Work machine

Abstract

A controller of a work machine (100) comprises: a sieving mode selection unit that selects a sieving mode for causing a cylinder device (109) to repeatedly perform a repetitive operation so that a bucket (106) performs a sieving operation; an amplitude determination unit that determines the amplitude in the sieving mode to be either a first amplitude, which is relatively large, or a second amplitude, which is relatively small, on the basis of at least one of the position of the bucket (106) and the angle thereof immediately before the sieving operation is started; and a sieving operation execution unit that makes the bucket (106) perform the sieving operation at the determined first or second amplitude while the sieving mode is selected.

Description

Work machinery

[0001] The present invention relates to controlling repetitive motions of work machines.

[0002] Work machines are known to perform repetitive operations, such as reciprocating motions, in which a forward and backward movement is repeated multiple times. For example, a sieve-shaped bucket, also known as a skeleton bucket, is attached to the end of the arm of the work machine, and an operator operates the work machine to repeatedly move the bucket multiple times to sift through soil, concrete debris, and the like. Specifically, the operator repeatedly pushes and pulls the operating lever in small increments, thereby swinging the bucket filled with soil and sand of various particle sizes in a certain amplitude, slightly in the excavation direction and slightly in the dumping direction, thereby sieving the soil and sand. Alternatively, the operator swings the arm supporting the bucket in a certain amplitude in a pushing direction or a pulling direction to sift through the soil and sand.

[0003] As a technique for reducing the operational burden on the pilot and automating and streamlining the screening work, for example, the control disclosed in Japanese Patent Laid-Open Publication No. 6-093630 (Patent Document 1) has been known.

[0004] In the technology described in Patent Document 1, instead of manual lever operation by an operator, a hydraulic controller that supplies hydraulic pressure to a bucket cylinder device is automatically controlled to rotate the bucket in the excavation direction and in the reverse direction in the soil removal direction, thereby executing repeated operations with a predetermined swing amplitude. Specifically, for two types of pilot pressure paths that operate the control valves of the cylinder device, a cycle that specifies the pressure oil supply time (push signal time) to the pilot pressure path on the rod retraction side of the cylinder device and the pressure oil supply time (pull signal time) to the pilot pressure path on the rod extension side of the cylinder device is repeatedly executed many times. This frees the operator from lever operation that repeatedly reciprocates the bucket lever with a predetermined amplitude.

[0005] Japanese Patent Application Publication No. 6-093630

[0006] However, the inventors have found that the above-described conventional automatic control still requires further improvement. Specifically, when the bucket is fully loaded with soil and sand at the beginning of the sieving operation, if the bucket is positioned close to the work machine body, such as the cabin, there is a risk that rocks will fall from the bucket during the sieving operation and fly into the cabin. Furthermore, if the bucket is positioned far from the work machine body, even if rocks fall from the bucket, they are unlikely to fly into the cabin, but the bucket swing amplitude may be excessively small, reducing the efficiency of the sieving operation.

[0007] In view of the above-mentioned circumstances, an object of the present invention is to improve safety and efficiency in the automatic control of screening work in a work machine.

[0008] The work machine provided by the present invention comprises a work machine main body, an arm having a base end connected to the work machine main body and a swingable tip, a sieving bucket connected to the tip of the arm, an arm actuator that alternately swings the arm from one side to 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, and the controller has a sieving mode selection unit that selects a sieving mode in which the arm actuator or the bucket actuator is repeatedly operated to cause the sieving bucket to perform a sieving operation, a swing width determination unit that determines the swing width for the sieving mode from at least a relatively large first swing width and 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 is started, and a sieving operation execution unit that causes the arm or sieving bucket to perform a sieving operation with the determined swing width while the sieving mode is selected.

[0009] FIG. 1 is a schematic overall view showing a work machine according to one embodiment of the present invention, and is a diagram showing a first swing width in the sieving mode. FIG. 2 is a schematic overall view showing a work machine according to one embodiment of the present invention, and is a diagram showing a second swing width in the sieving mode. FIG. 3 is a schematic overall view showing a work machine according to one embodiment of the present invention, and is a diagram showing a first swing width and a second swing width in the sieving mode. FIG. 4A is a schematic view showing a configuration including a cylinder device and a controller according to one embodiment of the present invention. FIG. 4B is a schematic view showing components related to the sieving mode in the controller of the work machine according to one embodiment of the present invention. FIG. 5 is a flowchart executed in the sieving mode according to one embodiment of the present invention. FIG. 6A is a graph showing the relationship between bucket toe distance and swing width. FIG. 6B is a graph showing the relationship between bucket ground angle and swing width. FIG. 6C is a graph showing the relationship between bucket toe distance and swing speed. FIG. 6D is a graph showing the relationship between bucket ground angle and swing speed. FIG. 7A is a map referenced to determine the switching cycle. FIG. 7B is a map referenced to determine the switching cycle. FIG. 7C is a map referenced to determine the switching cycle. FIG. 7D is a map referenced to determine the switching cycle. FIG. 8A is a time chart showing a switching cycle executed in a sieving mode according to one embodiment of the present invention, the time chart representing a first swing width. FIG. 8B is a time chart showing a switching cycle executed in a sieving mode according to one embodiment of the present invention, the time chart representing a second swing width. FIG. 9 is a schematic diagram showing components related to the sieving mode in a controller according to another embodiment of the present invention. FIG. 10 is a flowchart executed in the sieving mode according to another embodiment of the present invention. FIG. 11 is a time chart executed in the sieving mode according to another embodiment of the present invention. FIG. 12 is a schematic diagram showing a stroke range of a cylinder device according to another embodiment of the present invention.

[0010] An embodiment of the present invention will now be described in detail with reference to the drawings. Figures 1, 2, and 3 are schematic overall views showing a work machine according to an embodiment of the present invention. This work machine 100 is, for example, a construction machine, specifically, a hydraulic excavator that excavates ground, etc. The work machine 100 comprises a lower running body 101, an upper rotating body 102 which is a rotating body mounted on the lower running body 101 so as to be rotatable around a rotation axis X, a boom 104, an arm 105, and a screening bucket (hereinafter simply referred to as a bucket 106) which constitute a work device provided on the upper rotating body 102, a boom cylinder (hereinafter also referred to as a cylinder device 107), an arm cylinder (hereinafter also referred to as a cylinder device 108), and a bucket cylinder (hereinafter also referred to as a cylinder device 109) which serve as hydraulic actuators for operating these components, a rotation motor 110 which is a hydraulic motor that drives the upper rotating body 102 around the rotation axis X relative to the lower running body 101, and a cabin 111 provided on the upper rotating body 102.

[0011] The boom 104 has a base end connected to the upper rotating body 102 via a connecting shaft 103 so as to be rotatable in the hoisting direction, and a tip end on the opposite side. The arm 105 has a base end connected to the tip end 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 in a push / pull direction, approaching or receding from the upper rotating body 102.

[0012] The sieving bucket 106 is rotatably attached to the tip of the arm 105, and can press the claws 106c at the tip of the bucket 106 against the topsoil to scoop up the topsoil or to discharge the soil inside the bucket 106. The bucket 106 is connected to the tip of the arm 105 so that the opening of the bucket 106 faces upward, that is, so that when the bucket 106 is filled with soil, it is positioned below the boom 104 or arm 105, in a so-called cradle position. Therefore, when the bucket 106 filled with soil is rotated toward the soil discharge side, the claws 106c lower and the opening of the bucket 106 tilts toward the cabin 111.

