing the coordinated operation of the boom and arm. This is an explanatory diagram showing the technical significance of the coordinated operation of the boom and arm. This is a flowchart showing the processing performed by the controller. This is an external view showing an example of an electric lever or operating lever equipped with a sieving switch. This is an explanatory diagram showing an example of the appropriate range of posture for sieving work. This is an explanatory diagram showing an example of the appropriate range of posture for sieving work. This is an explanatory diagram showing a guidance display screen that prompts the user to correct the posture of the front work device to within the appropriate range. This is an explanatory diagram showing the behavior when the controller automatically vibrates the bucket when the sieving switch is pressed, in a modified example in which the bucket also moves in conjunction with the sieving operation. This is a schematic diagram showing the behavior of the pilot pressure in the pilot pipeline related to the supply of pressurized oil to the rod side and bottom side of the bucket cylinder. This is a graph and explanatory diagram conceptually representing the coordinated operation of the boom, arm, and bucket. This is a schematic diagram showing the behavior of the pilot pressure in the pilot pipeline related to the supply of pressurized oil to the bottom side and rod side of the boom cylinder and arm cylinder in a modified example in which the operation misalignment is corrected by adjusting the pilot waveform phase, and a graph conceptually representing the misalignment occurring in the coordinated operation of the boom and arm. This is a schematic diagram showing the state in which a command time difference is given to eliminate the misalignment in the behavior of the pilot pressure in the pilot pipeline related to the supply of pressurized oil to the bottom side and rod side of the boom cylinder and arm cylinder, and a graph conceptually representing the elimination of the misalignment in the coordinated operation of the boom and arm.These are explanatory diagrams illustrating a modified example in which the amplitude of the pilot waveform is adjusted, showing a state where the center of the arm's vibration position is misaligned, and a state where the misalignment has been corrected.

[0009] One embodiment of the present invention will be described below with reference to the drawings.

[0010] <Outline Configuration of Hydraulic Excavator> Figure 1 is a left side view of a hydraulic excavator, which is an example of a work machine according to this embodiment. In the following description, the up / down direction, front / back direction, and left / right direction correspond to the directions of the arrows shown as appropriate in Figure 1 and other figures. That is, "up," "down," "left," "right," "front," and "rear" in the figures correspond to the up / down, left / right, front / back directions as seen from the perspective of an operator seated in the driver's seat inside the cab 7. In Figure 1, the hydraulic excavator is equipped with a lower traveling body 1, an upper rotating body 2 mounted on the lower traveling body 1, and a front working device 3 mounted on the front side of the upper rotating body 2. The upper rotating body 2 and the lower traveling body 1 constitute the vehicle body.

[0011] The lower vehicle 1 is the base structure of the hydraulic excavator, and in this example, it is a crawler-type vehicle that moves using left and right tracks 4. The lower vehicle 1 moves by driving the left and right tracks 4 with left and right drive motors 113.

[0012] The upper slewing body 2 is mounted on top of the lower traveling body 1 via a slewing wheel 6, and has a cab 7 (driver's compartment) on the left front side where the operator sits. On the left side of the cab 7, there is an entrance / exit 7A for the operator to get in and out of the cab 7, and a door 7B for opening and closing the entrance / exit 7A. A slewing motor (not shown) is attached to the slewing frame 111, which is the base frame of the upper slewing body 2. In this example, a hydraulic motor is used for the slewing motor. A power room 9 is located behind the cab 7 of the upper slewing body 2, and a counterweight 10 is located at the rearmost part. The cab 7 has a driver's seat (not shown) where the operator sits.

[0013] Electric levers 16 (see Figure 3 below) are located on the left and right sides of the driver's seat to instruct the rotational movement of the upper slewing body 2 and the operation of the front work device 3. The power room 9 houses a hydraulic pump PM1 (see Figure 3 below) that discharges pressurized oil (hydraulic fluid) to drive the hydraulic actuators, an engine EG (see Figure 3 below) that drives the hydraulic pump PM1, and a control valve device (control valves 33, 34, 35, etc. in Figure 3 below) that controls the flow of pressurized oil supplied to the hydraulic actuators. In this example, an engine EG is used as the prime mover, but an electric motor may also be used as the prime mover. The upper slewing body 2 is also equipped with a controller 50 (see Figure 3 below) that controls the operation of the front work device 3 and automatically vibrates the front work device 3 by controlling each operating device, including the engine EG.

[0014] <Front Working Device> The front working device 3 is connected to the front side of the upper slewing body 2 (to the right of the cab 7 in this embodiment). The front working device 3 is a multi-jointed working device equipped with a boom 21, an arm 22, and a bucket 23 (a bucket in this embodiment).

[0015] In this embodiment, the boom 21 is connected to the upper slewing body 2 so as to be able to move up and down. The boom 21 is configured to move up and down in accordance with the extension and retraction of the boom cylinder 24. The boom cylinder 24 lowers the boom 21 when hydraulic fluid is supplied to the rod side and driven to the retraction side, and raises the boom 21 when hydraulic fluid is supplied to the bottom side and driven to the extension side. In this embodiment, the arm 22 is connected to the tip of the boom 21 so as to be able to move up and down. The arm 22 is configured to move up and down in accordance with the extension and retraction of the arm cylinder 25. The arm cylinder 25 dumps the arm 22 when hydraulic fluid is supplied to the rod side and driven to the retraction side, and clouds the arm 22 when hydraulic fluid is supplied to the bottom side and driven to the extension side.

[0016] In this embodiment, the bucket 23 is connected to the tip of the arm 22 so as to be able to move up and down. The bucket 23 is configured to move up and down in accordance with the extension and retraction of the bucket cylinder 26. The bucket cylinder 26 is driven to dump when hydraulic fluid is supplied to the rod side and it is retracted, and to cloud when hydraulic fluid is supplied to the bottom side and it is extended.

[0017] Although not shown in the diagram, angle sensors 131p, 131q, and 131r (attitude detection devices) are provided at the pivot points of the boom 21, arm 22, and bucket 23, respectively. The boom rotation angle, arm rotation angle, and bucket rotation angle, as detected by these sensors, are input to the controller 50 described later (see Figures 3 and 4 below).

[0018] <Detailed Structure of the Bucket> Figure 2 shows a perspective view illustrating the detailed structure of the bucket 23. In Figure 2, the bucket 23 has a bucket body 208 comprising a bottom plate 202 that is curved to have a roughly U-shaped cross-section from the rear end towards the opening at the front, and a left side plate 203L and a right side plate 203R provided on the left and right sides of the bottom plate 202, respectively. The bottom plate 202 forms the bottom and top surfaces of the bucket body 208, and the left side plate 203L and the right side plate 203R form both sides of the bucket body 208. The interior of the bucket body 208 constitutes a space for accommodating contents, such as excavated material. The opening end of the bucket body 8 has a plurality of excavation claws 270 arranged at equal intervals from each other.

[0019] In this embodiment, in particular, in order to perform a sieving operation (details will be described later), a sieving area 202A with a grid structure is provided on at least one wall surface (in this example, the bottom plate 202) of the aforementioned bottom plate 202, left side plate 203L, and right side plate 203R, and a plurality of openings 202B are formed in this sieving area 202A. In this embodiment, each of the openings 202B is a through hole with an inner diameter dimension of a predetermined size. For example, of the excavated material collected in the bucket body 208 by the excavation operation, excavated material of a predetermined size or smaller that passes through the openings 202B is sieved by the sieving area 202A (in this embodiment, excavated material of a predetermined size or larger remains in the bucket body 208, and smaller excavated material falls from the bucket body 208 through the sieving area 202A). In this embodiment, the bottom plate 202 has a mesh area as a sieving area 202A, in which rectangular openings 202B that penetrate the bottom plate 202 are arranged in a grid pattern. Here, an example is given in which the bucket 23 has openings 202B, but the bucket 23 does not necessarily have openings 202B. In that case, the sieving operation (details will be described later) is performed at the opening of the bucket body 208 instead of the openings 202B.

[0020] <Hydraulic Actuators> Returning to Figure 1, the boom cylinder 24, arm cylinder 25, bucket cylinder 26, and the aforementioned travel motor 113 and slewing motor constitute a plurality of hydraulic actuators for operating the front work device 3, lower travel body 1, upper slewing body 2, etc.

