Work machine and control method for work machine

Abstract

A work machine includes a work machine body, a work implement, a damping unit, a vibration information detection sensor, and a controller. The work machine body can travel. The work implement is attached to the work machine body. The damping unit can damp vibration of the work implement. The vibration information detection sensor detects information regarding vibration of the work machine body. The controller controls the damping unit based on the information regarding vibration detected by the vibration information detection sensor.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a U.S. National stage application of International Application No. PCT / JP2024 / 007863, filed on Mar. 1, 2024. This U.S. National stage application claims priority under 35 U.S.C. § 119(a) to Japanese Patent Application No. 2023-041965, filed in Japan on Mar. 16, 2023. The entire contents of Japanese Patent Application No. 2023-041965 is hereby incorporated herein by reference.BACKGROUNDTechnical Field

[0002] The present invention relates to a work machine and a control method for a work machine.Background Art

[0003] A work machine such as a wheel loader may travel in a state where earth and sand or the like are loaded in a bucket. In such a case, since the mass of a work implement increases, vibration during travel increases.

[0004] For this reason, a configuration of reducing vibration during travel by connecting an accumulator to a cylinder that drives a work implement is disclosed (see, for example, U.S. Pat. No. 3,122,246). For example, in U.S. Pat. No. 3,122,246, a valve is provided between the cylinder and the accumulator, the cylinder and the accumulator are connected during travel by switching on-off of the valve, and the connection between the cylinder and the accumulator is cut off during loading work.SUMMARY

[0005] However, in the configuration described in U.S. Pat. No. 3,122,246, since the valve is manually operated, an operator needs to operate the valve to open before travel or during travel, which complicates the work of the operator.

[0006] An object of the present disclosure is to provide a work machine and a control method for a work machine that can easily stabilize behavior during travel.

[0007] A work machine according to a first aspect of the present disclosure includes a work machine body, a work implement, a damping unit, a vibration information detection sensor, and a controller. The work machine body can travel. The work implement is attached to the work machine body. The damping unit can damp vibration of the work implement. The vibration detection sensor detects information regarding vibration of the work machine body. The controller controls the damping unit based on the information regarding vibration detected by the vibration information detection sensor.

[0008] A control method for a work machine according to a second aspect of the present disclosure is a control method for a work machine including a work machine body configured to travel and a work implement attached to the work machine body, and includes a vibration information detection step and a damping control step. The vibration information detection step is to detect information regarding vibration of the work machine body. The damping control step is to control the damping unit that damps vibration of the work implement based on the information regarding vibration.

[0009] According to the present disclosure, it is possible to provide a work machine and a control method for a work machine that can easily stabilize behavior during travel.BRIEF DESCRIPTION OF DRAWINGS

[0010] Referring now to the attached drawings which form a part of this original disclosure, an illustrative embodiment is shown.

[0011] FIG. 1 is a side view of a wheel loader.

[0012] FIG. 2 is a block diagram illustrating a system configuration of the wheel loader.

[0013] FIG. 3 is a view for explaining detection by an IMU.

[0014] FIG. 4 is a block diagram illustrating a configuration of a controller of the wheel loader.

[0015] FIG. 5 is a view showing an example of a vibration waveform of acceleration.

[0016] FIG. 6 is a view for explaining determination of state transition of the wheel loader.

[0017] FIG. 7 is a flowchart for explaining travel damper control by the controller.DETAILED DESCRIPTION OF EMBODIMENT(S)Outline of Wheel Loader

[0018] A wheel loader as an example of the work machine will be described below with reference to the drawings. In the following description, “front”, “rear”, “right”, “left”, “upper”, and “lower” are orientations with reference to a state of viewing forward from an operator seat. A “vehicle width direction” is synonymous with a “left-right direction”.

[0019] FIG. 1 is a side view illustrating the overall configuration of a wheel loader 10 according to the present embodiment.

