Work machine and method for controlling work machine

Abstract

To suppress vibrations in a vehicle body.SOLUTION: A work machine comprises a vehicle body, a work implement operably attached to the vehicle body and having an attachment at its tip, an operating device that outputs operation commands to operate the attachment, a vibration sensor that detects vibrations of the vehicle body, and a controller that sets restrictions on the operation of the attachment in response to the operation commands based on the detection results of vibrations of the vehicle body generated during work using the attachment.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to a work machine and a method for controlling a work machine. [Background technology]

[0002] As an example of the prior art, a work machine described in JP 2021-43804 A (Patent Document 1) is exemplified. In this work machine, an application unit that applies force to an operating lever that operates the work equipment is controlled based on the acceleration of the vehicle body to automatically adjust the magnitude of the force applied to the operating lever. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-43804 Summary of the Invention [Problem to be solved by the invention]

[0004] If the vibration of the work machine's body causes the operating lever to vibrate, the input of the operating lever may be unintentionally applied to the work equipment, causing the work equipment to vibrate, which may further increase the vibration of the body.

[0005] This disclosure proposes a work machine and a control method for a work machine that are capable of suppressing vibrations of the vehicle body. [Means for solving the problem]

[0006] A work machine according to the present disclosure comprises a vehicle body, a work implement operably attached to the vehicle body and having an attachment at its tip, an operating device that outputs operation commands to operate the attachment, a vibration sensor that detects vibrations of the vehicle body, and a controller that sets restrictions on the operation of the attachment in response to the operation commands based on the detection results of vibrations of the vehicle body generated during work by the attachment.

[0007] A method of controlling a work machine according to the present disclosure comprises receiving an input of an operation command to operate an attachment at the tip of a work machine operably attached to a vehicle body, detecting vibrations of the vehicle body generated by work performed by the attachment, and setting restrictions on operation of the attachment in response to the operation command based on the detection results of the vibrations of the vehicle body. Effect of the Invention

[0008] According to the work machine and the control method for the work machine of the present disclosure, vibrations of the vehicle body can be suppressed. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a side view of a wheel loader as an example of a work machine. [Diagram 2] FIG. 1 is a schematic block diagram showing a configuration of an entire system including a wheel loader. [Diagram 3] FIG. [Figure 4] 2 is a block diagram showing a functional configuration of a work machine controller. FIG. [Diagram 5] 10 is a flowchart showing an example of bucket operation control. [Figure 6] FIG. 4 is a first diagram showing a flow rate of hydraulic oil supplied to a bucket cylinder. [Figure 7] FIG. 4 is a second diagram showing the flow rate of the hydraulic oil supplied to the bucket cylinder. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the embodiments will be described with reference to the drawings. In the following description, the same parts and components are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated. In the drawings, configurations may be omitted or simplified for convenience of explanation. It is also intended from the beginning that any configurations may be extracted from the embodiments and arbitrarily combined.

[0011] <Overall configuration of wheel loader 1> In the embodiment, a wheel loader 1 will be described as an example of a work machine. Fig. 1 is a side view of a wheel loader 1 as an example of a work machine based on the embodiment.

[0012] As shown in Fig. 1, the wheel loader 1 comprises a vehicle body frame 2, a work implement 3, a traveling device 7, and a cab 5. The vehicle body (work machine body) of the wheel loader 1 is made up of the vehicle body frame 2, the cab 5, etc. The vehicle body of the wheel loader 1 has the work implement 3 and the traveling device 7 attached to it.

[0013] The traveling device 7 allows the body of the wheel loader 1 to travel, and includes traveling wheels 7A, 7B. The wheel loader 1 is a wheeled vehicle equipped with traveling wheels 7A, 7B on both the left and right sides of the body as rotating bodies for traveling. The wheel loader 1 is self-propelled by driving the running wheels 7A, 7B to rotate, and can perform desired work using the work machine 3.

[0014] In this specification, the direction in which the wheel loader 1 travels straight ahead is referred to as the fore-and-aft direction of the wheel loader 1. In the fore-and-aft direction of the wheel loader 1, the side where the work machine 3 is arranged with respect to the vehicle body frame 2 is referred to as the front direction, and the side opposite the front direction is referred to as the rear direction. The left-right direction of the wheel loader 1 is the direction perpendicular to the fore-and-aft direction when the wheel loader 1 is viewed in plan on a flat surface. Looking forward, the right and left sides in the left-and-right direction are the right direction and the left direction, respectively. The up-and-down direction of the wheel loader 1 is the direction perpendicular to the plane defined by the fore-and-aft direction and the left-and-right direction. In the up-and-down direction, the side with the ground is the lower side, and the side with the sky is the upper side.

[0015] The vehicle body frame 2 includes a front frame 2A and a rear frame 2B. The front frame 2A is disposed in front of the rear frame 2B. The front frame 2A is connected to the rear frame 2B so as to be able to bend. The front frame 2A and the rear frame 2B form the vehicle body frame 2 with an articulated structure. The wheel loader 1 is an articulated work machine in which the front frame 2A and the rear frame 2B are connected.

[0016] A work implement 3 and a pair of left and right running wheels (front wheels) 7A are attached to the front frame 2A. The work implement 3 is disposed at the front of the vehicle body and is supported by the vehicle body of the wheel loader 1. The work implement 3 includes a boom 32 and a bucket 31. The bucket 31 is disposed at the tip of the work implement 3. The bucket 31 is a working tool for excavation and loading. The bucket 31 is an example of an attachment that is detachably mounted to the tip of the boom 32. The attachment can be changed to a grapple, fork, plow, or the like depending on the type of work.

