Working machinery

Abstract

This prevents the sieving stroke range from becoming inappropriate during automated sieving operation. [Solution] The controller 31 of the work machine includes a standard cycle determination unit 33 that determines a standard cycle of a sieving bucket, which includes one time for connecting the control valve to one operating side of the cylinder device related to sieving and another time for connecting the control valve to the other operating side of the cylinder device, when the sieving mode is selected; a sieving operation execution unit 34 that controls the control valve with the standard cycle determined by the standard cycle determination unit 33; and a cycle correction unit 35 that calculates an additional time to be added to at least one of the one time and the other time during the control of the control valve with the standard cycle, corrects the standard cycle in accordance with the additional time, and causes the sieving operation execution unit 34 to execute control of the control valve with the corrected cycle.

Description

Technical Field

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

Background Art

[0002] As operations performed by a work machine, repetitive operations that repeatedly perform operations such as reciprocating movements, such as going and returning, are known. For example, a sieve-shaped bucket, also called a skeleton bucket, is attached to the tip of the arm of a work machine, and an operator operates the work machine to repeatedly operate the bucket many times to perform a sieving operation for earth and sand, concrete, etc. Specifically, the operator repeatedly presses and pulls the 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 earth discharge direction or swing it with a predetermined width to perform sieving of the earth and sand. Alternatively, the arm supporting the bucket is swung with a predetermined width in the pushing or pulling direction to perform sieving 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 control described in Patent Document 1, instead of repeating the lever operation (so-called manual operation) by the operator's hand, the bucket is rotated in the excavation direction, reversely rotated in the earth discharge direction, or repeatedly operated with a predetermined width 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 oil supply time (push signal time) of the rod contraction side pilot pressure path of the cylinder device and the oil supply time (pull signal time) of the rod extension side pilot pressure path is continuously repeated 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, the sieving stroke range of the bucket cylinder device performed in the sieving operation does not exceed the entire stroke area defined by the minimum position where the rod is most retracted and the maximum position where the rod is most extended (it is smaller than the entire stroke area). Also, the sieving stroke range is inefficient if it is too large or too small, and must be set to an appropriate range. On the other hand, with repeated sieving operations, a gradual shift accumulates in the minimum and maximum positions of the sieving stroke range, causing the sieving stroke range to become biased towards the minimum or maximum rod position, that is, the sieving stroke range to become compressed, resulting in an inappropriately small size, or causing the cylinder device to be subjected to stress such as the impact of sieving at the minimum or maximum rod position.

[0007] In view of the above-mentioned circumstances, the present invention aims to provide a control technology for sieving operations that can maintain an appropriate sieving stroke range even during prolonged sieving work. [Means for solving the problem]

[0008] For this purpose, the work machine according to the present invention comprises a sieving bucket, a cylinder device that alternately vibrates the sieving bucket to one side or the other, a control valve that supplies hydraulic fluid to either the one operating side or the other operating side of the cylinder device, and a controller that controls the control valve. The controller comprises a sieving mode selection unit that selects a sieving mode, a standard cycle determination unit that determines a standard cycle of bucket vibration including a one-way time when the control valve is connected to the one operating side of the cylinder device and a other-way time when 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 with 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-way time or the other-way time during the control of the control valve with the standard cycle, corrects the standard cycle in accordance with the additional time, and causes the sieving operation execution unit to execute control of the control valve with the corrected cycle.

[0009] According to this invention, manual operation by the operator, which involves repeatedly operating a lever by hand, becomes unnecessary, and sieving operation can be performed by automatic control based on a standard cycle. Furthermore, by adding an additional time to one of the standard cycle time, the sieving stroke range is lengthened. Therefore, the sieving stroke range that has become stuck on the other operation side can be restored to the one operation side. In addition, the other operation side of the sieving stroke range cycle, to which the additional time is not added, moves away from the stroke limit position of the cylinder device. Therefore, shock can be prevented.

