Working machinery

Abstract

This prevents rocks from flying from the bucket onto the main body of the work machine during the sieving operation. [Solution] The controller of the work machine 100 includes a sieving mode selection unit that selects a sieving mode in which the cylinder device 109 is repeatedly operated to sieve the bucket 106; a swing width determination unit that determines either a relatively large first swing width or a relatively small second swing width based on at least one of the position and angle of the bucket 106 immediately before the sieving mode is selected and the sieving operation starts; and a sieving operation execution unit that causes the bucket 106 to perform a sieving operation with the determined first or second swing width while the sieving mode is being selected.

Description

Technical Field

[0001] The present invention relates to the control of repetitive operations of a working machine. <严

Background Art

[0002] As an operation performed by a working machine, there is known a repetitive operation that repeatedly performs operations such as reciprocating movements, such as going and returning, many times. For example, a sieve-shaped bucket, also called a skeleton bucket, is attached to the tip of the arm of a working machine, and an operator operates the working machine to repeatedly move the bucket many times to perform a sieving operation such as screening earth and sand or concrete. Specifically, the operator repeatedly pushes and pulls the operation lever in small increments to slightly rotate the bucket filled with earth and sand of various sizes in the excavation direction or slightly rotate it in the soil discharge direction or sway it with a certain amplitude to perform the screening of the earth and sand. Alternatively, the arm supporting the bucket is swayed with a certain amplitude in the pushing or pulling direction to perform the screening of the earth and sand.

[0003] Conventionally, as a technique for reducing the operation burden of such an operator and automating and improving the efficiency of the sieving operation, for example, the control described in Japanese Patent Application Laid-Open No. 6-093630 (Patent Document 1) is known.

[0004] In the technique described in Patent Document 1, instead of the lever operation by the operator's hand, the bucket is rotated in the excavation direction, reversely rotated in the soil discharge direction, or repeatedly operated with a predetermined amplitude by automatically controlling a hydraulic controller that supplies hydraulic pressure to the cylinder device of the bucket. Specifically, regarding two types of pilot pressure paths that operate the control valve of the cylinder device, a cycle that defines the pressure oil supply time (push signal time) of the rod contraction side pilot pressure path and the pressure oil supply time (pull signal time) of the rod extension side pilot pressure path of the cylinder device is repeatedly executed continuously many times. As a result, the operator is released from the lever operation of repeatedly reciprocating the bucket lever with a predetermined width.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Application Publication No. 6-093630 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, the inventors have found that there are areas for further improvement in the conventional automatic control described above. Specifically, in the initial stages of the sieving operation, the bucket is fully loaded with soil, and if the bucket is close to the main body of the work machine, such as the cabin, there is a risk that rocks may spill out of the bucket during the sieving operation and fly into the cabin. On the other hand, if the bucket is far from the main body of the work machine, rocks will not fly into the cabin even if they spill out of the bucket, so it is preferable to increase the swing amplitude of the bucket to improve the efficiency of the sieving operation.

[0007] In view of the above circumstances, the present invention aims to improve safety and efficiency in the automatic control of sieving operations. [Means for solving the problem]

[0008] For this purpose, the work machine according to the present invention comprises a work machine body, an arm whose base end is connected to the work machine body and whose tip is pivotable, a sieving bucket connected to the tip of the arm, an arm actuator that alternately pivots the arm to one side or the other, a bucket actuator that rotates the sieving bucket relative to the arm, a controller that controls the arm actuator and the bucket actuator, and a bucket position detection unit that detects at least one of the position and angle of the sieving bucket. The controller comprises a sieving mode selection unit that selects a sieving mode in which the sieving bucket is sieved by repeatedly operating the arm actuator or the bucket actuator, a swing width determination unit that determines either a relatively large first swing width or a relatively small second swing width based on at least one of the position and angle of the sieving bucket immediately before the sieving mode is selected and the sieving operation starts, and a sieving operation execution unit that sieves the arm or the sieving bucket with the determined swing width while the sieving mode is being selected.

[0009] According to the present invention, when a sieving mode is selected and the sieving operation is automatically controlled, if the bucket is close to the main body of the work machine, the amplitude of the sieving bucket's swing is relatively reduced to prevent rocks from flying from the sieving bucket to the main body of the work machine, and if the sieving bucket is far from the main body of the work machine, the amplitude of the sieving bucket's swing is relatively increased to improve work efficiency.