[0020] The wheel loader 10 includes a body 1 (an example of the work machine body) and a work implement 3. The body 1 includes a vehicle body frame 2, a pair of front tires 4, a cab 5, an engine room 6, a pair of rear tires 7, and an articulated cylinder 8.

[0021] The vehicle body frame 2 is what is called an articulated type, and includes a front frame 11, a rear frame 12, and a coupling shaft portion 13. The front frame 11 is arranged in front of the rear frame 12. The coupling shaft portion 13 is provided at the center in the vehicle width direction, and swingably couples the front frame 11 and the rear frame 12 to each other. The pair of front tires 4 are attached to the left and right of the front frame 11. The pair of rear tires 7 are attached to the left and right of the rear frame 12.

[0022] The pair of articulated cylinders 8 are driven hydraulically. The pair of articulated cylinders 8 are arranged side by side on the left and right sides in the vehicle width direction of the coupling shaft portion 13. Each of the articulated cylinders 8 has one end attached to the front frame 11 and the other end thereof attached to the rear frame 12. The angle of the front frame 11 with respect to the rear frame 12 is adjusted by extension and contraction of the articulated cylinders 8.

[0023] The work implement 3 is attached to the body 1. The work implement 3 is used for various types of work (e.g., earth and sand loading work, earth and sand discharging work, and the like). The work implement 3 is driven by hydraulic oil from a hydraulic pump 64 described later. The work implement 3 includes a boom 14, a bucket 15, a lift cylinder 16 (an example of a hydraulic cylinder), a bucket cylinder 17, and a bell crank 18. The boom 14 is mounted to the front frame 11. The bucket 15 is attached to a tip end of the boom 14.

[0024] The lift cylinder 16 and the bucket cylinder 17 are hydraulic cylinders. One end of the lift cylinder 16 is attached to the front frame 11, and the other end of the lift cylinder 16 is attached to the boom 14. The boom 14 swings up and down by extension and contraction of the lift cylinder 16. One end of the bucket cylinder 17 is attached to the front frame 11, and the other end of the bucket cylinder 17 is attached to the bucket 15 via the bell crank 18. The bucket 15 swings up and down by the bucket cylinder 17 extending and contracting.

[0025] The cab 5 is placed on the rear frame 12. A steering wheel 55 for changing a travel direction of the wheel loader 10, a work implement operation lever 56 for operating the work implement 3, various pedals, various switches, a display device, and the like are arranged inside the cab 5 (see FIG. 2).

[0026] The engine room 6 is arranged on the rear frame 12 on the rear side of the cab 5. The engine room 6 houses an engine 31 described later. A counterweight 6a is arranged at the rear of the engine room 6. The counterweight 6a is arranged on a rear end portion of the rear frame 12.System Configuration of Wheel Loader

[0027] FIG. 2 is a block diagram schematically illustrating a system configuration of the wheel loader 10.

[0028] The wheel loader 10 includes a travel unit 21, a brake unit 22, an operation unit 23, an IMU 24 (an example of a vibration information detection sensor), a travel damper unit 25 (an example of a damping unit), and a controller 26.Travel Unit 21

[0029] The travel unit 21 includes an engine 31, a hydro static transmission (HST) 32, a transfer 33, an axle 34, a front tire 4, and a rear tire 7.

[0030] The engine 31 is, for example, a diesel engine. The HST 32 includes a pump 32a, a motor 32b, and a hydraulic circuit 32c.

[0031] The pump 32a is a swash plate type variable displacement pump. The angle of the swash plate of the pump 32a can be changed by a solenoid 32d. By being driven by the engine 31, the pump 32a discharges hydraulic oil. The hydraulic oil discharged from the pump 32a is sent to the motor 32b through the hydraulic circuit 32c. The motor 32b is a swash plate type pump. The angle of the swash plate of the motor 32b can be changed by a solenoid 32e.