[0010] The trigger conditions for adding extra time to the standard cycle are not particularly limited, but for example, it is preferable to ensure that the sieving stroke range does not reach the stroke limit position of the cylinder device. Specifically, for example, a stroke position sensor is installed in the cylinder device to monitor the sieving stroke range. If, during this monitoring, the sieving stroke range approaches a predetermined distance from the stroke limit position of the cylinder device, the standard cycle of the sieving stroke is automatically corrected. Furthermore, the timing for starting sieving in 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 by the standard cycle determined by the standard cycle determination unit, and as soon as the overlapping standard cycle is completed at the time of detection, it causes the sieving operation execution unit to execute control of the control valve in the corrected cycle. In this aspect, the sieving stroke range is corrected in a natural manner, and a smooth transition from the standard cycle to the corrected cycle is possible.

[0011] The additional time added to one or the other time in the standard cycle is not particularly limited, but as one aspect, the cycle correction unit calculates the additional time according to the amount of operation input to the operating unit of the work machine. In this aspect, if the operator of the work machine desires a large correction, the amount of operation can be increased and the additional time increased, and the screening stroke range can be corrected according to the operator's wishes.

[0012] The standard cycle may include a neutral period between the end of one time period and the start of the other. During this neutral period, the control valve is closed. It may also include a neutral period between the end of the other time period and the start of the next cycle's one time period. Preferably, the cycle correction unit calculates a neutral period between the one time period and the other time period during which the control valve is closed, and corrects the cycle by adding this neutral period. This approach, by lengthening the cycle, avoids the side effects of slowing down the sieving stroke operation and increasing the sieving stroke range.

[0013] The correction of the standard cycle may be based on the presence or absence of operator input, or it may be an automatic control without operator input. In one scenario, the controller further includes a stroke position detection unit that detects the stroke position of the cylinder device, and the controller corrects the standard cycle so as to prevent the detected stroke position from reaching either the limit position on one operating side or the limit position on the other operating side of the cylinder device. In this scenario, the filtered stroke range can be appropriately corrected automatically without waiting for operator input.

[0014] In one aspect of the present invention, the invention further includes a display device that indicates whether the operation input to the operating unit of the work machine is a manual operation while the control valve is being controlled by the sieving operation execution unit. In this aspect, it is possible to prevent operator error and misoperation because it is clearly indicated whether the current operation of the sieving bucket is a manual operation or not.

[0015] In one aspect of the present invention, the invention further includes a display device that indicates whether the operation input to the operating unit of the work machine is an operation that is part of the standard cycle while the control valve is being controlled by the sieving operation execution unit. In this aspect, the operator can confirm whether the current operation of the sieving bucket is under control of the control valve according to the standard cycle, thereby preventing operator error and erroneous operation.

[0016] In one aspect of the present invention, the cycle correction unit is configured to release the execution of control valve control in a correction cycle according to the amount of operation input to the operating unit of the work machine while control of the control valve is being executed in the correction cycle, and further includes a display device that indicates that the operation input to the operating unit of the work machine while control of the control valve is being executed in the correction cycle is an operation that is involved in the correction cycle. In 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 erroneous operation. [Effects of the Invention]

[0017] According to the present invention as described above, during the automatic control of the cylinder device in the screening mode, the screening stroke range of the cylinder device can be appropriately corrected.

Brief Description of the Drawings

[0018] [Figure 1] FIG. 1 is a schematic overall view showing a working machine according to an embodiment of the present invention. [Figure 2A] FIG. 2 is a schematic diagram showing a configuration including a cylinder device and a controller according to the same embodiment. [Figure 2B] FIG. 3 is a schematic diagram showing components related to the screening mode in the controller according to the same embodiment. [Figure 3] FIG. 4 is a flowchart executed in the screening mode according to the same embodiment. [Figure 4] FIG. 5 is a time chart executed in the screening mode according to the same embodiment. [Figure 5] FIG. 6 is a schematic diagram showing the stroke range of the cylinder device according to the same embodiment.

