Work equipment

Abstract

The swinging position of a work implement (24) is appropriately determined in accordance with the state of the work implement (24).　A work machine (1) comprises: an arm (23); a work implement (24) that is swingably attached to the arm (23); a work implement cylinder (C5) that is supported at one end on the arm (23) via a cylinder shaft (35), is supported at the other end on the work implement (24), and causes the work implement (24) to swing by extending and retracting; a cylinder sensor (80) that detects the operation of the work implement cylinder (C5); a control valve (72) that causes the work implement cylinder (C5) to retract by controlling the flow of hydraulic fluid to the work implement cylinder (C5); and a control device (71) that periodically determines the swing position of the work implement (24) on the basis of a value output by the cylinder sensor (80), the control device (71) changing the accuracy of determining the swing position of the work implement (24) in accordance with the operating state of the work implement cylinder (C5).

Description

Technical Field

[0001] The present invention relates to a working machine that swings a working tool to perform work.

Background Art

[0002] Conventionally, a working machine disclosed in Patent Document 1 is known. The working machine disclosed in Patent Document 1 includes an arm, a working tool pivotally supported swingably on the tip side of the arm, a working tool cylinder that swings the working tool, a control valve that controls the flow of hydraulic oil to the working tool cylinder, and a control device that determines the swing position of the working tool based on the swing angle of the cylinder shaft of the working tool cylinder.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a working machine as disclosed in Patent Document 1, in response to an operation of an operation member, the opening degree of the control valve changes, and the path and flow rate of the hydraulic oil flowing from the control valve to the working tool cylinder are switched, so that the working tool cylinder operates and the working tool swings. However, for example, when the operation amount of the operation member is small and the opening degree of the control valve is small, the hydraulic pressure acting on the working tool cylinder is low, so the working tool cylinder and the working tool may rattle due to external force by the amount of play generated in the working tool cylinder or the support portion of the working tool. In this case, since the output signal from the angle sensor that detects the swing angle of the working tool cylinder fluctuates irregularly, there is a risk that the control device may erroneously determine the swing position of the working tool.

[0005] One possible solution is to improve the accuracy of determining the oscillation position of a work tool by, for example, increasing the number of samples in the output signal of the angle sensor used to determine the oscillation position of the work tool. However, in this case, it may take time to determine the oscillation position of the work tool, and there is a risk that the oscillation position of the work tool may not be able to be appropriately determined in line with the operating speed of the work tool.

[0006] In view of the above problems, the present invention aims to appropriately determine the swinging position of a work tool according to the condition of the work tool. [Means for solving the problem]

[0007] A working machine according to one aspect of the present invention includes an arm, a working tool pivotably mounted on the arm, and a working tool cylinder whose one end is supported by the arm via a cylinder shaft and whose other end is supported by the working tool, and which pivots the working tool by extending and retracting. The oscillation of the work tool cylinder around the cylinder shaft and The aforementioned work tool cylinder The working tool cylinder is at least one of the following: The system comprises a cylinder sensor that detects movement, a control valve that controls the flow of hydraulic fluid to the work tool cylinder to extend and retract the work tool cylinder, and a control device that periodically determines the swinging position of the work tool based on the output value of the cylinder sensor, wherein the control device controls the movement of the work tool cylinder The aforementioned operation Values ​​of physical quantities related to these quantities Depending 、 The aforementioned By changing the sampling number, which is the number of output values ​​used to determine the oscillation position, the periodic determination is made. Oscillating position Accuracy Change the accuracy of the judgment.

[0008] The control valve is The hydraulic fluid is introduced into the first pressure chamber of the work tool cylinder. The first position in which the work tool cylinder is retracted, The hydraulic fluid is introduced into the second pressure chamber of the work tool cylinder. The second position for extending the work tool cylinder, and the work tool cylinder to the aforementioned hydraulic fluid of inflow Don't let them neutral The control device is switchable to either the first position or the second position when the control valve is in either the first position or the second position. When the predetermined conditions for the value of the physical quantity are not met to, The predetermined Conditions are met The number of samples is increased compared to the previous case. Judgment accuracy Towards You may raise it.

[0009] The working machine By changing the position and opening degree of the control valve the working tool cylinder In order to make it perform the above operation operation So operation member and, A sensor for detecting the amount of operation of the operating member, includes, The predetermined condition is that the manipulated quantity, which is the physical quantity, is greater than or equal to a threshold. when the control device starts operation of the operation member and the control valve is in either the first position or the second position, the Note operation amount is The aforementioned less than the threshold value Furthermore, when the manipulated amount is greater than or equal to the threshold, judgment accuracy Towards may be improved. height It may be.

[0010] The working machine includes a solenoid that operates the control valve according to the supplied control current, The predetermined condition is that the current value of the control current, which is the physical quantity, is equal to or greater than a threshold value. when the control device, the control valve is in either the first position or the second position , the electric when the current value is less than the threshold value<00XXXXXX76>judgment accuracy Towards may be improved. height It may be.

[0011] The working machine includes a flow rate sensor that measures the flow rate of the hydraulic oil flowing from the control valve to the working tool cylinder, The aforementioned The working machine includes a flow rate sensor that measures the flow rate of the hydraulic oil flowing from the control valve to the working tool cylinder, The predetermined condition is that the flow rate, which is the physical quantity, is equal to or greater than a threshold. when the control device, the control valve is in either the first position or the second position , the flow amount is The aforementioned less than the threshold value Furthermore, when the flow rate is greater than or equal to the threshold, judgment accuracy Towards may be improved. height It may be.

[0012] The working machine includes a pressure sensor that measures the hydraulic pressure of the hydraulic oil acting from the control valve to the working tool cylinder, The aforementioned The working machine includes a pressure sensor that measures the hydraulic pressure of the hydraulic oil acting from the control valve to the working tool cylinder, The predetermined condition is that the physical quantity, the hydraulic pressure, is equal to or greater than a threshold value. the control device, the control valve The front when it is in either the first position or the second position , the oil when the pressure is less than the threshold value Furthermore, when the hydraulic pressure is above the threshold, the judgment accuracy Towards may be improved. height It may be.

[0014] The control device ,before By changing at least one of the sampling time and sampling period for sampling the output value of the cylinder sensor, the previous Note You may change the number of pumps.

[0015] The work machine includes a body that supports the arm, and the cylinder sensor includes an angle sensor that detects the oscillation angle of the work tool cylinder when the work tool is positioned away from the body and when the work tool is positioned closer to the body, with respect to the neutral position of the work tool where the oscillation angle of the work tool cylinder around the cylinder axis is maximum, and the control device may determine the oscillation position of the work tool based on the trend of change in the output value of the angle sensor, the operating direction of either extension or contraction of the work tool cylinder, and the oscillation angle of the work tool cylinder detected from the output value of the angle sensor.

[0016] The control device determines that the output value of the angle sensor is on an upward trend when the output value of the angle sensor rises continuously for a predetermined period of time, and the control device determines that the output value of the angle sensor is on an upward trend. The aforementioned If the output value decreases continuously for a predetermined period of time, it is determined that the output value is on a downward trend, and the Value of a physical quantity The predetermined time may be changed accordingly.

[0017] The control device determines that the output value of the angle sensor is on an upward trend when the output value of the angle sensor rises for a predetermined number of consecutive samplings, and the output value of the angle sensor The aforementioned If the output value decreases for a predetermined number of consecutive samplings, it is determined that the output value is on a downward trend, and Value of a physical quantity in response Before The specified number of sampling cycles may be changed.

[0018] The aforementioned work machine is the work tool of Oscillation in order to operation So The control device includes an operating member, and the control device operates the operating member direction Based on the work tool cylinder The aforementionedYou may also determine the direction of operation.

[0019] The aforementioned work machine is equipped with a solenoid that operates the control valve in accordance with the supplied control current, and the control device is ,before Current of the control current value Based on the above, the work tool cylinder The aforementioned You may also determine the direction of operation. [Effects of the Invention]

[0022] According to the above configuration, the swinging position of the work tool can be appropriately determined according to the condition of the work tool. [Brief explanation of the drawing]

[0023] [Figure 1] This is a side view of the work machine. [Figure 2] This is a side view showing the operation of the bucket. [Figure 3] This is a side view showing the operation of the bucket cylinder. [Figure 4] This is a diagram illustrating an example of a bucket control system for a work machine. [Figure 5] This is a time chart illustrating an example of the operation of the bucket control system of a work machine. [Figure 6] A flowchart illustrating an example of the operation of the bucket control system for a work machine. [Figure 7A] Figure 6 is a flowchart showing an example of the details of the bucket position determination process. [Figure 7B] This is a flowchart that continues from Figure 7A. [Figure 8] Figure 6 is a flowchart illustrating another example of the bucket position determination process. [Figure 9] This is a time chart illustrating another example of the operation of the bucket control system of a work machine. [Figure 10] This is a cross-sectional view of a bucket cylinder. [Figure 11A] This figure shows the bucket cylinder in its fully extended state. [Figure 11B]This diagram shows the extension and retraction state of the bucket cylinder when it is in the reversed position. [Figure 11C] This figure shows the bucket cylinder in its most retracted state. [Figure 12] This is a diagram illustrating another example of a bucket control system for a work machine. [Figure 13] This is a diagram illustrating another example of a bucket control system for a work machine. [Figure 14] This is a diagram illustrating another example of a bucket control system for a work machine. [Modes for carrying out the invention]

[0024] The following describes one embodiment of the present invention, with appropriate reference to the drawings.

[0025] Figure 1 is a side view showing the entire working machine 1 according to this embodiment. In this embodiment, a backhoe (excavating machine) is exemplified as the working machine 1. The working machine according to the present invention may be a working machine other than a backhoe.

[0026] As shown in Figure 1, the work machine 1 comprises a body 2, a travel device 3, and a work device 4. A cabin 5 is mounted above the body 2. Inside the cabin 5 is a driver's seat 6 where the operator sits.

[0027] In this embodiment, the direction in which the work device 4 is positioned relative to the machine body 2 of the work machine 1 (direction of arrow A1 in Figure 1) is forward, the opposite direction of forward (direction of arrow A2 in Figure 1) is backward, the left side when facing forward is left (direction towards the foreground in Figure 1), and the right side when facing forward is right (direction towards the depth in Figure 1). Furthermore, the horizontal direction, which is perpendicular to the front-rear direction (front-rear direction of the machine body) K1 shown in Figure 1, will be described as the machine body width direction. In addition, the direction extending to the right or left from the center of the machine body width direction will be called the outward direction in the machine body width direction, and the opposite direction in the outward direction in the machine body width direction will be called the inward direction in the machine body width direction.

[0028] The travel device 3 supports the machine body 2 so that it can move. The travel device 3 has a first travel mechanism 3L provided on the left side of the travel frame 3A and a second travel mechanism 3R provided on the right side of the travel frame 3A. The first travel mechanism 3L and the second travel mechanism 3R are crawler-type travel mechanisms. The first travel mechanism 3L is driven by a left travel motor M1 provided on the left side of the travel frame 3A, and the second travel mechanism 3R is driven by a right travel motor M1 provided on the right side of the travel frame 3A. Each travel motor M1 is configured as, for example, a hydraulic motor (hydraulic actuator).