[0013] The boom cylinder (cylinder device 107) is interposed between the boom 104 and the upper rotating body 102 so that it extends when hydraulic oil is supplied from the hydraulic circuit described below, or contracts when hydraulic oil is discharged into the hydraulic circuit, and raises and lowers the boom 104 in conjunction with this extension and contraction movement.

[0014] Similarly, an arm cylinder (cylinder device 108) is interposed between the boom 104 and the arm 105 so as to swing the arm 105 in the push / pull direction by its extension / retraction motion, and a bucket cylinder (cylinder device 109) is interposed between the arm 105 and the bucket 106 so as to rotate the bucket 106 by its extension / retraction motion.

[0015] An IMU (Inertial Measurement Unit) sensor that detects the attitude angle of the attached member with respect to the horizontal plane is attached to each of the boom 104, arm 105, and bucket 106. Alternatively, a potentiometer (angle meter) that detects the relative angle between the two rotatably connected members is attached to the rotating part that connects the boom 104 or bucket 106 to each other.

[0016] In the case of an IMU sensor, the controller 31 calculates the stroke position and stroke amount (stroke amount of the piston inside the cylinder, same below) of the cylinder devices 107 to 109 from information about the screening work device (assembly from the boom 104 to the bucket 106, same below), such as the rotation axis position of each component of the screening work device and the dimensions of each component, the connection relationship of each component of the screening work device, the mounting position dimensions of the cylinder devices 107 to 109 attached to each component of the screening work device, the installation position of the IMU sensor relative to each component of the screening work device, and the attitude angle information of each component of the screening work device output from the IMU sensor, and based on the calculated stroke amount, detects the position of the bucket 106 and claws 106c and calculates the swing width V of the screening operation described below.

[0017] 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 about the sieving work device, such as the rotation axis position of each component of the sieving work device and the dimensions of each component, the connection relationship 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, and based on the calculated stroke amount, detects the position of the bucket 106 and claws 106c and calculates the swing width V of the sieving operation described below.

[0018] The operator in the cabin 111 operates a plurality of control levers, such as the control lever 113, to operate the boom 104, the arm 105, and the bucket 106, and scoops up soil and concrete debris (debris) from the ground with the skeleton-structured bucket 106.

[0019] Next, the operator uses the automatic sieving bucket control in this embodiment to shake the sieving bucket 106 filled with soil and sand multiple times to sift out small particle size soil and sand from the sieve holes of the sieving bucket 106. As a result, small particle size soil and sand pile up directly below the sieving bucket 106, and large pebbles and the like remain in the sieving bucket 106. Note that with the automatic sieving bucket control, the operator does not need to operate the operating lever 113 multiple times to shake the sieving bucket 106 multiple times.

[0020] Next, the operator operates multiple control levers to operate the boom 104, arm 105, and skeleton bucket 106, piled up large gravel and other debris in a predetermined location. This sieving operation is repeated thereafter. The device configuration from the arm 105 to the sieving bucket 106 is also referred to as the sieving device, and the lower traveling body 101 and upper rotating body 102 side are also referred to as the work machine body.

[0021] 4A is a diagram showing a hydraulic circuit mounted on a work machine 100 of this embodiment. The work machine 100 includes, as its hydraulic circuit, a hydraulic pump 20 that discharges hydraulic oil, an engine 21 as the drive source of the hydraulic pump 20, a tilting proportional valve 22 that controls the discharge rate of the hydraulic pump 20, a control valve 23 to which hydraulic oil is supplied from the hydraulic pump 20, a cooler 24 that cools the oil returning from the control valve 23, and a hydraulic oil tank 25 that stores the return oil and supplies hydraulic oil to the hydraulic pump 20. The control valve 23 is a device that includes a plurality of directional control valves, proportional valves, throttle valves, and on-off valves. These directional control valves, proportional valves, throttle valves, and on-off valves are solenoid valves that are electrically opened and closed, and are connected to the cylinder devices 107-109, the swing motor 110, and other hydraulic equipment (not shown), respectively. For example, the direction switching valve 23 r is connected to the cylinder device 107 , the direction switching valve 23 s is connected to the cylinder device 108 , and the direction switching valve 23 t is connected to the cylinder device 107 .

[0022] 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 a screening mode operator 112 provided in the cabin 111, an operation lever 113, and an operation lever not shown, and controls each valve in the control valve 23 in accordance with these signals. This causes the control valve 23 to supply or discharge hydraulic oil to or stop the supply or discharge of hydraulic oil to or from the cylinder devices 107 to 109 and other hydraulic equipment not shown.

[0023] To avoid repetition, of the cylinder devices 107 to 109, the cylinder device 108 that pushes and pulls the arm 105 will be described as a representative example. The cylinder device 108 has a cylinder body 108b, a piston 108c, and a rod 108d. The hydraulic oil chamber in the cylinder body 108b is divided by the piston 108c into a hydraulic oil chamber 108f on the rod 108d side and a hydraulic oil chamber 108g on the opposite side. The hydraulic oil 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 is therefore also referred to as a control valve for supplying hydraulic oil to the cylinder device 108.

[0024] The direction switching valve 23s is, for example, a three-position direction switching valve. Specifically, by changing the position of a spool housed therein, the direction switching valve 23s is configured to be switchable between a first position in which the cylinder device 108 can be driven in the extension direction, a second position in which the cylinder device 108 can be driven in the retraction direction, and a neutral position in which the supply and discharge of hydraulic oil to the cylinder device 108 is stopped. Note that the direction switching valve 23s may be configured to adjust the supply flow rate (inflow flow rate) of hydraulic oil 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 position or the second position, or may function as a control valve that can adjust the inflow flow rate of hydraulic oil supplied to the cylinder device 108. Note that the control valve is not limited to the above-described three-position switchable direction switching valve and may include, for example, a throttle valve provided separately from the three-position direction switching valve. The same applies to the other direction switching valves 23r and 23t. The three-position switching cycle (extension-side signal time, compression-side signal time, neutral time) executed in the screening mode will be described in detail later.

[0025] By switching the directional control valve 23s in this manner, the controller 31 performs the following operations: supplying pressurized oil to the hydraulic oil chamber 108g while discharging it from the hydraulic oil chamber 108f to extend the rod 108d; supplying pressurized oil to the hydraulic oil chamber 108f while discharging it from the hydraulic oil chamber 108g to retract the rod 108d; and blocking the oil passages connecting each of the hydraulic oil chambers 108f, 108g to stop the operation of the rod 108d, i.e., maintaining the stroke position of the rod 108d.

[0026] The screening 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 on the operation screen. The screening mode operator 112 outputs a signal (a screening mode selection signal) to the controller 31 for selecting or deselecting a screening mode (described later) when the controller 31 executes automatic screening operation without the operator having to push or pull the operation lever 113 each time.