[0032] The hydraulic circuit 32c is connected to the pump 32a and the motor 32b. The hydraulic circuit 32c includes a first drive circuit 32c1 and a second drive circuit 32c2. When the hydraulic oil is supplied from the pump 32a to the motor 32b via the first drive circuit 32c1, the motor 32b is driven in one direction (e.g., the forward direction). When the hydraulic oil is supplied from the pump 32a to the motor 32b via the second drive circuit 32c2, the motor 32b is driven in the other direction (e.g., the rearward direction). Note that the discharge direction of the hydraulic oil to the first drive circuit 32c1 or the second drive circuit 32c2 can be changed by the solenoid 32d.

[0033] The motor 32b is connected to the transfer 33 via a drive shaft 35. The drive shaft 35 is provided with a vehicle speed sensor 36. The vehicle speed sensor 36 detects a speed (hereinafter, called a vehicle speed) of the body 1. The vehicle speed sensor 36 detects the vehicle speed based on the rotation speed of the drive shaft 35. The vehicle speed sensor 36 transmits a detection signal indicating the vehicle speed to the controller 26.

[0034] The transfer 33 distributes the output from the engine 31 to the axle 34 on the front side and the axle 34 on the rear side. The pair of front tires 4 are connected to the axle 34 on the front side. The pair of front tires 4 are rotated by the output distributed to the axle 34 on the front side. The pair of rear tires 7 are connected to the axle 34 on the rear side. The pair of rear tires 7 are rotated by the output distributed to the axle 34 on the rear side.Brake Unit 22

[0035] The brake unit 22 includes a brake valve 41, a service brake 42, and a parking brake 43. The brake valve 41 is, for example, an electric proportional valve (EPC valve). The amount of hydraulic oil sent to the service brake 42 is adjusted according to the opening degree of the brake valve 41. The opening degree of the brake valve 41 is controlled by the controller 26. The controller 26 controls the opening degree of the brake valve 41 according to the operation amount of a brake pedal 54 described later.

[0036] The service brake 42 is provided at the axle 34 on the front side and the axle 34 on the rear side. The service brake 42 is a hydraulic brake. The braking force of the service brake 42 increases as the opening degree of the brake valve 41 is large.

[0037] The parking brake 43 is provided at the transfer 33. As the parking brake 43, for example, a wet multistage brake switchable between a braking state and a non-braking state, a disc brake, or the like can be used.Operation Unit 23

[0038] The operation unit 23 includes an accelerator 51, an FNR lever 52, a parking switch 53, the brake pedal 54, the steering wheel 55, the work implement operation lever 56, and an automatic travel damper switch 57.

[0039] The accelerator 51 is provided in the cab 5. The accelerator 51 transmits an operation signal indicating an accelerator operation amount to the controller 26. The controller 26 controls a throttle opening degree of the engine 31 based on the received operation signal.

[0040] The FNR lever 52 is provided in the cab 5. The FNR lever 52 is switchable to any of a forward position, a neutral position, and a reverse position. The FNR lever 52 transmits an operation signal indicating a position of the FNR lever 52 to the controller 26. The controller 26 switches forward, neutral, or reverse by controlling the solenoid 32d based on the received operation signal.

[0041] The parking switch 53 is provided in the cab 5. The parking switch 53 is switchable to any of an on position and an off position. The parking switch 53 transmits an operation signal indicating a position of the parking switch 53 to the controller 26. The controller 26 brings the parking brake 43 into a braking state or a non-braking state based on the received operation signal.

[0042] The brake pedal 54 is provided in the cab 5. The brake pedal 54 transmits an operation signal indicating a pedal operation amount and a pedal operation speed to the controller 26. The controller 26 controls the opening degree of the brake valve 41 based on the received operation signal.

[0043] The steering wheel 55 is provided in the cab 5. The steering wheel 55 transmits an operation signal indicating a steering wheel operation direction and a steering wheel operation amount to the controller 26. The controller 26 extends and contracts the articulated cylinders 8 arranged at the vehicle body frame 2 based on the received operation signal.