[0010] The amplitude determination unit may determine only one of the first and second amplitudes of the sieving operation, or it may determine an amplitude other than those two. In one aspect of the present invention, the amplitude determination unit determines an amplitude between the first and second amplitudes based on at least one of the position and angle of the sieving bucket immediately before the sieving mode is selected and the sieving operation starts. According to this aspect, if the bucket is in an intermediate position, neither too close nor too far from the work machine body, the amplitude of the sieving bucket can be set to an intermediate amplitude that is neither too small nor too large.

[0011] The sieving operation unit may change the swing amplitude or swing speed after performing the sieving operation with the second swing amplitude. In one aspect of the present invention, the sieving operation unit may, after repeatedly moving the arm or bucket with the second swing amplitude a predetermined number of times, or after performing the sieving operation for a predetermined time, increase the speed required for the second swing amplitude, or perform the sieving operation of the arm or sieving bucket with a swing amplitude larger than the second swing amplitude. In this aspect, after repeatedly moving the sieving bucket with the second swing amplitude a predetermined number of times (or after performing the sieving operation for a predetermined time), when the amount of soil in the sieving bucket decreases, the swing amplitude can be made larger than the second swing amplitude or the swing speed can be increased. As a result, when the amount of soil in the sieving bucket decreases and there is no longer a risk of rocks spilling out of the sieving bucket, the work efficiency can be improved. [Effects of the Invention]

[0012] Thus, according to the present invention, while selecting a sieving mode and automatically controlling the sieving operation, it is possible to appropriately select whether to prevent rocks from spilling out of the bucket or to perform the sieving operation efficiently, depending on the position or angle of the bucket. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic overall diagram showing a work machine that is one embodiment of the present invention, representing the first amplitude of the sieving mode. [Figure 2] This is a schematic overall diagram showing the working machine of the same embodiment, representing the second amplitude of the sieving mode. [Figure 3] This is a schematic overall diagram showing the working machine of the same embodiment, representing the first and second amplitudes of the sieving mode. [Figure 4A] This is a schematic diagram showing the configuration of the cylinder device and controller of the same embodiment. [Figure 4B] This is a schematic diagram showing the components related to the screening mode in the controller of the same embodiment. [Figure 5] This is a flowchart of the screening mode performed in the same embodiment. [Figure 6]This graph shows the relationship between the bucket tip position and the amplitude of the swing. [Figure 7] These are various maps referenced to determine the switching cycle. [Figure 8] A time chart showing the switching cycle performed in the screening mode of the embodiment, where (a) represents the first amplitude and (b) represents the second amplitude. [Modes for carrying out the invention]

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Figures 1 to 3 are schematic overall diagrams showing a work machine that is one embodiment of the present invention. This work machine 100 is, for example, a construction machine, specifically a hydraulic excavator for excavating the ground, etc. The work machine 100 comprises a lower traveling body 101, an upper slewing body 102 which is a slewing body mounted on the lower traveling body 101 so as to be rotatable around a pivot axis X, a boom 104, an arm 105, and a sieving bucket (hereinafter also simply referred to as bucket 106) which constitute a work device provided on the upper slewing body 102, a boom cylinder (hereinafter also referred to as cylinder device 107), an arm cylinder (hereinafter also referred to as cylinder device 108), and a bucket cylinder (hereinafter also referred to as cylinder device 109) which are hydraulic actuators that operate these parts, a slewing motor 110 which is a hydraulic motor that drives the upper slewing body 102 around the pivot axis X relative to the lower traveling body 101, and a cabin 111 provided on the upper slewing body 102.

[0015] The boom 104 has a base end connected to the upper slewing body 102 via a connecting shaft 103 so as to be rotatable in the luffing direction, and a tip end on the opposite side. The arm 105 has a base end connected to the tip of the boom 104 via a connecting shaft 114 so as to be rotatable, and a tip end on the opposite side, and can swing toward or away from the upper slewing body 102 in the pushing and pulling direction.

[0016] The screening bucket 106 is rotatably attached to the tip of the arm 105, and can scoop up topsoil by pressing the claws 106c at the tip of the bucket 106 against the topsoil, or discharge the earth and sand in the bucket 106. The bucket 106 is connected to the tip of the arm 105 so as to be in a so-called holding posture, that is, so that when the opening of the bucket 106 faces upward, that is, when the bucket 106 is filled with earth and sand, it comes under the boom 104 or the arm 105. For this reason, when the bucket 106 filled with earth and sand rotates toward the earth-discharging side, the claws 106c lower, and the opening of the bucket 106 inclines toward the cab 111 side.