[0021] In the hydraulic excavator with the above configuration, pressurized oil discharged from the hydraulic pump PM1 is supplied to the slewing motor, boom cylinder 24, arm cylinder 25, and bucket cylinder 26 in accordance with the operating signals of the left and right electric levers 16. When the slewing motor is driven, the upper slewing body 2 sways relative to the lower traveling body 1. When the boom cylinder 24, arm cylinder 25, and bucket cylinder 26 are driven, the boom 21, arm 22, and bucket 23 rotate, respectively, and the position and orientation of the bucket 23 change. The lower traveling body 1 moves when a pedal-equipped lever (not shown) for driving operation, located in front of the driver's seat, is operated, and the travel motor 113 drives the tracks 4.

[0022] <Hydraulic System (Part 1)> Figure 3 is a hydraulic circuit diagram related to the essential parts of the hydraulic system of the hydraulic excavator shown in Figure 1. In Figure 3, the hydraulic circuits that drive the boom cylinder 24, arm cylinder 25, and bucket cylinder 26 are shown separately, but similar circuits can be applied to the hydraulic circuits of the slewing motor and travel motor.

[0023] In Figure 3, this hydraulic system includes the engine EG, hydraulic pump PM1, pilot-operated control valves 33, 34, 35, controller 50, at least one (multiple in this example; only one is shown in a simplified illustration in Figure 3) electric lever 16, pilot pump PM2, solenoid valves 31, 32, 36, 37, 38, 39, etc.

[0024] <Electric Lever> The electric lever 16 is equipped with multiple sensors (e.g., potentiometers, angle sensors) that detect the lever tilt angle in accordance with the lever tilt direction. The outputs of these sensors are input to the controller 50, and the controller 50 calculates the operating direction and amount of the electric lever 16. One of the electric levers 16 is, for example, a cross-shaped operating lever located on the right side of the driver's seat. When the operator pushes the electric lever 16 forward, an operating signal is generated to lower the boom; when pushed backward, the boom is raised; when pushed left, the bucket is clouded; and when pushed right, the bucket is dumped. Another electric lever 16 is, for example, a cross-shaped operating lever located on the left side of the driver's seat. When the operator pushes the electric lever 16 forward, an operating signal is generated to rotate to the right; when pushed backward, the rotation is left; when pushed left, the arm is dumped; and when pushed right, the arm is clouded. The relationship between the operating direction of the left and right electric levers 16 and the operated objects (slewing motor, boom cylinder 24, arm cylinder 25, bucket cylinder 26) can be changed as appropriate.

[0025] <Hydraulic Pumps> Hydraulic pump PM1 is a variable displacement pump that discharges pressurized oil to drive hydraulic actuators such as boom cylinders 24. A fixed displacement pump can also be used for hydraulic pump PM1. Pilot pump PM2 is a fixed displacement pump that discharges pressurized oil to drive control valves 33, 34, 35, etc. These hydraulic pumps PM1 and pilot pump PM2 are driven by the engine EG to draw hydraulic oil from tank TK and discharge pressurized oil into the center bypass oil passage 32a and primary pressurized oil passage 33a, respectively.

[0026] <Control Valve> The control valve 34 is a proportional hydraulically driven three-position switching valve that controls the flow (direction and flow rate) of pressurized oil supplied from the hydraulic pump PM1 to the boom cylinder 24. This control valve 34 is a pilot-operated control valve having pilot chambers (pressure receiving chambers) 34a and 34b, and is driven by the movement of the spool 34c due to the differential pressure of the pilot pressure acting on the pilot chambers 34a and 34b via the pilot lines 84a and 84b. When the spool 34c moves to the left in Figure 3, the control valve 34 switches to the switching position on the right in Figure 3. Conversely, when the spool 34c moves to the right in Figure 3, the control valve 34 switches to the switching position on the left in Figure 3.

[0027] The control valve 33 is a proportional hydraulically driven three-position switching valve that controls the flow (direction and flow rate) of pressurized oil supplied from the hydraulic pump PM1 to the arm cylinder 25. Like the control valve 34, this control valve 33 is a pilot-operated control valve having pilot chambers (pressure-receiving chambers) 33a and 33b, and the spool 33c is driven by the differential pressure of the pilot pressure acting on the pilot chambers 33a and 33b via the pilot lines 83a and 83b, causing it to move.

[0028] The control valve 35 is a proportional hydraulically driven three-position switching valve that controls the flow (direction and flow rate) of pressurized oil supplied from the hydraulic pump PM1 to the bucket cylinder 26. Like the control valve 34, this control valve 35 is a pilot-operated control valve having pilot chambers (pressure-receiving chambers) 35a and 35b, and the spool 35c is driven by the differential pressure of the pilot pressure acting on the pilot chambers 35a and 35b via the pilot lines 85a and 85b, causing the spool 35c to move.

[0029] <Solenoid Valves> Solenoid valves 31, 32, 36, 37, 38, and 39 are proportional electromagnetically driven pressure reducing valves (solenoid proportional valves) installed in the pilot lines 83a, 83b, 84a, 84b, 85a, and 85b, respectively, which are connected to the primary pressure oil passage 33a. They are individually provided to correspond to the pilot chambers 33a, 33b, 34a, 34b, 35a, and 35b of the control valves 33, 34, and 35. These solenoid valves 31 to 39 are driven by a command signal (an operation signal to the control valve, for example, an electric current; hereinafter, this may be referred to as the "drive current") output from the controller 50 according to the amount of operation of the electric lever 16, which energizes the solenoid. The discharge oil from the pilot pump PM2 flowing through the primary pressure oil passage 33a is reduced in pressure in the solenoid valves 31 to 39 according to the magnitude of the drive current, thereby generating a pilot pressure to act on the corresponding pilot chamber.

[0030] <Driven Control Valves> For example, the solenoid valve 36 is configured to connect the pilot chamber 34a of the control valve 34 to the primary pressure oil passage 33a (pilot pump PM2) and the tank oil passage Ta (tank TK). When the spool position of the solenoid valve 36 changes, the ratio of the opening area connecting the pilot chamber 34a to the primary pressure oil passage 33a and the opening area connecting the pilot chamber 34a to the tank oil passage Ta changes, and the pilot pressure acting on the pilot chamber 34a changes. Solenoid valves 31, 32, 37-39 have the same configuration as the solenoid valve 36, and each changes the pilot pressure acting on the corresponding pilot chambers 33a, 33b, 34b, 35a, and 35b with the spool position. In this example, the spools 31c, 32c, 36c-39c of the solenoid valves 31, 32, 36-39 are pressed by springs in a direction that reduces the pilot pressure to the pilot chambers 33a, 33b, 34a, 34b, 35a, and 35b, and are configured so that the pilot pressure increases as the drive current received by the solenoid increases.

[0031] In the above configuration, for example, if there is no differential pressure in the pilot pressure generated by the solenoid valves 36 and 37 (solenoid proportional valves for the boom), the spool 34c of the control valve 34 (boom control valve) is maintained in the neutral position (the position shown in Figure 3) by spring force. In this case, the center bypass oil passage 32a is connected to the tank oil passage Tb via the control valve 34, and the pressurized oil discharged from the hydraulic pump PM1 is returned to the tank TK without being supplied to the boom cylinder 24. Also, the circuit for the boom cylinder 24 is closed.

[0032] If the pilot pressure generated by the solenoid valve 36 is greater than the pilot pressure generated by the solenoid valve 37, the spool 34c moves to the left side in the figure against the spring force, and the control valve 34 switches to the switching position on the right side in the figure. In this case, the center bypass oil passage 32a is constricted, and the pressurized oil discharged from the hydraulic pump PM1 flows into the parallel oil passage 32b that branches off from the center bypass oil passage 32a. The pressurized oil guided into the parallel oil passage 32b flows into the rod chamber of the boom cylinder 24 via the check valve 34d and the control valve 34, causing the boom cylinder 24 to contract. The pressurized oil pushed out of the bottom chamber of the boom cylinder 24 is returned to the tank TK via the control valve 34 and the tank oil passage Tb. As a result, the boom cylinder 24 can be driven at a speed corresponding to the opening of the control valve 34, and the boom 21 can be lowered and operated.