[0044] The work implement operation lever 56 is provided in the cab 5. The work implement operation lever 56 transmits an operation signal indicating operation amounts of the lift cylinder 16 and the bucket cylinder 17 to the controller 26. The controller 26 controls the hydraulic pump 64, a lift cylinder control valve 65, and a bucket cylinder control valve 81 based on the received operation signal. The hydraulic pump 64 is driven and the lift cylinder control valve 65 and the bucket cylinder control valve 81 are controlled, whereby the lift cylinder 16 and the bucket cylinder 17 are supplied with hydraulic oil, and the work implement 3 is driven.

[0045] The automatic travel damper switch 57 is provided in the cab 5. For example, the automatic travel damper switch 57 may be displayed on a display, and may also be a physical switch. The automatic travel damper switch 57 is switchable to any of an on state and an off state. The automatic travel damper switch 57 transmits an operation signal indicating the state of the automatic travel damper switch 57 to the controller 26. The controller 26 brings the automatic travel damper control into an operating state or a non-operating state based on the received operation signal. In the operating state of the automatic travel damper control, as described later, the controller 26 automatically brings a travel damper function of the travel damper unit 25 into an on state or an off state.IMU 24

[0046] The IMU 24 is an inertial measurement unit. The IMU 24 is arranged at the rear frame 12 as illustrated in FIG. 1. The IMU 24 includes an acceleration sensor and a gyro sensor. The IMU 24 measures acceleration and angular velocity on an X axis, a Y axis, and a Z axis illustrated in FIG. 3. Here, the X axis faces the front direction of the body 1, the Y axis faces the right direction of the body 1, and the Z axis faces the lower direction of the body 1. A pitch angle pθ, a yaw angle yθ, and a roll angle rθ are calculated from the acceleration and the angular velocity on the X axis, the Y axis, and the Z axis.

[0047] The IMU 24 outputs, to the controller 26, a detection signal including the acceleration and the angular velocity on the X axis, the Y axis, and the Z axis, and information on the pitch angle pθ, the yaw angle yθ, and the roll angle rθ.Travel Damper Unit 25

[0048] The travel damper unit 25 includes a hydraulic circuit 61, an on-off valve 62, an accumulator 63, the hydraulic pump 64, the lift cylinder control valve 65, and a hydraulic oil tank 66.

[0049] The hydraulic circuit 61 is connected to the pair of lift cylinders 16, the on-off valve 62, and the lift cylinder control valve 65.

[0050] The on-off valve 62 is arranged between each of the lift cylinders 16 and the accumulator 63. The on-off valve 62 is a two-position switching valve switchable to any of an open position X (open state) and a closed position Y (closed state). The position of the on-off valve 62 is controlled by the controller 26.

[0051] When the on-off valve 62 is positioned at the open position X, the on-off valve 62 causes each of the lift cylinders 16 and the accumulator 63 to communicate with each other. By this, each of the lift cylinders 16 and the accumulator 63 are connected, and the travel damper function of the wheel loader 10 is brought into the on state (an example of the first state). When the on-off valve 62 is positioned at the closed position Y, the on-off valve 62 blocks each of the lift cylinders 16 and the accumulator 63. By this, the connection between each of the lift cylinders 16 and the accumulator 63 is disconnected, and the travel damper function of the wheel loader 10 is brought into the off state (an example of the second state).

[0052] The accumulator 63 is connected to the hydraulic circuit 61 via the on-off valve 62. When the on-off valve 62 is positioned at the open position X, the accumulator63 is connected to each of the lift cylinders 16 via the hydraulic circuit 61. In this case, the accumulator 63 functions as a damper mechanism that reduces vibration of each of the lift cylinders 16.