[0017] The work implement 3 includes a boom cylinder 36. The front frame 2A and the boom 32 are connected by a pair of boom cylinders 36. A base end of the boom cylinder 36 is attached to the front frame 2A. A tip end of the boom cylinder 36 is attached to the boom 32. The boom cylinder 36 is a hydraulic actuator that moves the boom 32 up and down relative to the front frame 2A. As the boom 32 rises and falls, the bucket 31 attached to the tip of the boom 32 also rises and falls. The work implement 3 is operably attached to the front frame 2A.

[0018] The work machine 3 further includes a bell crank 33, a connecting link 34, and a bucket cylinder 35. The bell crank 33 is rotatably supported on the boom 32 at approximately the center of the boom 32. The bucket cylinder 35 connects the bell crank 33 to the front frame 2A. The connecting link 34 is connected to the tip of the bell crank 33. The connecting link 34 connects the bell crank 33 to the bucket 31.

[0019] A base end of the bucket cylinder 35 is attached to the front frame 2A. A tip end of the bucket cylinder 35 is attached to a base end of the bell crank 33. The bucket cylinder 35 is a hydraulic actuator that rotates the bucket 31 up and down relative to the boom 32. The bucket cylinder 35 is a work tool cylinder that drives the bucket 31. The bucket 31 is configured to be movable relative to the boom 32.

[0020] A cab 5 in which an operator sits, and a pair of left and right running wheels (rear wheels) 7B are attached to the rear frame 2B. The box-shaped cab 5 is disposed behind the boom 32. The cab 5 is placed on the vehicle body frame 2. A seat in which the operator sits, operating devices described below, and the like are disposed within the cab 5. The cab 5 may be mounted on the front frame 2A.

[0021] <System configuration> 2 is a schematic block diagram showing the configuration of an entire system including a wheel loader 1 according to the embodiment. The wheel loader 1 is equipped with a work machine controller 10, an engine 11, and a power take off (PTO: power take off device) 12.

[0022] The engine 11 is a drive source that generates a drive force for driving the work implement 3, and is, for example, a diesel engine. The output of the engine 11 is controlled by adjusting the amount of fuel injected into the cylinder of the engine 11. The PTO 12 distributes the output of the engine 11 to a traveling system that drives the traveling device 7, and a hydraulic system that drives the work implement 3. The engine 11, PTO 12, and hydraulic system are mounted behind the cab 5 on the rear frame 2B.

[0023] The hydraulic system is a mechanism for mainly driving the work implement 3 (for example, the boom 32 and the bucket 31). The hydraulic system includes a hydraulic pump 21 for the work implement driven by the PTO 12, a hydraulic pilot type bucket operation valve 22 and a boom operation valve 23 provided in the discharge circuit of the hydraulic pump 21, electromagnetic proportional control valves 24, 25 for the bucket connected to each pilot pressure receiving portion of the bucket operation valve 22, and electromagnetic proportional control valves 26, 27 for the boom connected to each pilot pressure receiving portion of the boom operation valve 23.

[0024] The work implement 3 is driven by hydraulic oil from the hydraulic pump 21. The hydraulic pump 21 is driven by the engine 11, and operates the work implement 3 by the hydraulic oil it discharges. The boom cylinder 36 receives a supply of hydraulic oil from the hydraulic pump 21 and expands and contracts, thereby raising and lowering the boom 32. The bucket cylinder 35 receives a supply of hydraulic oil from the hydraulic pump 21 and expands and contracts, thereby rotating the bucket 31 up and down.

[0025] The electromagnetic proportional control valves 24 to 27 are connected to a pilot pump (not shown), and control the supply of pilot oil from the pilot pump to each pilot pressure receiving portion of the boom operating valve 23 and the bucket operating valve 22 in response to a control signal from the work machine controller 10.

[0026] Specifically, the electromagnetic proportional control valve 24 contracts the bucket cylinder 35 and switches the bucket operation valve 22 so that the bucket 31 moves in the dump direction (the direction in which the blade tip of the bucket 31 descends). In addition, the electromagnetic proportional control valve 25 expands the bucket cylinder 35 and switches the bucket operation valve 22 so that the bucket 31 moves in the tilt direction (the direction in which the blade tip of the bucket 31 ascends).

[0027] The electromagnetic proportional control valve 26 switches the boom operation valve 23 so that the boom cylinder 36 is retracted and the boom 32 is lowered. In addition, the electromagnetic proportional control valve 27 switches the boom operation valve 23 so that the boom cylinder 36 is extended and the boom 32 is raised.

[0028] The work machine controller 10 is connected to an operation device, a boom angle sensor 44, a bucket angle sensor 45, a boom bottom pressure sensor 46, and an IMU (Inertial Measurement Unit) 47. The operation device is provided in the cab 5. The operation device includes a boom operation lever 41 and a bucket operation lever 42. The operation device also includes a steering handle, a steering lever, an accelerator pedal, etc., which are not shown.

[0029] The boom operation lever 41 is disposed, for example, on the right side of the seat in the cab 5. The boom operation lever 41 incorporates a lever angle sensor that detects the lever angle. The boom operation lever 41 can be manually operated by an operator to operate the boom 32. When the operator operates the boom operation lever 41, the lever angle sensor detects the lever angle according to the amount of operation. The lever angle sensor generates a boom lever signal. The boom lever signal is an operation command for operating the boom 32 according to the lever angle. The lever angle sensor outputs the boom lever signal to the work machine controller 10.