[0033] Conversely, if the pilot pressure generated by the solenoid valve 37 is greater than the pilot pressure generated by the solenoid valve 36, the control valve 34 switches to the switching position shown on the left in the figure. In this case, the center bypass oil passage 32a is constricted, and the pressurized oil discharged from the hydraulic pump PM1 flows into the bottom chamber of the boom cylinder 24 via the parallel oil passage 32b, check valve 34d, and control valve 34, extending the boom cylinder 24. The pressurized oil pushed out of the rod chamber of the boom cylinder 24 is returned to the tank TK via the control valve 34 and tank oil passage Tb. As a result, the boom cylinder 24 can be driven at a speed corresponding to the opening of the control valve 34, and the boom 21 can be raised and operated.

[0034] The operation of the control valve 33 (control valve for the arm) is the same as that of the control valve 34. For example, if there is no differential pressure in the pilot pressure generated by the solenoid valves 31 and 32 (solenoid proportional valves for the arm), the pressurized oil discharged from the hydraulic pump PM1 is returned to the tank TK without being supplied to the arm cylinder 25. If there is a differential pressure in the pilot pressure generated by the solenoid valves 31 and 32, the center bypass oil passage 32a is constricted, and the discharged oil from the hydraulic pump PM1 flows into the parallel oil passage 32b. The pressurized oil that flows into the parallel oil passage 32b flows into the bottom chamber or rod chamber of the arm cylinder 25 via the check valve 33d and the control valve 33, causing the arm cylinder 25 to extend and retract. Consequently, the pressurized oil discharged from the arm cylinder 25 is returned to the tank TK via the control valve 33 and the tank oil passage Tb. As a result, the arm cylinder 25 can be driven at a speed corresponding to the opening of the control valve 33, and the arm 22 can be made to perform a clouding or dumping motion.

[0035] The operation of the control valve 35 (bucket control valve) is the same as that of the control valve 34. For example, if there is no differential pressure in the pilot pressure generated by the solenoid valves 38 and 39 (bucket solenoid proportional valves), the pressurized oil discharged from the hydraulic pump PM1 is returned to the tank TK without being supplied to the bucket cylinder 26. If there is a differential pressure in the pilot pressure generated by the solenoid valves 38 and 39, the center bypass oil passage 32a is constricted, and the discharged oil from the hydraulic pump PM1 flows into the parallel oil passage 32b. The pressurized oil that flows into the parallel oil passage 32b flows into the bottom chamber or rod chamber of the bucket cylinder 26 via the check valve 35d and the control valve 35, causing the bucket cylinder 26 to expand and contract. Consequently, the pressurized oil discharged from the bucket cylinder 26 is returned to the tank TK via the control valve 35 and the tank oil passage Tb. As a result, the bucket cylinder 26 can be driven at a speed corresponding to the opening of the control valve 35, and the bucket 23 can be made to perform a clouding or dumping motion.

[0036] In addition, a pilot relief valve RV and a solenoid valve SV are provided in the primary pressure oil passage 33a. The pilot relief valve RV controls the pressure in the primary pressure oil passage 33a (the base pressure for pilot pressure). The solenoid valve SV is driven by a command signal output from the controller 50 in accordance with the amount of operation of the electric lever 16 and the discharge pressure of the hydraulic pump PM1 detected by the pressure sensor PS, and controls the regulator PR of the hydraulic pump PM1.

[0037] <Hydraulic System (Part 2)> In Figure 3 above, a hydraulic system equipped with a so-called electric lever type operating lever (electric lever) 16 was used as an example, but the system is not limited to this, and a hydraulic system equipped with a so-called hydraulic pilot type operating lever may also be used. Figure 4 is an example of a hydraulic circuit diagram representing the hydraulic pilot type hydraulic system mounted on the hydraulic excavator in this embodiment. The same reference numerals are used for parts equivalent to those in Figure 3, and the explanation is simplified or omitted.

[0038] <Operating Lever> In the hydraulic system shown in Figure 4, multiple operating levers 16' are provided in place of the multiple electric levers 16 in Figure 3. The operating levers 16' are hydraulically piloted with a built-in pressure reducing valve (remote control valve) and are connected to the discharge oil passage (not shown) of the pilot pump PM2. The pressure reducing valve generates a command pilot pressure (pilot secondary pressure) corresponding to the amount and direction of operation of the operating lever 16' operated by the operator, based on the hydraulic pressure (pilot primary pressure) generated by the pilot pump PM2.

[0039] One of the control levers 16' is, for example, a cross-shaped lever located to the right of the driver's seat. When the operator pushes the control lever 16' forward, it generates a signal to lower the boom; when pushed backward, it generates a signal to raise the boom; when pushed left, it generates a signal to clog the bucket; and when pushed right, it generates a signal to clog the bucket. Another control lever 16' is, for example, a cross-shaped lever located to the left of the driver's seat. When the operator pushes the control lever 16' forward, it generates a signal to turn right; when pushed backward, it generates a signal to turn left; when pushed left, it generates a signal to clog the arm; and when pushed right, it generates a signal to clog the arm.

[0040] In other words, for example, when an operator pushes the operating lever 16' on the right side of the driver's seat forward to instruct the boom to be lowered, the command pilot pressure for lowering the boom from the pressure reducing valve is guided to the pilot pipeline 94a as an operation signal. In this example, a shuttle valve 184a is provided in the pilot pipeline 84a that communicates with the pilot chamber 34a of the control valve 34, and the pilot pipeline 94a is connected to this shuttle valve 184a. As a result, the larger of the two—the pilot pressure for lowering the boom guided from the operating lever 16' via the pilot pipeline 94a and the pilot pressure guided via the solenoid valve 36 (driven by the command signal output from the controller 50, i.e., the drive current which is the operation signal to the control valve)—is selected and supplied to the pilot chamber 34a of the control valve 34. As a result, during normal operation of the hydraulic excavator by the operator, the pilot pressure for lowering the boom from the operating lever 16' switches the control valve 34 to the switching position shown on the right in the figure, and during the sieving operation described later, the pilot pressure via the solenoid valve 36 controlled by the controller 50 switches the control valve 34 to the switching position shown on the right.

[0041] For example, if the operator pushes the operating lever 16' on the right side of the driver's seat backward to instruct the boom to be raised, a command pilot pressure for raising the boom is generated from the pressure reducing valve via the pilot pipeline 94b. The shuttle valve 184b selects the larger of this command pilot pressure and the pilot pressure guided through the solenoid valve 37 (driven by the drive current, which is the command signal output from the controller 50, i.e., the operation signal to the control valve), and supplies it to the pilot chamber 34b of the control valve 34. As a result, during normal operation of the hydraulic excavator by the operator, the control valve 34 is switched to the left-hand side of the diagram by the pilot pressure for raising the boom from the operating lever 16', and during the sieving operation described later, the control valve 34 is switched to the left-hand side of the diagram by the pilot pressure via the solenoid valve 37 controlled by the controller 50.

[0042] For example, if the operator moves the operating lever 16' on the right side of the driver's seat to the left to instruct the bucket to clog, a command pilot pressure for bucket clog is generated from the pressure reducing valve via the pilot pipeline 95b. The shuttle valve 185b selects the larger of this command pilot pressure and the pilot pressure guided through the solenoid valve 39 (driven by a drive current, which is an operation signal to the control valve output from the controller 50), and supplies it to the pilot chamber 35b of the control valve 35. As a result, during normal operation of the hydraulic excavator by the operator, the control valve 35 is switched to the left-hand position shown in the figure by the pilot pressure for bucket clog from the operating lever 16', and during the sieving operation described later, the control valve 35 is switched to the left-hand position shown by the pilot pressure via the solenoid valve 39 controlled by the controller 50. For example, if the operator moves the operating lever 16' on the right side of the driver's seat to the right to instruct the bucket to dump, a command pilot pressure for bucket dump is generated from the pressure reducing valve via the pilot pipeline 95a. Of the command pilot pressure and the pilot pressure guided via the solenoid valve 38 (driven by a drive current which is an operation signal to the control valve output from the controller 50), the larger of the two is selected by the shuttle valve 185a and supplied to the pilot chamber 35a of the control valve 35. As a result, during normal operation of the hydraulic excavator by the operator, the control valve 35 is switched to the switching position shown on the right in the figure by the pilot pressure for bucket dumping from the operating lever 16', and during the sieving operation described later, the control valve 35 is switched to the switching position shown on the right in the figure by the pilot pressure via the solenoid valve 38 controlled by the controller 50.