[0053] When the on-off valve 62 is positioned at the closed position Y, the connection of the accumulator 63 with the lift cylinder 16 is disconnected by the on-off valve 62. In this case, the accumulator 63 does not function as a damper mechanism that reduces vibration of each of the lift cylinders 16.

[0054] The hydraulic pump 64 is driven by the engine 31. The hydraulic pump 64 supplies the hydraulic oil stored in the hydraulic oil tank 66 to each of the lift cylinders 16 via the lift cylinder control valve 65 and the hydraulic circuit 61. The hydraulic pump 64 supplies the hydraulic oil stored in the hydraulic oil tank 66 to the bucket cylinder 17 via the bucket cylinder control valve 81.Controller 26

[0055] The controller 26 includes a processor and a storage device. The processor is, for example, a central processing unit (CPU). Alternatively, the processor may be a processor different from the CPU. The processor executes processing for controlling the wheel loader 10 according to a program stored in the storage device. The storage device includes a nonvolatile memory such as a read only memory (ROM) and a volatile memory such as a random access memory (RAM). The storage device may include a hard disc or an auxiliary storage device such as a solid state drive (SSD). The storage device is an example of a non-transitory computer-readable recording medium.

[0056] FIG. 4 is a block diagram illustrating the configuration of the controller 26. However, FIG. 4 omits a basic system configuration regarding the travel unit 21.

[0057] The controller 26 includes a travel determination unit 71, a calculation unit 72, a vibration determination unit 73, and a travel damper control unit 74. The processor executes the program stored in the storage device, thereby implementing functions of the travel determination unit 71, the calculation unit 72, the vibration determination unit 73, and the travel damper control unit 74.

[0058] The travel determination unit 71 determines whether or not to be traveling based on the detection signal received from the vehicle speed sensor 36. The travel determination unit 71 determines to be traveling when the vehicle speed is larger than a predetermined threshold, and determines not to be traveling when the vehicle speed is equal to or less than the predetermined threshold.

[0059] The calculation unit 72 calculates the frequency and amplitude of vibration of acceleration in the Z axis direction from the detection signal input from the IMU 24. The acceleration in the Z axis direction can also be said to be acceleration in an up-down direction. FIG. 5 is a graph showing a temporal change in acceleration in the Z axis direction. The vertical axis represents amplitude, and the horizontal axis represents time. The calculation unit 72 calculates an amplitude A and a frequency f shown in FIG. 5 from the detection signal. The frequency f is a reciprocal of a period T in FIG. 5.

[0060] The vibration determination unit 73 determines whether or not vibration is generated in the wheel loader 10 based on the calculated amplitude and frequency. FIG. 6 is a state transition diagram illustrating a vibration state of the wheel loader 10. In a case where a condition (1) is satisfied, the vibration determination unit 73 determines that the wheel loader 10 has transitioned from a non-vibration state M1 to a vibrating state M2. The case where the condition (1) is satisfied is a case where the amplitude A is larger than a predetermined threshold and the frequency f is larger than a predetermined threshold. That is, the vibration determination unit 73 determines that vibration is generated in the body 1 when the amplitude A of the acceleration is larger than the predetermined threshold and the frequency f of the acceleration is larger than the predetermined threshold. FIG. 5 shows +A0 and −A0 as the predetermined threshold of the amplitude A. The amplitude A being larger than the predetermined threshold means that the upward amplitude is larger than +A0 and the downward amplitude is smaller than −A0 as shown in FIG. 5, for example. Determination that the amplitude in the condition (1) is larger than the predetermined threshold may be appropriately set. For example, when the upward amplitude being larger than +A0 and the downward amplitude being smaller than −A0 are repeated a predetermined number of times (or a predetermined time), the amplitude A may be determined to be larger than the predetermined threshold. The amplitude A may be determined to be larger than the predetermined threshold when any one of the upward amplitude being larger than +A0 and the downward amplitude being smaller than −A0 is satisfied. Determination that the frequency in the condition (1) is larger than the predetermined threshold may be appropriately set. The period T may be obtained, for example, from the time when the amplitude becomes maximum and the time when the amplitude becomes minimum, or may be obtained from the time when the amplitude exceeds the predetermined threshold and the time when the amplitude becomes smaller than the predetermined threshold. When the frequency f obtained from this period T is continuously larger than a predetermined threshold for a predetermined time, the frequency f may be determined to be larger than the predetermined threshold.