[0017] The boom cylinder (cylinder device 107) is interposed between the boom 104 and the upper swing body 102 so as to extend by being supplied with hydraulic oil from a hydraulic circuit described later, or contract by discharging the hydraulic oil into the hydraulic circuit, and to raise and lower the boom 104 along with such expansion and contraction operations.

[0018] Similarly, the arm cylinder (cylinder device 108) is interposed between the boom 104 and the arm 105 so as to swing the arm 105 in the pushing and pulling direction by its expansion and contraction operation, and the bucket cylinder (cylinder device 109) is interposed between the arm 105 and the bucket 106 so as to rotate the bucket 106 by its expansion and contraction operation.

[0019] An IMU (Inertial Measurement Unit) sensor for detecting the posture angle of the attached member with respect to the horizontal plane is attached to each of the boom 104, the arm 105, and the bucket 106. Alternatively, a potentiometer for detecting the relative angle between two members that are rotatably connected is attached to a rotating part that connects the boom 104 to the bucket 106.

[0020] In the case of an IMU sensor, the controller 31 calculates the stroke position and stroke amount of the cylinder devices 107 to 109 (stroke amount of the piston inside the cylinder, hereinafter the same) from information related to the sieving work device (assembly from boom 104 to bucket 106, hereinafter the same), including the rotation axis position and dimensions of each component of the sieving work device, the connection relationships of each component of the sieving work device, the mounting position dimensions of the cylinder devices 107 to 109 attached to each component of the sieving work device, the installation position of the IMU sensor on each component of the sieving work device, and the attitude angle information of each component of the sieving work device output from the IMU sensor. Based on the calculated stroke amount, the controller 31 detects the positions of the bucket 106 and claws 106c and calculates the amplitude V of the sieving operation, which will be described later.

[0021] In the case of a potentiometer, the controller 31 calculates the stroke position and stroke amount of the cylinder devices 107 to 109 from information related to the sieving work device, such as the rotation axis position and dimensions of each component of the sieving work device, the connection relationships of each component of the sieving work device, the mounting position dimensions of the cylinder devices 107 to 109 attached to each component of the sieving work device, and the relative angle information of each component of the sieving work device output from the potentiometer. Based on the calculated stroke amount, the controller 31 detects the positions of the bucket 106 and the claws 106c and calculates the amplitude V of the sieving operation, which will be described later.

[0022] The operator, seated in cabin 111, operates several control levers, including control lever 113, to move the boom 104, arm 105, and bucket 106, using the skeletal bucket 106 to scoop up soil and concrete debris from the ground.

[0023] Next, the operator uses the automatic sieving bucket control provided in this embodiment to shake the sieving bucket 106, which is filled with soil and other materials, many times to sift out small-particle soil and other materials from the sieve of the sieving bucket 106. As a result, small-particle soil and other materials pile up directly below the sieving bucket 106, while larger gravel and other materials remain inside the sieving bucket 106. With the automatic sieving bucket control, the operator does not need to shake the operating lever 113 many times in order to shake the sieving bucket 106 many times.

[0024] Next, the operator operates multiple control levers to move the boom 104, arm 105, and skeletal bucket 106 to pile up large gravel and other materials in designated locations. This sieving operation is then repeated. The device configuration from arm 105 to sieving bucket 106 is also called the sieving device, and the lower traveling body 101 and upper rotating body 102 are also called the work machine body.

[0025] Figure 4A shows the hydraulic circuit installed in the work machine 100 of this embodiment. The work machine 100 comprises a hydraulic pump 20 that discharges hydraulic fluid, an engine 21 as the driving source for the hydraulic pump 20, a tilt proportional valve 22 that controls the discharge amount of the hydraulic pump 20, a control valve 23 that is supplied with hydraulic fluid from the hydraulic pump 20, a cooler 24 that cools the return oil from the control valve 23, and a hydraulic fluid tank 25 that stores the return oil while supplying hydraulic fluid to the hydraulic pump 20. The control valve 23 is a device that includes multiple directional control valves, proportional valves, throttle valves, and on-off valves. These directional control valves, proportional valves, throttle valves, and on-off valves are electrically operated solenoid valves and are connected to cylinder devices 107-109, a swing motor 110, and other hydraulic equipment not shown. For example, directional control valve 23r is connected to cylinder device 107, directional control valve 23s is connected to cylinder device 108, and directional control valve 23t is connected to cylinder device 107.