[0030] Bucket operation lever 42 is disposed, for example, on the right side of the seat in cab 5. Bucket operation lever 42 has a built-in lever angle sensor that detects the lever angle. Bucket operation lever 42 can be manually operated by the operator to operate bucket 31. When the operator operates bucket operation lever 42, the lever angle sensor detects the lever angle according to the amount of operation. The lever angle sensor generates a bucket lever signal. The bucket lever signal is an operation command for operating bucket 31 according to the lever angle. The lever angle sensor outputs the bucket lever signal to work machine controller 10.

[0031] The boom angle sensor 44 is configured, for example, by a rotary encoder provided on a mounting portion (support shaft) of the boom 32 to the vehicle body frame 2. The boom angle sensor 44 detects the boom angle between the center line of the boom 32 and the horizontal line, and outputs a boom angle detection signal to the work machine controller 10.

[0032] Here, the center line of the boom 32 is line YY in Fig. 2, which is a line connecting the attachment portion (center of the support shaft) of the boom 32 to the body frame 2 and the attachment portion of the bucket 31 (center of the bucket support shaft). When line YY in Fig. 2 is along the horizontal line, the boom angle sensor 44 outputs a boom angle of 0 degrees. When the tip of the boom 32 is raised from a boom angle of 0 degrees, the boom angle sensor 44 outputs a positive value, and when the tip of the boom 32 is lowered, the boom angle sensor 44 outputs a negative value.

[0033] Bucket angle sensor 45 is composed of, for example, a rotary encoder provided on the rotating shaft of bell crank 33. Bucket angle sensor 45 detects the bucket angle and outputs a bucket angle detection signal to work machine controller 10. Bucket angle sensor 45 outputs a bucket angle of 0 degrees when the bucket 31 is in a state where the blade tip of the bucket 31 is horizontal on the ground with the bucket 31 on the ground. Bucket angle sensor 45 outputs a positive value when the bucket 31 is moved in the tilt direction (upward), and outputs a negative value when the bucket 31 is moved in the dump direction (downward).

[0034] The boom bottom pressure sensor 46 detects the pressure (boom bottom pressure) on the bottom side of the boom cylinder 36, and outputs a boom bottom pressure detection signal to the work machine controller 10. The boom bottom pressure becomes high when the bucket 31 is loaded, and becomes low when the bucket 31 is empty.

[0035] The IMU 47 is mounted on the body of the wheel loader 1. The IMU 47 is attached to the body frame 2, for example, and detects the attitude of the body frame 2. The IMU 47 detects the acceleration and angular velocity of the body frame 2 in the front-rear, left-right, and up-down directions. The IMU 47 corresponds to an example of an acceleration sensor that detects the acceleration of the body. Since the acceleration of the body is an example of a physical quantity that represents the vibration of the body, it can be said that the IMU 47 corresponds to an example of a vibration sensor that detects the vibration of the body. The IMU 47 outputs a detection signal of the acceleration of the body to the work machine controller 10.

[0036] 3 is a schematic diagram of the operating lever 43. The operating device has the operating lever 43 that can be manually operated by the operator. The operating lever 43 is a multifunction lever that has the functions of both the boom operating lever 41 and the bucket operating lever 42. Tilting the operating lever 43 in the forward / backward direction is set as an operation for moving the boom 32 up and down, and tilting the operating lever 43 in the left / right direction is set as an operation for rotating the bucket 31. The boom angle and bucket angle described above are set according to the angle of tilt of the operating lever 43 from the neutral state.

[0037] The operating lever 43 has a base portion 52, a shaft portion 53, and an expanded diameter portion 54. The base portion 52 is attached to a right console disposed on the right side of the seat in the cab 5, for example. The shaft portion 53 and the expanded diameter portion 54 can be integrally moved to tilt in the front-rear and left-right directions with respect to the base portion 52. The expanded diameter portion 54 constitutes the tip of the operating lever 43. The operating lever 43 has the expanded diameter portion 54 at its tip. The shaft portion 53 has a rod-like shape. The expanded diameter portion 54 is formed to have a larger diameter than the shaft portion 53. In a cross section perpendicular to the longitudinal direction of the shaft portion 53, the expanded diameter portion 54 has a larger cross-sectional area than the shaft portion 53. The weight of the tip of the operating lever 43 is relatively large. The center of gravity of the operating lever 43 is located closer to the tip side than the center in the longitudinal direction.

[0038] The enlarged diameter portion 54 has at least one switch 55. The switch 55 can be operated by an operator. For example, an operator seated on the seat can operate the switch 55 with his / her right thumb while holding the shaft portion 53 with his / her right palm. The operating lever 43 is a joystick in which the lever and the switch 55 are integrated.

[0039] The switch 55 has push button switches 56, 57 and a rocker switch 58. The switch 55 may have other types of switches, such as a slide switch. The switch 55 may have a switch for operating a direction indicator. The switch 55 may have a forward / reverse switch, a switch for operating the work machine 3, a traction control release switch, or the like, or may have a switch having another function. The switch 55 may be provided on the back surface of the enlarged diameter portion 54.

[0040] The operating lever 43 has an electric wire 59. The electric wire 59 extends from the inside to the outside of the operating lever 43. The electric wire 59 is disposed penetrating the shaft portion 53 and the base portion 52. One end of the electric wire 59 is electrically connected to the switch 55. The electric wire 59 transmits an electric signal generated by operating the switch 55. The electric wire 59 has a portion that is disposed inside the right console.