[0029] A dozer device 7 is mounted on the front of the traveling device 3. The dozer device 7 can be raised and lowered (the blade can be raised and lowered) by extending and retracting the dozer cylinder (hydraulic actuator).

[0030] The machine body 2 is supported on the travel frame 3A so as to be able to rotate around a pivot axis X1 via a pivot bearing 8. The pivot axis X1 is the axis passing through the center of the pivot bearing 8 and extends in the vertical direction. The machine body 2 is equipped with a prime mover (not shown). The prime mover is, for example, a diesel engine. The prime mover may also be a gasoline engine or an electric motor. Furthermore, the work implement 1 may be a hybrid type work implement having both an engine and an electric motor as prime movers.

[0031] The aircraft body 2 has a rotating base plate 9 that rotates around a rotation axis X1. The rotating base plate 9 is made of steel plate or the like and forms the bottom of the aircraft body 2. Longitudinal ribs 9L and 9R (reinforcement members) are provided in the center of the upper surface of the rotating base plate 9, extending from the front to the rear of the rotating base plate 9. A weight 10 is provided at the rear of the aircraft body 2. The weight 10 is erected on the rotating base plate 9.

[0032] A support body 20 is provided at the front of the machine body 2 to support the work device 4. The support body 20 has a support bracket 20A and a swing bracket 20B. The support bracket 20A is fixed to the front of the longitudinal ribs 9L and 9R and is provided so as to protrude forward from the machine body 2. The swing bracket 20B is attached to the front part of the support bracket 20A (the part that protrudes from the machine body 2) via a swing shaft 26 so as to be able to swing around the longitudinal axis (the axis that extends in the vertical direction). As a result, the swing bracket 20B is able to rotate in the machine body width direction (horizontally around the swing shaft 26). As a result, the work device 4 is able to rotate around the swing shaft 26.

[0033] The working device 4 is attached to the swing bracket 20B. The working device 4 has a boom 22, an arm 23, and a bucket (working tool) 24. The base 22A of the boom 22 is pivotally supported (rotatably supported) on the upper part of the swing bracket 20B via the boom shaft 27. The boom shaft 27 has an axis that extends in the width direction of the machine body. The boom 22 swings up and down by rotating around the boom shaft 27.

[0034] The base end 23A of the arm 23 is pivotally supported at the tip 22B of the boom 22 via the arm axis 28. The axis of the arm axis 28 is parallel to the axis of the boom axis 27. Therefore, the arm 23 rotates around the arm axis 28. In addition, the arm 23 swings back and forth as it rotates around the arm axis 28, causing the tip 23B to move closer to and further away from the boom 22 and the machine body 2.

[0035] The base 24A of the bucket 24 is pivotally supported at the tip 23B of the arm 23 via a bucket shaft (work tool shaft) 29. The axis of the bucket shaft 29 is parallel to the axis of the arm shaft 28. The bucket 24 is rotatable around the bucket shaft 29. By rotating around the bucket shaft 29, the bucket 24 swings back and forth, causing the tip 24B to move closer to and further away from the boom 22 and the machine body 2.

[0036] In this embodiment, the direction in which the arm 23 and bucket 24 swing toward the boom 22 and machine body 2 is called the shovel direction, and the direction in which they swing toward the boom 22 and machine body 2 is called the dump direction. That is, the bucket 24 is capable of both shoveling and dumping operations. Shoveling operation is the operation of bringing the bucket 24 toward the boom 22 and machine body 2 to scoop up soil and sand. Dumping operation is the operation of moving the bucket 24 toward the boom 22 and machine body 2 to drop (discharge) the soil and sand inside the bucket 24.

[0037] The bucket 24 is connected to the arm 23 via a link mechanism 30. The link mechanism 30 has a first link 30A and a second link 30B. One end of the first link 30A is pivotally supported on the arm 23 via a first link shaft 31. One end of the second link 30B is pivotally supported on the base 24A of the bucket 24 via a second link shaft 32. The other ends of the first link 30A and the second link 30B are pivotally supported on each other via a connecting shaft 33. The axes of the first link shaft 31, the second link shaft 32, and the connecting shaft 33 are parallel to the axis of the bucket shaft 29.

[0038] In this embodiment, a bucket 24 is attached to the work machine 1 as a work tool, but other work tools (hydraulic attachments) that can be driven by a hydraulic actuator can be attached in place of or in addition to the bucket 24. Examples of other work tools include hydraulic breakers, hydraulic crushers, angle brooms, earth augers, pallet forks, sweepers, mowers, and snow blowers.

[0039] The swing bracket 20B is pivotable by the extension and retraction of the swing cylinder C2 located within the machine body 2. The boom 22 is pivotable by the extension and retraction of the boom cylinder C3. The arm 23 is pivotable by the extension and retraction of the arm cylinder C4. The bucket 24 is pivotable by the extension and retraction of the bucket cylinder C5. These cylinders C2, C3, C4, and C5 are double-acting hydraulic cylinders (hydraulic actuators).

[0040] The bucket cylinder C5 is positioned on the front side of the arm 23. It is also positioned along the arm 23. One end of the bucket cylinder C5 is pivotally supported at the base end 23A of the arm 23. More specifically, one end of the bucket cylinder C5 is pivotally supported via a cylinder shaft 35 to a bracket 34 fixed to the base end 23A of the arm 23. The axis of the cylinder shaft 35 is parallel to the axis of the arm shaft 28. The other end of the bucket cylinder C5 is pivotally supported via a connecting shaft 33 to the other ends of the first link 30A and the second link 30B.

[0041] Figure 2 is a side view showing the operation of the bucket 24. The bucket cylinder C5 has a cylinder tube 36, a rod 37, and a piston 38. The piston 38 is housed within the cylinder tube 36. The piston 38 is movable in the axial direction of the cylinder tube 36. The base end of the rod 37 is connected to the piston 38 within the cylinder tube 36. As the piston 38 moves in the axial direction of the cylinder tube 36, the rod 37 protrudes and retracts relative to the cylinder tube 36, causing the bucket cylinder C5 to extend and retract.

[0042] A head 37A is provided at the tip of the rod 37. The head 37A is pivotally supported on the bracket 34 via the cylinder shaft 35. A mounting portion 36C is provided at the bottom end of the cylinder tube 36 (the side with the piston 38 relative to the head 37A). The mounting portion 36C is pivotally supported on the other end of the first link 30A and the second link 30B via the connecting shaft 33.

[0043] Figure 3 is a side view showing the operation of the bucket cylinder C5. As shown in Figure 3, the bucket cylinder C5 oscillates around the cylinder shaft 35 by extending and retracting. As a result of this operation (extension and oscillation) of the bucket cylinder C5, the bucket 24 oscillates around the bucket shaft 29 in the dumping direction Y1 or the shoveling direction Y2, as shown in Figure 2.

[0044] Furthermore, the bucket 24 swings around the bucket axis 29, causing it to oscillate between the dump end position P1, where the tip 24B is furthest from the arm 23 (as shown by the solid line in Figure 2), and the shovel end position P2, where the tip 24B is closest to the arm 23 (as shown by the dashed line). The dump end position P1 is the end position of the bucket 24 in the dumping direction Y1 when the bucket cylinder C5 is most retracted (the most retracted position Ps shown in Figure 3). The shovel end position P2 is the end position of the bucket 24 in the shoveling direction Y2 when the bucket cylinder C5 is most extended (the most extended position PL shown in Figure 3).

[0045] As shown in Figure 3, the bucket cylinder C5 is parallel to the arm 23 when it is in its most retracted position Ps and when it is in its most extended position PL. When the bucket cylinder C5 is extended from its most retracted position Ps, it swings away from the arm 23 for a while, and the swing angle of the bucket cylinder C5 gradually increases. Then, when the bucket cylinder C5 is further extended, at the reversal position Pm, the direction of the swing of the bucket cylinder C5 reverses, and the bucket cylinder C5 swings closer to the arm 23, and the swing angle of the bucket cylinder C5 gradually decreases.

[0046] The oscillation angle of the bucket cylinder C5 is minimal (e.g., 0°) when it is in its most retracted position Ps and its most extended position PL. The oscillation angle of the bucket cylinder C5 is maximum when it is in its reverse position Pm. The direction of oscillation and the tendency of increase or decrease in the oscillation angle of the bucket cylinder C5 reverse at the reverse position Pm.

[0047] When the bucket cylinder C5 is in the reverse position Pm, the bucket 24 is in the neutral position P3 as shown in Figure 2. When the bucket cylinder C5 is oscillating while contracting from the reverse position Pm toward the most retracted position Ps, the bucket 24 oscillates away from the arm 23 (and the machine body 2) (dumping action). When the bucket cylinder C5 is oscillating while extending from the reverse position Pm toward the most extended position PL, the bucket 24 oscillates closer to the arm 23 (and the machine body 2) (shoveling action).

[0048] The inversion position Pm of the bucket cylinder C5 and the neutral position P3 of the bucket 24 are conceptual positions. As shown in Figure 2, the bucket 24 can swing toward the dump side E1, which is away from the machine body 2, and toward the shovel side E2, which is closer to the machine body 2, with the neutral position P3, which corresponds to the inversion position Pm of the bucket cylinder C5, as the boundary.

[0049] Figure 4 is a schematic diagram of an example of a bucket control system mounted on the work machine 1. The bucket control system is a system that controls the movement (oscillation) of the bucket 24.

[0050] The control device 71 is the controller of the bucket control system and is composed of a microcomputer including, for example, a CPU, volatile memory, and non-volatile memory. The storage unit 71a provided in the control device 71 is composed of non-volatile memory. Control data for the control device 71 to control each part is stored in the storage unit 71a in a read / write manner. The storage unit 71a is an example of a storage device. As another example, a separate storage device may be provided in the work machine 1, separate from the control device 71. The bucket control valve 72, operating device 75, cylinder sensor 80, and display device 90 are electrically connected to the control device 71.

[0051] The bucket control valve 72 is a control valve that controls the flow of hydraulic fluid (supply amount and supply direction) to the bucket cylinder C5. The bucket control valve 72 is composed of, for example, an electromagnetic proportional valve. The bucket control valve 72 is switchable between a first position 72a, a second position 72b, and a third position (neutral position) 72c. The control device 71 electrically controls the switching position and opening area of ​​the bucket control valve 72.

[0052] The bucket control valve 72 is connected to the hydraulic pump 92 via the discharge oil passage 73A. The bucket control valve 72 is connected to the tank 74 via the discharge oil passage 73B. The bucket control valve 72 is connected to the rod 37 of the bucket cylinder C5 via the first supply oil passage 73C and the second supply oil passage 73D. Inside the rod 37, there are first oil passages 39A and 39B. The inside of the cylinder tube 36 is divided into a first pressure chamber 36A and a second pressure chamber 36B by the piston 38. The first supply oil passage 73C, the first oil passage 39A, and the first pressure chamber 36A are in communication. The second supply oil passage 73D, the second oil passage 39B, and the second pressure chamber 36B are in communication.

[0053] The bucket control valve 72 has a first solenoid 72d and a second solenoid 72e. The first solenoid 72d and the second solenoid 72e are energized when a current signal is input from the control device 71, and demagnetized when the current signal is no longer input from the control device 71.