[0027] The operating lever 113 is in a neutral position when not operated by the operator, but can be operated in multiple directions when the operator applies force to it, and when tilted to one side or the other, it sends a signal to the controller 31 to move the arm 105 in a pushing or pulling direction.

[0028] The controller 31 receives a signal output from the operation lever 113 and controls the directional control valve 23s in the control valve 23 based on the signal. As a result, the corresponding cylinder device 108 expands or contracts in accordance with the operation input to the operation lever 113, and the arm 105 swings in the push / pull direction so as to move away from or towards the cabin 111.

[0029] 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 push / pull direction in response to tilting of the control lever 113 operated by the operator. Such control of swinging the arm 105 based on the control lever 113 is also called manual mode.

[0030] In contrast, while the controller 31 receives a sieving mode selection signal output from the sieving mode operator 112 (automatic control based on the sieving mode), even if the operator does not operate the operating 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 and sand in the bucket 106.

[0031] In this embodiment, the controller 31 controls the directional control valve 23s of the control valve 23 in response to the pilot repeatedly pushing and pulling the operation lever 113, and normally operates in a manual mode in which the arm 105 is repeatedly swung, but while the screening mode is selected, even if the operation lever 113 remains in the neutral position, the controller 31 controls the directional control valve 23s of the control valve 23 to repeatedly swung the arm 105 on the condition that a hydraulic lock lever (not shown) is released. Note that the condition of the hydraulic lock lever is not essential.

[0032] 4B is a schematic diagram showing the components within the controller 31. The controller 31 has a sieving mode selection unit 32, a swing width determination unit 33, and a sieving operation execution unit 34 as components that execute the sieving mode.

[0033] 5 is a flowchart showing control related to the sieving mode. First, in step S10, the controller 31 determines whether the sieving mode has been selected (ON) (whether the sieving mode operator 112 is outputting a sieving mode selection signal) (the subsequent processes may be performed by components such as the sieving mode selection unit 32, the amplitude width determination unit 33, and the sieving operation execution unit 34). If the sieving mode has not been selected (No), the controller 31 exits this flowchart (End). Conversely, if the sieving mode has been selected by the sieving mode selection unit 32 (Yes), the controller 31 proceeds to the next step S20.

[0034] In step S20, the controller 31 calculates the toe position (bucket toe distance) of the claws 106c of the bucket 106 at the start of the screening mode, and then proceeds to the next step S30. In step S30, the controller 31 calculates the angle φb (bucket ground angle) of the bucket 106, and then proceeds to the next step S40. The toe position and angle φb are calculated based on the output from the IMU sensor. The toe position (bucket toe distance) is represented by the distance Db in the fore-and-aft direction from the upper rotating body 102 (cabin 111) to the toe of the claw 106c, as shown in FIGS. 1, 2, and 3.

[0035] In step S40, the controller 31 determines whether it is appropriate to determine the swing width V ( FIG. 1 ) of the bucket 106 rotation based on the state of the bucket 106, such as the toe position, angle φb, toe height, and amount of soil and sand in the bucket 106. If it is appropriate (Yes), the controller 31 proceeds to the next step S50. If it is not appropriate (No), the controller 31 proceeds to the end and terminates this flowchart. Specifically, for example, if the distance Db is extremely small, for example, if Db is less than a preset threshold D3, the controller 31 determines that rocks in the bucket 106 may fly toward the cabin 111 and terminates the screening mode (proceeds to the end). Alternatively, if the angle φb is significantly different from horizontal (e.g., outside a predetermined threshold), screening is inappropriate, and the controller 31 terminates the screening mode (proceeds to the end). The threshold D3 is set as the distance when the bucket 106 and the cabin 111 are extremely close to each other, for example, 1.0 m. In addition, if it is not appropriate to determine the amplitude in step S40 (No), it is preferable to provide a display device or speaker in the cabin 111 to notify the user that the screening is inappropriate. As a variant, step S40 may be omitted, and the process may proceed from step S30 to step S50.

[0036] In step S50, in order to sort the buckets 106 by automatic control, the switching cycle of the directional control valve 23t that extends and retracts the cylinder device 109 is determined, and the process proceeds to the next step S60.

[0037] To facilitate understanding of the switching cycle determined in step S50, the swing width determined in the sieving mode according to the automatic control of this embodiment will be briefly described below. Determining the switching cycle in step S50 can be interpreted as determining whether the swing width V of the bucket 106 about the connecting shaft 115 in step S50 is to be the relatively large first swing width V1, the relatively small second swing width V2 (FIG. 2), or another swing width.

[0038] FIG. 6A is a graph showing the relationship between the toe position (bucket toe distance) and the swing amplitude V. FIG. 6B is a graph showing the relationship between the angle φb (bucket ground angle) and the swing amplitude V. Based on the information about the toe position (position of the claw 106c) acquired as described above, the distance Db from the claw 106c of the bucket 106 to the cabin 111 is calculated. Although the distance Db is a planar distance, as a modified example, the difference in altitude between the claw 106c and the cabin 111 may also be taken into consideration. For example, if the claw 106c is greater than a predetermined threshold (i.e., sufficiently high), there is a high risk that rocks will spill from the bucket 106 during repetitive motion and fly into the cabin 111. Therefore, a correction may be performed to shorten the distance Db. Note that as a modified example not shown, the distance Db may be the distance from the claw 106c to the connecting shaft 103.

[0039] 6A, when the distance Db is less than the threshold value D2, i.e., when the distance Db is sufficiently small, the swing width V is determined to be the relatively small second swing width V2. When the distance Db is equal to or greater than the threshold value D1, i.e., 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). When the distance Db is equal to or greater than the threshold value D2 but less than the threshold value D1, the swing width V is determined to be a swing width V3 (not shown in FIG. 6A) between the first and second swing widths (V2<V3<V1). As can be seen from FIG. 6, this swing width V3 may be proportional to the distance Db.

[0040] As shown in FIG. 3 , the angle φb in this embodiment is an indicator of whether the opening of the bucket 106 is tilted relative to the horizontal plane so that it opens toward the cabin 111. If the bucket 106 is tilted toward the upper rotating structure 102, i.e., so that the opening of the bucket 106 is easily visible from the cabin 111, the angle φb is a negative angle. If the opening of the bucket 106 is horizontal, the angle φb is 0 degrees. If the bucket 106 is tilted away from the upper rotating structure 102, i.e., in a direction that hides the opening of the bucket 106 as viewed from the cabin 111, the angle φb is a positive angle. If the opening of the bucket 106 is horizontal or approximately horizontal (angle φb = 0), rocks in the bucket 106 are unlikely to spill out even when the bucket 106 is swung. Referring to FIG. 6B , if the angle φb is equal to or less than the threshold value φ2, i.e., if the angle φb is sufficiently tilted, the swing width V is determined to be a relatively small second swing width V2. Furthermore, when the distance Db is equal to or greater than the threshold value φ1, i.e., when the angle φb is substantially horizontal or a positive value, the swing width V is determined to be the relatively large first swing width V1. This is because the bucket 106 is holding soil and sand, making it less likely to spill. Furthermore, when the angle φb is equal to or greater than the threshold value φ2 but less than the threshold value φ1, the swing width V is determined to be V3 (not shown in FIG. 6B ), which is between the first and second swing widths (V2<V3<V1). As illustrated in FIG. 6B , the swing width V3 is proportional to the angle φb in the negative range, or in other words, may be inversely proportional to the absolute value of the angle φb. Based on this premise, the controller 31 determines the first swing width switching cycle and the second swing width switching cycle in step S50.