[0041] <Configuration of work machine controller 10> Fig. 4 is a block diagram showing the functional configuration of the work machine controller 10. As shown in Fig. 4, the work machine controller 10 mainly includes a vibration detection unit 101, a command calculation unit 102, a storage unit 108, and a timer 109.

[0042] The vibration detection unit 101 receives an input of the detection result of the acceleration of the vehicle body from the acceleration sensor (IMU 47). The vibration detection unit 101 calculates the vibration of the vehicle body using the acceleration of the vehicle body. The vibration detection unit 101 calculates the vibration of the vehicle body caused by work using the bucket 31. One example of work using the bucket 31 is bucket swinging work. The bucket swinging work is work in which the bucket 31 is repeatedly moved in the dump direction and in the tilt direction, causing the bucket 31 to vibrate quickly. The bucket swinging work is performed to remove dirt and other adhering matter from the bucket 31. The vibration detection unit 101 detects that the bucket swinging work is causing large vibrations in the vehicle body that are greater than or equal to a threshold value. The vibration detection unit 101 outputs the detection result of the vibration of the vehicle body to the command calculation unit 102.

[0043] The command calculation unit 102 receives an input of an operation command for operating the bucket 31 from the operation lever 43 (bucket operation lever 42). The command calculation unit 102 basically outputs a control signal (EPC current) according to the operation command to the bucket electromagnetic proportional control valves 24, 25 connected to the bucket operation valve 22.

[0044] The command calculation unit 102 checks the vibration of the vehicle body detected by the vibration detection unit 101. When the command calculation unit 102 detects a large vibration of the vehicle body, it outputs a control signal that corrects the input of the operation command to the electromagnetic proportional control valves 24, 25. The command calculation unit 102 determines a command flow rate of hydraulic oil to be supplied to the bucket cylinder 35 according to the magnitude of the vibration of the vehicle body, and outputs an EPC current according to the command flow rate to the electromagnetic proportional control valves 24, 25. The command calculation unit 102 controls the operation of the bucket cylinder 35 in response to the operation of the bucket operation lever 42 based on the detection result of the vibration of the vehicle body. The command calculation unit 102 changes the limit value of the movement of the bucket 31 in response to the operation command when the vibration of the vehicle body reaches a certain threshold value or more.

[0045] The command calculation unit 102 sets a limit on the amplitude of the bucket swinging operation that quickly vibrates the bucket 31. For example, the command calculation unit 102 limits the maximum flow rate of hydraulic oil supplied to the bucket cylinder 35. Alternatively, the command calculation unit 102 reduces the allowable number of bucket swinging operations per unit time. The command calculation unit 102 changes the maximum frequency at which the operator can operate the bucket operating lever 42 to perform the bucket swinging operation, depending on the magnitude of the vibration of the vehicle body.

[0046] The memory unit 108 is a non-volatile memory, and is provided as an area for storing necessary data. The memory unit 108 stores programs for controlling various operations of the wheel loader 1, and various data required for executing the programs. The memory unit 108 also temporarily stores working data that is generated in association with the operation of the wheel loader 1. The work machine controller 10 executes various processes for controlling the operation of the wheel loader 1 based on the programs stored in the memory unit 108. The timer 109 keeps track of time.

[0047] <Bucket movement control> 5 is a flowchart showing an example of bucket operation control in the embodiment. As shown in FIG. 5, in step S1, the work machine controller 10 acquires the acceleration of the vehicle body. The vibration detection unit 101 receives an input of a detection signal of the acceleration of the vehicle body from the IMU 47.

[0048] When the vehicle body vibrates, it repeats upward and downward displacement. Differentiating the displacement with respect to time results in velocity, and differentiating the velocity with respect to time results in acceleration. When the vehicle body vibrates, upward and downward acceleration act alternately on the vehicle body, and there is a moment when the acceleration becomes zero. The vibration detection unit 101 converts the acceleration of the vehicle body input from the IMU 47 into time-series data arranged in chronological order. The vibration detection unit 101 obtains the peak value of the acceleration of the vehicle body from the time-series data of the acceleration of the vehicle body.

[0049] In step S2, the work machine controller 10 determines whether the acceleration of the vehicle body is equal to or greater than a predetermined threshold. The command calculation unit 102 reads out the threshold of the vehicle body acceleration from the memory unit 108. The threshold of the vehicle body acceleration is set, for example, as a value at which no autonomous vibration of the vehicle body occurs, and is stored in advance in the memory unit 108. The command calculation unit 102 compares the peak value of the vehicle body acceleration acquired in step S1 with the threshold read out from the memory unit 108.

[0050] If the peak value of the acceleration of the vehicle body is equal to or greater than the threshold value (YES in step S2), in step S3, the work machine controller 10 determines whether or not the bucket swing state determination time t1 has elapsed. The command calculation unit 102 reads the time from the timer 109. The command calculation unit 102 starts counting time from the time when it is determined in step S2 that the peak value of the acceleration of the vehicle body is equal to or greater than the threshold value and the process proceeds to step S3. The command calculation unit 102 calculates the elapsed time up to the current time. The command calculation unit 102 reads the time t1 from the memory unit 108. The command calculation unit 102 compares the elapsed time up to the current time with the time t1. The command calculation unit 102 determines whether or not the state in which the peak value of the acceleration of the vehicle body is equal to or greater than the threshold value has continued for the time t1.