[0054] When the first solenoid 72d and the second solenoid 72e are demagnetized, the bucket control valve 72 is in the third position (neutral position) 72c, and the hydraulic fluid discharged from the hydraulic pump 92 to the discharge oil passage 73A is discharged to the tank 74 through the inside of the third position 72c of the bucket control valve 72 and the discharge oil passage 73B. At this time, since the hydraulic fluid does not flow from the bucket control valve 72 to the bucket cylinder C5 via the supply oil passages 73C and 73D, the bucket cylinder C5 does not extend or retract and swing, and the bucket 24 does not swing either.

[0055] When the first solenoid 72d is energized and the second solenoid 72e is demagnetized, the spool of the bucket control valve 72 moves, and the bucket control valve 72 switches to the first position 72a. As a result, the hydraulic fluid discharged from the hydraulic pump 92 into the discharge oil passage 73A flows into the second pressure chamber 36B of the bucket cylinder C5 through the inside of the first position 72a of the bucket control valve 72, the second supply oil passage 73D, and the second oil passage 39B, pressing the piston 38 towards the bottom side of the cylinder tube 36. The hydraulic fluid in the first pressure chamber 36A is then discharged into the tank 74 through the first oil passage 39A, the first supply oil passage 73C, the inside of the first position 72a of the bucket control valve 72, and the discharge oil passage 73B. As a result, the piston 38 and rod 37 of the bucket cylinder C5 move towards the bottom side of the cylinder tube 36, reducing the amount of protrusion of the rod 37 from the cylinder tube 36, causing the bucket cylinder C5 to oscillate while contracting, and the bucket 24 to oscillate in the dumping direction Y1.

[0056] Furthermore, when the second solenoid 72e is energized and the first solenoid 72d is demagnetized, the spool of the bucket control valve 72 moves, and the bucket control valve 72 switches to the second position 72b. As a result, the hydraulic fluid discharged from the hydraulic pump 92 to the discharge oil passage 73A flows into the first pressure chamber 36A of the bucket cylinder C5 through the inside of the second position 72b of the bucket control valve 72, the first supply oil passage 73C, and the first oil passage 39A, pressing the piston 38 towards the rod side of the cylinder tube 36. The hydraulic fluid in the second pressure chamber 36B is then discharged to the tank 74 through the second oil passage 39B, the second supply oil passage 73D, the inside of the second position 72b of the bucket control valve 72, and the discharge oil passage 73B. As a result, the piston 38 and rod 37 of the bucket cylinder C5 move towards the rod side of the cylinder tube 36, increasing the amount of rod 37 protruding from the cylinder tube 36, causing the bucket cylinder C5 to oscillate while extending, and the bucket 24 to oscillate in the shovel direction Y2.

[0057] Furthermore, when the bucket control valve 72 switches to the first position 72a, as the current value of the current signal input from the control device 71 to the first solenoid 72d increases, the opening area of ​​the first position 72a widens (opening degree increases), the flow rate of hydraulic fluid output from the bucket control valve 72 to the bucket cylinder C5 via the second supply oil passage 73D increases, and the hydraulic pressure of the hydraulic fluid increases. Also, when the bucket control valve 72 switches to the second position 72b, as the current value of the current signal input from the control device 71 to the second solenoid 72e increases, the opening area of ​​the second position 72b widens (opening degree increases), the flow rate of hydraulic fluid output from the bucket control valve 72 to the bucket cylinder C5 via the first supply oil passage 73C increases, and the hydraulic pressure of the hydraulic fluid increases.

[0058] The operating device 75 includes an operating lever (operating member) 76 for operating the bucket 24, and a sensor (potentiometer, not shown) for detecting the amount of operation (swing angle) of the operating lever 76. The operating lever 76 is operated by an operator seated in the driver's seat 6 (Figure 1).

[0059] When the operating lever 76 is first operated so that it tilts from the neutral position in the first direction U1, a first operation signal (voltage signal) corresponding to the amount of operation (tilt angle) is output from the operating device 75 to the control device 71. When the control device 71 starts receiving the first operation signal, it periodically samples (detects) the voltage value of the first operation signal. The control device 71 then determines the operating direction and amount of the operating lever 76 according to the multiple voltage values ​​of the sampled first operation signal, and supplies a control signal (current signal) corresponding to the amount of operation to the first solenoid 72d corresponding to the operating direction (in this case, the first direction U1), thereby exciting the first solenoid 72d. As a result, the control device 71 switches the bucket control valve 72 to the first position 72a and changes the opening degree of the first position 72a. In other words, the first operation of the operating lever 76 is an operation to move the bucket 24 in the dump direction Y1 (Figure 2).

[0060] Furthermore, when the operating lever 76 is secondly operated so that it tilts from the neutral position in the second direction U2 (Figure 4), a second operating signal (voltage signal) corresponding to the amount of operation (tilt angle) is output from the operating device 75 to the control device 71. When the control device 71 begins to receive the second operating signal, it periodically samples (detects) the voltage value of the second operating signal. The control device 71 then determines the operating direction and amount of the operating lever 76 according to the multiple voltage values ​​of the sampled second operating signal, and supplies a control signal (current signal) corresponding to the amount of operation to the second solenoid 72e corresponding to the operating direction (in this case, the second direction U2), thereby exciting the second solenoid 72e. As a result, the control device 71 switches the bucket control valve 72 to the second position 72b and changes the opening degree of the second position 72b. The second operation of the operating lever 76 is an operation to move the bucket 24 in the shovel direction Y2 (Figure 2).

[0061] When the operating lever 76 is operated to return to the neutral position, a third operating signal corresponding to that operation is output from the operating device 75. The control device 71 returns the bucket control valve 72 to the third position 72c in response to the third operating signal. Alternatively, when the operating lever 76 is returned to the neutral position, the operating device 75 may stop outputting an operating signal, and the control device 71 may return the bucket control valve 72 to the third position 72c in response to the absence of an operating signal.

[0062] Alternatively, the operating lever 76 may be replaced with another operating component, such as a joystick, on the operating device 75. In this case, the operating device 75 should be equipped with an electrical circuit that outputs an operating signal (electrical signal) corresponding to the operating direction and amount of the joystick.

[0063] The cylinder sensor 80 detects the movement of the bucket cylinder C5. The cylinder sensor 80 includes an angle sensor 81. The angle sensor 81 is, for example, a potentiometer and detects the oscillation of the bucket cylinder C5. The angle sensor 81 detects the oscillation angle of the bucket cylinder C5 when the bucket 24 is positioned on the dump side E1 (Figure 2), away from the arm 23 and the machine body 2, relative to the neutral position P3 of the bucket 24 where the oscillation angle of the bucket cylinder C5 around the cylinder axis 35 is maximum. The angle sensor 81 also detects the oscillation angle of the bucket cylinder C5 when the bucket 24 is positioned on the shovel side E2 (Figure 2), closer to the arm 23 and the machine body 2, relative to the neutral position P3.

[0064] As shown in Figure 3, the angle sensor 81 is connected to the head 37A of the rod 37 of the bucket cylinder C5 by an interlocking link 82. The angle sensor 81 detects the rotation angle of the head 37A around the cylinder shaft 35 via the interlocking link 82 as the oscillation angle of the bucket cylinder C5. Alternatively, the angle sensor 81 may directly detect the rotation angle of the bucket cylinder C5 around the cylinder shaft 35 as the oscillation angle.

[0065] The angle sensor 81 outputs an electrical signal (voltage signal) to the control device 71 corresponding to the oscillation angle of the bucket cylinder C5. In this embodiment, when the bucket cylinder C5 is in its most retracted position Ps and when the bucket cylinder C5 is in its most extended position PL, the oscillation angle of the bucket cylinder C5 is at its minimum, and the voltage value of the output signal from the angle sensor 81 is also at its minimum. As the bucket cylinder C5 extends and the oscillation angle of the bucket cylinder C5 increases, the voltage value of the output signal from the angle sensor 81 increases. Then, when the bucket cylinder C5 is in the reversed position Pm, the oscillation angle of the bucket cylinder C5 is at its maximum, and the voltage value of the output signal from the angle sensor 81 is also at its maximum.

[0066] The control device 71 periodically detects the voltage value of the output signal from the angle sensor 81 as the output value (potentiometer value) of the angle sensor 81. Based on the multiple output values ​​of the angle sensor 81, the control device 71 periodically determines the swinging position of the bucket 24. The control device 71 also stores the determination result of the swinging position of the bucket 24 in the storage unit 71a. Furthermore, the control device 71 may display the determination result of the swinging position of the bucket 24 on the display device 90.

[0067] Figure 5 is a time chart of the bucket control system of the work machine 1. In Figure 5, "Operating lever 1st / 2nd operation amount" indicates the amount of operation of the operating lever 76 to either the first operation (operation in the first direction U1 in Figure 4) or the second operation (operation in the second direction U2 in Figure 4). "Control valve input current" indicates the current value flowing from the control device 71 to either the solenoid 72d or 72e of the bucket control valve 72. "Control valve opening degree" indicates the opening degree of the opening portion (output port) of the bucket control valve 72 at either the first position 72a or the second position 72b. "Angle sensor output value detection," "Output value change trend judgment," "Cylinder oscillation angle detection," and "Bucket oscillation position judgment" indicate the operations performed by the control device 71 (CPU).

[0068] In the bucket control system of the work machine 1, when the operating lever 76 is operated in the first or second operation, the control device 71 determines the operating state (direction of operation and amount of operation) of the operating lever 76, and switches the bucket control valve 72 from the third position 72c to either the first position 72a or the second position 72b according to the operating state, thereby extending and swinging the bucket cylinder C5 and swinging the bucket 24 in the dump direction Y1 or the shovel direction Y2. At this time, as the amount of operation of the operating lever 76 increases ("Operating lever first / second operation amount" in Figure 5), the control device 71 increases the current value of the control current supplied to the first solenoid 72d or the second solenoid 72e ("control valve input current"), thereby increasing the opening degree of the bucket control valve 72 in the first position 72a or the second position 72b ("control valve opening degree").

[0069] In this process, it is necessary to prevent the bucket 24 from suddenly and significantly oscillating, and to suppress variations in the operating state of the bucket control valve 72, bucket cylinder C5, or bucket 24 depending on the surrounding environmental conditions (such as temperature). Therefore, the control device 71 gradually increases the current supplied to the first solenoid 72d or second solenoid 72e corresponding to the first or second operation of the operating lever 76 from a low value to a high value, setting it to a value corresponding to the increase in the first or second operation amount of the operating lever 76 ("control valve input current"). As a result, the opening degree of the first position 72a or second position 72b of the bucket control valve 72 corresponding to the first or second operation of the operating lever 76 gradually increases ("control valve opening degree").

[0070] For a short period immediately after the start of the first or second operation t1 of the operating lever 76, the amount of movement of the operating lever 76 is small, resulting in a low input current value supplied from the control device 71 to the corresponding solenoids 72d and 72e. This causes the bucket control valve 72 to open to a small degree, and insufficient hydraulic pressure is applied to the bucket cylinder C5. At this time, the bucket cylinder C5 and bucket 24 may rattle due to external forces, due to the amount of play in the support portion of the bucket cylinder C5 and the support portion of the bucket 24. Similarly, if the amount of movement of the operating lever 76 when the operation to the first or second operation is stopped is too small, insufficient hydraulic pressure may be applied to the bucket cylinder C5, and the bucket cylinder C5 and bucket 24 may rattle.