Embodiments of the Invention

[0019] Hereinafter, embodiments of the present invention will be described in detail based on the drawings. FIG. 1 is a schematic view showing a working machine according to an embodiment of the present invention. This working machine 100 is, for example, a construction machine, specifically, for example, a hydraulic excavator that excavates the ground or the like. The working machine 100 includes a lower traveling body 101, an upper revolving body 102 that is mounted on the lower traveling body 101 so as to be rotatable about a revolving axis X, a boom 104, an arm 105, and a screening bucket (hereinafter also simply referred to as bucket 106) that constitute a working device provided on the upper revolving body 102, boom cylinders (hereinafter also referred to as cylinder device 107), arm cylinders (hereinafter also referred to as cylinder device 108), bucket cylinders (hereinafter also referred to as cylinder device 109) as hydraulic actuators for operating these components, a swing motor 110 that drives the upper revolving body 102 about the revolving axis X with respect to the lower traveling body 101, and a cabin 111 provided on the upper revolving body 102.

[0020] The boom 104 has a base end portion connected to the upper swing body 102 so as to be rotatable in the undulating direction, and a tip end portion on the opposite side thereof. The arm 105 has a base end portion rotatably connected to the tip end portion of the boom 104, and a tip end portion on the opposite side thereof, and can swing in the approaching or separating or pushing and pulling direction as viewed from the upper swing body 102.

[0021] The screening bucket 106 is rotatably mounted on the tip end portion of the arm 105 and can scoop up or discharge topsoil. The boom cylinder (cylinder device 107) is extended by supplying hydraulic oil from a hydraulic circuit described later, or is contracted by discharging the hydraulic oil to the hydraulic circuit, and is interposed between the boom 104 and the upper swing body 102 so as to undulate the boom 104 along with such expansion and contraction operation.

[0022] 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.

[0023] An IMU (Inertial Measurement Unit) sensor for detecting the attitude 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 rotatably connected is attached to a rotating portion that connects the boom 104 to the bucket 106.

[0024] In the case of an IMU sensor, the controller 31 calculates the stroke amount of the cylinder devices 107 to 109 (stroke amount of the piston inside the cylinder, hereinafter the same) from information relating 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 calculates the stroke range and stroke position of the sieving operation described later.

[0025] In the case of a potentiometer, the controller 31 calculates the stroke amount of 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 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 calculates the stroke range and stroke position of the sieving operation, which will be described later.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] Figure 2A 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 receives 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.

[0030] 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).

[0031] 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.

[0032] 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.

[0033] The switching of the directional control valve 23s causes the controller 31 to perform the following actions: extend the rod 108d by supplying oil to the hydraulic oil chamber 108g while draining oil from the hydraulic oil chamber 108f; retract the rod 108d by supplying oil to the hydraulic oil chamber 108f while draining oil 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] In this embodiment, the controller 31 normally operates in manual mode, where it controls the directional control valve 23s of the control valve 23 and repeatedly swings the arm 105 in response to the operator repeatedly pushing and pulling the operating lever 113. However, while the screening mode is selected, it controls the directional control valve 23s of the control valve 23 and repeatedly swings the arm 105 even if the operating lever 113 remains in the neutral position.

[0040] Prior to a detailed explanation of the screening mode, the stroke range in screening will be explained with reference to the schematic diagram showing the stroke range of the cylinder device in Figure 5. Referring to Figure 5, the cylinder device 108 has defined extension stroke limit positions and retraction stroke limit positions. Referring to Figure 1, the extension stroke limit position corresponds to the limit position of the arm 105 in the pulling direction. Conversely, the retraction stroke limit position corresponds to the limit position of the arm 105 in the pushing direction.

[0041] In Figure 5, the sieving stroke range Ss used for sieving bucket 106 is approximately the central region Sc of the entire range from the extension stroke limit position to the compression stroke limit position.

[0042] In this embodiment, the cylinder device 108 typically repeatedly strokes in the central region Sc while the controller 31 automatically controls the control valve 23 in sieving mode. However, for some reason, such as the stroke reciprocating motion being repeated many times over a long period of time, the sieving stroke range Ss may become biased towards the stroke limit position in the compression direction. Possible reasons for this include differences in the cross-sectional area of ​​the hydraulic oil chambers 108f and 108g, resulting in different oil discharge and supply flow rates, or the accumulation of slight errors in the push signal time and pull signal time. As a result, the sieving stroke range Ss becomes biased towards the pull side of the arm 105, and sieving is not performed properly.