[0051] At the time of the judgment in step S3, if the state in which the peak value of the acceleration of the vehicle body is equal to or greater than the threshold has not continued for time t1 (NO in step S3), the processes in steps S1 to S3 are executed again. If it is judged in step S2 that the peak value of the acceleration of the vehicle body is equal to or greater than the threshold, the process proceeds to step S3, and the judgment as to whether the state in which the peak value of the acceleration of the vehicle body is equal to or greater than the threshold is repeated.

[0052] If it is determined in step S3 that the peak value of the vehicle body acceleration is equal to or greater than the threshold value for time t1 (YES in step S3), then in step S4, the work machine controller 10 corrects the input value from the operation device. The command calculation unit 102 corrects the input value of the bucket lever signal from the bucket operation lever 42.

[0053] Fig. 6 is a first diagram showing the flow rate of hydraulic oil supplied to the bucket cylinder 35. The horizontal axis of Fig. 6 represents time, and the vertical axis of Fig. 6 represents the flow rate of hydraulic oil supplied to the bucket cylinder 35. "0%" in Fig. 6 indicates a state in which the bucket operation lever 42 is in neutral, the bucket 31 is stopped, and the supply of hydraulic oil to the bucket cylinder 35 has stopped.

[0054] The positive direction of the vertical axis in FIG. 6 indicates the flow rate of hydraulic oil supplied to the bottom side oil chamber of the bucket cylinder 35 to move the bucket 31 in the tilt direction. "+100%" in FIG. 6 is the maximum value of the flow rate of hydraulic oil supplied to the bucket cylinder 35 to move the bucket 31 in the tilt direction. The negative direction of the vertical axis in FIG. 6 indicates the flow rate of hydraulic oil supplied to the head side oil chamber of the bucket cylinder 35 to move the bucket 31 in the dump direction. "-100%" in FIG. 6 is the maximum value of the flow rate of hydraulic oil supplied to the bucket cylinder 35 to move the bucket 31 in the dump direction.

[0055] The dashed line in Fig. 6 indicates a target flow rate of the hydraulic oil that is determined in accordance with an operation command output from the bucket operating lever 42. The solid line in Fig. 6 indicates a command flow rate of the hydraulic oil after the flow rate of the hydraulic oil has been restricted. A control signal based on the command flow rate shown in Fig. 6 is output from the command calculation unit 102 to the electromagnetic proportional control valves 24, 25.

[0056] At time T1, bucket operation lever 42, which is in the neutral position, begins to tilt in a direction that moves bucket 31 in the tilt direction. At time T2, the tilt of bucket operation lever 42 reaches its maximum. After time T2, the tilt of bucket operation lever 42 decreases. When bucket operation lever 42 reaches the neutral state at time T3, bucket operation lever 42 continues to tilt in that state, and begins to tilt in a direction that moves bucket 31 in the dump direction. At time T4, the tilt of bucket operation lever 42 reaches its maximum. After time T4, the tilt of bucket operation lever 42 decreases.

[0057] When the operator operates the bucket operation lever 42 to perform bucket swing work, the operator usually alternates between operating the bucket operation lever 42 to the maximum extent to move the bucket 31 in the tilt direction and operating the bucket operation lever 42 to the maximum extent to move the bucket 31 in the dump direction. In FIG. 6, the operator starts operating the bucket operation lever 42 in the tilt direction from the neutral position at time T1. When the operator reaches the maximum amount of operation in the tilt direction at time T2, he immediately reduces the amount of operation in the tilt direction. When the amount of operation in the tilt direction becomes zero at time T3 and the bucket operation lever 42 is in the neutral state, the operator starts operating it in the dump direction as is. When the operator reaches the maximum amount of operation in the dump direction at time T4, he immediately reduces the amount of operation in the dump direction.

[0058] In the example shown in FIG. 6, the maximum allowable flow rate of hydraulic oil supplied to the bucket cylinder 35 is limited. At time T11, the target flow rate of hydraulic oil determined by an operation command from the bucket operation lever 42 increases to the maximum allowable flow rate in the tilt direction. After time T11, the target flow rate becomes greater than the maximum allowable flow rate, but even in this case, the commanded flow rate is limited to the maximum allowable flow rate. At time T12, the target flow rate decreases to the maximum allowable flow rate, so after time T12, the commanded flow rate is made equal to the target flow rate. At time T13, the target flow rate increases to the maximum allowable flow rate in the dump direction. Between time T13 and time T14, the target flow rate becomes greater than the maximum allowable flow rate, but even in this case, the commanded flow rate is limited to the maximum allowable flow rate.

[0059] By controlling the command flow rate in this manner, amplitude A of the command flow rate shown in Fig. 6 is smaller than the amplitude of the target flow rate calculated in accordance with the operation command input from the bucket operating lever 42. The input value of the bucket lever signal from the bucket operating lever 42 is corrected, reducing the amount of movement of the bucket 31. The amplitude of the movement of the bucket 31 in the dump direction and tilt direction is reduced. The control signal output to the electromagnetic proportional control valves 24, 25 is corrected in response to the operation command output from the bucket operating lever 42, and limitations are placed on the movement of the bucket 31. Limits are placed on the amplitude of the bucket swinging operation.

[0060] FIG. 7 is a second diagram showing the flow rate of hydraulic oil supplied to the bucket cylinder 35. As in FIG. 6, the horizontal axis of FIG. 7 indicates time, and the vertical axis of FIG. 7 indicates the flow rate of hydraulic oil supplied to the bucket cylinder 35. "0%" in FIG. 7 indicates a state in which the supply of hydraulic oil to the bucket cylinder 35 is stopped. The positive direction of the vertical axis of FIG. 7 indicates the flow rate of hydraulic oil that moves the bucket 31 in the tilt direction. The negative direction of the vertical axis of FIG. 7 indicates the flow rate of hydraulic oil that moves the bucket 31 in the dump direction.