[0026] The work machine 100 also includes a controller 31 as a control device for the control valve 23. The controller 31 receives various signals from the sieving mode operator 112, the operating lever 113, and other operating levers (not shown) located in the cabin 111, and controls each valve in the control valve 23 according to these signals. As a result, hydraulic fluid is supplied or discharged from the control valve 23 to the cylinder devices 107-109 and other hydraulic equipment (not shown).

[0027] To avoid repetition in the explanation, the cylinder device 108, which pushes and pulls the arm 105, will be described as representative of the cylinder devices 107 to 109. The cylinder device 108 has a cylinder body 108b, a piston 108c, and a rod 108d. The hydraulic fluid chamber within the cylinder body 108b is divided by the piston 108c into a hydraulic fluid chamber 108f on the rod 108d side and a hydraulic fluid chamber 108g on the opposite side. The hydraulic fluid chambers 108f and 108g are each connected to a directional control valve 23s provided in the control valve 23. The directional control valve 23s is controlled by the controller 31 and can therefore also be called a control valve for supplying hydraulic fluid to the cylinder device 108.

[0028] The directional control valve 23s is, for example, a three-position directional control valve, and is configured to be switchable between a first position that allows the cylinder device 108 to be driven in the extension direction, a second position that allows the cylinder device 108 to be driven in the shortening direction, and a neutral position that stops the supply and discharge of hydraulic fluid to the cylinder device 108, by changing the position of the spool housed inside it. The directional control valve 23s may also be configured to adjust the supply flow rate (inflow flow rate) of hydraulic fluid supplied to the cylinder device 108 by continuously changing the amount of spool movement when moving the spool from the neutral position to the first or second position, and may function as a control valve that can adjust the inflow flow rate of hydraulic fluid supplied to the cylinder device 108. The control valve is not limited to the three-position switchable directional control valve described above, and may include, for example, a throttle valve provided separately from the three-position directional control valve. The same applies to the other directional control valves 23r and 23t. Details of the three-position switching cycle (extension signal time, compression signal time, and neutral time) performed in sieving mode will be described later.

[0029] The switching of the directional control valve 23s causes the controller 31 to perform the following actions: extend the rod 108d by supplying pressurized oil to the hydraulic oil chamber 108g while discharging it from the hydraulic oil chamber 108f; retract the rod 108d by supplying pressurized oil to the hydraulic oil chamber 108f while discharging it from the hydraulic oil chamber 108g; and stop the movement of the rod 108d by blocking the oil passages connected to the hydraulic oil chambers 108f and 108g, respectively, thus maintaining the stroke position of the rod 108d.

[0030] The sieving mode operator 112 may be a lever that can be operated in multiple directions, a switch that can be operated in one direction or the other, a pushable operation button, or a touch panel projected onto the operation screen. The sieving mode operator 112 outputs a signal (sieving mode selection signal) to the controller 31 to select or deselect the sieving mode, as described later, when the controller 31 performs automatic sieving operation without the operator having to push or pull the operation lever 113 each time.

[0031] The control lever 113 is in a neutral position when not operated by the operator, but can be operated in multiple directions when force is applied by the operator. By tilting it to one side or the other, it sends a signal to the controller 31 to move the arm 105 in the pushing or pulling direction.

[0032] The controller 31 receives a signal output from the operating lever 113 and controls the directional control valve 23s in the control valve 23 based on the signal. This causes the corresponding cylinder device 108 to extend and retract according to the operation input to the operating lever 113, and the arm 105 to swing in the pushing and pulling direction so as to move away from or closer to the cabin 111.

[0033] While the controller 31 does not receive a screening mode selection signal output from the screening mode operator 112, the controller 31 swings the arm 105 in the pushing and pulling direction in response to the tilting of the operating lever 113 operated by the operator. This type of control, which swings the arm 105 based on the operating lever 113, is also called manual mode.