[0043] Therefore, in this embodiment, the cylinder device 108 corrects the push signal time (or pull signal time) if the sieving stroke range Ss becomes biased towards one of the stroke limit positions during automatic control of the control valve 23 in sieving mode. This correction can be started not by waiting until the stroke range Ss actually becomes biased towards the stroke limit position, but by triggering the operator to operate the operating lever 113 above a predetermined threshold M1, as shown in the time chart of Figure 3 described later.

[0044] Alternatively, although not shown in the time chart, as a modified example, during the automatic control of the screening mode by the controller 31, the IMU sensor may monitor the cylinder device 108 and detect if the screening stroke range Ss actually deviates towards the stroke limit position of the cylinder device 108. The controller 31, upon receiving this detection result, may then automatically correct the push signal time (or pull signal time).

[0045] Figure 2B is a schematic diagram showing the components within the controller 31. The controller 31 has a sieving mode selection unit 32, a standard cycle determination unit 33, a sieving operation execution unit 34, and a cycle correction unit 35 as components for executing the sieving mode.

[0046] Figure 3 is a flowchart showing the control related to the screening mode. Figure 4 is a time chart of the signals transmitted from the controller 31 to the control valve 23 in the screening mode. The flowchart in Figure 3 is executed by the controller 31 at intervals of 100 msec to 10 sec. 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), this flowchart is exited (end). Conversely, if the screening mode is selected by the screening mode selection unit 32 (Yes), the process proceeds to the next step S20.

[0047] 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-pull direction even if the operating lever 113 remains in the neutral position. To explain the output signals of the controller 31 in sieving mode, referring to Figure 4, the sieving mode flag rises from OFF to ON, and while the sieving mode flag is ON, the arm push signal and 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 intervened 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 a standard cycle, and is determined by the standard cycle determination unit 33. In such a standard cycle, the arm 105 operates for one cycle in the push-pull direction. Subsequently, the standard cycle is repeated, executing the standard sieving operation. The predetermined times tb, tc, td, and te are, for example, predetermined default values. The predetermined times tb, tc, td, and te are predetermined so that the sieving stroke range Ss is within an approximately appropriate range, neither too large nor too small. However, the sieving stroke range Ss may become inappropriate due to long-term sieving operations or other reasons, so the correction cycle described later restores the sieving stroke range Ss to an appropriate range.

[0048] Returning to the explanation in Figure 3, in the next step S30, it is determined whether the operator has moved the control lever 113 in the pushing direction by a predetermined amount (threshold M1). If the amount of movement Ms, such as the control lever 113 remaining in the neutral position, is less than or equal to the threshold M1 (No), the process returns to step S20, and the arm 105 continues to swing repeatedly in the pushing and pulling directions. Conversely, if the control lever 113 is tilted in the pushing direction by more than the threshold M1 (Yes), the process proceeds to step S40.

[0049] It should be added here that the operating time during which the operating lever 113 is operated more than the threshold M1 is not particularly limited. As a variation, the threshold T1 may be set to the operating time Tm during which the lever is operated more than the threshold M1, and if the operating time Tm is greater than or equal to the threshold T1, the system may proceed to step S40 with a "Yes" response.

[0050] Furthermore, as a variation, if an operation is input to another control unit, such as a push button, touch panel, or on / off switch, instead of the lever operation by the operating lever 113, the process may proceed to step S40.

[0051] In the next step S40, it is determined whether the sieving stroke range Ss satisfies predetermined conditions. Specifically, the predetermined conditions are determined by whether the sieving stroke range Ss is within a stroke distance Su of the stroke limit position of the cylinder device 108 (the limit position on the pulling side of the arm 105) (i.e., whether it is jammed). 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 a standard one-cycle. If the sieving stroke range Ss satisfies the predetermined conditions, 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 a standard one-cycle (step S20). Conversely, if the sieving stroke range Ss does not satisfy the predetermined conditions (No), the process proceeds to step S50 because the margin from the sieving stroke range Ss to the stroke limit position is too small, or the sieving stroke range Ss is inappropriately small due to the blockage.

[0052] It should be added here that, as a modified example not shown in the diagram, step S40 is optional, and the process may proceed from step S30 to step S50.

[0053] In the next step S50, the sieving cycle correction flag is set in the controller 31 (cycle correction unit 35), and the cycle correction unit 35 calculates the additional time Δt based on the push operation amount Ms in step S30 described above. Specifically, for example, the additional time Δt is set to be longer in proportion to the operation amount Ms.