[0061] On the other hand, in a case where the condition (1) is not satisfied, the vibration determination unit 73 determines that the wheel loader 10 maintains the non-vibration state M1 and no vibration is generated. That is, the vibration determination unit 73 determines that no vibration is generated in the wheel loader 10 when the amplitude A is equal to or less than the predetermined threshold or the frequency f is equal to or less than the predetermined threshold.

[0062] In a case where a condition (2) is satisfied after the body 1 is determined to be in the vibrating state M2, the vibration determination unit 73 determines that the state of the body 1 has transitioned from the vibrating state M2 to the non-vibration state M1, and vibration is no longer generated. The case where the condition (2) is satisfied is a case where the state where the condition (1) is not satisfied continues for a predetermined threshold time or more.

[0063] When the vibration determination unit 73 determines that the wheel loader 10 is in the vibrating state M2, the travel damper control unit 74 switches the on-off valve 62 to the open position X and brings the travel damper function of the wheel loader 10 into the on state. When the vibration determination unit 73 determines that the wheel loader 10 is in the non-vibration state M1, the travel damper control unit 74 switches the on-off valve 62 to the closed position Y and brings the travel damper function of the wheel loader 10 into the off state.

[0064] Note that although acceleration in the Z axis direction is used for determination of vibration in the above description, the pitch angle pθ input from the IMU 24 may be used. The calculation unit 72 calculates the frequency and amplitude of vibration at the pitch angle pθ. When the amplitude of the pitch angle pθ that is calculated is larger than a predetermined threshold and the frequency of the pitch angle pθ is larger than a predetermined threshold, the vibration determination unit 73 determines that vibration is generated.

[0065] Determination may be performed for both the acceleration in the up-down direction and the pitch angle, and in a case where the condition (1) is satisfied in any one of them, vibration may be determined to be generated. That is, when the amplitude A of the acceleration is larger than a predetermined threshold A0 and the frequency f of the acceleration is larger than the predetermined threshold, or when the amplitude of the pitch angle pθ is larger than the predetermined threshold and the frequency of the pitch angle pθ is larger than the predetermined threshold, the vibration determination unit 73 determines that vibration is generated. The acceleration or pitch angle in the up-down direction corresponds to an example of information regarding vibration.Control Operation

[0066] Next, a control operation of the wheel loader 10 of the present embodiment will be described. FIG. 7 is a flowchart showing the control operation of the wheel loader 10 of the present embodiment.

[0067] First, in step S10, the controller 26 determines whether or not the automatic travel damper switch 57 is in the on state. When the automatic travel damper switch 57 is in the off state in step S10, the control ends. When the automatic travel damper switch 57 is in the on state in step S10, the control proceeds to step S11.

[0068] Next, in step S11, the travel determination unit 71 of the controller 26 determines whether or not to be traveling based on the detection signal received from the vehicle speed sensor 36.

[0069] When it is determined to be traveling in step S11, the calculation unit 72 of the controller 26 acquires a detection signal from the IMU 24 in step S12. Step S12 corresponds to an example of the vibration information acquisition step.

[0070] Next, in step S13, the calculation unit 72 of the controller 26 calculates the frequency and amplitude of vibration of up-down acceleration included in the detection signal from the IMU 24. Note that as described above, the frequency and amplitude of the vibration at the pitch angle pθ may be calculated.