[0041] 7A, 7B, 7C, and 7D illustrate examples of maps referenced in step S50 to determine the first swing width switching cycle and the second swing width switching cycle. As shown in FIG. 7A, if the distance Db is less than the threshold value D2, the extension side signal (time) tp of the second swing width V2 is selected. If the distance Db is equal to or greater than the threshold value D1, the extension side signal (time) tb of the first swing width V1 is selected (tp<tb). If the distance Db is equal to or greater than the threshold value D2 but less than D1, the intermediate value between tp and tb (corresponding to the swing width V3) is selected. As can be seen from FIG. 7A, the intermediate value may increase in proportion to the distance Db. The selection of the compression side signal (time) td and tr shown in FIG. 7B is similar to the selection of the extension side signal described above (tr<td). The filtering operation based on the extension side signal time and the compression side signal time will be described later with reference to FIG. 8.

[0042] Continuing the explanation of the switching cycle calculated in step S50 with reference to FIG. 7C, if the distance Db is less than the threshold value D2, the neutral time tq for the second swing width V2 is selected. If the distance Db is equal to or greater than the threshold value D1, the neutral time tc for the first swing width V1 is selected (tc<tq). If the distance Db is equal to or greater than the threshold value D2 but less than D1, the intermediate value of tq and tc (corresponding to the swing width V3) is selected. Note that, as can be seen from FIG. 7C, the intermediate value may decrease in inverse proportion to the distance Db. The selection of the neutral times te and ts shown in FIG. 7D is similar to the selection of the neutral time described above (te<ts). The filtering operation based on the neutral time will be described later with reference to FIG. 8.

[0043] In step S60, in order to execute the switching cycle of step S50, the controller 31 outputs a cycle command for expanding and contracting the cylinder device to the control valve 23, and then this flowchart ends.

[0044] 8A and 8B are diagrams showing the cylinder extension / retraction cycle command output from the controller 31 to the control valve 23, with FIG. 8A corresponding to the first deflection width V1 and FIG. 8B corresponding to the second deflection width V2. In both FIGS. 8A and 8B, the horizontal axis represents time, the upper vertical axis represents the extension side signal (time) of the cylinder device, and the lower vertical axis represents the retraction side signal (time) of the cylinder device. The time when switching from extension to retraction and the time when transitioning from retraction to the next cycle are respectively referred to as neutral times. The extension side signal, the next neutral time, the next retraction side signal, and the next neutral time constitute one cycle of repetitive operation. Each neutral time is also referred to as a time without signal input.

[0045] The extension-side signal tb of the first swing width V1 in Fig. 8A is longer in duration than the extension-side signal tp of the second swing width V2 in Fig. 8B, and similarly, the contraction-side signal td of the first swing width V1 is longer in duration than the contraction-side signal tr of the second swing width V2. Also, the neutral time tc of the first swing width V1 is shorter in duration than the neutral time tq of the second swing width V2, and the neutral time te of the first swing width V1 is shorter in duration than the neutral time ts of the second swing width V2.

[0046] That is, in the first swing width V1, the extension-side signal tb and the compression-side signal td are relatively long, resulting in a large swing width V. Also, in the first swing width V1, the neutral times tc and te are relatively short, resulting in a short idling time and a high swing speed.

[0047] As described above, Figure 8B is a diagram showing the switching cycle when rotating the bucket 106 with the second swing width V2. The horizontal axis represents time, the upper vertical axis represents the extension-side signal tp of the cylinder device, and the lower vertical axis represents the retraction-side signal tr of the cylinder device. The neutral time tq is the time when switching from extension to retraction, and the neutral time ts is the time when transitioning from retraction to the next cycle. With the second swing width V2, the extension-side signal tp and the retraction-side signal tr are relatively short, so the swing width V is small. Furthermore, with the second swing width V2, the neutral times tq and ts are relatively long, so idling is long and the swing speed is slow.

[0048] The work machine 100 according to this embodiment comprises an upper rotating body 102 which is the main body of the work machine 100, an arm 105 whose base end is connected to a boom 104 on the upper rotating body 102 side and whose tip is swingable, a screening bucket 106 connected to the tip of the arm 105, a cylinder device 108 which serves as an arm actuator that alternately swings the arm 105 from one side to the other, a cylinder device 109 which serves as a bucket actuator that rotates the screening bucket 106 relative to the arm 105, a controller 31 which controls these cylinder devices, and an IMU sensor which detects the position of the screening bucket 106. The controller 31 has a sieving mode selection unit 32 that selects a sieving mode in which the cylinder device 109 is repeatedly operated to cause the sieving bucket 106 to perform a sieving operation, a swing width determination unit 33 that determines the swing width V from at least the first swing width V1 and the second swing width V2 based on the position of the sieving bucket 106 immediately before the sieving mode is selected and the sieving operation is started, and a sieving operation execution unit 34 that causes the bucket 106 to perform a sieving operation with the swing width determined by the swing width determination unit 33 while the sieving mode is selected. According to this embodiment, as shown in FIG. 6A, when the position of the bucket 106 is close to the cabin 111 (distance Db < D2), the swing width V of the sieving bucket 106 is automatically reduced (second swing width V2) to prevent rocks from flying 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 sieving bucket 106 is automatically increased (first swing width V1), thereby improving work efficiency.

[0049] 6 , the swing width determination unit 33 of this embodiment may determine the swing width V to be 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 angle φb of the sieving bucket 106 immediately before the sieving mode is selected and the sieving operation is started. This allows the swing width V to be optimally and automatically controlled depending on the state of the sieving bucket 106 immediately before the sieving operation is started. In this case, the swing width may be determined depending on the position (distance Db) and angle φb of the sieving bucket 106, whichever is more stringent (lower-level selection). This lower-level selection may also be applied when the first swing width V1 or the second swing width V2 is selected.

[0050] Next, a modified example of the above-described embodiment will be described. The basic configuration of the modified example is the same as that of the above-described embodiment, so a description thereof will be omitted. The main difference will be described below. In the modified example of the sieving mode, the swing speed M of the sieving bucket 106 is changed. Fig. 6C is a graph showing the relationship between the bucket toe distance and the swing speed, etc. Fig. 6D is a graph showing the relationship between the bucket toe ground angle and the swing speed, etc.

[0051] 6C , when the distance Db is less than the threshold value D2, i.e., when the distance Db is sufficiently small, the shake velocity M is determined to be a relatively small second shake velocity M2. On the other hand, when the distance Db is equal to or greater than the threshold value D1, i.e., when the distance Db is sufficiently large, the shake velocity M is determined to be a relatively large first shake velocity M1. On the other hand, when the distance Db is equal to or greater than the threshold value D2 but less than the threshold value D1, the shake velocity M is determined to be a shake velocity M3 (not shown in FIG. 6C ) between the first and second shake velocities (M2<M3<M1). As can be seen from FIG. 6C , the shake velocity M3 may be proportional to the distance Db.