[0061] The dashed line in Fig. 7 indicates a target flow rate of hydraulic oil that is determined in accordance with an operation command output from bucket operating lever 42. The solid line in Fig. 7 indicates a command flow rate of hydraulic oil after limiting the rate of change of the flow rate of hydraulic oil. A control signal based on the command flow rate shown in Fig. 7 is output from command calculation unit 102 to electromagnetic proportional control valves 24, 25.

[0062] In the example shown in Fig. 7, the rate of change of the flow rate of hydraulic oil supplied to the bucket cylinder 35 is limited, and the slope of the graph of the command flow rate shown by the solid line in Fig. 7 is limited. The command flow rate of hydraulic oil shown by the solid line in Fig. 7 is controlled so as to approach the target flow rate shown by the dashed line.

[0063] At time T1, bucket operation lever 42, which is in the neutral position, begins to tilt in a direction that moves bucket 31 in the tilt direction. At time T1, the commanded flow rate of hydraulic oil in the tilt direction also begins to increase, but the commanded flow rate is smaller than the target flow rate. Even when the tilt of bucket operation lever 42 begins to decrease at time T2, the commanded flow rate continues to increase because it is still smaller than the target flow rate. The commanded flow rate continues to increase until the target flow rate and the commanded flow rate match at time T5. After time T5, the target flow rate becomes smaller than the commanded flow rate, so the commanded flow rate decreases to approach the target flow rate.

[0064] At time T3, bucket operation lever 42 becomes neutral. The commanded flow rate continues to decrease even after time T3. When the commanded flow rate in the tilt direction becomes zero at time T6, bucket operation lever 42 is tilted in a direction that moves bucket 31 in the dump direction and the target flow rate in the dump direction has been calculated, so the commanded flow rate of hydraulic oil also begins to increase in the dump direction. Even when the tilt of bucket operation lever 42 begins to decrease at time T4, the commanded flow rate continues to increase because it is still smaller than the target flow rate. The commanded flow rate continues to increase until the target flow rate and the commanded flow rate match at time T7. After time T7, the target flow rate becomes smaller than the commanded flow rate, so the commanded flow rate decreases to approach the target flow rate.

[0065] By controlling the command flow rate in this manner, the amplitude A of the command flow rate shown in Fig. 7 is smaller than the amplitude of the target flow rate calculated in accordance with the operation command input from the bucket operating lever 42. The input value of the bucket lever signal from the bucket operating lever 42 is corrected, reducing the amount of movement of the bucket 31. The amplitude of the movement of the bucket 31 in the dump direction and tilt direction is reduced. Restrictions are imposed on the movement of the bucket 31 in response to the operation command output from the bucket operating lever 42. Restrictions are imposed on the amplitude of the bucket swinging operation.

[0066] Returning to FIG. 5, in step S5, the work machine controller 10 determines whether or not the work machine lever filtering duration time t2 has elapsed. The command calculation unit 102 reads the time from the timer 109. The command calculation unit 102 starts counting time, starting from the time when the input value from the operating device was corrected in step S4. The command calculation unit 102 calculates the elapsed time up to the current time. The command calculation unit 102 reads the time t2 from the memory unit 108. The command calculation unit 102 compares the elapsed time up to the current time with the time t2. The command calculation unit 102 determines whether or not the time t2 has elapsed since the input value from the operating device was corrected.

[0067] If the time t2 has not elapsed (NO in step S5), the determination in step S5 is repeated. The process is put on hold until the time t2 has elapsed.

[0068] When time t2 has elapsed (YES in step S5), in step S6, the work machine controller 10 acquires the acceleration of the vehicle body. In step S7, the work machine controller 10 determines whether or not the peak value of the acceleration of the vehicle body is equal to or greater than a predetermined threshold value. The processing in steps S6 and S7 is performed in the same manner as the processing in steps S1 and S2.

[0069] If it is determined in step S7 that the peak value of the acceleration of the vehicle body is equal to or greater than the threshold value (YES in step S7), the process returns to step S4, and the processes of steps S4 to S7 are repeated. In step S4, a process of further correcting the input value from the operating device is performed, and in a state in which the amplitude A shown in Figures 6 and 7 is further reduced, it is determined in step S7 whether or not the peak value of the acceleration of the vehicle body is still equal to or greater than a predetermined threshold value. The correction of the input value is continued until the peak value of the acceleration of the vehicle body becomes smaller than the threshold value.

[0070] When the peak value of the vehicle body acceleration becomes smaller than the threshold value (NO in step S7), in step S8, work machine controller 10 changes the correction of the input value from the operation device to the initial state. Command calculation unit 102 releases the restriction on the movement of bucket 31 in response to the operation command output from bucket operation lever 42. Restrictions are no longer placed on the movement of bucket 31 in response to the operation command. Command calculation unit 102 outputs a control signal to electromagnetic proportional control valves 24, 25 in accordance with the operation command input from operation lever 43 (bucket operation lever 42). Then, the processing is returned.

[0071] If it is determined in step S2 that the peak value of the acceleration of the vehicle body is smaller than the threshold value (NO in step S2), the process of correcting the input value from the operation device is not performed. The command calculation unit 102 outputs a control signal according to the operation command input from the operation lever 43 (bucket operation lever 42) to the electromagnetic proportional control valves 24, 25. The process is then returned.

[0072] <Action and Effects> Although some of the description overlaps with the above description, the characteristic configurations and effects of the embodiment can be summarized as follows.