[0071] In that case, the output value (voltage value) of the angle sensor 81 that detects the oscillation angle of the bucket cylinder C5 fluctuates irregularly, which may cause the control device 71 to incorrectly determine the oscillation position of the bucket 24 based on that output value. To counter this, the control device 71 changes the accuracy of determining the oscillation position of the bucket 24 according to the operating state of the bucket cylinder C5.

[0072] Figure 6 is a flowchart showing an example of the operation of the bucket control system of the work machine 1. Figures 7A and 7B are flowcharts detailing the bucket swing position determination process in Figure 6. Each process in Figures 6 to 7B is executed by the control device 71 (CPU) according to the software program stored in the memory unit 71a (the same applies to Figure 8, which will be described later).

[0073] When the operating lever 76 is operated for the first time (S1 in Figure 6: YES, "Operating lever first / second operation amount" in Figure 5), the control device 71 energizes the first solenoid 72d (Figure 4) to switch the bucket control valve 72 to the first position 72a (S2 in Figure 6, "Control valve opening degree" in Figure 5). Also, when the operating lever 76 is operated for the second time (S3 in Figure 6: YES, "Operating lever first / second operation amount" in Figure 5), the control device 71 energizes the second solenoid 72e (Figure 4) to switch the bucket control valve 72 to the second position 72b (S4 in Figure 6, "Control valve opening degree" in Figure 5).

[0074] During the execution of processes S2 and S4 in Figure 6, the control device 71 gradually increases the input current (control current) to the corresponding first solenoid 72d or second solenoid 72e from a low value according to the operating direction and amount of the operating lever 76, as described above, and sets the input current value to a target value Ag corresponding to the amount of operation when the operation of the operating lever 76 is stopped (see "Operating lever first / second operating amount" and "Control valve input current" in Figure 5). The control device 71 also compares the amount of operation of the first or second operation of the operating lever 76 with a predetermined threshold Xt read from the storage unit 71a.

[0075] The threshold Xt is set by, for example, the manufacturer or dealer of the work equipment 1, to the amount of operation of the operating lever 76 that is detected when the bucket 24 continues to swing in one direction without rattling in response to the first or second operation of the operating lever 76. In other words, the threshold Xt is an inherent threshold for the work equipment 1. In the example shown in Figure 5, the threshold Xt is a value lower than the amount of operation Xg when the operation of the operating lever 76 is stopped. The amount of operation of the first or second operation of the operating lever 76 is an example of a physical quantity that changes in response to the operation of the operating lever 76 and is included in the conditions (processing S5 in Figure 6) that change the accuracy of determining the swinging position of the bucket 24.

[0076] If the amount of operation of the operating lever 76 (first operation amount or second operation amount) is less than the threshold Xt (S5:YES in Figure 6), the control device 71 turns ON the accuracy improvement flag provided in a predetermined storage area of ​​the storage unit 71a (S6). If the amount of operation of the operating lever 76 is greater than or equal to the threshold Xt (S5:NO), the control device 71 turns OFF the accuracy improvement flag (S6). Then, the control device 71 executes the bucket position determination process (S8).

[0077] The accuracy improvement flag is a flag used in the bucket position determination process (S8) to determine whether the control device 71 improves the accuracy of determining the swinging position of the bucket 24 compared to normal. When the accuracy improvement flag is OFF, the control device 71 determines the swinging position of the bucket 24 with normal accuracy, and when the accuracy improvement flag is ON, the control device 71 determines the swinging position of the bucket 24 with improved accuracy compared to normal.

[0078] In the bucket position determination process shown in Figures 7A and 7B, the control device 71 first samples the output value (voltage value) of the angle sensor 81 at a predetermined period Ra (S11 in Figure 7A, "Angle Sensor Output Value Detection" in Figure 5). The control device 71 then compares the latest output value with the output value immediately preceding it (the previous value) from among the multiple output values ​​of the angle sensor 81 that were sampled, and determines whether the trend of change in the latest output value relative to the previous output value is upward or downward, and records the result of this determination in the storage unit 71a (S12 in Figure 7A).

[0079] Next, if the accuracy improvement flag is ON (S13:YES), the control device 71 determines whether the output value of the angle sensor 81 has been continuously increasing for a predetermined first time (sampling time) T1, or whether it has been continuously decreasing for a predetermined first time (sampling time) T1. The first time T1 is a time for determining the trend of change in the output value of the angle sensor 81 with higher accuracy than under normal conditions, and is set to be longer than the second time (sampling time) T2 of the processes S18 and S19 described later (T1 and T2 in Figure 5). The second time T2 is a time for determining the trend of change in the output value of the angle sensor 81 under normal conditions. Since the sampling period Ra of the output value of the angle sensor 81 is constant, the number of samples of the output value of the angle sensor 81 in the first time T1 is greater than the number of samples of the output value of the angle sensor 81 in the second time T2. In the example in Figure 5, the number of samples of the output value of the angle sensor 81 in the first time T1 is 6, while the number of samples of the output value of the angle sensor 81 in the second time T2 is 4.

[0080] If the output value of the angle sensor 81 has not increased or decreased for a continuous period T1 (S14: NO, S16: NO), the control device 71 determines the trend of change of the latest output value among the multiple output values ​​of the newly sampled angle sensor 81 relative to the previous output value, and records the result of this determination in the storage unit 71a (S12).

[0081] If the output value of the angle sensor 81 rises continuously for the first time period T1 (S14: YES), the control device 71 determines that the output value of the angle sensor 81 is on an upward trend ("Output Value Change Trend Determination" in Figure 5), and records this determination result in the storage unit 71a (S15 in Figure 7A). Also, if the output value of the angle sensor 81 falls continuously for the first time period T1 (S16: YES), the control device 71 determines that the output value of the angle sensor 81 is on a downward trend ("Output Value Change Trend Determination" in Figure 5), and records this determination result in the storage unit 71a (S17 in Figure 7A).

[0082] On the other hand, if the accuracy improvement flag is OFF (S13: NO), the control device 71 determines whether the output value of the angle sensor 81 has been rising for a predetermined second time T2 continuously, or whether it has been falling for a second time T2 continuously. If the output value of the angle sensor 81 has not been rising or falling for a second time T2 continuously (S18: NO, S19: NO), the control device 71 determines the trend of change of the latest output value among the multiple output values ​​of the newly sampled angle sensor 81 relative to the previous output value, and records the result of this determination in the storage unit 71a (S12).

[0083] If the output value of the angle sensor 81 rises continuously for the second time period T2 (S18: YES), the control device 71 determines that the output value of the angle sensor 81 is on an upward trend ("Output Value Change Trend Determination" in Figure 5) and records this determination result in the storage unit 71a (S15 in Figure 7A). Also, if the output value of the angle sensor 81 falls continuously for the second time period T2 (S19: YES), the control device 71 determines that the output value of the angle sensor 81 is on a downward trend ("Output Value Change Trend Determination" in Figure 5) and records this determination result in the storage unit 71a (S20 in Figure 7A).

[0084] Next, the control device 71 checks whether bucket position information, which indicates the swinging position of the bucket 24, is recorded in the storage unit 71a. If bucket position information is recorded in the storage unit 71a (S21 in Figure 7B: YES), the control device 71 checks whether the bucket position information indicates that the bucket 24 is positioned in the neutral position P3.

[0085] If the bucket position information does not indicate that the bucket 24 is positioned in the neutral position P3 (S22: NO), the control device 71 checks whether the trend of change in the output value of the angle sensor 81 has reversed from an upward trend or a downward trend to the other. If the trend of change in the output value of the angle sensor 81 has not reversed from an upward trend or a downward trend to the other (S23: NO), the control device 71 reads the bucket position information and checks whether the bucket 24 is positioned on the dump side E1 or the shovel side E2.

[0086] On the other hand, if, for example, the bucket control system is initialized for maintenance and the bucket placement information is not recorded in the storage unit 71a (S21: NO), the control device 71 determines either the extension or contraction direction of the bucket cylinder C5 based on the operating state of the operating lever 76 (S24). Also, if the bucket placement information indicates that the bucket 24 is positioned in the neutral position P3 (S22: YES), or if the trend of change in the output value of the angle sensor 81 reverses from an upward trend or a downward trend to the other (S23: YES), the control device 71 also determines either the extension or contraction direction of the bucket cylinder C5 based on the operating state of the operating lever 76 (S24).

[0087] In process S24, for example, if a first operation signal is output from the operating device 75 to the control device 71 in response to a first operation of the operating lever 76, the control device 71 determines that the operating direction of the bucket cylinder C5 is the contraction direction. Also, if a second operation signal is output from the operating device 75 to the control device 71 in response to a second operation of the operating lever 76, the control device 71 determines that the operating direction of the bucket cylinder C5 is the extension direction.

[0088] As another example, if the trend of change in the output value of the angle sensor 81 reverses from an upward trend or a downward trend to the other (S23:YES), the control device 71 may not execute processes S24 and S25, but instead determine that the bucket 24 is located on the opposite side E2 and E1 from the bucket placement information indicated by either bucket placement side E1 and E2.

[0089] Next, the control device 71 determines whether the bucket 24 is positioned on the dump side E1 or the shovel side E2 based on the trend of change in the output value of the angle sensor 81 and the operating direction of the bucket cylinder C5 (S25).

[0090] In process S25, for example, if the trend of change in the output value of the angle sensor 81 is upward and the operating direction of the bucket cylinder C5 is extension, the control device 71 determines that the bucket 24 is located on the dump side E1. Also, if the trend of change in the output value of the angle sensor 81 is upward and the operating direction of the bucket cylinder C5 is contraction, the control device 71 determines that the bucket 24 is located on the shovel side E2. Also, if the trend of change in the output value of the angle sensor 81 is downward and the operating direction of the bucket cylinder C5 is extension, the control device 71 determines that the bucket 24 is located on the shovel side E2. Furthermore, if the trend of change in the output value of the angle sensor 81 is downward and the operating direction of the bucket cylinder C5 is contraction, the control device 71 determines that the bucket 24 is located on the dump side E1.

[0091] Next, the control device 71 detects the oscillation angle of the bucket cylinder C5 based on the output value of the angle sensor 81 (S26, "Cylinder oscillation angle detection" in Figure 5). At this time, for example, the control device 71 refers to a control table previously stored in the storage unit 71a and determines the oscillation angle of the bucket cylinder C5 corresponding to the latest output value among the multiple output values ​​of the detected angle sensor 81. Alternatively, the control device 71 may calculate the oscillation angle of the bucket cylinder C5 by substituting the latest output value of the angle sensor 81 into a calculation formula previously stored in the storage unit 71a.

[0092] The control device 71 then determines the swing position of the bucket 24 based on the swing angle of the bucket cylinder C5 and the sides E1 and E2 on which the bucket 24 is located ("Bucket Swing Position Determination" in Figure 5), and records the determination result as bucket position information in the storage unit 71a (S27 in Figure 7). At this time, for example, the control device 71 may refer to a control table previously stored in the storage unit 71a and determine the swing angle of the bucket 24 from the swing angle of the bucket cylinder C5. Alternatively, the control device 71 may calculate the swing angle of the bucket 24 by substituting the swing angle of the bucket cylinder C5 into a calculation formula previously stored in the storage unit 71a.