[0043] For example, if the operator moves the operating lever 16' on the left side of the driver's seat to the right to instruct arm clouding, a command pilot pressure for arm clouding is generated from the pressure reducing valve via the pilot pipeline 93b. The shuttle valve 183b selects the larger of this command pilot pressure and the pilot pressure guided through the solenoid valve 32 (driven by a drive current, which is an operation signal to the control valve output from the controller 50), and supplies it to the pilot chamber 33b of the control valve 33. As a result, during normal operation of the hydraulic excavator by the operator, the control valve 33 is switched to the left-hand position shown in the figure by the pilot pressure for arm clouding from the operating lever 16', and during the sieving operation described later, the control valve 33 is switched by the pilot pressure via the solenoid valve 32 controlled by the controller 50. For example, if the operator moves the operating lever 16' on the left side of the driver's seat to the left to instruct arm dumping, a command pilot pressure for arm dumping is generated from the pressure reducing valve via the pilot pipeline 93a. Of the command pilot pressure and the pilot pressure guided via the solenoid valve 31 (driven by a command signal output from the controller 50, i.e., a drive current which is an operation signal to the control valve), the larger of the two is selected by the shuttle valve 183a and supplied to the pilot chamber 33a of the control valve 33. As a result, during normal operation of the hydraulic excavator by the operator, the control valve 33 is switched to the switching position shown on the right in the figure by the pilot pressure for arm dumping from the operating lever 16', and during the sieving operation described later, the control valve 33 is switched to the switching position shown on the right in the figure by the pilot pressure via the solenoid valve 31 controlled by the controller 50.

[0044] <Sieving Operation> In the hydraulic excavator of the present embodiment provided with the hydraulic system shown in FIG. 3 or FIG. 4 above, when an operator operates a sieving switch 60 (see FIGS. 3 and 4, details will be described later) provided on either the electric lever 16 or the operation lever 16' (hereinafter, these are collectively referred to as "operation lever 16, etc." as appropriate), the controller 50 controls the boom 21 and the arm 22 to automatically vibrate, whereby sieving of the contents stored inside the bucket 23 (hereinafter, appropriately referred to as "sieving operation", "sieving work", etc.) is performed. That is, this sieving work is automatically performed only by the operator operating the sieving switch 60, without the operator manually operating the operation lever 16 or the like. Details of the method by the controller 50 will be described with reference to FIGS. 5 to 7.

[0045] <Repeated Boom Raising and Boom Lowering> The behavior when the controller 50 automatically vibrates the boom 21 when the sieving switch 60 is pressed will be described with reference to FIGS. 5(a) to 5(c). FIG. 5(a) shows the behavior of a voltage signal (boom raising / lowering command signal) generated by the controller 50 when the sieving switch 60 is operated, with time t plotted on the horizontal axis. As shown in the figure, the voltage in the boom raising direction and the voltage in the boom lowering direction of the boom raising / lowering command signal are switched at times tb1, tb2, tb3, tb4, tb5, ..., and behave to alternate repeatedly at a predetermined first period Tb.

[0046] FIGS. 5(b) and 5(c) respectively show the behavior of the drive current output from the controller 50 to the electromagnetic valve 37 and the electromagnetic valve 36 based on the boom raising / lowering command signal generated as described above, with time t plotted on the horizontal axis. As shown in FIG. 5(b), the drive current to the electromagnetic valve 37 corresponding to the boom raising operation side is output at the timing when the voltage in the boom raising direction is generated among the boom raising / lowering command signals shown in FIG. 5(a). Similarly, as shown in FIG. 5(c), the drive current to the electromagnetic valve 36 corresponding to the boom lowering operation side is output at the timing when the voltage in the boom lowering direction is generated among the boom raising / lowering command signals shown in FIG. 5(a).

[0047] As described above, the output of the drive current to the solenoid valve 37 and the output of the drive current to the solenoid valve 36 are alternately repeated in the aforementioned first cycle Tb. As a result of the alternate switching control of the pilot pressure to the control valve 34 via the pilot pipelines 84b and 84a, the boom 21 can be automatically vibrated in the first cycle Tb.

[0048] <Repeated Arm Dump and Arm Crowding> The behavior when the controller 50 automatically vibrates the arm 22 when the sieving switch 60 is pressed will be described with reference to Figs. 6(a) to 6(c). Similar to Fig. 5(a), Fig. 6(a) shows the behavior of the voltage signal (arm dump and crowd command signal) generated by the controller 50 when the sieving switch 60 is operated, with time t plotted on the horizontal axis. As shown in the figure, in the arm dump and crowd command signal, the voltage in the arm dump direction and the voltage in the arm crowd direction are switched at time ta1, ta2, ta3, ta4, ta5, ..., and the behavior is alternately repeated in a predetermined second cycle Ta (as will be described later, in the present embodiment, this cycle is the same as the first cycle Tb mentioned above). As can be seen from the comparison between Fig. 6(a) and Fig. 5(a), in this example, the voltage values of the arm dump and crowd command signal in the arm dump direction and the arm crowd direction are larger than the voltage values of the boom up and down command signal in the boom up direction and the boom down direction.

[0049] Figures 6(b) and 6(c) show the behavior of the drive currents output from the controller 50 to the solenoid valves 31 and 32 based on the arm dump / arm cloud command signals generated as described above, with time t on the horizontal axis. As shown in Figure 6(b), the drive current to the solenoid valve 31 corresponding to the arm dump operation is output at the timing when a voltage in the arm dump direction is generated in the arm dump / cloud command signal shown in Figure 6(a). Similarly, as shown in Figure 6(c), the drive current to the solenoid valve 32 corresponding to the arm cloud operation is output at the timing when a voltage in the arm cloud direction is generated in the arm dump / cloud command signal shown in Figure 6(a). As can be seen by comparing Figures 6(b) and 6(c) with Figures 5(b) and 5(c), in this example, the drive current values ​​to the solenoid valves 31 and 32 related to the arm dump / cloud are greater than the drive current values ​​to the solenoid valves 37 and 36 related to boom raising and lowering.

[0050] As described above, the output of the drive current to the solenoid valve 31 and the output of the drive current to the solenoid valve 32 alternately repeat in the aforementioned second period Ta, and as a result of the pilot pressure to the control valve 33 via the pilot lines 83a and 83b being alternately switched and controlled, the arm 22 can be automatically vibrated in the second period Ta.

[0051] <Features of the Embodiment> The feature of this embodiment is that, when the controller 50 automatically vibrates the boom 21 and the arm 22 as described above, the control valves 34 and 33 are switched and controlled so that the boom raising operation and the arm dumping operation are performed simultaneously, and the boom lowering operation and the arm clouding operation are performed simultaneously.

[0052] In other words, in this embodiment, the controller 50 executes both the control processes shown in Figures 5(a) to (c) and Figures 6(a) to (c) to automatically vibrate the boom 21 in a first period Tb and the arm 22 in a second period Ta, and sets the times, for example, tb1 = ta1, tb2 = ta2, tb3 = ta3, tb4 = ta4, tb5 = ta5, ... This synchronizes the timing of switching from boom raising to boom lowering and the timing of switching from arm dumping to arm clouding, as well as the timing of switching from boom lowering to boom raising and the timing of switching from arm clouding to arm dumping. As a result, the first period Tb and the second period Ta also coincide.

[0053] As a result of the control described above, the behavior of the pilot pressure in the pilot lines 84b and 84a related to the supply of pressurized oil to the bottom and rod sides of the boom cylinder 24 is schematically shown in Figure 7(a). As shown in the figure, the pilot pressure in the pilot line 84b corresponding to boom raising and the pilot pressure in the pilot line 84a corresponding to boom lowering alternate in the first cycle Tb, switching at times tb1, tb2, tb3, tb4, tb5, ... Similarly, the behavior of the pilot pressure in the pilot lines 83a and 83b related to the supply of pressurized oil to the rod and bottom sides of the arm cylinder 25 is schematically shown in Figure 7(b). As shown in the figure, the pilot pressure in the pilot line 83a corresponding to arm dump and the pilot pressure in the pilot line 83b corresponding to arm cloud alternate in the second cycle Ta, switching at times ta1, ta2, ta3, ta4, ta5, ... As can be seen by comparing Figure 7(b) and Figure 7(a), in this example, the magnitude of the pilot pressure in the pilot lines 83a and 83b corresponding to arm dump and arm cloud, respectively, is greater than the pilot pressure in the pilot lines 84b and 84a corresponding to boom raising and boom lowering, respectively, corresponding to the difference in the voltage values ​​of the command signals (in other words, the difference in the drive current values) mentioned above.