[0052] 6D, when the angle φb is less than the threshold value φ2, i.e., when the angle φb is significantly tilted, the shake velocity M is determined to be the relatively small second shake velocity M2. When the distance Db is equal to or greater than the threshold value φ1, i.e., when the angle φb is substantially horizontal or a positive value, the shake velocity M is determined to be the relatively large first shake velocity M1. When the angle φb is equal to or greater than the threshold value φ2 but less than the threshold value φ1, the shake velocity M is determined to be the shake velocity M3 between the first and second shake velocities (M2<M3<M1). As can be seen from FIG. 6D, the shake width V3 is proportional to the angle φb in the negative range, in other words, it may be inversely proportional to the absolute value of the angle φb. Based on this premise, the switching cycle of the shake velocity M is determined in step S50. With reference to FIG. 8B, the longer the neutral time, the slower the shake velocity M. With reference to FIG. 8A, the shorter the neutral time, the faster the shake velocity M.

[0053] According to this modified example, when the position of the bucket 106 is close to the cabin 111 (distance Db < D2), the swing speed M of the sieving bucket 106 is automatically slowed down (second swing speed M2) to prevent rocks from flying from the bucket 106 into the cabin 111, and when the bucket 106 is far from the cabin 111 (D1 < distance Db), the swing speed M of the sieving bucket 106 is automatically increased (first swing speed M1), thereby improving work efficiency.

[0054] Although an embodiment of the present invention has been described above with reference to the drawings, the present invention is not limited to the illustrated embodiment. Various modifications and variations can be made to the illustrated embodiment within the same scope as the present invention or within an equivalent scope.

[0055] As a further modification, the sifting operation executing unit 34 may increase the swing width V beyond the second swing width V2 or increase the swing speed M when the amount of soil in the bucket 106 decreases after performing the sifting operation with the bucket 106 at the second swing width V2 a predetermined number of times. Alternatively, as a further modification, the sifting operation executing unit 34 may increase the swing width V beyond the second swing width V2 or increase the swing speed M when the amount of soil in the bucket 106 decreases after performing the sifting operation with the second swing width V2 for a predetermined time. In this way, according to this further modification, work efficiency can be improved when the amount of soil in the bucket 106 decreases and there is no longer a risk of rocks spilling out.

[0056] As a further modification, in the sieving mode, the controller 31 may cause the arm 105 to perform a sieving operation with a swing width W. When the distance Db is less than the threshold value D2, i.e., the distance Db is sufficiently small, the swing width W is determined to be a relatively small second swing width W2. When the distance Db is equal to or greater than the threshold value D1, i.e., the distance Db is sufficiently large, the swing width W is determined to be a relatively large first swing width W1. When the distance Db is equal to or greater than the threshold value D2 but 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 logic for determining the swing width W may be the same as the logic for determining the swing width V shown in FIG. 6.

[0057] Next, another embodiment of the present invention will be described in detail with reference to the drawings. The basic configuration of the work machine 100 shown in Figures 1 and 4A is the same in this embodiment.

[0058] In this embodiment, when the detection unit is an IMU sensor for detecting the attitude angles of the boom 104, arm 105, and bucket 106 relative to the horizontal plane, the controller 31 calculates the stroke range and stroke position of the screening operation described below based on the calculated stroke amount.

[0059] On the other hand, if the detection unit is a potentiometer, the controller 31 calculates the stroke range and stroke position of the sieving operation (described later) based on the calculated stroke amount. Prior to a detailed description of the sieving mode in this embodiment, the stroke range in sieving will be described with reference to the schematic diagram of the stroke range of the cylinder device shown in FIG. 12. Referring to FIG. 12, the cylinder device 108 has a stroke limit position in the extension direction and a stroke limit position in the retraction direction defined for the cylinder device 108. Referring to FIG. 1, the stroke limit position in the extension direction corresponds to the limit position in the pulling direction of the arm 105. Conversely, the stroke limit position in the retraction direction corresponds to the limit position in the pushing direction of the arm 105.

[0060] In FIG. 12, the sieving stroke range Ss used in sieving the bucket 106 is approximately the central region Sc of the entire range from the stroke limit position in the extension direction to the stroke limit position in the retraction direction.

[0061] In this embodiment, the cylinder device 108 is typically configured to repeatedly stroke the cylinder device 108 in the central region Sc while the controller 31 automatically controls the control valve 23 in the screening mode. However, for some reason, such as repeated reciprocating strokes over a long period of time, the screening stroke range Ss may be biased toward the contraction stroke limit position. Possible reasons for this include, for example, differences in the cross-sectional areas of the hydraulic oil chambers 108f and 108g, which can cause differences in the oil discharge flow rate and oil supply flow rate, or the accumulation of slight errors in the push signal time and pull signal time. In this case, the screening stroke range Ss is biased toward the pull side of the arm 105, preventing proper screening.

[0062] Therefore, in the cylinder device 108 of this embodiment, if the screening stroke range Ss deviates toward one of the stroke limit positions during automatic control of the control valve 23 in the screening mode, the controller 31 corrects the push signal time (or pull signal time). This correction can be started by being triggered by the operator operating the control lever 113 by a predetermined threshold value M1 or more, as shown in the time chart of Figure 11, which will be described later, without having to wait until the stroke range Ss actually deviates toward the stroke limit position.

[0063] Alternatively, as a modified example, which is not shown in the time chart, during automatic control of the sieving mode by the controller 31, the IMU sensor may monitor the cylinder device 108 and detect that the sieving stroke range Ss is actually biased toward the stroke limit position of the cylinder device 108, and the controller 31, upon receiving this detection result, may automatically correct the push signal time (or pull signal time).

[0064] 9 is a schematic diagram showing the components within the controller 31. The controller 31 has a screening mode selection unit 32, a standard cycle determination unit 36, a screening operation execution unit 34, and a cycle correction unit 37 as components that execute the screening mode.

[0065] FIG. 10 is a flowchart showing control related to the sieving mode. FIG. 11 is a time chart of signals transmitted from the controller 31 to the control valve 23 in the sieving mode. The flowchart in FIG. 10 is executed by the controller 31 at intervals of 100 msec to 10 sec. First, in step S10, the controller 31 determines whether the sieving mode has been selected (ON) (whether the sieving mode operator 112 is outputting a sieving mode selection signal). If the sieving mode has not been selected (No), the controller 31 exits this flowchart (End). Conversely, if the sieving mode has been selected by the sieving mode selection unit 32 (Yes), the controller 31 proceeds to the next step S20.

[0066] In step S20, the sieving mode flag is set in the controller 31 (sieving mode selection unit 32), and the controller 31 repeatedly swings the arm 105 in the push and pull directions even if the operating lever 113 remains in the neutral position. Now, referring to FIG. 11 , the output signal of the controller 31 in the sieving mode will be described. When the sieving mode flag changes from OFF to ON, and while the sieving mode flag is ON, an arm push signal and an arm pull signal are repeatedly and alternately transmitted from the sieving operation execution unit 34 to the directional control valve 23s. The arm push signal has a predetermined push time tb, and the arm pull signal has a predetermined pull time td. A predetermined neutral time tc is provided between the arm push signal and the arm pull signal, and a predetermined neutral time te is provided after the arm pull signal. The total time length of this series (tb + tc + td + te) is called one standard cycle, and is determined by the standard cycle determination unit 36. In this standard cycle, the arm 105 moves in the push and pull directions for one cycle. Thereafter, the standard cycle is repeated to perform the standard sieving operation. Each of the predetermined times tb, tc, td, and te is, for example, a predetermined default value. The predetermined times tb, tc, td, and te are determined in advance so that the sieving stroke range Ss is neither too large nor too small, but is within an approximately appropriate range. However, since the sieving stroke range Ss may become inappropriate due to a long-term sieving operation or other reasons, the sieving stroke range Ss is restored to an appropriate range by a correction cycle described below.