[0093] Furthermore, the control device 71 determines, for example, that if the swing angle of the bucket cylinder C5 is θ1, the swing angle of the bucket 24 detected from the swing angle θ1 is θ1a, and the bucket 24 is positioned on the dump side E1, then the bucket 24 is in a position that has swung from the neutral position P3 to the dump side E1 by an angle θ1a.

[0094] Furthermore, the control device 71 determines, for example, that if the swing angle of the bucket cylinder C5 is θ2, the swing angle of the bucket 24 detected from the swing angle θ2 is θ2a, and the bucket 24 is positioned on the shovel side E2, then the bucket 24 is in a position that has swung from the neutral position P3 to the shovel side E2 by an angle of θ2a. Note that if the bucket cylinder C5 is in the reverse position Pm and the swing angle of the bucket cylinder C5 is 0°, the control device 71 determines that the bucket 24 is in the neutral position P3.

[0095] As another example, if the dump side E1 is represented as "-" (minus) and the shovel side E2 is represented as "+" (plus), and the swing angle of the bucket 24 is "θa", the control device 71 may determine the swing position of the bucket 24 as "-θa" or "+θa" depending on the sides E1 and E2 on which the bucket 24 is located. In this case, if the swing angle of the bucket cylinder C5 is 0°, the control device 71 may determine the swing angle and swing position of the bucket 24 as "0°".

[0096] As described above, once the bucket position determination process is complete, the control device 71 checks the operating status of the operating lever 76. If the operating lever 76 is not operated to the neutral position (S9:NO in Figure 6), the control device 71 repeats the process from S1 onwards.

[0097] Subsequently, if the operating lever 76 is operated to the neutral position (S9:YES), the control device 71 demagnetizes the first solenoid 72d / second solenoid 72e and switches the bucket control valve 72 to the third position 72c (S10). This stops the operation of the bucket cylinder C5 and the bucket 24. At this time, the control device 71 may also execute the processes S12 to S27 shown in Figure 7 to record the trend of change in the output value of the angle sensor 81 and the swinging position of the bucket 24 in the storage unit 71a.

[0098] According to the embodiment described above, as shown in Figure 5, immediately after the start of the first or second operation of the operating lever 76, while the amount of operation of the operating lever 76 is less than the threshold Xt, it takes time Ta for the control device 71 to determine the trend of change in the output value of the angle sensor 81. When the amount of operation of the operating lever 76 becomes equal to or greater than the threshold Xt, it takes time Tb, which is shorter than time Ta, for the control device 71 to determine the trend of change in the output value of the angle sensor 81. In other words, time Ta becomes longer than time Tb. Also, while the amount of operation of the operating lever 76 is less than the threshold Xt, it takes time Tc for the control device 71 to determine the swinging position of the bucket 24, and when the amount of operation of the operating lever 76 becomes equal to or greater than the threshold Xt, it takes time Td, which is shorter than time Tc, for the control device 71 to determine the swinging position of the bucket 24. In other words, time Tc becomes longer than time Td.

[0099] As described above, when the amount of operation of the operating lever 76 is less than the threshold Xt, the control device 71 samples the output value of the angle sensor 81 more times than when the amount of operation is greater than or equal to the threshold Xt, and determines the trend of change of these many output values ​​over a long period of time (times T1, T2, Ta, Tb in Figure 5), thereby improving the accuracy of determining the swing position of the bucket 24. In other words, there is a trade-off between the accuracy of determining the swing position of the bucket 24 and the time required for the determination. For this reason, depending on the state of the operating lever 76, the bucket cylinder C5, and the bucket 24, the control device 71 prioritizes the accuracy of determining the swing position of the bucket 24 when the amount of operation of the operating lever 76 is less than the threshold Xt, and prioritizes shortening the time required for the determination when the amount of operation is greater than or equal to the threshold Xt.

[0100] In the embodiment shown in Figure 7A, the control device 71 determines that the output value of the angle sensor 81 is trending upward or downward when the output value of the angle sensor 81 rises or falls continuously for predetermined times T1 and T2. However, the first time T1 and the second time T2 may not only be set to different values ​​(T1≠T2), but the first time T1 and the second time T2 may also be set to the same value (T1=T2). Alternatively, as in the embodiment shown in Figure 8, for example, the control device 71 may determine that the output value of the angle sensor 81 is trending upward or downward when the output value of the angle sensor 81 rises or falls continuously for a predetermined number of sampling times N1 and N2.

[0101] In detail, as shown in Figure 8, when the accuracy improvement flag is ON (S13: YES), the control device 71 determines whether the output value of the angle sensor 81 has been rising for a predetermined first number of consecutive times N1 and whether it has been falling for a first number of consecutive times N1. The first number of consecutive times N1 is the number of samples used to determine the trend of change in the output value of the angle sensor 81 with higher accuracy than under normal conditions, and is set to 2 or more samples, which is more than the second number of consecutive times N2 in the processes S18a and S19a described later. The second number of consecutive times N2 is the number of samples used to determine the trend of change in the output value of the angle sensor 81 under normal conditions.

[0102] If the output value of the angle sensor 81 increases for a first sampling count N1 consecutive times (S14a: YES), the control device 71 determines that the output value of the angle sensor 81 is trending upward and records this determination result in the storage unit 71a (S15). Also, if the output value of the angle sensor 81 decreases for a first sampling count N1 consecutive times (S16a: YES), the control device 71 determines that the output value of the angle sensor 81 is trending downward and records this determination result in the storage unit 71a (S17).

[0103] On the other hand, if the accuracy improvement flag is OFF (S13: NO), the control device 71 determines whether the output value of the angle sensor 81 has been rising for a predetermined second sampling number N2 consecutive times, and whether it has been falling for a second sampling number N2 consecutive times. If the output value of the angle sensor 81 has been rising for a second sampling number N2 consecutive times (S18a: YES), the control device 71 determines that the output value of the angle sensor 81 is trending upward and records this determination result in the storage unit 71a (S15). Also, if the output value of the angle sensor 81 has been falling for a second sampling number N2 consecutive times (S19a: YES), the control device 71 determines that the output value of the angle sensor 81 is trending downward and records this determination result in the storage unit 71a (S20). After this, the control device 71 executes the processes from S21 onwards as shown in Figure 7B, as described above.

[0104] As shown in the embodiment of Figure 8 described above, the control device 71 can improve the accuracy of determining the swinging position of the bucket 24 by sampling more output values ​​from the angle sensor 81 when the amount of operation of the operating lever 76 is less than the threshold Xt, compared to when the amount of operation is greater than or equal to the threshold Xt, and by judging the trend of change of these many output values ​​over a long period of time. In other words, the control device 71 can improve the accuracy of determining the swinging position of the bucket 24 by increasing the number of samples of output values ​​from the angle sensor 81 when the amount of operation of the bucket cylinder C5 is relatively small, compared to when the amount of operation is relatively large. As another example, the first sampling count N1 and the second sampling count N2 may not only be set to different values ​​(N1≠N2), but the first sampling count N1 and the second sampling count N2 may also be set to the same value (N1=N2).

[0105] In the above-described embodiment, as shown in FIG. 5, the control device 71 detects the output value of the angle sensor 81 at a constant period Ra. Instead of this, for example, as in the embodiment shown in FIG. 9, the control device 71 may make the sampling time T1 when the operation amount of the operation lever 76 is less than the threshold value Xt and the sampling time T2 when the operation amount is greater than or equal to the threshold value Xt equal (T1 = T2, that is, the sampling time is constant), and make the period R1 for detecting the output value of the angle sensor 81 when the operation amount of the operation lever 76 is less than the threshold value Xt shorter than the period R2 for detecting the output value of the angle sensor 81 when the operation amount is greater than or equal to the threshold value Xt (R1 < R2, that is, R1 ≠ R2).

[0106] Even so, when the operation amount of the operation lever 76 is small and the operation amount of the bucket cylinder C5 is also small, the control device 71 samples the output value of the angle sensor 81 more frequently than when the operation amount of the operation lever 76 is large and the operation amount of the bucket cylinder C5 is also large. Based on the many output values, the control device 71 determines the change trend of the output value of the angle sensor 81 and can improve the determination accuracy of the swing position of the bucket 24. In the example of FIG. 9, the number of samples of the output value of the angle sensor 81 when the operation amount of the operation lever 76 is less than the threshold value Xt is 6, while the number of samples of the output value of the angle sensor 81 when the operation amount is greater than or equal to the threshold value Xt is 4. Also, as another example, both the sampling time and the sampling period may be changed when the operation amount of the operation lever 76 is less than the threshold value Xt and when it is greater than or equal to the threshold value Xt.

[0107] In the above-described embodiment, in the process S24 of FIG. 7B, based on the operation state of the operation lever 76, the operation direction of either the extension or the contraction of the bucket cylinder C5 was determined. In addition to this, for example, as shown in FIGS. 10 and 11A to 11C, a position sensor 83 may be provided on the bucket cylinder C5 (working machine 1), and based on the detection signal output from the position sensor 83, the operation direction of either the extension or the contraction of the bucket cylinder C5 may be determined. As shown in FIG. 12, the position sensor 83 is included in the cylinder sensor 80.

[0108] As shown in Figures 10 and 11A to 11C, the position sensor 83 includes a first detectable member 86a, a second detectable member 86b, and a detector 87. The first detectable member 86a and the second detectable member 86b are fixed to the cylinder tube 36 of the bucket cylinder C5 via a plate 44. The first detectable member 86a extends further away from the head 37A than the second detectable member 86b. Furthermore, the extension direction of the first detectable member 86a is parallel to the extension and retraction direction of the bucket cylinder C5.

[0109] The detector 87 is fixed to the rod 37 via a sensor case 54 and a connecting member 59, etc. The detector 87 has a first detection element 87a and a second detection element 87b. For example, the detection elements 87a and 87b are proximity sensors, and the detected members 86a and 86b are magnetic materials in which permanent magnets 47 (Figure 19) are embedded. The first detection element 87a and the second detection element 87b are electrically connected to the control device 71. The first detection element 87a detects the first detected member 86a, and the second detected member 86b detects the second detected member 86b.

[0110] The configuration of the detection elements 87a, 87b and the detected members 86a, 86b is not limited to the above. For example, the detection elements 87a, 87b may be composed of optical sensors or limit switches, and the detected members 86a, 86b may be detected by the detected elements 87a, 87b.

[0111] When the rod 37 is the moving body, the detection elements 87a and 87b detect the members to be detected 86a and 86b while moving in conjunction with the rod 37. Alternatively, when the cylinder tube 36 is the moving body, the detection elements 87a and 87b detect the members to be detected 86a and 86b while moving in conjunction with the cylinder tube 36. As another example, the members to be detected 86a and 86b may be provided on the rod 37, and the detection elements 87a and 87b may be provided on the cylinder tube 36.

[0112] The detection elements 87a and 87b output ON / OFF signals to the control device 71 according to the relative position of the rod 37 with respect to the cylinder tube 36 when the bucket cylinder C5 extends or retracts. Specifically, the detection elements 87a and 87b output ON signals to the control device 71 when they detect the members to be detected 86a and 86b, respectively. Also, the detection elements 87a and 87b output OFF signals to the control device 71 when they do not detect the members to be detected 86a and 86b, respectively. The ON / OFF signals of the detection elements 87a and 87b are, for example, voltage signals, and the voltage value of the ON signal is set higher than that of the OFF signal.