[0054] Figure 7(c) is a schematic diagram that conveniently overlays Figures 7(a) and 7(b) to facilitate understanding of the coordinated operation of the boom 21 and arm 22 described above. As previously stated, the time intervals are tb1 = ta1, tb2 = ta2, tb3 = ta3, tb4 = ta4, tb5 = ta5, etc., and the first period Tb = the second period Ta. Therefore, the timing of switching from boom raising to boom lowering and the timing of switching from arm dumping to arm clouding are synchronized, and the timing of switching from boom lowering to boom raising and the timing of switching from arm clouding to arm dumping are synchronized.

[0055] <Angular Behavior of Boom and Arm> Figures 8(a) to 8(d) show graphs and explanatory diagrams conceptually representing the coordinated operation of the boom 21 and arm 22. The graph in Figure 8(a) shows the changes in the rotation angle of the boom 21 and the rotation angle of the arm 22 detected by the angle sensors 131p and 131q, with time t on the horizontal axis. The period T (=T1, T2) of the rotation angles of the boom 21 and arm 22, the maximum amplitude αb of the rotation angle of the boom 21, and the maximum amplitude αa of the rotation angle of the arm 22 are also shown. Furthermore, the posture of the hydraulic excavator at times tA, tB, and tC in the graph is schematically shown in Figures 8(b), 8(c), and 8(d), respectively.

[0056] The coordinated operation of the boom 21 and arm 22 as described above has the following technical significance. Specifically, as shown in Figure 9, when the arm 22 moves during the aforementioned sieving operation, the boom cylinder 24 receives a reaction force, causing the boom 21 to move on its own. At this time, by flowing pressurized oil into the cylinder in the direction in which the boom cylinder 24 receives the reaction force, the reaction force can be released (vibration absorption effect), and the shaking of the vehicle body (upper slewing body 2 and lower traveling body 1) and the cab 7 can be reduced.

[0057] <Control Flow> The process executed by the controller 50 to realize the above method will be explained by the flowchart shown in Figure 10.

[0058] In Figure 10, first in S5, it is determined whether the aforementioned sieving switch 60 is operated to the ON state. As mentioned above, the sieving switch 60 is provided on the operating lever 16, etc. An example of an operating lever 16, etc. (electric lever 16 or operating lever 16') equipped with the sieving switch 60 is shown in Figure 11.

[0059] <Sieving Switch> In Figure 11, in this example, the sieving switch 60 is provided as a roughly circular operating button and is configured as a momentary switch that is ON only while the operator is pressing it and OFF when the operator releases their hand. However, it is not limited to this, and it may also be configured as an alternate switch that alternates between ON and OFF states each time it is pressed. Furthermore, as shown in the figure, if a slide switch 61 is provided on the operating lever 16 or the like, the function of the sieving switch 60 may be assigned to this slide switch 61.

[0060] Furthermore, in the illustrated example, a strength setting dial (or button) 62 is provided on the operating lever 16, etc., allowing the operating intensity during the sieving operation to be set to the desired level from "strong," "medium," "weak," or "silent," as described later. In other words, the strength setting dial 62 is a setting device that allows the operating amplitude and operating frequency during automatic vibration to be changed by manual operation.

[0061] Returning to Figure 10, once S5 is completed, the process moves to S10. In S10, the posture of the hydraulic excavator (especially the front working device 3) is detected based on the detection results of the angle sensors 131p, 131q, and 131r. Then, in S15, it is determined whether the posture detected in S10 is within an appropriate range suitable for sieving work. In other words, when sieving the contents of the bucket 23, there is a certain appropriate range for the posture of the front working device 3. For example, a preferred position is one in which the central axis of the arm 22 is approximately ±10° with respect to the rotation axis direction (in other words, the vertical direction during flat ground work) K (see Figures 12(a), 12(b), and 13). A more preferred range is one in which the height position of the axis N of the pin that serves as the pivot point of the bucket 23, which is provided at the tip of the arm 22, is approximately the same as the height position C of the bottom surface of the cab 7 (see Figure 12(a), from a position in which the arm 22 is parallel to the rotation axis direction K to a position in which the arm 22 is moved up and down until the height of the axis N of the pin, which is the connection point between the arm 22 and the bucket 23, coincides with the bottom surface of the cab 7). Whether the distance to the bucket 23 is longer than the appropriate range shown in Figures 12(a), 12(b), and 13 (i.e., the reach is longer), or whether the distance to the bucket 23 is shorter than the appropriate range (i.e., the reach is longer), the vibration of the arm 22 does not contribute much to the sieving operation, which is undesirable.

[0062] Returning to Figure 10, in S10, it is determined whether the posture is within the appropriate range as described above. If the posture is within the appropriate range, it is determined as Yes and the process moves to S25, which will be described later. If the posture is not within the appropriate range, it is determined as No and the process moves to S20, where a warning (guidance display) is shown on an appropriate display unit (display device; not shown) installed inside the cab 7, instructing the user to correct the posture of the front work device 3 to within the appropriate range. Figure 14 shows an example of such a warning display. In the example shown, the central axis of the arm 22 is outside the range of ±10° with respect to the pivot axis direction K, and the warning message "Arm angle is outside the range. Please change the posture" is displayed. If the requirement is to have the "position where the height direction position of the pin axis position N is approximately the same as the height direction of the bottom surface of the cab 7", the content of "height outside the range" may be added to make the warning message "Arm angle outside the range, height outside the range. Please change the posture". Once S20 is completed in this manner, the process moves to S10, and the same process is repeated. In other words, until it is determined in S15 that the result is within the appropriate range (Yes), the screening process in S30, S40, S50, or S60 described later will not be performed.

[0063] Returning to Figure 10, in S25, the strength setting dial 62 provided on the operating lever 16, etc., determines whether the operating strength "strong" for the aforementioned sieving operation has been selected. If "strong" is selected, the result is "Yes," and in S30, the above sieving operation is performed in "power mode."

[0064] In other words, in this embodiment, four operating modes are pre-configured for the sieving process: "Power Mode," "Normal Mode," "Soft Mode," and "Silent Mode."

[0065] The "Power Mode" is a mode for stronger sieving of the contents in the bucket 23. In this mode, the first period Tb and the second period Ta in the command signals shown in Figures 5(a) and 6(a) are made relatively long and the voltage values ​​of these command signals are made relatively large, thereby increasing the drive signal current values ​​in Figures 5(b), 5(c), 6(b), and 6(c). As a result, the period T shown in Figure 8 becomes longer (in other words, the frequency becomes smaller), and the maximum amplitudes αb and αa of the rotation angles of the boom 21 and arm 22 become larger. The "Soft Mode" is a mode for weaker sieving of the contents in the bucket 23. In this mode, the first period Tb and the second period Ta in the command signals shown in Figures 5(a) and 6(a) are made relatively short and the voltage values ​​of these command signals are made relatively small, thereby decreasing the drive signal current values ​​in Figures 5(b), 5(c), 6(b), and 6(c). As a result, the period T shown in Figure 8 becomes shorter (in other words, the frequency becomes higher), and the maximum amplitudes αb and αa of the rotation angles of the boom 21 and arm 22 become smaller.

[0066] "Normal mode" is an intermediate mode between "power mode" and "soft mode," where the period T shown in Figure 8 is moderate (moderate frequency), and the maximum amplitudes αb and αa of the rotation angles of the boom 21 and arm 22 are also moderate. "Silent mode" is a mode that focuses on quiet operation during sieving. In this mode, the first period Tb and second period Ta in the command signals shown in Figures 5(a) and 6(a) are made relatively long, and the voltage values ​​of these command signals are made relatively small, thereby making the drive signal current values ​​in Figures 5(b), 5(c), 6(b), and 6(c) relatively small. As a result, the period T shown in Figure 8 becomes longer (in other words, the frequency becomes smaller), and the maximum amplitudes αb and αa of the rotation angles of the boom 21 and arm 22 become smaller.

[0067] In S30, the screening operation is initiated using the "power mode" of the control configuration described above.

[0068] In S25, if "Strong" is not selected on the strength setting dial 62, it is determined to be No, and in S35, it is determined whether or not "Medium" is set. If "Medium" is selected, it is determined to be Yes, and in S40, the screening process is started according to the "normal mode" of the control mode described above.