[0034] In contrast, while the controller 31 receives the sieving mode selection signal output from the sieving mode operator 112 (automatic control based on the sieving mode), even without the operator operating the control lever 113, the controller 31 controls the directional control valve 23s in the control valve 23 to repeatedly swing the arm 105 in the pushing and pulling directions, thereby sieving the soil in the bucket 106.

[0035] In this embodiment, the controller 31 normally operates in manual mode, where it controls the directional control valve 23s of the control valve 23 to repeatedly swing the arm 105 in response to the operator repeatedly pushing and pulling the operating lever 113. However, while the screening mode is selected, even if the operating lever 113 remains in the neutral position, the controller controls the directional control valve 23s of the control valve 23 to repeatedly swing the arm 105, provided that a hydraulic lock lever (not shown) is released.

[0036] Figure 4B is a schematic diagram showing the components within the controller 31. The controller 31 has a sieving mode selection unit 32, a amplitude determination unit 33, and a sieving operation execution unit 34 as components for executing the sieving mode.

[0037] Figure 5 is a flowchart showing the control related to the screening mode. First, in step S10, it is determined whether the screening mode is selected (ON) (whether the screening mode operator 112 is outputting a screening mode selection signal). If the screening mode is not selected (No), exit this flowchart (end). Conversely, if the screening mode is selected by the screening mode selection unit 32 (Yes), proceed to the next step S20.

[0038] In step S20, the position of the claws 106c of the bucket 106 at the start of the screening mode is calculated, and the process proceeds to the next step S30. In step S30, the angle φb of the bucket 106 is calculated, and the process proceeds to the next step S40. The calculation of the claw position and angle φb is based on the output from the IMU sensor.

[0039] In step S40, it is determined whether it is acceptable to determine the amplitude V (Figure 1) of the rotation of the bucket 106 based on the conditions of the bucket 106, such as the toe position, angle φb, toe height, and the amount of soil in the bucket 106. If it is acceptable (Yes), proceed to the next step S50. If it is not acceptable (No), proceed to the end and terminate this flowchart. Specifically, for example, if the distance Db is extremely small, for example, if Db is less than the threshold D3, the screening mode is terminated (proceed to the end) because there is a risk that rocks in the bucket 106 may fly into the cabin 111. Alternatively, if the angle φb is extremely different from horizontal (e.g., outside a predetermined threshold), the screening mode is terminated (proceed to the end) because the screening is inappropriate. The threshold D3 is the distance from the bucket 106 to the cabin 111 when it is extremely close, for example, 1.0m. Regarding the aforementioned undesirable case (No), it is advisable to install a display device or speaker in the cabin 111 to indicate that the screening process is inappropriate. As a modification, step S40 may be omitted, and the process may proceed from step S30 to step S50.

[0040] In step S50, the switching cycle of the directional control valve 23t, which extends and retracts the cylinder device 109 in order to automatically screen the buckets 106, is determined, and the process proceeds to the next step S60.

[0041] To facilitate understanding of the switching cycle determined in step S50, the amplitude determined by the screening mode related to the automatic control of this embodiment will be briefly explained. In short, determining the switching cycle in step S50 can be interpreted as deciding whether the amplitude V of the bucket 106 around the connecting shaft 115 is set to a relatively large first amplitude V1, a relatively small second amplitude V2 (Figure 2), or another amplitude.

[0042] FIG. 6 is a graph showing the relationship between the toe position and the swing width V, and the relationship between the angle φb and the swing width V. From the toe position (the position of the claw 106c), the distance Db from the claw 106c of the bucket 106 to the cabin 111 is calculated. The distance Db is a planar distance, but as a modification, the height difference between the claw 106c and the cabin 111 may be considered. For example, when the claw 106c is larger than a predetermined threshold value (i.e., sufficiently high), since there is a greater risk that rocks will spill out of the repeatedly operating bucket 106 and fly into the cabin 111, a correction to shorten the distance Db is executed. As a modification not shown, the distance Db may be the distance from the claw 106c to the connecting shaft 103.

[0043] Referring to FIG. 6, when the distance Db is less than the threshold value D2, that is, when the distance Db is sufficiently small, the swing width V is determined to be the relatively small second swing width V2. Also, when the distance Db is greater than or equal to the threshold value D1, that is, when the distance Db is sufficiently large, the swing width V is determined to be the relatively large first swing width V1 (D3 < D2 < D1). Further, when the distance Db is greater than or equal to the threshold value D2 and less than the threshold value D1, the swing width V is determined to be the swing width V3 between the first and second swing widths (V2 < V3 < V1). As illustrated in FIG. 6, the swing width V3 may be proportional to the distance Db.