[0073] 5 to 7, work machine controller 10 places restrictions on the movement of bucket 31 in response to an operation command to operate bucket 31, based on the detection results of vehicle body vibrations generated by work using bucket 31. The vibration of the vehicle body is detected by a vibration sensor, and when the magnitude of the vehicle body vibration exceeds a threshold value, the sensitivity of the operation of bucket 31 in response to the operation command output by the operating device is reduced to prevent resonance. By intervening in the operation command according to the vibration state of the vehicle body, the vibration of the vehicle body can be suppressed, thereby stabilizing the vehicle body.

[0074] The operation command output by the operating device for operating the bucket 31 may be a bucket lever signal generated by the operator's operation of the bucket operating lever 42. For example, the operation command may be a bucket lever signal generated when an operator who is about to perform bucket swinging work operates to tilt the operating lever 43 alternately to the left and right. The operation command may also be a bucket lever signal generated when the bucket operating lever 42 is swung due to vibrations of the vehicle body. For example, the operation command may be a bucket lever signal generated when the bucket operating lever 42 is swung due to vibrations of the vehicle body generated by the bucket swinging work after the operator has finished the bucket swinging work and released his / her hand from the bucket operating lever 42.

[0075] In addition to detecting the vibration of the vehicle body using a vibration sensor, the period of the vibration of the vehicle body may be obtained. By detecting the period of the vibration, it is possible to determine that the vehicle body has vibrated due to the bucket swinging operation. It is also possible to determine that the bucket swinging operation has been performed from the operation details of the bucket operating lever 42.

[0076] As shown in Fig. 2 and 5, the vibration sensor may be an acceleration sensor that detects the acceleration of the vehicle body. Since the acceleration of the vehicle body is an example of a physical quantity that represents the vibration of the vehicle body, the vibration of the vehicle body can be detected by detecting the acceleration of the vehicle body with the acceleration sensor. In addition to acceleration, physical quantities that represent vibration include displacement and velocity. The vibration sensor may include a displacement sensor and / or a velocity sensor instead of or in addition to the acceleration sensor.

[0077] 5, when a state in which the acceleration of the vehicle body is equal to or greater than a threshold continues for time t1 or more, work machine controller 10 may impose a restriction on the movement of bucket 31 in response to an operation command to operate bucket 31. When large vibrations of the vehicle body continue for a predetermined time, the vibrations of the vehicle body can be reduced and the vehicle body can be reliably stabilized by intervening in the operation command output by the operating device to restrict the movement of bucket 31.

[0078] As shown in Fig. 5, work machine controller 10 may release the restriction on the movement of bucket 31 when the acceleration of the vehicle body becomes smaller than a threshold value. When the vibration of the vehicle body decreases and the vehicle body becomes stable as a result of restricting the movement of bucket 31, the work machine controller 10 controls the bucket 31 to move in accordance with an operation command from the operating device. The operator operates bucket operating lever 42, and the bucket 31 is moved in accordance with the operation of bucket operating lever 42. In this manner, responsiveness to the operation of the operator can be improved.

[0079] As shown in FIGS. 1 to 3, the operating device may be disposed in a cab 5 in which an operator sits. Since the cab 5 is mounted on the vehicle body, when the vehicle body vibrates, the vibration is transmitted to the operating device in the cab 5. When the operating device is vibrated due to the vibration of the vehicle body, the movement of the operating device may become an operation command for operating the bucket 31. The vibration of the bucket 31 may increase the vibration of the vehicle body. By configuring the device to limit the movement of the bucket 31 when large vibration of the vehicle body is detected, it is possible to prevent the vibration of the vehicle body from increasing and stabilize the vehicle body.

[0080] 3, operating lever 43 may have an expanded diameter portion 54 at its tip. Operating lever 43 having expanded diameter portion 54 at its tip is prone to swinging when vibrations of the vehicle body are transmitted to it. By setting a limit on the movement of bucket 31 in response to an operation command for operating bucket 31 output from operating lever 43 when large vibrations of the vehicle body are detected, it is possible to prevent the vibrations of the vehicle body from increasing and stabilize the vehicle body.

[0081] 3, expanded diameter section 54 may have a switch 55 that can be operated by the operator. If expanded diameter section 54 at the tip of operating lever 43 has switch 55, operating lever 43 will have a top-heavy structure with a large weight at the tip end, and will be prone to shaking when vibrations of the vehicle body are transmitted to it. By setting a limit on the movement of bucket 31 in response to an operation command for operating bucket 31 output from operating lever 43 when large vibrations of the vehicle body are detected, it is possible to prevent the vibrations of the vehicle body from increasing and to stabilize the vehicle body.

[0082] 6 and 7, the work performed by bucket 31 when vibration of the vehicle body occurs may be a bucket swinging operation in which bucket 31 is repeatedly moved in the dump direction and in the tilt direction. When the operator performs the bucket swinging operation, vibration is likely to occur in the vehicle body. When the vibration of the vehicle body becomes large, an increase in the vibration of the vehicle body can be avoided and the vehicle body can be stabilized by setting a limit on the movement of bucket 31 in response to an operation command output from operating lever 43 for operating bucket 31.

[0083] 6 and 7, the work machine controller 10 may set a limit on the amplitude A of the bucket swinging work. In this way, an increase in vibration of the vehicle body can be reliably avoided, and the vehicle body can be stabilized.