[0069] In S35, if "Medium" is not selected on the strength setting dial 62, it is determined to be No, and in S45, it is determined whether or not "Weak" is set. If "Weak" is selected, it is determined to be Yes, and in S50, the screening process is started using the "soft mode" of the control method described above.

[0070] If "Weak" is not selected on the strength setting dial 62 in S45, the result is determined to be No, and in S55, it is determined whether or not "Silent" is set. If "Silent" is selected, the result is determined to be Yes, and in S60, the screening process is started according to the "Silent Mode" of the control mode described above. If "Silent" is not selected, the result is determined to be No, and the process returns to S25 and the same procedure as above is repeated.

[0071] After steps S30, S40, S50, and S60, the process moves to S65. In S65, it is determined whether the aforementioned sieving switch 60 is in the OFF state or not. If it remains in the ON state, the result is No, and the process returns to S10, repeating the same procedure as above. If it is in the OFF state, the result is Yes, and this flow ends.

[0072] <Effects of the Embodiment> As described above, the hydraulic excavator of this embodiment comprises an upper slewing body 2 and a lower traveling body 1, a front working device 3 provided on the front side of the upper slewing body 2 and the lower traveling body 1, a hydraulic pump PM1, a boom cylinder 24, an arm cylinder 25, a bucket cylinder 26 for operating the front working device 3 with hydraulic fluid discharged from the hydraulic pump PM1, and a controller 50 that controls the working operation of the front working device 3 by controlling the boom cylinder 24, the arm cylinder 25, and the bucket cylinder 26. The front working device 3 comprises a boom 21 connected to the upper slewing body 2 and the lower traveling body 1 so as to be able to move up and down, an arm 22 connected to the tip of the boom 21 so as to be able to move up and down, and a part connected to the tip of the arm 22 so as to be able to move up and down The apparatus includes a bucket 23 with an opening for discharging contents of a predetermined size or smaller from the contents contained inside to the outside. The hydraulic actuators 24, 25, and 26 include a boom cylinder 24 for lowering and raising the boom 21, and an arm cylinder 25 for dumping and clouding the arm 22. The controller 50 automatically vibrates the boom 21 and the arm 22, and controls the boom cylinder 24 and the arm cylinder 25 to alternately repeat the simultaneous raising of the boom 21 and the dumping of the arm 22, and the simultaneous lowering of the boom 21 and the clouding of the arm 22, at a predetermined cycle, as control (automatic vibration control) for sifting the contents contained inside the bucket 23. In other words, in this embodiment, when sifting the contents of the bucket 23, the controller 50 controls the repeated operation of boom raising / arm dumping → boom lowering / arm clouding → boom raising / arm dumping → boom lowering / arm clouding →... (see Figures 5 to 8). In this way, by performing the operation using a combination of "boom raising + arm dump" and "boom lowering + arm cloud," the inertia (moment) generated when the arm 22 swings can be canceled out by the inertia (moment) generated when the boom 21 swings (see Figure 9). As a result, the inertia (moment) transmitted to the lower traveling body 1 and the upper slewing body 2 can be reduced, thereby reducing the swaying of the cab 7.As a result, even when the boom 21 and arm 22 are vibrated at a relatively large angle, the shaking of the cab 7 can be suppressed, thereby reducing physical fatigue for the operator and improving the efficiency of the sieving work. In addition, the reduction in vibration of the lower traveling body 1 and the upper slewing body 2 has the effect of extending the lifespan of the hydraulic excavator.

[0073] In this embodiment, the hydraulic excavator further includes angle sensors 131p to r for detecting the posture of the front work device 3, and a display device. The controller 50 determines, based on the detection results of the angle sensors 131p to r, whether the posture of the front work device 3 is within the appropriate range for sieving control. If it is not within the appropriate range, the display device provides guidance to bring the posture within the appropriate range. That is, the controller 50 determines whether the posture of the front work device 3 is within the appropriate range (see S15 in Figure 10), and if it is not within the appropriate range, it provides guidance to bring the posture within the appropriate range (see S20 in Figure 10 and Figure 14). This allows the operator to confirm what posture they are in while performing the sieving work, while reliably suppressing the shaking of the cab 7.

[0074] Furthermore, if the sieving operation is performed in an inappropriate posture that deviates from the appropriate range already described, vibrations to the lower traveling body 1 and the upper rotating body 2 will increase, potentially increasing the burden on various parts of the hydraulic excavator and the operator's fatigue. In this embodiment, the hydraulic excavator further includes angle sensors 131p to r for detecting the posture of the front working device 3, and a display device. The controller 50 determines, based on the detection results of the angle sensors 131p to r, whether the posture of the front working device 3 is within the appropriate range suitable for sieving control. If it is not within the appropriate range, the controller does not execute (prohibits) the sieving control. In other words, by preventing sieving operation from being performed in the inappropriate posture (S15: No. in Figure 10), it is possible to reduce the lifespan of the hydraulic excavator and avoid the risk of operator fatigue.

[0075] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are possible without departing from its spirit and technical concept. Such modifications will be described in order below.

[0076] (1) When the buckets are also operated in conjunction with the sieving operation <Repetition of bucket dump and bucket cloud> In this modified example, the behavior when the controller 50 automatically vibrates the buckets 23 when the sieving switch 60 is pressed will be explained with reference to Figures 15(a) to 15(b). Figure 15(a), like Figures 5(a) and 6(a) above, shows the behavior of the voltage signal (bucket dump / cloud command signal) generated by the controller 50 when the sieving switch 60 is operated, with time t on the horizontal axis. As shown in the figure, the bucket dump / cloud command signal switches between the voltage in the bucket dump direction and the voltage in the bucket cloud direction at times tc1, tc2, tc3, tc4, tc5, ... and repeats alternately in a predetermined third period Tc (which is the same as the first period Tb and second period Ta above in this modified example). As can be seen by comparing Figure 15(a) and Figure 5(a), in this example, the voltage values ​​in the bucket dump direction and bucket cloud direction of the bucket dump / cloud command signal are smaller than the voltage values ​​in the boom raise direction and boom lower direction of the boom raise / lower command signal.

[0077] Figures 15(b) and 15(c) show the behavior of the drive currents output from the controller 50 to the solenoid valves 38 and 39 based on the bucket dump / bucket cloud command signals generated as described above, with time t on the horizontal axis. As shown in Figure 15(b), the drive current to the solenoid valve 38 corresponding to the bucket dump operation is output at the timing when a voltage in the bucket dump direction is generated in the bucket dump / cloud command signal shown in Figure 15(a). Similarly, as shown in Figure 15(c), the drive current to the solenoid valve 39 corresponding to the bucket cloud operation is output at the timing when a voltage in the bucket cloud direction is generated in the bucket dump / cloud command signal shown in Figure 15(a). As can be seen by comparing Figures 15(b) and 15(c) with Figures 5(b) and 5(c), in this example, the drive current values ​​to the solenoid valves 38 and 39 related to bucket dump / cloud are smaller than the drive current values ​​to the solenoid valves 37 and 36 related to boom raising and lowering.

[0078] As described above, the output of the drive current to the solenoid valve 38 and the output of the drive current to the solenoid valve 39 alternately repeat in the aforementioned third cycle Tc, and as a result of the pilot pressure to the control valve 35 via the pilot lines 85a and 85b being alternately switched and controlled, the bucket 23 can be automatically vibrated in the third cycle Tc.

[0079] <Features of the modified version> In this modified version, when the controller 50 automatically vibrates the boom 21, arm 22, and bucket 23 as described above, the control valves 34, 33, and 35 are switched on and off so that the boom raising operation, arm dumping operation, and bucket dumping operation are performed simultaneously, and the boom lowering operation, arm clouding operation, and bucket clouding operation are performed simultaneously.

[0080] In other words, in this modified example, the controller 50 performs the control processes shown in Figures 5(a) to (c), Figures 6(a) to (c), and Figures 15(a) to (c) to automatically vibrate the boom 21 in the first period Tb, the arm 22 in the second period Ta, and the bucket 23 in the third period Tc, and sets the time to, for example, tb1=ta1=tc1, tb2=ta2=tc2, tb3=ta3=tc3, tb4=ta4=tc4, tb5=ta5=tc5, and so on. This synchronizes the switching timing from boom raising to boom lowering, from arm dumping to arm clouding, and from bucket dumping to bucket clouding, as well as the switching timing from boom lowering to boom raising, from arm clouding to arm dumping, and from bucket clouding to bucket dumping. As a result, the first period Tb, the second period Ta, and the third period Tc also coincide.