[0054] In the next step S60, the standard cycle is corrected by an additional time Δt, and based on this corrected cycle, the arm 105 is repeatedly oscillated in the pushing and pulling directions. Now, to explain the output signal of the controller 31 in the screening mode, referring to Figure 4, the screening cycle correction flag rises from OFF to ON, and at the end of the standard one-cycle screening operation at the time of rising, the screening operation transitions to a corrected one-cycle.

[0055] A correction cycle is a cycle during which the screening cycle correction flag is ON. During this cycle, the arm push signal time tb+Δt (the reference arm push signal time tb plus an additional time Δt) and the arm pull signal time td are repeatedly and alternately transmitted to the directional control valve 23s. The sum of these series (tb+Δt+tc+td+te) is called a correction cycle. In such a correction cycle, the arm 105 operates for one cycle in the push-pull direction. Subsequently, multiple correction cycles are repeated to perform the corrected screening operation.

[0056] Returning to Figure 3, the process proceeds from step S60, where the corrected sieving operation is performed, to step S70. In the next step, S70, it is determined whether the additional operating amount Mt of the operating lever 113 is less than a predetermined threshold M2. If the additional operating amount Mt of the operating lever 113 is less than the predetermined threshold M2 (Yes), the process returns to step S60 as described above, the sieving cycle correction flag remains ON, and the corrected sieving operation continues with the additional time Δt added to the pushing direction time tb. As a result, as shown in the time chart in Figure 4, a reciprocating motion continues where the pushing signal time is longer than the pulling signal time. Consequently, the stroke range Ss of the arm 105 is gradually corrected towards the pushing side.

[0057] When the operator determines that the stroke range Ss of arm 105 has been sufficiently corrected to the pushing side, the operator operates the operating lever 113. In other words, in step S70 of Figure 3, the additional operating amount Mt of the operating lever 113 becomes greater than or equal to a predetermined threshold M2 (No), and the process proceeds to step S80.

[0058] As a variation, threshold T2 may be set for the operation time Tn that is greater than or equal to threshold M2, and if the operation time Tn is greater than or equal to threshold T2, the system may proceed to step S80 with the response "Yes".

[0059] In the next step, S80, the sieving cycle correction flag is deactivated from ON to OFF. The sieving mode flag remains ON. The sieving mode selection unit 32 starts controlling the control valve in the standard cycle as soon as the one correction cycle that overlaps when the sieving cycle correction flag is switched from ON to OFF is completed. As a result, the sieving stroke range switches to the standard cycle with natural operation, allowing for a smooth transition from the correction cycle to the standard cycle.

[0060] It should be added here that, as an unillustrated variation of the sieving cycle correction performed by the flow of steps S30→S40→S50→S60→S70→S80, the sieving cycle correction may be performed only while the operator holds the lever operation amount Ms greater than M1, and the process may proceed to the release of the sieving cycle correction (S80) when the operator returns the operation amount Ms of the control lever 113 to 0 (neutral position). It is not mandatory to proceed to step S80 if the additional lever operation amount Mt in step S70 is M2 ≤ Ms ≤ M1.

[0061] Preferably, a display device for the operator, such as a cluster screen, monitor screen, or mobile terminal, is provided inside the cabin 111. The display device may show that the sieving mode is selected, the lever operation method for correcting the sieving stroke, the degree of correction, and a predetermined stroke range as illustrated in Figure 5. By displaying such information, the operator can confirm whether the operation of the operation lever 113 is a manual operation or an operation related to the automatic sieving operation, an operation related to the standard cycle in step S30, or an operation related to the cycle correction in step S70, thereby preventing erroneous operation.

[0062] Furthermore, the display device may continuously show a message indicating that when the sieving mode in step S10 is ON, the lever operation is used for the cycle correction in step S30, until the sieving mode is turned OFF.