[0067] 10, in the next step S30, the controller 31 determines whether the operator has operated the control lever 113 in the pushing direction by more than a predetermined operation amount (threshold value M1). If the operation amount Ms is equal to or less than the threshold value M1, such as when the control lever 113 remains in the neutral position (No), the process returns to step S20, and the arm 105 continues to be repeatedly swung in the pushing and pulling directions. Conversely, if the control lever 113 has been tilted in the pushing direction by more than the threshold value M1 (Yes), the controller 31 proceeds to step S40.

[0068] It should be noted here that there is no particular limitation on the operation time during which the operating lever 113 is operated more than the threshold value M1. As a modified example, a threshold value T1 may be set for the operation time Tm during which the operating lever 113 is operated more than the threshold value M1, and if the operation time Tm is equal to or greater than the threshold value T1, the determination is Yes and the controller 31 proceeds to step S40.

[0069] Additionally, as a variant, instead of operating the operating lever 113, when an operation is input to another operating unit, such as a push button, a touch panel, an on / off switch, etc., the controller 31 may proceed to step S40.

[0070] In the next step S40, the controller 31 determines whether the sieving stroke range Ss satisfies a predetermined condition. Specifically, the predetermined condition is, for example, whether the sieving stroke range Ss is within the stroke distance Su of the stroke limit position of the cylinder device 108 (the limit position on the retraction side of the arm 105) (whether it is clogged). If the condition is satisfied (Yes), the sieving stroke range Ss is away from the limit position of the cylinder device 108, so the process returns to step S20 described above, and the sieving operation is performed in one standard cycle. If the sieving stroke range Ss satisfies the predetermined condition, no impact occurs, such as the cylinder device 108 hitting the limit position, the sieving stroke range Ss is appropriate, and the sieving operation continues to be performed in one standard cycle (step S20). Conversely, if the sieving stroke range Ss does not satisfy the specified conditions (No), the controller 31 proceeds to step S50 because the space from the sieving stroke range Ss to the stroke limit position is clogged or the sieving stroke range Ss has become inappropriately small due to clogging.

[0071] It should be noted here that, as a modified example not shown, step S40 can be omitted, and the controller 31 may proceed from step S30 to step S50.

[0072] In the next step S50, a screening cycle correction flag is set in the controller 31 (cycle correction unit 37), and the cycle correction unit 37 calculates the additional time Δt based on the pushing operation amount Ms in the above-mentioned step S30. Specifically, for example, the cycle correction unit 37 sets the additional time Δt to be longer in proportion to the operation amount Ms.

[0073] In the next step S60, the standard one cycle is corrected by the additional time Δt, and the controller 31 repeatedly swings the arm 105 in the push and pull directions based on this corrected cycle. Now, the output signal of the controller 31 in the sieving mode will be described with reference to Figure 11. The sieving cycle correction flag rises from OFF to ON, and upon the end of the standard one cycle of sieving operation at the time of rise, the sieving operation transitions to the corrected one cycle.

[0074] One correction cycle is a cycle during which the sieving cycle correction flag is ON, and an arm push signal time tb+Δt, which is the standard arm push signal time tb plus an additional time Δt, and an arm pull signal time td are alternately and repeatedly transmitted to the directional control valve 23s. The sum of these series (tb+Δt+tc+td+te) is called one correction cycle. In this one correction cycle, the arm 105 moves in the push and pull direction for one cycle. Thereafter, multiple correction cycles are repeated to perform the corrected sieving operation.

[0075] Returning to FIG. 10 , the controller 31 proceeds from step S60, where the controller 31 executes the corrected screening operation, to step S70. In the next step S70, the controller 31 determines whether the additional operation amount Mt of the operating lever 113 is smaller than a predetermined threshold value M2. If the additional operation amount Mt of the operating lever 113 is smaller than the predetermined threshold value M2 (Yes), the controller 31 returns to step S60, keeps the screening cycle correction flag ON, and continues the corrected screening operation in which the additional time Δt is added to the pushing direction time tb. As a result, as shown in the time chart of FIG. 11 , a reciprocating motion continues in which the pushing signal time is longer than the pulling signal time. As a result, the stroke range Ss of the arm 105 is gradually corrected toward the pushing side.

[0076] When the operator determines that the stroke range Ss of the arm 105 has been sufficiently corrected toward the push side, the operator operates the control lever 113. That is, in step S70 of Fig. 10, the additional operation amount Mt of the control lever 113 becomes equal to or greater than the predetermined threshold value M2 (No), and the controller 31 proceeds to step S80.

[0077] As a modified example, a threshold value T2 may be set for the operation time Tn during which the operation is performed longer than the threshold value M2, and if the operation time Tn is equal to or longer than the threshold value T2, the answer may be Yes and the process may proceed to step S80.

[0078] In the next step S80, the controller 31 resets the sieving cycle correction flag from ON to OFF. The sieving mode flag remains ON. The sieving mode selection unit 32 causes the sieving operation execution unit to start controlling the control valve in the standard cycle as soon as one correction cycle that overlaps with switching the sieving cycle correction flag from ON to OFF is completed. This allows the sieving stroke range to switch to the standard cycle in a natural manner, allowing for a smooth transition from the correction cycle to the standard cycle.

[0079] It should be noted here that, as a modified example (not shown) of the screening cycle correction executed by the flow of steps S30 → S40 → S50 → S60 → S70 → S80, the controller 31 may execute the screening cycle correction only while the operator keeps the lever operation amount Ms greater than M1, and transition to canceling the screening cycle correction (S80) when the operator returns the operation amount Ms of the control lever 113 to 0 (neutral position). It is not essential to transition to step S80 when the additional lever operation amount Mt in step S70 described above is M2≦Ms≦M1.

[0080] Preferably, a display device for the pilot, such as a cluster screen, a monitor screen, or a portable terminal, is provided in the cabin 111. The display device may display information such as that the screening mode is being selected, a lever operation method for correcting the screening stroke, the degree of correction, and the predetermined stroke range exemplified in Fig. 12. By displaying such information, the pilot can confirm whether the operation of the control lever 113 is not a manual operation but an operation related to the automatic screening operation, an operation related to the standard cycle of step S30, or an operation related to the cycle correction of step S70, thereby preventing erroneous operation.

[0081] Furthermore, the display device may constantly display a message that indicates that the lever operation is used for the cycle correction in step S30 when the sieving mode is ON in step S10 until the sieving mode is released from OFF.