[0081] As a result of the control described above, the behavior of the pilot pressure in the pilot lines 85a and 85b, which are involved in supplying pressurized oil to the rod side and bottom side of the bucket cylinder 26, is schematically shown in Figure 16(a). As shown in the figure, the pilot pressure in the pilot line 85a corresponding to bucket dump and the pilot pressure in the pilot line 85b corresponding to bucket cloud alternate in the third cycle Tc, switching at times tc1, tc2, tc3, tc4, tc5, ... Note that, as can be seen by comparing Figure 16(a) with the aforementioned Figure 7(a), in this example, the magnitude of the pilot pressure in the pilot lines 85a and 85b corresponding to bucket dump and bucket cloud, respectively, is smaller than the pilot pressure in the pilot lines 84b and 84a corresponding to boom raising and boom lowering, respectively, corresponding to the difference in the voltage value of the command signal (in other words, the difference in the drive current value).

[0082] Figure 16(b) is a schematic diagram that conveniently overlays Figures 7(a), 7(b), and 16(a) to facilitate understanding of the coordinated operation of the boom 21, arm 22, and bucket 23 described above. As previously stated, the time intervals are tb1 = ta1 = tc1, tb2 = ta2 = tc2, tb3 = ta3 = tc3, tb4 = ta4 = tc4, tb5 = ta5 = tc5, and the first period Tb = second period Ta = third period Tc. Therefore, the timing of switching from boom raising to boom lowering, the timing of switching from arm dumping to arm clouding, and the timing of switching from bucket dumping to bucket clouding are synchronized, and the timing of switching from boom lowering to boom raising, the timing of switching from arm clouding to arm dumping, and the timing of switching from bucket clouding to bucket dumping are also synchronized.

[0083] <Angular Behavior of Boom, Arm, and Bucket> Figures 17(a) to (d) show graphs and explanatory diagrams conceptually representing the coordinated operation of the boom 21, arm 22, and bucket 23. The graph in Figure 17(a) shows the changes in the rotation angles of the boom 21, arm 22, and bucket 23 detected by the angle sensors 131p, 131q, and 131r, with time t on the horizontal axis. The period T (=T1, T2, T3) of the rotation angles of the boom 21, arm 22, and bucket 23, as well as the maximum amplitude αb of the rotation angle of the boom 21, the maximum amplitude αa of the rotation angle of the arm 22, and the maximum amplitude αc of the rotation angle of the bucket 23 are also shown. Furthermore, the posture of the hydraulic excavator at times tD, tE, and tF in the graph is schematically shown in Figures 17(b), 17(c), and 17(d), respectively.

[0084] <Effects of Modified Version> In this modified version, the hydraulic excavator further includes a bucket cylinder 26 that causes the bucket 23 to perform dumping and clouding operations, and the controller 50 controls the boom cylinder 24, arm cylinder 25, and bucket cylinder 26 to automatically vibrate the boom 21, arm 22, and bucket 23, by simultaneously performing the raising of the boom 21, the dumping of the arm 22, and the dumping of the bucket 23, and the lowering of the boom 21, the clouding of the arm 22, and the clouding of the bucket 23, alternately and repeatedly at a predetermined period. In other words, during the execution of automatic vibration, the bucket cylinder 26 is controlled to cause the bucket 23 to perform dumping operations simultaneously with the raising of the boom 21 and the dumping of the arm 22, and the bucket 23 to perform clouding operations simultaneously with the lowering of the boom 21 and the clouding of the arm 22. In other words, as described above, when sieving the contents of bucket 23, the controller 50 controls the repeated operation of boom raising, arm dumping, bucket dumping → boom lowering, arm cloud, bucket cloud → boom raising, arm dumping, bucket dumping → boom lowering, arm cloud, bucket cloud →... In this way, the operation is performed in combinations of "boom raising + arm dumping + bucket dumping" and "boom lowering + arm cloud + bucket cloud" (bucket 23 also performs a complex operation), which allows bucket 23 to move more widely and further improves the efficiency of the sieving operation.

[0085] (2) When correcting operational deviations by adjusting the pilot waveform phase, in the above embodiment, as described above, the repeated operation of boom raising / arm dumping → boom lowering / arm clouding →... is performed. In order to perform this repeated operation smoothly, as shown in Figures 7(a) and 7(b) above, it is preferable to match as much as possible the first period Tb, which is the switching period for boom raising / boom lowering, and the second period Ta, which is the switching period for arm dumping / arm clouding, and to make the switching timings of each pilot pressure, the above times tb1, tb2, tb3, tb4, tb5,... and the above times ta1, ta2, ta3, ta4, ta5,... the same.

[0086] However, if the above sieving operation is performed continuously or over many years, even if the solenoid valves 37, 36, 38, and 39 are controlled from the controller 50 using the aforementioned method so that the first period Tb = second period Ta and tb1 = ta1, tb2 = ta2, tb3 = ta3, tb4 = ta4, and tb5 = ta5 (see Figure 18(a) corresponding to Figure 7(c) above), in reality, as shown in Figure 18(b) corresponding to Figure 8 above, the timing of the boom 21's operation switching (the timing of switching between boom raising and boom lowering) or the timing of the arm 22's operation switching (the timing of switching between arm dump and arm cloud) may be shifted due to factors such as the individual characteristics of each work machine, the number of years of use, or the oil temperature during operation. In the example shown in Figure 18(b), the transition times between boom raising and boom lowering (times tb1, tb2, tb3, tb4, tb5...) are slightly delayed compared to the transition times between arm dumping and arm clouding (times ta1, ta2, ta3, ta4, ta5...).

[0087] In this modified example, the controller 50 detects the above-mentioned deviation based on the rotation angles of the boom 21 and arm 22 detected by, for example, the angle sensors 131p, 131q, 131r, etc., and adjusts the waveform phase of the pilot pressure according to the detection result. Specifically, the hydraulic excavator has control valves 33, 34, and 35 that control the supply of pressurized oil from the hydraulic pump PM1 to the boom cylinder 24 and arm cylinder 25, and the controller 50 synchronizes the switching timing between the raising and lowering of the boom 21 and the switching timing between the dumping and clouding of the arm 22 by adjusting the waveform phase of the operation signals to the control valves 33 and 34. In other words, in this example, to address the aforementioned discrepancy, as shown in Figure 19(a), the timing of the output of drive current from the controller 50 to the solenoid valves 37 and 36 is set earlier than the timing of the output of drive current from the controller 50 to the solenoid valves 38 and 39, so that the switching timings between boom raising and boom lowering (times tb1, tb2, tb3, tb4, tb5...) are slightly earlier than the switching timings between arm dump and arm cloud (times ta1, ta2, ta3, ta4, ta5...). This corrects the discrepancy and synchronizes the switching timing between boom raising and boom lowering with the switching timing between arm dump and arm cloud, as shown in Figure 19(b).

[0088] (3) When adjusting the pilot waveform amplitude, as described above, when repeated operations of boom raising / arm dumping → boom lowering / arm clouding →... are performed, it is preferable to maintain the position of the vibration center of the operation amplitude during automatic vibration in the boom 21, or the arm 22, or the virtual integrated unit of boom 21 and arm 22, as much as possible in order to perform the repeated operations smoothly.

[0089] However, if the above screening process is performed continuously or over many years, the position of the vibration center may gradually shift. The example shown in Figure 20(a) illustrates the case where the center of vibration of arm 22 gradually shifts towards the cloud direction when the boom raising / arm dumping → boom lowering / arm clouding → ... operation is repeated.