[0071] Next, in step S14, the vibration determination unit 73 of the controller 26 determines whether or not the condition (1) (the amplitude is larger than the predetermined threshold and the frequency is larger than the predetermined threshold) is satisfied. In step S14, when the condition (1) is satisfied, the vibration determination unit 73 of the controller 26 determines that the body 1 is in the vibrating state M2.

[0072] Next, in step S15, the travel damper control unit 74 of the controller 26 sets the on-off valve 62 to the open position X and brings the travel damper function of the wheel loader 10 into the on state. Step S15 corresponds to an example of the damping control step.

[0073] Next, in step S16, the vibration determination unit 73 of the controller 26 determines whether or not the condition (2) (the condition (1) is not satisfied continuously for a predetermined time or more) is satisfied. When the condition (2) is satisfied, the vibration determination unit 73 of the controller 26 determines that the body 1 has transitioned from the vibrating state M2 to the non-vibration state M1.

[0074] Next, when in step S16, the condition (2) is determined to be satisfied, the travel damper control unit 74 of the controller 26 switches, in step S17, the on-off valve 62 to the closed position Y and brings the travel damper function of the wheel loader 10 into the off state, and the control ends. Step S17 corresponds to an example of the damping control step.

[0075] Note that when it is determined not to be traveling in step S11, the control proceeds to step S16, and the travel damper control unit 74 of the controller 26 sets the on-off valve 62 to the closed position Y and brings the travel damper function of the wheel loader 10 into the off state, and the control ends.

[0076] When the condition (1) is not satisfied in step S14, the wheel loader 10 is determined to be in the non-vibration state M1, and the travel damper control unit 74 of the controller 26 sets the on-off valve 62 to the closed position Y and brings the travel damper function of the wheel loader 10 into the off state, and the control ends.

[0077] When the condition (2) is not satisfied in step S16, the wheel loader 10 is determined to maintain the vibrating state M2, and ends the control.

[0078] When the on-off valve 62 is at the open position X in advance in step S15, the controller 26 needs not operate the on-off valve 62. When the on-off valve 62 is at the closed position Y in advance in step S17, the controller 26 needs not operate the on-off valve 62.Features and the Like(1)

[0080] The wheel loader 10 of the present embodiment includes the body 1, the work implement 3, the travel damper unit 25, the IMU 24, and the controller 26. The body 1 can travel. The work implement 3 is attached to the body 1. The travel damper unit 25 can damp vibration of the work implement 3. The IMU 24 detects information regarding vibration of the body 1. The controller 26 controls the travel damper unit 25 based on the information regarding vibration detected by the IMU 24.

[0081] This enables control of the travel damper unit 25 to be automatically performed based on the information regarding vibration detected by the IMU 24. Therefore, it is possible to easily stabilize the behavior during travel of the wheel loader 10.

[0082] (2)

[0083] In the wheel loader 10 of the present embodiment, the controller 26 can switch the travel damper unit 25 between a travel damper function ON state in which the function of damping the vibration of the work implement 3 is exerted and a travel damper function OFF state in which the function of damping the vibration of the work implement 3 is not exerted. When determining that the body 1 is vibrating based on the information regarding vibration, the controller 26 switches the travel damper unit 25 to the travel damper function ON state.

[0084] This enables the travel damper unit 25 to be automatically brought into the travel damper function ON state when the body 1 is determined to be in the vibrating state M2 based on the information regarding vibration detected by the IMU 24.

[0085] (3)

[0086] The wheel loader 10 of the present embodiment further includes the pair of lift cylinders 16 that drive the work implement 3. The travel damper unit 25 includes the on-off valve 62 and the accumulator 63. The accumulator 63 is connected to the lift cylinders 16 via the on-off valve 62. When the on-off valve 62 is at the open position X, the travel damper unit 25 is brought into the travel damper function ON state, and when the on-off valve 62 is at the closed position Y, the travel damper unit 25 is brought into the travel damper function OFF state. The controller 26 controls the on-off valve 62 based on the information regarding vibration.