[0113] As another example, the detection elements 87a and 87b may output OFF signals when they detect members 86a and 86b, respectively, and output OFF signals when they do not detect members 86a and 86b.

[0114] As shown in Figure 11C, when the bucket cylinder C5 is in its most retracted position Ps (most retracted state), the detection elements 87a and 87b are located on the bottom side of the bucket cylinder C5 (the side without the head 37A) relative to the detected members 86a and 86b. Furthermore, both detection elements 87a and 87b are far from the detected members 86a and 86b, and therefore do not detect them, outputting an OFF signal.

[0115] As the bucket cylinder C5 extends from its most retracted position Ps, the detection elements 87a and 87b pass each other. First, the first detection element 87a detects the first detection member 86a and outputs an ON signal. Then, as shown in Figure 11B, when the detection members 86a and 86b and the detection elements 87a and 87b are at the reference position Pb, the first detection element 87a detects the first detection member 86a and continues to output an ON signal. At the same time, the second detection element 87b also detects the second detection member 86b and outputs an ON signal.

[0116] When the first detection element 87a detects the first member to be detected 86a and the second detection element 87b detects the second member to be detected 86b, the bucket cylinder C5 is in the inversion position Pm and the bucket 24 is in the neutral position P3 (Figure 2). The reference position Pb corresponds to the inversion position Pm and the neutral position P3. When the bucket cylinder C5 extends further and the members to be detected 86a and 86b pass the detection elements 87a and 87b, both detection elements 87a and 87b no longer detect the members to be detected 86a and 86b and output an OFF signal.

[0117] As shown in Figure 11A, even when the bucket cylinder C5 is in its fully extended position PL (maximum extension state), both detection elements 87a and 87b are separated from the members to be detected 86a and 86b, and do not detect the members to be detected 86a and 86b, outputting an OFF signal. As the bucket cylinder C5 retracts from its fully extended position PL, and as shown in Figure 11B, when the members to be detected 86a and 86b and the detection elements 87a and 87b are at the reference position Pb, the first detection element 87a detects the first member to be detected 86a and outputs an ON signal, and the second detection element 87b also detects the second member to be detected 86b and outputs an ON signal.

[0118] As the bucket cylinder C5 contracts further, the first detection element 87a detects the first member to be detected 86a and continues to output an ON signal, while the second detection element 87b no longer detects the second member to be detected 86b and outputs an OFF signal. As the bucket cylinder C5 contracts further and the members to be detected 86a and 86b pass the detection elements 87a and 87b, both detection elements 87a and 87b no longer detect the members to be detected 86a and 86b and output an OFF signal.

[0119] As described above, the position sensor 83 detects whether the positions of the detected members 86a and 86b, which move as the work tool cylinder C5 expands and contracts, are on the extension side E4 or the contraction side E3 of the work tool cylinder C5 relative to the reference position Pb (Figure 11B) corresponding to the neutral position P3 of the work tool 24, and outputs an ON / OFF signal according to the detected state. The control device 71 determines the direction of operation of the bucket cylinder C5, either extension or contraction, based on the switching pattern of the ON / OFF signals from the detection elements 87a and 87b, when the bucket cylinder C5 is operating (contracting and oscillating) near the reversal position Pm and the bucket 24 is operating (oscillating) near the neutral position P3.

[0120] More specifically, when OFF signals are input from detection elements 87a and 87b, the control device 71 determines that the operating direction of the bucket cylinder C5 is extension when an ON signal is first input from the first detection element 87a, then from the second detection element 87b, and then from both detection elements 87a and 87b. Furthermore, when OFF signals are input from detection elements 87a and 87b, the control device 71 determines that the operating direction of the bucket cylinder C5 is contraction when an ON signal is first input from both detection elements 87a and 87b, then from the second detection element 87b, and then from the first detection element 87a.

[0121] The configuration of the position sensor 83 described above is merely an example and is not limiting. For example, the detector 87 may be provided with a single detection element, which can detect both the first member to be detected 86a and the second member to be detected 86b, and the control device 71 may determine the operating direction of the bucket cylinder C5, either expansion / contraction or contraction, based on the fluctuation pattern of the voltage value of the detection signal from the detection element.

[0122] Alternatively, for example, multiple detectable members of different lengths may be spaced apart in the extension and retraction direction of the bucket cylinder C5, and these multiple detectable members may be detected by a single detection element. The control device 71 may then determine the operating direction of the bucket cylinder C5, either extension or retraction, based on the fluctuation pattern of the voltage value of the detection signal from the detection element.

[0123] Alternatively, as shown in Figures 10 and 11A to 11C, only the first detectable member 86a and the first detection element 87a may be arranged (the second detectable member 86b and the second detection element 87b may be omitted), and the control device 71 may determine the operating direction of either extension or contraction of the bucket cylinder C5 based on the switching pattern of the ON / OFF signal of the first detection element 87a and the output value of the angle sensor 81. The configurations of the other examples described above are also examples of position sensor configurations and are not limiting.

[0124] In the embodiment described above, in process S25 of Figure 7B, the control device 71 determined the placement sides E1 and E2 of the bucket 24 based on the operating direction of the bucket cylinder C5 and the trend of change in the output value of the angle sensor 81. However, in addition to this, for example, Figure 13 As shown, the bucket control system (work equipment 1) may be provided with input switches 85 for inputting the placement sides E1 and E2 of the bucket 24. In this case, the input switches 85 are located near the driver's seat 6 of the work equipment 1 and are electrically connected to the control device 71.

[0125] For example, if the operator operates the control lever 76 to swing the bucket 24 to the dump side E1, when the bucket 24 reaches the dump end position P1, the operator operates the input switch 85 to input that the bucket 24 is positioned on the dump side E1. Also, if the operator operates the control lever 76 to move the bucket 24 to the shovel side E2, when the bucket 24 reaches the shovel end position P2, the operator operates the input switch 85 to input that the bucket 24 is positioned on the shovel side E2. The control device 71 records the bucket 24's position E1 and E2, as input by the input switch 85 as described above, in the storage unit 71a.

[0126] Another example is that the control device 71 may be configured to automatically recognize the positions E1 and E2 of the bucket 24. For example, the output value of the angle sensor 81 when the bucket 24 is at the dump end position P1 may be set to a predetermined first voltage value, and the output value of the angle sensor 81 when the bucket 24 is at the shovel end position P2 may be set to a predetermined second voltage value different from the first voltage value. The control device 71 may then determine that the bucket 24 is positioned at the dump end position P1 when the output value of the angle sensor 81 matches the first voltage value, and determine that the bucket 24 is positioned at the shovel end position P2 when the output value of the angle sensor 81 matches the second voltage value, and record these determination results in the storage unit 71a.

[0127] Furthermore, the control device 71 may determine the operating direction of the bucket cylinder C5 or the positioning sides E1 and E2 of the bucket 24 by appropriately combining two or more of the following: the operating state of the operating lever 76, the output value of the angle sensor 81, the ON / OFF signal of the position sensor 83, the input switch 85, and the automatic recognition of the bucket 24's positioning sides E1 and E2.

[0128] In the embodiment described above, the amount of operation of the operating lever 76 was used as the physical quantity (physical quantity for changing accuracy) included in the condition (processing S5 in Figure 6) that changes in response to the operation of the operating lever 76 and changes the accuracy of determining the swinging position of the bucket 24. However, instead, for example, the control current value (input current value) to the corresponding solenoids 72d and 72e when switching the bucket control valve 72 to either the first position 72a or the second position 72b, or the flow rate or hydraulic pressure of the hydraulic fluid flowing from the bucket control valve 72 to the bucket cylinder C5 (output value from the bucket control valve 72) may be used as the physical quantity for changing accuracy.

[0129] When the control current values ​​for solenoids 72d and 72e are used as the physical quantities for changing the accuracy as described above, the control device 71, in response to the first or second operation of the operating lever 76, switches the bucket control valve 72 to either the first position 72a or the second position 72b (processing S2 or S4 in Figure 6), comparing the control current values ​​for solenoids 72d and 72e corresponding to the operation of the operating lever 76 with a predetermined threshold value At read from the storage unit 71a. Then, instead of processing S5 in Figure 6, the control device 71 confirms that the control current values ​​for solenoids 72d and 72e are less than the threshold value At, and turns on the accuracy improvement flag (S6). Conversely, if it confirms that the control current values ​​for solenoids 72d and 72e are greater than or equal to the threshold value At, it turns off the accuracy improvement flag (S7).

[0130] As the threshold value At, for example, the manufacturer of the work implement 1 may pre-set the input current value to the first solenoid 72d or the second solenoid 72e, measured when the bucket 24 continues to swing in one direction without rattling in response to the first or second operation of the operating lever 76, for each individual work implement 1. In other words, the threshold value At may be a unique threshold value set for each individual work implement 1, even if they are the same model.

[0131] Furthermore, if the flow rate of hydraulic fluid from the bucket control valve 72 to the bucket cylinder C5 is used as the physical quantity for changing the accuracy, for example, as shown in Figure 13, a first flow sensor 91a is provided in the first supply oil passage 73C and a second flow sensor 91b is provided in the second supply oil passage 73D, of the supply oil passages 73C and 73D connected to the bucket control valve 72 and the bucket cylinder C5. When the bucket control valve 72 is switched to the first position 72a, the control device 71 measures the flow rate of hydraulic fluid flowing from the bucket control valve 72 to the bucket cylinder C5 using the second flow sensor 91b. When the bucket control valve 72 is switched to the second position 72b, the control device 71 measures the flow rate of hydraulic fluid flowing from the bucket control valve 72 to the bucket cylinder C5 using the first flow sensor 91a.

[0132] In other words, after the process S2 shown in Figure 6, the control device 71 measures the flow rate of the hydraulic fluid using the second flow sensor 91b, and after the process S4, measures the flow rate of the hydraulic fluid using the first flow sensor 91a, and compares the measured value with a predetermined threshold Zt stored in the storage unit 71a. Then, instead of process S5, if the measured value (flow rate of hydraulic fluid) is less than the threshold Zt, the accuracy improvement flag is turned ON (S6). If the measured value is greater than or equal to the threshold Zt, the accuracy improvement flag is turned OFF (S7). As the threshold Zt, for example, the manufacturer of the work machine 1 may set the flow rate of the hydraulic fluid from the bucket control valve 72 to the bucket cylinder C5, measured when the bucket 24 continues to swing in one direction without rattling in response to the first or second operation of the operating lever 76, for each individual work machine 1. That is, the threshold Zt is a unique threshold for each individual work machine 1.

[0133] Furthermore, if the hydraulic pressure of the hydraulic fluid flowing from the bucket control valve 72 to the bucket cylinder C5 is used as the physical quantity for changing the accuracy, for example, as shown in Figure 14, a first pressure sensor 92a is provided in the first supply oil passage 73C and a second pressure sensor 92b is provided in the second supply oil passage 73D, among the supply oil passages 73C and 73D connected to the bucket control valve 72 and the bucket cylinder C5. When the bucket control valve 72 is switched to the first position 72a, the control device 71 measures the hydraulic pressure of the hydraulic fluid flowing from the bucket control valve 72 to the bucket cylinder C5 using the second pressure sensor 92b. When the bucket control valve 72 is switched to the second position 72b, the control device 71 measures the hydraulic pressure of the hydraulic fluid flowing from the bucket control valve 72 to the bucket cylinder C5 using the first pressure sensor 92a.