[0063] Incidentally, the work machine 100 of this embodiment includes a sieving bucket 106, a cylinder device 108 that vibrates an arm 105 supporting the sieving bucket 106 alternately in the pushing and pulling directions, a directional control valve 23s that is controlled to supply hydraulic fluid 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 includes a sieving mode selection unit 32 for selecting a sieving mode, a standard cycle determination unit 33 for determining a standard cycle of bucket 106 vibration, which includes a pushing time for connecting the directional control valve 23s to one operating side of the cylinder device 108 and a pulling time for connecting the directional control valve 23s to the other operating side of the cylinder device 108 when the sieving mode is selected, a sieving operation execution unit 34 for controlling the directional control valve 23s with the standard cycle determined by the standard cycle determination unit 33, and a cycle correction unit 35 for calculating an additional time Δt to be added to either the one time tb or the other time td after the control of the directional control valve 23s with the standard cycle, correcting the standard cycle in accordance with the additional time Δt, and causing the sieving operation execution unit 34 to execute control of the directional control valve 23s with the corrected cycle. According to this embodiment, even if the sieving stroke range Ss becomes biased towards the limit position on the pulling side of the arm 105 for some reason due to the long-term execution of automatic sieving in sieving mode, this bias can be corrected and the stroke range Ss can be maintained appropriately.

[0064] Furthermore, the cycle correction unit 35 of this embodiment detects an operation input to the operating lever 113, which is the operating unit of the work machine, while the directional control valve 23s is being controlled by the standard cycle determined by the standard cycle determination unit 33. Once the standard cycle that overlaps with the detection is completed, the unit starts controlling the control valve with the corrected cycle. As a result, the sieving stroke range is corrected with natural operation, and a smooth transition from the standard cycle to the corrected cycle is possible.

[0065] In this embodiment, the cycle correction unit 35 may calculate an additional time Δt corresponding to the amount Ms input to the operating lever 113 of the work machine 100. This allows the stroke range of the sieving operation to be corrected as desired by the operator. In particular, by increasing the pushing amount Ms, the operator can shift the sieving stroke range toward the arm pushing side. Although not shown in the time chart of Figure 4, the operator can also shift the sieving stroke range toward the arm pulling side by inputting a pulling amount to the operating lever 113.

[0066] Calculating the additional time Δt in accordance with the manipulated variable Ms means that the additional time Δt may be calculated in proportion to the manipulated variable Ms, or the cycle correction unit 35 may have a map (not shown) that shows the relationship between the manipulated variable Ms and the additional time Δt, and the additional time Δt may be calculated by referring to this map.

[0067] In this embodiment, the system is further equipped with a stroke position detection unit, such as an IMU sensor, for detecting the stroke position of the cylinder device 108. The controller 31 stops the automatic control of the screening mode by the screening 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 5, or when the screening stroke range Ss, which is the difference between the maximum and minimum values ​​of the detected stroke position, falls outside the predetermined cylinder stroke range (central region Sc). This prevents the cylinder device 108 from reaching the stroke limit position and causing an impact during the execution of the screening mode, and prevents the stroke range Ss of the screening mode from becoming excessively large.

[0068] The work machine 100 of this embodiment includes an arm 105 whose tip is connected to a sieving bucket 106 via a pivot shaft, and whose base end is connected to the boom 104 (main body side member) of the work machine 100 via a pivot shaft. A cylinder device 108 provided between the boom 104 and the arm 105 performs a sieving mode in which the arm 105 is repeatedly pushed and pulled. However, 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 direction.

[0069] The work machine 100 of this embodiment may further be equipped with a display device that indicates whether the operation input to the operating lever 113 is a manual operation while the directional control valve 23s is being controlled by the sieving operation execution unit 34. This makes it clear whether the current operation of the bucket 106 is based on manual operation by the operator, thereby preventing operator error and misoperation.

[0070] The work machine 100 of this embodiment may further include a display device that indicates whether the operation input to the operating lever 113 is an operation that is part of the standard cycle while the directional control valve 23s is being controlled by the sieving operation execution unit 34. This allows the operator of the work machine 100 to confirm whether the current operation of the bucket 106 is in the process of sieving according to the standard cycle, thereby preventing operator error and misoperation.