[0044] The angle φb in this embodiment indicates whether the opening of the bucket 106 is inclined so as to open toward the cabin 111 with respect to the horizontal plane. If it is inclined toward the upper swing body 102, it is a negative angle. If the opening of the bucket 106 is horizontal, it is 0 degrees. If it is inclined so as to move away from the upper swing body 进行翻译 102, it is a positive angle. If the opening of the bucket 106 is horizontal or substantially horizontal (angle φb = 0), the rocks in the bucket 106 are difficult to spill even if the bucket 106 is swayed. Referring to FIG. 6, when the angle φb is less than or equal to the threshold value φ2, that is, when the angle φb is sufficiently inclined, the swing amplitude V is determined to be the relatively small second swing amplitude V2. Also, when the distance Db is greater than or equal to the threshold value φ1, that is, when the angle φb is substantially horizontal or a positive value, the swing amplitude V is determined to be the relatively large first swing amplitude V1. Also, when the angle φb is greater than or equal to the threshold value φ2 and less than the threshold value φ1, the swing amplitude is determined to be the swing amplitude V3 between the first and second swing amplitudes (V2 < V3 < V1). As illustrated in FIG. 6, the swing amplitude V3 may be inversely proportional to the angle φb. Based on such a premise, in step S50, the switching cycle of the first swing amplitude and the switching cycle of the second swing amplitude are determined.

[0045] FIG. 7 illustrates a map referred to for determining the switching cycle of the first swing amplitude and the switching cycle of the second swing amplitude in step S50. If the distance Db is less than the threshold value D2, the extension side signal (time) tp of the second swing amplitude V2 is selected. If the distance Db is greater than or equal to the threshold value D1, the extension side signal (time) tb of the first swing amplitude V1 is selected (tp < tb). If the distance Db is greater than or equal to the threshold value D2 and less than D1, the intermediate value between tp and tb (corresponding to the swing amplitude V3) is selected. The intermediate value may also be larger in proportion to the distance Db. The selection of the contraction side signals (time) td, tr is the same as the selection of the extension side signals described above (tr < td). The sieving operation based on the time of the extension side signal and the time of the contraction side signal will be described later with reference to FIG. 8.

[0046] Continuing the explanation of the switching cycle calculated in step S50, if the distance Db is less than the threshold value D2, the neutral time tq of the second swing width V2 is selected. If the distance Db is greater than or equal to the threshold value D1, the neutral time tc of the first swing width V1 is selected (tc < tq). If the distance Db is greater than or equal to the threshold value D2 and less than D1, the intermediate value between tq and tc (corresponding to the swing width V3) is selected. Note that the intermediate value may be small and inversely proportional to the distance Db. The selection of the neutral times te and ts is the same as the selection of the neutral times described above (te < ts). The sieving operation by the neutral time will be described later with reference to FIG. 8.

[0047] In step S60, the controller 31 outputs a cycle command for the expansion and contraction of the cylinder device to the control valve 23 in order to execute the switching cycle of step S50, and this flowchart ends.

[0048] FIG. 8 is a diagram showing the expansion and contraction cycle command output from the controller 31 to the control valve 23. (a) corresponds to the first swing width V1, and (b) corresponds to the second swing width V2. In both (a) and (b), the horizontal axis represents time, the upper side of the vertical axis represents the extension side signal (of the cylinder device) (over time), the lower side of the vertical axis represents the contraction side signal (of the cylinder device) (over time), the time when switching from extension to contraction is taken as the neutral time, and the time when switching from contraction to the next cycle is taken as the neutral time. The extension side signal, the next neutral time, the next contraction side signal, and the next neutral time constitute one cycle of the repetitive operation. The neutral time is also referred to as the signal input - free time.

[0049] (a) The extension side signal tb of the first swing width V1 is longer than (b) the extension side signal tp of the second swing width V2, and (a) the contraction side signal td of the first swing width V1 is longer than (b) the contraction side signal tr of the swing width V2. Also, (a) the neutral time tc of the first swing width V1 is shorter than (b) the neutral time tq of the second swing width V2, and (a) the neutral time te of the first swing width V1 is shorter than (b) the neutral time ts of the second swing width V2.