[0134] In other words, after processing S2 in Figure 6, the control device 71 measures the hydraulic pressure of the hydraulic fluid using the second pressure sensor 92b, and after processing S4, measures the hydraulic pressure of the hydraulic fluid using the first pressure sensor 92a, and compares the measured value with a predetermined threshold Zh stored in the storage unit 71a. Then, instead of processing S5, if the measured value (hydraulic fluid pressure) is less than the threshold Zh, the accuracy improvement flag is turned ON (S6). If the measured value is equal to or greater than the threshold Zh, the accuracy improvement flag is turned OFF (S7). As the threshold Zh, for example, the manufacturer of the work machine 1 may set the hydraulic pressure of the hydraulic fluid from the bucket control valve 72 to the bucket cylinder C5, measured when the bucket 24 continues to swing in one direction without rattling in response to the first or second operation of the operating lever 76, for each individual work machine 1. That is, the threshold Zh is a unique threshold for each individual work machine 1.

[0135] Of the candidate physical quantities for accuracy modification described above (operating amount of the operating lever 76, control current value to the bucket control valve, flow rate of hydraulic fluid from the bucket control valve 72 to the bucket cylinder C5, and hydraulic pressure), the adopted physical quantity and the accuracy modification conditions including the applied physical quantity are stored in the non-volatile memory contained in the storage unit 71b. Furthermore, any of the physical quantities and accuracy modification conditions stored in the non-volatile memory can be rewritten, for example, by a manufacturer using a rewriting terminal device consisting of a personal computer, and any of the other candidate physical quantities and the corresponding accuracy modification conditions. physical quantity The conditions for changing the accuracy, including the conditions for accuracy, can be rewritten accordingly.

[0136] The work machine 1 of this embodiment has the following configuration and achieves the following effects.

[0137] The work machine 1 of this embodiment includes an arm 23, a work tool (bucket) 24 swingably mounted on the arm 23, a work tool cylinder (bucket cylinder) C5 whose one end is supported by the arm via a cylinder shaft and whose other end is supported by the work tool 24, and which swings the work tool 24 by extending and retracting, a cylinder sensor 80 that detects the operation of the work tool cylinder C5, a control valve (bucket control valve) 72 that controls the flow of hydraulic fluid to the work tool cylinder C5 to contract the work tool cylinder C5, and a control device 71 that periodically determines the swinging position of the work tool 24 based on the output value of the cylinder sensor 80, wherein the control device 71 changes the accuracy of determining the swinging position of the work tool 24 according to the operating state of the work tool cylinder C5.

[0138] With the above configuration, the accuracy of the control device 71's determination of the swinging position of the work tool 24 is not always constant, but changes according to the operating state of the work tool cylinder C5. Therefore, the swinging position of the work tool 24 can be appropriately determined according to the state of the work tool 24 swinging according to the operating state of the work tool cylinder C5.

[0139] In one embodiment, the control valve 72 has a first solenoid 72d and a second solenoid 72e, and is switchable to a first position 72a that retracts the work tool cylinder C5, a second position 72b that extends the work tool cylinder C5, and a third position 72c in which the work tool cylinder C5 is not extended or retracted. When the control valve 72 is in either the first position 72a or the second position 72b, the control device 71 improves the accuracy of determining the swinging position of the work tool 24 until a predetermined condition is met, compared to the predetermined accuracy of determination under normal circumstances.

[0140] As described above, the control device 71 improves the accuracy of determining the oscillation position of the work tool 24 from the start of operation of the control valve 72 until the predetermined conditions are met, so even if sufficient hydraulic pressure is not applied from the control valve 72 to the work tool cylinder C5, and the work tool cylinder C5 and work tool 24 rattle due to external forces, causing the output value of the cylinder sensor 80 to fluctuate irregularly, it is possible to prevent misjudgment of the oscillation position of the work tool 24. Furthermore, since the predetermined conditions are met, the control device 71 does not improve the accuracy of determining the oscillation position of the work tool 24, but determines the oscillation position of the work tool 24 with the normal judgment accuracy. This suppresses the time required to determine the oscillation position of the work tool 24 from becoming longer when sufficient hydraulic pressure is applied from the control valve 72 to the work tool cylinder C5 and the work tool cylinder C5 and work tool 24 are operating stably in response to the operation of the control valve 72, and allows the oscillation position of the work tool 24 to be appropriately determined in accordance with the operating speed of the work tool 24. As a result, based on the determined swing position of the work tool 24, the work machine 1 can perform the work appropriately using the work tool 24.

[0141] In one embodiment, the work machine 1 is equipped with an operating member (operating lever) 76 for operating the swing of the work tool cylinder C5, and the control device 71, when the operating member 76 is started to be operated and the control valve 72 is in either the first position 72a or the second position 72b, improves the accuracy of determining the swing position of the work tool 24 to the normal accuracy when the amount of operation of the operating member 76 is less than a predetermined threshold Xt, and sets the accuracy of determining the swing position of the work tool 24 to the normal accuracy when the amount of operation becomes equal to or greater than the threshold Xt.

[0142] As described above, when the amount of operation of the operating member 76 is less than the threshold Xt after operation of the operating member 76 is started, sufficient hydraulic pressure does not act on the work tool cylinder C5, causing the work tool cylinder C5 and the work tool 24 to rattle and the output value of the cylinder sensor 80 to fluctuate irregularly. However, the control device 71 improves the accuracy of determining the oscillation position of the work tool 24 compared to normal conditions, so that the oscillation position can be appropriately determined. Furthermore, when the amount of operation of the operating member 76 is greater than or equal to the threshold Xt, the control device 71 determines the oscillation position of the work tool 24 with the accuracy of normal conditions. Therefore, when sufficient hydraulic pressure acts on the work tool cylinder C5 and the work tool cylinder C5 and the work tool 24 are operating stably, the oscillation position of the work tool 24 can be appropriately determined in accordance with the operating speed of the work tool 24.

[0143] In one embodiment, the work machine 1 includes solenoids 72d and 72e that operate a control valve in accordance with a control current supplied from the control device 71. When the control valve 72 is in either the first position 72a or the second position 72c, the control device 71 improves the accuracy of determining the swing position of the work tool compared to the normal accuracy when the control current value, which is the current value of the control current supplied to the solenoid, is less than a predetermined threshold At. When the control current value becomes equal to or greater than the threshold At, the accuracy of determining the swing position of the work tool 24 is set to the normal accuracy.

[0144] In a configuration where the control current supplied to solenoids 72d and 72e is gradually increased to a target value Ag when the control valve 72 is activated, the opening degree of the control valve 72 is low while the control current value is low, and sufficient hydraulic pressure does not act on the work tool cylinder C5, causing the work tool cylinder C5 and work tool 24 to rattle, which can cause the output value of the cylinder sensor 80 to fluctuate irregularly. However, when the control current value to solenoids 72d and 72e is less than the threshold value At, the control device 71 improves the accuracy of determining the swing position of the work tool 24 compared to normal conditions. Therefore, even if sufficient hydraulic pressure does not act on the work tool cylinder C5, causing the work tool cylinder C5 and work tool 24 to rattle, and the output value of the cylinder sensor 80 to fluctuate irregularly, the swing position of the work tool 24 can be appropriately determined. Furthermore, when the control current values ​​to the solenoids 72d and 72e exceed the threshold At, the control device 71 determines the oscillation position of the work tool 24 with normal accuracy. This allows the oscillation position of the work tool 24 to be appropriately determined in accordance with the operating speed of the work tool 24 when sufficient hydraulic pressure is acting on the work tool cylinder C5 and the work tool cylinder C5 and work tool 24 are operating stably.

[0145] In one embodiment, the work machine 1 is equipped with flow sensors 91a and 91b that measure the flow rate of hydraulic fluid flowing from the control valve 72 to the work tool cylinder C5. When the control valve 72 is in either the first position 72a or the second position 72c, the control device 71 improves the accuracy of determining the oscillation position of the work tool 24 to the normal accuracy when the flow rate of hydraulic fluid measured by the flow sensors 91a and 91b is less than a predetermined threshold Zt, and sets the accuracy of determining the oscillation position of the work tool 24 to the normal accuracy when the flow rate of hydraulic fluid is equal to or greater than the threshold Zt.

[0146] As described above, when the control valve 72 is activated, if the flow rate of hydraulic fluid from the control valve 72 to the tool cylinder C5 is less than the threshold Zt, sufficient hydraulic pressure does not act on the tool cylinder C5, causing the tool cylinder C5 and the tool 24 to rattle and the output value of the cylinder sensor 80 to fluctuate irregularly. However, the control device 71 improves the accuracy of determining the oscillation position of the tool 24 compared to normal conditions, so that the oscillation position can be appropriately determined. Furthermore, when the flow rate of hydraulic fluid from the control valve 72 to the tool cylinder C5 is equal to or greater than the threshold Zt, the control device 71 determines the oscillation position of the tool 24 with the accuracy of normal conditions. Therefore, when sufficient hydraulic pressure acts on the tool cylinder C5 and the tool cylinder C5 and the tool 24 are operating stably, the oscillation position of the tool 24 can be appropriately determined in accordance with the operating speed of the tool 24.

[0147] In one embodiment, the work machine 1 is equipped with pressure sensors 92a and 92b that measure the hydraulic pressure of the hydraulic fluid acting on the work tool cylinder C5 from the control valve 72. When the control valve 72 is in either the first position 72a or the second position 72c, the control device 71 improves the accuracy of determining the swing position of the work tool 24 to the normal accuracy when the hydraulic pressure of the hydraulic fluid measured by the pressure sensors 92a and 92b is less than a predetermined threshold Zh, and sets the accuracy of determining the swing position of the work tool 24 to the normal accuracy when the hydraulic pressure of the hydraulic fluid is equal to or greater than the threshold Zh.

[0148] As described above, when the control valve 72 is activated, if the hydraulic pressure of the hydraulic fluid from the control valve 72 to the tool cylinder C5 is below the threshold Zh, sufficient hydraulic pressure does not act on the tool cylinder C5, causing the tool cylinder C5 and the tool 24 to rattle and the output value of the cylinder sensor 80 to fluctuate irregularly. However, the control device 71 improves the accuracy of determining the oscillation position of the tool 24 compared to normal conditions, so that the oscillation position can be appropriately determined. Furthermore, when the hydraulic pressure of the hydraulic fluid from the control valve 72 to the tool cylinder C5 exceeds the threshold Zh, the control device 71 determines the oscillation position of the tool 24 with the accuracy of normal conditions. Therefore, when sufficient hydraulic pressure acts on the tool cylinder C5 and the tool cylinder C5 and the tool 24 are operating stably, the oscillation position of the tool 24 can be appropriately determined in accordance with the operating speed of the tool 24.

[0149] In one embodiment, the control device 71 changes the accuracy of determining the swing position of the work tool 24 by changing the sampling rate of the output value of the cylinder sensor 80 used to determine the swing position of the work tool 24. By increasing the sampling rate of the output value of the cylinder sensor 80, the accuracy of determining the swing position of the work tool 24 can be improved.