[0084] In the embodiment, an example has been described in which the operation device has the operation lever 43, and the operation lever 43 has the functions of both the boom operation lever 41 and the bucket operation lever 42. The boom operation lever 41 and the bucket operation lever 42 may be configured as separate levers. The operation of tilting the boom operation lever 41 in the forward / backward direction may be set as an operation for moving the boom 32 up and down, and the operation of tilting the bucket operation lever 42 in the forward / backward direction may be set as an operation for rotating the bucket 31.

[0085] The operating device does not necessarily have to be arranged inside the cab 5. The operating device may be arranged outside the wheel loader 1. The operator may operate the operating device inside the cab 5, or may operate the operating device outside the wheel loader 1.

[0086] In the embodiment, an example has been described in which the acceleration of the vehicle body in the up-down direction is detected by the IMU 47. The IMU 47 can detect the acceleration of the vehicle body in the forward-backward and left-right directions. The detected values ​​of the acceleration of the vehicle body in the forward-backward and left-right directions may be used to control the bucket operation.

[0087] The attachment at the tip of the work implement 3 is not limited to the bucket 31, but may be another type of attachment. The work machine is not limited to the wheel loader 1, but may be another type of work machine capable of performing excavation work.

[0088] <Additional Notes> The above description includes the following additional features.

[0089] (Appendix 1) The car body and A work machine operably attached to the vehicle body and having an attachment at a tip thereof; An operation device that outputs an operation command to operate the attachment; a vibration sensor for detecting vibration of the vehicle body; a controller that sets limits on operation of the attachment in response to the operation command based on detection results of vibrations of the vehicle body generated during work by the attachment.

[0090] (Appendix 2) 2. The work machine according to claim 1, wherein the vibration sensor includes an acceleration sensor that detects acceleration of the vehicle body.

[0091] (Appendix 3) The work machine according to claim 2, wherein the controller imposes limitations on operation of the attachment in response to the operation command when a state in which the acceleration is equal to or greater than a threshold continues for a predetermined time.

[0092] (Appendix 4) The work machine according to claim 2 or 3, wherein the controller releases restrictions on movement of the attachment when the acceleration becomes smaller than the threshold value.

[0093] (Appendix 5) The work machine is mounted on the vehicle body and includes a cab in which an operator can ride, 5. The work machine according to any one of claims 1 to 4, wherein the operating device is disposed within the cab.

[0094] (Appendix 6) The operating device has an operating lever, The work machine according to claim 5, wherein the operating lever has an enlarged portion at a tip thereof.

[0095] (Appendix 7) 7. The work machine of claim 6, wherein the expansion section has a switch that can be operated by the operator.

[0096] (Appendix 8) The attachment has a bucket, 8. The work machine according to any one of Supplementary Note 1 to Supplementary Note 7, wherein the work is a bucket swinging work in which movement of the bucket in a dump direction and movement of the bucket in a tilt direction are repeated.

[0097] (Appendix 9) 9. The work machine of claim 8, wherein the controller sets a limit on an amplitude of the bucket swinging operation.

[0098] The embodiments disclosed herein are illustrative in all respects and should not be considered as limiting. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0099] 1 wheel loader, 2 vehicle frame, 3 work machine, 5 cab, 7 travelling device, 10 work machine controller, 11 engine, 21 hydraulic pump, 22 bucket operation valve, 23 boom operation valve, 24-27 electromagnetic proportional control valve, 31 bucket, 32 boom, 35 bucket cylinder, 36 boom cylinder, 41 boom operation lever, 42 bucket operation lever, 43 operation lever, 44 boom angle sensor, 45 bucket angle sensor, 46 boom bottom pressure sensor, 47 IMU, 52 base portion, 53 shaft portion, 54 expansion portion, 55 switch, 56, 57 push button switch, 58 rocker switch, 59 electric wire, 101 vibration detection portion, 102 command calculation portion, 108 memory portion, 109 timer, A amplitude, t1, t2 time.

Claims

1. The car body and A work machine operably attached to the vehicle body and having an attachment at a tip thereof; An operation device that outputs an operation command to operate the attachment; a vibration sensor for detecting vibration of the vehicle body; a controller that sets limits on operation of the attachment in response to the operation command based on detection results of vibrations of the vehicle body generated during work by the attachment.

2. The work machine according to claim 1 , wherein the vibration sensor includes an acceleration sensor that detects acceleration of the vehicle body.

3. The work machine according to claim 2 , wherein the controller imposes a limit on a movement of the attachment in response to the movement command when a state in which the acceleration is equal to or greater than a threshold continues for a predetermined time.

4. The work machine according to claim 3 , wherein the controller releases restrictions on the movement of the attachment when the acceleration becomes smaller than the threshold value.

5. The work machine is mounted on the vehicle body and includes a cab in which an operator can ride, The work machine of claim 1 , wherein the operating device is located within the cab.

6. The operating device has an operating lever, The work machine according to claim 5 , wherein the operating lever has an enlarged diameter portion at a tip end thereof.

7. The work machine according to claim 6 , wherein the enlarged diameter portion has a switch operable by the operator.

8. The attachment has a bucket, 2. The work machine according to claim 1, wherein the work is a bucket swing work in which movement of the bucket in a dump direction and movement of the bucket in a tilt direction are repeated.

9. The work machine of claim 8 , wherein the controller sets a limit on an amplitude of the bucket swinging operation.

10. Receiving an input of an operation command to operate an attachment at the tip of a work machine operably attached to a vehicle body; Detecting vibrations of the vehicle body generated by the work of the attachment; setting limitations on the operation of the attachment in response to the operation command based on the detection results of the vibration of the vehicle body.

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