[0050] In other words, in the first amplitude V1, the extension signal tb and the compression signal td are relatively long, resulting in a large amplitude V. Also, in the first amplitude V1, the neutral times tc and te are relatively short, resulting in a short idling time and a high oscillation speed.

[0051] Figure 8(b) shows the switching cycle when rotating the bucket 106 at the second amplitude V2. The horizontal axis represents time, the upper part of the vertical axis represents the extension signal tp of the cylinder device, and the lower part of the vertical axis represents the compression signal tq of the cylinder device. The neutral time tr is when switching from extension to compression, and the neutral time ts is when transitioning from compression to the next cycle. At the second amplitude V2, the extension signal tp and the compression signal tr are relatively short, so the amplitude V is small. Also, at the second amplitude V2, the neutral times tq and ts are relatively long, resulting in a longer idling time and a slower swing speed.

[0052] Incidentally, the working machine 100 of the present embodiment includes an upper swing body 102 which is the main body of the working machine 100, an arm 105 whose base end is connected to the upper swing body 102 side and whose tip can swing, a screening bucket 106 connected to the tip of the arm 105, a cylinder device 108 as an arm actuator that swings the arm 105 alternately to one side or the other, a cylinder device 109 as a bucket actuator that rotates the screening bucket 106 with respect to the arm 105, a controller 31 that controls these cylinder devices, and an IMU sensor that detects the position of the screening bucket 106. The controller 31 includes a screening mode selection unit 32 that selects a screening mode in which the cylinder device 109 is repeatedly operated to perform a screening operation on the screening bucket 106, a swing width determination unit 33 that determines either the first swing width V1 or the second swing width V2 based on the position of the screening bucket 106 immediately before the screening mode is selected and the screening operation is started, and a screening operation execution unit 34 that performs a screening operation on the bucket 106 with the swing width determined by the swing width determination unit 33 during the selection of the screening mode. According to such an embodiment, as shown in FIG. 6, when the position of the bucket 106 is close to the cabin 111 (distance Db < D2), the swing width V of the screening bucket 106 is automatically reduced (second swing width V2) so that rocks do not fly from the bucket 106 to the cabin 111, and when the bucket 106 is far from the cabin 111 (D1 < distance Db), the swing width V of the screening bucket 106 is automatically increased (first swing width V1), thereby improving the working efficiency.

[0053] Also referring to FIG. 6, the swing width determination unit 33 of the present embodiment determines a swing width V3 between the first swing width V1 and the second swing width V2 based on at least one of the position (distance Db) and the angle φb of the screening bucket 106 immediately before the screening mode is selected and the screening operation is started. Thereby, the swing width V can be optimally automatically controlled according to the state of the screening bucket 106 immediately before the screening operation is started.

[0054] Next, a modification of the above-described embodiment will be described. Since the basic configuration of the modification is common to the above-described embodiment, the description thereof will be omitted, and the main differences will be described. In the modification of the screening mode, the swing speed M of the screening bucket 106 is changed.

[0055] Referring to FIG. 6, when the distance Db is less than the threshold value D2, that is, when the distance Db is sufficiently small, the swing speed M is determined to be a relatively small second swing speed M2. Also, when the distance Db is greater than or equal to the threshold value D1, that is, when the distance Db is sufficiently large, the swing speed M is determined to be a relatively large first swing speed M1. Further, when the distance Db is greater than or equal to the threshold value D2 and less than the threshold value D1, it is determined to be a swing speed M3 between the first and second swing speeds (M2 < M3 < M1). As illustrated in FIG. 6, the swing speed M3 may be proportional to the distance Db.

[0056] Also referring to FIG. 6, when the angle φb is less than or equal to the threshold value φ2, that is, when the angle φb is sufficiently inclined, the swing speed M is determined to be a relatively small second swing speed M2. Also, when the distance Db is greater than or equal to the threshold value φ1, that is, when the angle φb is substantially horizontal or positive, the swing speed M is determined to be a relatively large first swing speed M1. Further, when the angle φb is greater than or equal to the threshold value φ2 and less than the threshold value φ1, the swing speed M is determined to be a swing speed M3 between the first and second swing speeds (M2 < M3 < M1). As illustrated in FIG. 6, the swing width V3 may be inversely proportional to the angle φb. Based on such a premise, the switching cycle of the swing speed M is determined in step S50. Referring to FIG. 8(b), the longer the neutral time, the slower the swing speed M. Referring to FIG. 8(a), the shorter the neutral time, the faster the swing speed M.