[0150] In one embodiment, the control device 71 changes the number of samples of the output values ​​of the cylinder sensor 80 used to determine the swinging position of the work tool 24 by changing at least one of the sampling times T1, T2 and sampling periods R1, R2. This allows the number of samples of the output values ​​of the cylinder sensor 80 to be increased, for example, by increasing the sampling time T1 or shortening the sampling period R1.

[0151] In one embodiment, the work machine 1 includes a body 2 that supports the arm 23, and the cylinder sensor 80 includes an angle sensor 81 that detects the swing angle of the work tool cylinder C5 when the work tool 24 is positioned on the side away from the body 2 (dump side) E1 and when the work tool 24 is positioned on the side closer to the body 2 (shovel side) E2, with respect to the neutral position P3 of the work tool 24 where the swing angle of the work tool cylinder C5 around the cylinder axis 35 is maximum. The control device 71 detects the output value of the angle sensor 81 at a predetermined period, determines the trend of change of the output value, and determines the swing position of the work tool 24 based on the trend of change of the output value, the operating direction of either extension or contraction of the work tool cylinder C5, and the swing angle of the work tool cylinder C5 detected from the output value of the angle sensor 81. As a result, even if the working tool 24 swings past the neutral position P3 and the direction of swing of the working tool cylinder C5 reverses, the swing position of the working tool 24 on the side E1 away from the machine body 2 and the side E2 approaching the machine body 2 can be accurately determined.

[0152] In one embodiment, the control device 71 determines that the output value of the angle sensor 81 is trending upward if it rises continuously for predetermined times T1 and T2 (first time T1, second time T2), and determines that the output value is trending downward if it falls continuously for predetermined times T1 and T2, and changes the predetermined times T1 and T2 according to the operating state of the work tool cylinder C5. This makes it possible to accurately determine the swing position of the work tool 24 when the output value of the angle sensor 81 is stably changing to either an upward or downward trend. Furthermore, from immediately after the start of operation of the control valve 72 until predetermined conditions are met, the trend of change in the output value can be determined with higher accuracy based on a large number of sampled output values ​​from the cylinder sensor 80, compared to after the predetermined conditions are met, and the swing position of the work tool 24 can be determined with improved accuracy.

[0153] Furthermore, in one embodiment, the control device 71 determines that the output value of the angle sensor 81 is trending upward when it rises for a predetermined number of sampling times N1, N2 (first number N1, second number N2), and determines that the output value is trending downward when it falls for a predetermined number of sampling times N1, N2. The control device 71 changes the predetermined number of sampling times N1, N2 according to the operating state of the work tool cylinder C5. This allows for accurate determination of the swing position of the work tool 24 when the output value of the angle sensor 81 is stably changing to either an upward or downward trend. In addition, from immediately after the start of operation of the control valve 72 until a predetermined condition is met, the change trend of the output value can be determined with higher accuracy based on the numerous sampled output values ​​of the cylinder sensor 80, compared to after the predetermined condition is met, and the swing position of the work tool 24 can be determined with improved accuracy.

[0154] In one embodiment, the work machine 1 is equipped with an operating member 76 for operating the swing of the work tool 24, and the control device 71 determines the operating direction of the work tool cylinder C5 based on the operating state of the operating member 76. This makes it possible to reliably detect either the extension / contraction or retraction direction of the work tool cylinder C5 in response to the operation of the operating member 76. Furthermore, even if the work tool 24 swings past the neutral position P3 and the swing direction of the work tool cylinder C5 reverses, the swing position of the work tool 24 on either the side E1 away from the machine body 2 or the side E2 approaching the machine body 2 can be accurately determined from the operating direction of the work tool cylinder C5.

[0155] Furthermore, in one embodiment, solenoids 72d and 72e are provided to operate control valves 72 in accordance with control current supplied from the control device 71, and the control device 71 determines the operating direction of the work tool cylinder C5 based on the control current values ​​supplied to the solenoids 72d and 72e. This makes it possible to reliably detect either the extension / contraction or retraction direction of the actual work tool cylinder C5 that is operated in response to the operation of the operating member 76. Even if the work tool 24 swings past the neutral position P3 and the swing direction of the work tool cylinder C5 reverses, the swing position of the work tool 24 on either the side E1 away from the machine body 2 or the side E2 approaching the machine body 2 can be accurately determined from the operating direction of the work tool cylinder C5.

[0156] In one embodiment, the work machine 1 is equipped with a storage device (storage unit) 71b that stores changeable setting information regarding predetermined conditions for changing the accuracy of determining the swing position of the work tool 24, and the control device 71 determines the predetermined conditions according to the setting information stored in the storage device 71b. As a result, the predetermined conditions for changing the accuracy of determining the swing position of the work tool 24 can be arbitrarily changed by rewriting the setting information stored in the storage device 71b.

[0157] Furthermore, in one embodiment, the setting information stored in the storage device 71b includes a threshold value specific to the work machine 1, which is used for comparison with a physical quantity included in predetermined conditions that change in response to the operation of the operating member 76 and change the accuracy of determining the swing position of the work tool 24. This allows the accuracy of determining the swing position of the work tool 24 to be changed according to the operating state of the work tool cylinder C5 for each work machine 1, thereby appropriately determining the swing position of the work tool 24 according to the state of the work tool 24.

[0158] Although one embodiment of the present invention has been described above, the embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than the foregoing description, and all modifications within the meaning and scope of equivalents of the claims are intended to be included. [Explanation of Symbols]

[0159] 2 units 23 Arms 24 Buckets (work tools) 35 Cylinder shaft 71 Control device 71a Storage unit (storage device) 72 Bucket control valve (control valve) 72a 1st position 72b 2nd position 72c 3rd position 72d First solenoid 72e Second solenoid 76 Operating lever (operating component) 80 Cylinder Sensor 81 Angle Sensor 83 Position Sensor 86 Detected Member 86a First detected member 86b Second detected member 91a First flow sensor 91b Second flow sensor 92a First pressure sensor 92b Second pressure sensor At the threshold of the control current C5 Bucket Cylinder (Tool Cylinder) D1 1st direction D2 2nd direction E1 Dump side (side away from the aircraft) E2 Shovel side (the side approaching the aircraft) E3 contraction side E4 Extension side N1: First sampling count N2 Second sampling count P3 neutral position R1, R2, Ra sampling period Tx predetermined period T1: First hour, sampling time (predetermined time) T2 Second time, sampling time (predetermined time) Threshold for the Xt manipulation variable Zt threshold for hydraulic fluid flow rate Zh Hydraulic fluid pressure threshold

Claims

1. Arm and A work tool is pivotably mounted on the aforementioned arm, A work tool cylinder, one end of which is supported by the arm via a cylinder shaft and the other end of which is supported by the work tool, swings the work tool by extending and retracting, A cylinder sensor that detects the operation of the work tool cylinder, which is at least one of the oscillation of the work tool cylinder around the cylinder axis and the extension and retraction of the work tool cylinder, A control valve controls the flow of hydraulic fluid to the work tool cylinder to extend and retract the work tool cylinder, The system includes a control device that periodically determines the swinging position of the work tool based on the output value of the cylinder sensor, The control device changes the judgment accuracy, which is the accuracy of the periodically determined oscillation position, by changing the sampling number, which is the number of output values ​​used to determine the oscillation position, according to the value of a physical quantity related to the operation of the work tool cylinder.

2. The control valve is switchable to a first position in which the hydraulic fluid flows into the first pressure chamber of the work tool cylinder to contract the work tool cylinder, a second position in which the hydraulic fluid flows into the second pressure chamber of the work tool cylinder to extend the work tool cylinder, and a neutral position in which the hydraulic fluid does not flow into the work tool cylinder. The work machine according to claim 1, wherein the control device, when the control valve is in either the first position or the second position, improves the judgment accuracy by increasing the number of samples compared to when the predetermined conditions are met, if the predetermined conditions are not met.

3. An operating member that is operated to change the position and opening degree of the control valve and cause the work tool cylinder to perform the operation, The system includes a sensor that detects the amount of operation of the operating member, The predetermined condition is that the manipulated quantity, which is the physical quantity, is greater than or equal to a threshold. The work machine according to claim 2, wherein the control device improves the judgment accuracy when the operating amount is less than the threshold when the operating amount is greater than or equal to the threshold when the operating member is started to be operated and the control valve is in either the first position or the second position.

4. It includes a solenoid that operates the control valve in accordance with the supplied control current, The predetermined condition is that the current value of the control current, which is the physical quantity, is equal to or greater than a threshold value. The work machine according to claim 2, wherein the control device improves the judgment accuracy when the current value is less than the threshold value when the control valve is in either the first position or the second position, compared to when the current value is equal to or greater than the threshold value.

5. The system includes a flow sensor for measuring the flow rate of the hydraulic fluid that flows from the control valve to the work tool cylinder, The predetermined condition is that the flow rate, which is the physical quantity, is equal to or greater than a threshold. The work machine according to claim 2, wherein the control device improves the judgment accuracy when the flow rate is less than the threshold when the flow rate is greater than or equal to the threshold when the control valve is in either the first position or the second position.

6. The control valve is equipped with a pressure sensor that measures the hydraulic pressure of the hydraulic fluid acting on the work tool cylinder, The predetermined condition is that the physical quantity, the hydraulic pressure, is equal to or greater than a threshold value. The work machine according to claim 2, wherein the control device improves the judgment accuracy when the hydraulic pressure is less than the threshold when the hydraulic pressure is greater than or equal to the threshold when the control valve is in either the first position or the second position.

7. The work machine according to claim 1, wherein the control device changes the number of samples by changing at least one of the sampling time and sampling period for sampling the output value of the cylinder sensor.

8. The machine comprises a body that supports the aforementioned arm, The cylinder sensor includes an angle sensor that detects the oscillation angle of the work tool cylinder when the work tool is positioned away from the machine body and the oscillation angle of the work tool cylinder when the work tool is positioned closer to the machine body, with respect to the neutral position of the work tool where the oscillation angle of the work tool cylinder around the cylinder axis is maximum. The control device determines the swing position of the work tool based on the trend of change in the output value of the angle sensor, the operating direction of either extension or contraction of the work tool cylinder, and the swing angle of the work tool cylinder detected from the output value of the angle sensor, according to any one of claims 1 to 7.

9. The control device is When the output value of the angle sensor rises continuously for a predetermined period of time, it is determined that the output value is on an upward trend. If the output value of the angle sensor decreases continuously for a predetermined period of time, it is determined that the output value is in a downward trend. The work machine according to claim 8, wherein the predetermined time is changed according to the value of the physical quantity.

10. The control device is When the output value of the angle sensor increases for a predetermined number of consecutive samplings, it is determined that the output value is on an upward trend. When the output value of the angle sensor decreases for a predetermined number of consecutive samplings, it is determined that the output value is in a downward trend. The work machine according to claim 8, wherein the predetermined number of samplings is changed according to the value of the physical quantity.

11. The tool is equipped with an operating member that is operated to swing the aforementioned work tool, The work machine according to claim 8, wherein the control device determines the operating direction of the work tool cylinder based on the operating direction of the operating member.

12. It includes a solenoid that operates the control valve in accordance with the supplied control current, The work machine according to claim 8, wherein the control device determines the operating direction of the work tool cylinder based on the current value of the control current.

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