[0090] In this modified example, the hydraulic excavator has control valves 34 and 33 that control the supply of pressurized oil from the hydraulic pump PM1 to the boom cylinder 24 and arm cylinder 25. The controller 50 maintains the vibration center position of the operating amplitude during automatic vibration of the bucket 23 by adjusting the waveform amplitude of the operation signals to the control valves 34 and 33. Specifically, the controller 50 detects the deviation of the vibration center position based on the rotation angles of the boom 21 and arm 22 detected by, for example, the angle sensors 131p, 131q, 131r, etc., and adjusts the waveform amplitude of the pilot pressure according to the detection result. Specifically, the deviation is corrected by reducing the amplitude of the biased part (or increasing the amplitude of the unbiased part) of the boom 21, arm 22, or the virtual integrated part of the boom 21 and arm 22. In the example shown in Figure 20(b), corresponding to the misalignment in Figure 20(a), the drive current value from the controller 50 to the solenoid valve 31 is made larger than the drive current value from the controller 50 to the solenoid valve 32 so that the pilot pressure in the pilot pipeline 83a on the arm dump side is larger. This corrects the aforementioned misalignment and allows the sieving operation to be performed while the vibration center position of the operating amplitude during automatic vibration is maintained at a predetermined position. This vibration center position may be configured to be adjustable within the range of postures shown in Figure 12, for example. For example, the function of adjusting the vibration center position may be assigned to the slide switch 61. Alternatively, for example, the central axis of the arm 22 may be set to a posture along the pivot axis direction (vertical direction during flat ground work) K (see Figure 12) as the initial position of the vibration center, and the vibration center position (the angle to the ground that becomes the vibration center of the arm) may be finely adjusted by operating the slide switch 61. For example, the operator operates the slide switch 61 before the start of the vibration operation (sieving operation) or during the operation after the start. The controller 50, in response to the operation of the slide switch 61, controls and adjusts the vibration operation so that the vibration operation is performed with the position adjusted according to the operation as the vibration center, either from the start of vibration if vibration control (vibration operation) has not yet begun, or from the next control cycle if vibration operation is already underway.This allows the sieving operation to be performed with a high degree of freedom, by selecting an appropriate posture depending on the surrounding conditions and the state of the excavated material contained in the bucket body 208.

[0091] (4) Other than the above, the controller 50 installed in the hydraulic excavator performed the operations described using Figure 10 to operate in combinations of "boom raising + arm dump" and "boom lowering + arm cloud," but it is not limited to these. That is, a control module capable of performing the operations in Figure 10 may be added to a standard controller (vehicle control controller) that is normally installed in a hydraulic excavator and does not have the above functions, thereby achieving the effect of suppressing the shaking of the cab 7 in the hydraulic excavator. In this case, the control module (vibration control device) is configured to be attachable to a hydraulic excavator that includes a boom 21, an arm 22, a bucket 23, a boom cylinder 24 driven by a hydraulic pump PM1 to raise and lower the boom 21, and an arm cylinder 25 driven by the hydraulic pump PM1 to dump and cloud the arm 22. The vibration control device for the hydraulic excavator controls the boom cylinder 24 and the arm cylinder 25 to automatically vibrate the boom 21 and the arm 22, and controls the boom cylinder 24 and the arm cylinder 25 so that simultaneous raising of the boom 21 and dumping of the arm 22, and simultaneous lowering of the boom 21 and clouding of the arm 22 are repeated alternately at a predetermined cycle. In other words, the control module (vibration control device) is configured to switch control the control valves 34 and 33 and output command signals to automatically vibrate the boom 21 and arm 22, and has the function of outputting command signals to simultaneously perform the raising operation of the boom 21 and the dumping operation of the arm 22, and the lowering operation of the boom 21 and the clouding operation of the arm 22.

[0092] Furthermore, the arrows on the signal lines shown in Figures 3, 4, and other figures above represent only one example of signal flow and do not limit the direction of signal flow.

[0093] Furthermore, the flowchart shown in Figure 10 does not limit the present invention to the procedures shown in the flowchart above, and procedures may be added, deleted, or their order changed within the scope that does not depart from the spirit and technical idea of ​​the invention.

[0094] In addition to what has already been described above, the methods described in the above embodiments and their respective modifications may be used in appropriate combinations.

[0095] Furthermore, although not to be exemplified individually, the present invention may be implemented with various modifications without departing from its spirit.

[0096] 1 Lower running body (vehicle) 2 Upper slewing body (vehicle) 3 Front working device 4 Tracks 7 Cab (driver's cabin) 16 Electric lever 16' Operating lever 21 Boom 22 Arm 23 Bucket 24 Boom cylinder (hydraulic actuator) 25 Arm cylinder (hydraulic actuator) 26 Bucket cylinder (hydraulic actuator) 31, 32 Solenoid valve (solenoid proportional valve for arm, solenoid proportional valve) 36, 37 Solenoid valve (solenoid proportional valve for boom, solenoid proportional valve) 38, 39 Solenoid valve (solenoid proportional valve for bucket, solenoid proportional valve) 33 Control valve (control valve for arm) 34 Control valve (control valve for boom) 35 Control valve (control valve for bucket) 50 Controller 60 Screening switch 62 Strength setting dial (setting device) 83a, 83b Pilot lines 84a, 84b Pilot lines 85a, 85b Pilot lines 113 Travel motor (hydraulic actuator) 131p, q Angle sensors (attitude detection devices) 131r Angle sensor (attitude detection devices) 202 Bottom plate 202B Opening 203L Left side plate 203R Right side plate EG Engine N Axle center position PM1 Hydraulic pump Ta 2nd cycle Tb 1st cycle Tc 3rd cycle

Claims

1. A work machine comprising: a vehicle body; a front work device provided on the front side of the vehicle body; a hydraulic pump; a plurality of hydraulic actuators for operating the front work device with hydraulic fluid discharged from the hydraulic pump; and a controller that controls the plurality of hydraulic actuators to control the work operation of the front work device and to cause the front work device to vibrate automatically, wherein the front work device includes: a boom connected to the vehicle body so as to be able to move up and down; an arm connected to the tip of the boom so as to be able to move up and down; and a bucket connected to the tip of the arm so as to be able to move up and down, wherein the plurality of hydraulic actuators include: a boom cylinder for lowering and raising the boom; and an arm cylinder for dumping and clouding the arm, wherein the controller controls the boom cylinder and the arm cylinder so as to control the automatic vibration, that simultaneous operation of raising the boom and dumping the arm, and simultaneous operation of lowering the boom and clouding the arm are repeated alternately at a predetermined period.

2. A work machine according to claim 1, comprising a control valve for controlling the supply of pressurized oil from the hydraulic pump to the boom cylinder and the arm cylinder, wherein the controller synchronizes the switching timing between the raising and lowering of the boom and the switching timing between the dumping and clouding of the arm by adjusting the waveform phase of the operation signal to the control valve.

3. A work machine according to claim 1, comprising a control valve for controlling the supply of pressurized oil from the hydraulic pump to the boom cylinder and the arm cylinder, wherein the controller maintains the vibration center position of the operating amplitude during automatic vibration by adjusting the waveform amplitude of the operation signal to the control valve.

4. A work machine according to claim 1, wherein the plurality of hydraulic actuators further include bucket cylinders for performing dumping and clouding operations on the bucket, and the controller controls the bucket cylinders such that, during the execution of the automatic vibration, the bucket dumping operation is performed simultaneously with the raising operation of the boom and the dumping operation of the arm, and the bucket clouding operation is performed simultaneously with the lowering operation of the boom and the clouding operation of the arm.

5. A work machine according to claim 1, further comprising: a posture detection device for detecting the posture of the front work device; and a display device, wherein the controller determines, based on the detection result of the posture detection device, whether the posture of the front work device is within an appropriate range suitable for controlling the automatic vibration; and if it is not within the appropriate range, the display device provides guidance to bring the posture within the appropriate range.

6. A work machine according to claim 1, further comprising: a posture detection device for detecting the posture of the front work device; and a display device, wherein the controller determines, based on the detection result of the posture detection device, whether the posture of the front work device is within an appropriate range suitable for controlling the automatic vibration, and if it is not within the appropriate range, prohibits the control of the automatic vibration.

7. A work machine according to claim 5 or claim 6, wherein the vehicle body comprises a lower traveling body and an upper rotating body provided on the upper part of the lower traveling body, the upper rotating body comprises a cab on which an operator sits, and the appropriate range is a range from a position in which the arm is parallel to the rotation axis of the upper rotating body to a position in which the arm is moved up and down so that the height of the connection position between the arm and the bucket coincides with the bottom surface of the cab.

8. The work machine according to claim 1, wherein the bucket has a bottom plate that is curved to have a substantially U-shaped cross-section and side plates provided on the left and right sides of the bottom plate, and an opening is formed in at least one of the bottom plate and the side plates.

9. A work machine according to claim 1, characterized in that it is equipped with a setting device for changing the operating amplitude and operating frequency during automatic vibration by manual operation.

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