[0057] According to such a modification, when the position of the bucket 106 is close to the cabin 111 (distance Db < D2), the swing speed M of the screening bucket 106 is automatically slowed down (second swing speed M2) so that the rock does not fly from the bucket 106 to the cabin 111. When the bucket 106 is far from the cabin 111 (D1 < distance Db), the swing speed M of the screening bucket 106 can be automatically increased (first swing speed M1) to improve the working efficiency.

[0058] As described above, the embodiments of the present invention have been described with reference to the drawings. However, the present invention is not limited to the illustrated embodiments. Various modifications and variations can be made within the same scope or the equivalent scope as the present invention with respect to the illustrated embodiments.

[0059] As a further modification example, after the screening operation execution unit 34 operates the bucket 106 in a screening operation with the second swing width V2 for a predetermined number of times, when the amount of earth and sand in the bucket 106 decreases, the swing width V is made larger than the second swing width V2 or the swing speed M is increased. Alternatively, as a further modification example, after the screening operation execution unit 34 operates the bucket 106 in a screening operation with the second swing width V2 for a predetermined time, when the amount of earth and sand in the bucket 106 decreases, the swing width V is made larger than the second swing width V2 or the swing speed M is increased. According to a further modification example, when the amount of earth and sand in the bucket 106 decreases and there is no risk of the rocks in the bucket 106 spilling out, the working efficiency can be improved.

[0060] As a further modification example, in the screening mode, the controller 31 may operate the arm 105 in a screening operation with the swing width W. When the distance Db is less than the threshold value D2, that is, when the distance Db is sufficiently small, the swing width W is determined to be a relatively small second swing width W2. Also, when the distance Db is greater than or equal to the threshold value D1, that is, when the distance Db is sufficiently large, the swing width W is determined to be a relatively large first swing width W1. Also, when the distance Db is greater than or equal to the threshold value D2 and less than the threshold value D1, the swing width W is determined to be a swing width W3 between the first and second swing widths (W2 < W3 < W1). The swing width W3 may be proportional to the distance Db. The determination logic of the swing width W may be the same as the determination logic of the swing width V shown in FIG. 6.

Industrial Applicability

[0061] The present invention is advantageously used in working machines such as construction machines and machines used in other industries.

Explanation of Reference Numerals

[0062] 23 control valve, 23r, 23s, 23t Directional control valve (control valve) 31 Controller, 32 Sieving mode selection unit, 33. Swing amplitude determination unit, 34. Sieving operation execution unit, 100. Working machine, 102 Upper rotating body (main body of the work machine), 105 Arm, 106 Buckets, 107-109 Cylinder devices (actuators).

Claims

1. The system comprises a work machine body, an arm whose base end is connected to the work machine body and whose tip is pivotable, a sieving bucket connected to the tip of the arm, an arm actuator that alternately pivots the arm in one direction or the other, a bucket actuator that rotates the sieving bucket relative to the arm, a controller that controls the arm actuator and the bucket actuator, and a bucket position detection unit that detects at least one of the position and angle of the sieving bucket. The controller includes a sieving mode selection unit that selects a sieving mode in which the sieving bucket is sieved by repeatedly operating the arm actuator or the bucket actuator, A swing amplitude determination unit that determines either a relatively large first swing amplitude or a relatively small second swing amplitude based on at least one of the position and angle of the sieving bucket immediately before the sieving mode is selected and the sieving operation is started, A work machine having a sieving operation execution unit that causes the arm or the sieving bucket to perform a sieving operation with the determined swing amplitude while the sieving mode is selected.

2. The work machine according to claim 1, wherein the swing amplitude determination unit determines the swing amplitude between the first swing amplitude and the second swing amplitude based on at least one of the position and angle of the sieving bucket immediately before the sieving mode is selected and the sieving operation is started.

3. The work machine according to claim 1 or 2, wherein the sieving operation execution unit increases the speed required for the second swing or performs a sieving operation on the arm or the sieving bucket with a swing larger than the second swing after performing a sieving operation on the arm or the sieving bucket a predetermined number of times with the second swing amplitude, or after performing a sieving operation for a predetermined time.

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