[0082] The work machine 100 of this embodiment comprises a screening bucket 106, a cylinder device 108 that vibrates the arm 105 that supports the screening bucket 106 alternately in pushing and pulling directions, a directional control valve 23s that is controlled to supply hydraulic oil to either the pushing side or the pulling side of the cylinder device 108, and a controller 31 that controls the directional control valve 23s. The controller 31 has a screening mode selection unit 32 that selects the screening mode, a standard cycle determination unit 36 ​​that determines a standard cycle of vibration of the bucket 106, which includes a push time during which the directional control valve 23s is connected to one operating side of the cylinder device 108 and a pull time during which the directional control valve 23s is connected to the other operating side of the cylinder device 108 when the screening mode is selected, a screening operation execution unit 34 that controls the directional control valve 23s using the standard cycle determined by the standard cycle determination unit 36, and a cycle correction unit 37 that calculates an additional time Δt to be added to either the one time tb or the other time td after controlling the directional control valve 23s using the standard cycle, corrects the standard cycle according to the additional time Δt, and causes the screening operation execution unit 34 to control the directional control valve 23s using the corrected corrected cycle. According to this embodiment, even if the sieving stroke range Ss becomes biased toward the retraction limit position of the arm 105 for some reason due to the long-term execution of automatic sieving in the sieving mode, such bias can be corrected and the stroke range Ss can be maintained appropriately.

[0083] Furthermore, the cycle correction unit 37 of this embodiment detects an operation input to the operating lever 113, which is the operating unit of the work machine 100, while the directional control valve 23s is being controlled by the standard cycle determined by the standard cycle determination unit 36, and as soon as one standard cycle that overlaps with the time of detection is completed, causes the sieving operation execution unit to begin executing control of the control valve with the corrected cycle. This allows the sieving stroke range to be corrected with a natural operation, enabling a smooth transition from the standard cycle to the corrected cycle.

[0084] Here, the cycle correction unit 37 of this embodiment may calculate the additional time Δt corresponding to the operation amount Ms input to the operation lever 113 of the work machine 100. This makes it possible to correct the stroke range of the screening operation as desired by the operator. In particular, by increasing the pushing operation amount Ms, the operator can shift the screening stroke range toward the arm pushing side. Furthermore, although not shown in the time chart of FIG. 11 , the operator can shift the screening stroke range toward the arm pulling side by inputting a pulling operation amount to the operation lever 113.

[0085] Calculating the additional time Δt in accordance with the operation amount Ms may mean calculating the additional time Δt in proportion to the operation amount Ms, or the cycle correction unit 37 may have a map (not shown) showing the relationship between the operation amount Ms and the additional time Δt, and may calculate the additional time Δt by referring to the map.

[0086] Furthermore, this embodiment further includes a stroke position detection unit, such as an IMU sensor, that detects the stroke position of the cylinder device 108, and the controller 31 stops automatic control of the sieving mode by the sieving operation execution unit 34 when the detected stroke position reaches within a predetermined distance Su of either the stroke limit position on one side or the stroke limit position on the other side of the cylinder device shown in Figure 12, or when the sieving stroke range Ss, which is the difference between the maximum and minimum values ​​of the detected stroke position, falls outside a predetermined cylinder stroke range (central region Sc). This makes it possible to prevent the cylinder device 108 from reaching the stroke limit position during execution of the sieving mode, causing an impact, or the stroke range Ss of the sieving mode from becoming excessively large.

[0087] The work machine 100 of this embodiment is equipped with an arm 105 whose tip is connected to a sieving bucket 106 via a pivot shaft and whose base end is connected to a boom 104 (main body member) of the work machine 100 via a pivot shaft, and a cylinder device 108 provided between the boom 104 and the arm 105 executes a sieving mode in which the arm 105 is repeatedly pushed and pulled, but the sieving mode is not limited to this, and a cylinder device 109 provided between the arm 105 and the sieving bucket 106 may repeatedly swing the sieving bucket 106 in the excavation and soil discharge directions.

[0088] The work machine 100 of the present embodiment can further include a display device that displays that the operation input to the operation lever 113 is not a manual operation while the directional control valve 23s is being controlled by the screening operation execution unit 34. This clearly indicates whether the current operation of the bucket 106 is based on a manual operation by the operator, thereby preventing operator error and operational errors.

[0089] The work machine 100 of this embodiment can further include a display device that displays that the operation input to the operation lever 113 is an operation related to the standard cycle while the sieving operation execution unit 34 is controlling the directional control valve 23s. This allows the operator of the work machine 100 to confirm whether the current operation of the bucket 106 is during a sieving operation according to the standard cycle, preventing operator error and operational errors.

[0090] The cycle correction unit 37 of the present embodiment cancels the execution of control of the directional control valve 23s in a correction cycle in accordance with the amount of operation input to the control lever 113 of the work machine 100 while control of the directional control valve 23s is being executed in that correction cycle, as in step S70 of Fig. 10 (step S80). The work machine 100 can further be equipped with a display device that displays that the operation input to the control lever 113 while control of the directional control valve 23s in that correction cycle is an operation related to that correction cycle. This allows the operator of the work machine 100 to confirm whether the current operation of the sieving bucket is being controlled by the directional control valve 23s in the correction cycle, preventing operator error and operational errors.

[0091] Although other embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited to the illustrated embodiments. Various modifications and variations can be made to the illustrated embodiments within the same scope as the present invention or within an equivalent scope.

[0092] For example, the cycle correction unit 37 may calculate a neutral time tc during which the directional control valve 23s is closed between the one-way time tb and the other-way time td, and add the neutral time tc to the standard cycle to correct the corrected cycle. The same applies to the neutral time te. This allows the sieving operation in the sieving mode to be slowed down. The cycle correction may be performed for at least one of the one-way time and the other-way time. The correction of the other-way time is also performed as described above for the one-way time based on the time chart of FIG. 11.

[0093] The work machine provided by the present invention comprises a work machine body, an arm having a base end connected to the work machine body and a swingable tip, a sieving bucket connected to the tip of the arm, an arm actuator that alternately swings the arm from one side to 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, and the controller has a sieving mode selection unit that selects a sieving mode in which the arm actuator or the bucket actuator is repeatedly operated to cause the sieving bucket to perform a sieving operation, a swing width determination unit that determines the swing width for the sieving mode from at least a relatively large first swing width and 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 is started, and a sieving operation execution unit that causes the arm or sieving bucket to perform a sieving operation with the determined swing width while the sieving mode is selected.

[0094] According to the present invention, when the sieving mode is selected and the sieving operation is automatically controlled, if the bucket is close to the work machine body, the swing amplitude of the sieving bucket is made relatively small to prevent rocks from flying from the sieving bucket to the work machine body, and if the sieving bucket is far from the work machine body, the swing amplitude of the sieving bucket is made relatively large to improve work efficiency.

[0095] The swing width determination unit may determine only one of the first swing width and the second swing width for the sieving operation, or may determine a swing width other than these. In one aspect of the present invention, the swing width determination unit determines a swing width for the sieving mode that is between the first swing width and the second swing width (third 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 is started. According to this aspect, when the bucket position is intermediate, neither close nor far from the work machine body, the swing width of the sieving bucket can be set to an intermediate swing width that is neither small nor large.