[0071] The cycle correction unit 35 of this embodiment is configured to release the execution of control of the directional control valve 23s in the correction cycle according to the amount of operation input to the operating lever 113 of the work machine 100 while the control of the directional control valve 23s is being executed in the correction cycle, as shown in step S70 of Figure 3 (step S80). The work machine 100 may further be equipped with a display device that indicates that the operation input to the operating lever 113 during the control of the directional control valve 23s in the correction cycle is an operation related to the correction cycle. This allows the operator of the work machine 100 to confirm whether the current operation of the sieving bucket is under control of the directional control valve 23s by the correction cycle, thereby preventing operator error and erroneous operation.

[0072] Although 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.

[0073] For example, the cycle correction unit 35 may calculate a neutral time Tc for closing the directional control valve 23s between one time Tb and the other time Td, and correct the correction cycle by adding the neutral time Tc to the standard cycle. The same applies to the neutral time Te. This makes it possible to slow down the screening operation in screening mode. The cycle correction only needs to be applied to at least one of the one time and the other time. The correction of the other time is also done as described above based on the time chart in Figure 4 for the one time. [Industrial applicability]

[0074] This invention is advantageously applicable to construction machinery and other work machines. [Explanation of symbols]

[0075] 23 control valve, 23r, 23s, 23t Directional control valve (control valve) 31 Controller, 32 Sieving mode selection unit, 33 Standard cycle determination unit, 34 Sieving operation execution unit, 35 Cycle correction unit, 100 work machines, 102 Upper rotating body (main body of the work machine), 105 Arm, 106 Buckets, 107-109 Cylinder equipment.

Claims

1. The system comprises a sieving bucket, a cylinder device that vibrates the sieving bucket alternately to one side or the other, a control valve that supplies hydraulic fluid to either the one operating side or the other operating side of the cylinder device, and a controller that controls the control valve. The controller includes a sieving mode selection unit for selecting a sieving mode, With the aforementioned screening mode selected, a standard cycle determination unit determines a standard cycle of bucket vibration including one time for connecting the control valve to one operating side of the cylinder device and another time for connecting the control valve to the other operating side of the cylinder device. A screening operation execution unit that controls the control valve using the standard cycle determined by the standard cycle determination unit, A working machine having a cycle correction unit that calculates an additional time to be added to either the one time or the other time during the control of the control valve by the standard cycle, corrects the standard cycle in accordance with the additional time, and causes the sieving operation execution unit to execute the control of the control valve with the corrected cycle.

2. The work machine according to claim 1, wherein the cycle correction unit detects an operation input to the work machine's operating unit while the control valve is being controlled by the standard cycle determined by the standard cycle determination unit, and, as soon as the overlapping standard cycle at the time of detection is completed, causes the sieving operation execution unit to execute control of the control valve with the correction cycle.

3. The work machine according to claim 1, wherein the cycle correction unit calculates the additional time according to the amount of operation input to the operation unit of the work machine.

4. The work machine according to claim 3, wherein the cycle correction unit calculates a neutral time for closing the control valve between the one time and the other time, and corrects the standard cycle by adding the neutral time.

5. The system further includes a stroke position detection unit for detecting the stroke position of the cylinder device, The aforementioned controller, The working machine according to claim 1, wherein the standard cycle is corrected so as to prevent the detected stroke position from reaching either the limit position on one operating side or the limit position on the other operating side of the cylinder device.

6. The arm comprises an arm whose tip is connected to the sieving bucket via a pivot shaft, and whose base end is connected to the main body member of the work machine via a pivot shaft. The work machine according to claim 1, wherein the cylinder device is at least one of a cylinder device provided between the sieving bucket and the arm, and a cylinder device provided between the arm and the main body side member.

7. The work machine according to claim 1, further comprising a display device that indicates that the operation input to the operation unit of the work machine is not a manual operation while the control valve is being controlled by the sieving operation execution unit.

8. The work machine according to claim 2, further comprising a display device that indicates that the operation input to the operation unit of the work machine is an operation that is involved in the standard cycle while the control valve is being controlled by the screening operation execution unit.

9. The cycle correction unit is configured to release the execution of the control valve in the correction cycle according to the amount of operation input to the operating unit of the work machine while the control of the control valve is being executed in the correction cycle. The work machine according to any one of claims 1 to 8, further comprising a display device that indicates that an operation input to the operating section of the work machine is an operation involved in the correction cycle while the control valve is being controlled in the correction cycle.

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