[0096] The sieving operation execution unit may change the swing width or the swing speed after performing the sieving operation with the second swing width. In one aspect of the present invention, after repeatedly moving the arm or bucket with the second swing width a predetermined number of times or after performing the sieving operation for a predetermined time, the sieving operation execution unit increases the speed required for the second swing width or performs the sieving operation of the arm or sieving bucket with a swing width larger than the second swing width. According to this aspect, after repeatedly moving the sieving bucket with the second swing width a predetermined number of times (or after performing the sieving operation for a predetermined time), if the amount of sediment in the sieving bucket becomes low, the swing width is increased to be larger than the second swing width or the swing speed is increased. This reduces the amount of sediment in the sieving bucket, eliminating the risk of rocks spilling out of the sieving bucket and improving work efficiency.

[0097] Thus, according to the present invention, while the sieving mode is selected and the sieving operation is automatically controlled, it is possible to appropriately select whether to prevent rocks from falling out of the bucket or to perform the sieving operation efficiently, depending on the position or angle of the bucket.

[0098] A work machine according to the present invention includes a sieving bucket, a cylinder device that alternately vibrates the sieving bucket in one direction or the other, a control valve that supplies hydraulic oil to either one operating side or the other operating side of the cylinder device, and a controller that controls the control valve. The controller has a sieving mode selection unit that selects a sieving mode, a standard cycle determination unit that determines a standard cycle of bucket vibration that includes one time during which the control valve is connected to one operating side of the cylinder device and another time during which the control valve is connected to the other operating side of the cylinder device when the sieving mode is selected, a sieving operation execution unit that controls the control valve using the standard cycle determined by the standard cycle determination unit, and a cycle correction unit that calculates an additional time to be added to either the one time or the other time during control of the control valve using the standard cycle, corrects the standard cycle in accordance with the additional time, and causes the sieving operation execution unit to control the control valve using the corrected corrected cycle.

[0099] This invention eliminates the need for an operator to repeatedly operate the lever manually, enabling sieving operations to be performed under automatic control based on a standard cycle. Furthermore, by adding additional time to one side of the standard cycle, the sieving stroke range is lengthened. Therefore, the sieving stroke range that has become clogged on the other side can be restored to the one side. Furthermore, the other side of the cycle of the sieving stroke range, to which additional time is not added, moves away from the stroke limit position of the cylinder device. Therefore, impacts can be prevented.

[0100] The trigger condition for adding the additional time to the standard cycle is not particularly limited, but may be, for example, to prevent the sieving stroke range from reaching the stroke limit position of the cylinder device. Specifically, for example, a stroke position sensor is provided in the cylinder device to monitor the sieving stroke range. During this monitoring, if the sieving stroke range approaches the stroke limit position of the cylinder device within a predetermined distance, the standard cycle of the sieving stroke is automatically corrected. The timing for starting sieving using the corrected cycle is not particularly limited. In one aspect, the cycle correction unit detects an operation input to the operating unit of the work machine while the control valve is being controlled using the standard cycle determined by the standard cycle determination unit, and causes the sieving operation execution unit to control the control valve using the corrected cycle upon completion of the standard cycle that overlaps with the detection. According to this aspect, the sieving stroke range is corrected using natural movements, enabling a smooth transition from the standard cycle to the corrected cycle.

[0101] The additional time added to one or the other of the standard cycle is not particularly limited, but in one aspect the cycle correction unit calculates the additional time according to the amount of operation input to the operation unit of the work machine. According to this aspect, if the operator of the work machine desires a large correction, the amount of operation can be increased to lengthen the additional time, and the screening stroke range can be corrected in accordance with the operator's desires.

[0102] The standard cycle may include a neutral time between the end of one period and the start of the other period. The control valve is closed during the neutral time. The standard cycle may also include a neutral time between the end of the other period and the start of the one period of the next cycle. In a preferred aspect, the cycle correction unit calculates a neutral time during which the control valve is closed between the one period and the other period, and corrects the cycle by adding the neutral time. According to this aspect, the cycle becomes longer, which slows down the operation of the sieving stroke, thereby avoiding the side effect of an increased sieving stroke range.

[0103] The correction of the standard cycle may be based on whether or not an operator operates the cylinder device, or may be an automatic control without being based on the operator operation. In one aspect, a stroke position detection unit that detects the stroke position of the cylinder device is further provided, and the controller corrects the standard cycle so that the detected stroke position does not reach either one of the one operating side limit position and the other operating side limit position of the cylinder device. According to this aspect, the screening stroke range can be automatically corrected appropriately without waiting for an operator operation.

[0104] In one aspect of the present invention, the work machine further includes a display device that displays, while the screening operation execution unit is controlling the control valve, that the operation input to the operation unit of the work machine is not a manual operation. According to this aspect, whether the current operation of the screening bucket is a manual operation or not is clearly indicated, thereby preventing operator error and incorrect operation.

[0105] In one aspect of the present invention, the work machine further includes a display device that displays, while the sieving operation execution unit is controlling the control valve, that an operation input to the operation unit of the work machine is an operation related to the standard cycle. According to this aspect, the operator can confirm whether the current operation of the sieving bucket is being controlled by the control valve according to the standard cycle, thereby preventing operator error and incorrect operation.

[0106] In one aspect of the present invention, the cycle correction unit is configured to cancel execution of control of the control valve in a correction cycle in accordance with an operation amount input to the operation unit of the work machine while control of the control valve is being executed in that correction cycle, and further includes a display device that displays, while control of the control valve in that correction cycle is being executed, that an operation input to the operation unit of the work machine is an operation related to that correction cycle. According to this aspect, the operator can confirm whether the current operation of the sieving bucket is under control of the control valve by the correction cycle, thereby preventing operator error and operational errors.

[0107] As described above, according to the present invention, the sieving stroke range of the cylinder device can be appropriately corrected during automatic control of the cylinder device in the sieving mode.

[0108] The present invention is advantageously used in work machines, such as construction machines and machines used in other industries.

Claims

1. A working machine comprising: a work machine body; an arm having a base end connected to the work machine body and a swingable tip; a sieving bucket connected to the tip of the arm; an arm actuator for alternately swinging the arm from one side to the other; a bucket actuator for rotating the sieving bucket relative to the arm; a controller for controlling the arm actuator and the bucket actuator; and a bucket position detection unit for detecting at least one of the position and angle of the sieving bucket, wherein the controller comprises: a sieving mode selection unit for selecting a sieving mode in which the arm actuator or the bucket actuator is repeatedly operated to cause the sieving bucket to perform a sieving operation; and a swing width determination unit for determining the swing width in the sieving mode from at least a relatively large first swing width and 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 is started. a sieving operation execution unit that causes the arm or the sieving bucket to perform a sieving operation with the determined swing width while the sieving mode is selected.

2. A work machine as described in claim 1, wherein the swing width determination unit determines a third swing width between the first swing width and the second swing width as the swing width in the sieving mode 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. A work machine as described in claim 1 or 2, wherein the sieving operation execution unit, after performing the sieving operation of the arm or the sieving bucket at the second swing width a predetermined number of times or after performing the sieving operation for a predetermined time, increases the speed required for the second swing width or performs the sieving operation of the arm or the sieving bucket at a swing width larger than the second swing width.

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