[0087] This can switch the state of the travel damper unit 25 between the travel damper function ON state in which the function of damping the vibration of the work implement 3 is exerted and the travel damper function OFF state in which the function of damping the vibration of the work implement 3 is not exerted.

[0088] (4)

[0089] In the wheel loader 10 of the present embodiment, the information regarding vibration is the acceleration generated at the body 1. The controller 26 determines that the body 1 is vibrating when the amplitude of the acceleration being larger than the predetermined threshold and the frequency of the acceleration being larger than the predetermined threshold are satisfied.

[0090] By detecting the acceleration generated in the body 1 in this manner, it is possible to determine whether or not the body 1 is vibrating.

[0091] (5)

[0092] In the wheel loader 10 of the present embodiment, the information regarding vibration is the pitch angle generated at the body 1. The controller 26 determines that the body 1 is vibrating when the amplitude of the pitch angle being larger than the predetermined threshold and the frequency of the pitch angle being larger than the predetermined threshold are satisfied.

[0093] By detecting the pitch angle generated in the body 1 in this manner, it is possible to determine whether or not the body 1 is vibrating.

[0094] (6)

[0095] The control method for the wheel loader 10 of the present embodiment is a control method for a work machine including the body 1 that can travel and the work implement 3 attached to the body 1, and includes step S12 and step S14. In step S12, information regarding vibration of the body 1 is acquired. In step S14, the travel damper unit 25 that damps the vibration of the work implement 3 is controlled based on the information regarding vibration.

[0096] This enables control of the travel damper unit 25 to be automatically performed based on the information regarding vibration acquired in step S12. Therefore, it is possible to easily stabilize the behavior during travel of the wheel loader 10.Other Embodiments

[0097] While one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the invention.

[0098] (A)

[0099] In the above embodiment, the pitch angle pθ is calculated by the IMU 24 and input to the controller 26, but the controller 26 may calculate the pitch angle pθ from the acceleration and angular velocity of the X axis, Y axis, and Z axis input from the IMU 24.

[0100] (B)

[0101] In the above embodiment, determination as to whether or not to be traveling is performed based on the detection signal of the vehicle speed sensor 36, but the present invention is not limited to this. Determination as to whether or not to be traveling may be performed based on the operation signal input from the accelerator 51 or the operation signal of the FNR lever 52.

[0102] (C)

[0103] In the above embodiment, the controller 26 determines that the body 1 is in the vibrating state M2 when the amplitude of the acceleration being larger than the predetermined threshold and the frequency of the acceleration being larger than the predetermined threshold are satisfied, but the present invention is not limited to this. For example, the controller 26 may determine that the body 1 is in the vibrating state M2 when at least one of the amplitude of the acceleration being larger than the predetermined threshold and the frequency of the acceleration being larger than the predetermined threshold is satisfied.

[0104] In the above embodiment, the controller 26 determines that the body 1 is in the vibrating state M2 when the amplitude of the pitch angle being larger than the predetermined threshold and the frequency of the pitch angle being larger than the predetermined threshold are satisfied, but the present invention is not limited to this. For example, the controller 26 may determine that the body 1 is in the vibrating state M2 when at least one of the amplitude of the pitch angle being larger than the predetermined threshold and the frequency of the pitch angle being larger than the predetermined threshold is satisfied.

[0105] (D)

[0106] In the above embodiment, the wheel loader 10 is provided with the IMU 24, but the present invention is not limited to the IMU. For example, when determination of vibration is performed using the acceleration in the up-down direction, an acceleration sensor may be provided in place of the IMU. When determination of vibration is performed using the pitch angle, an angle sensor may be provided in place of the IMU.

[0107] (E)

[0108] In the above embodiment, the IMU 24 is provided at the rear frame 12, but the present invention is not limited to this. For example, the IMU 24 may be provided at the front frame 11, but is preferably at a place less affected by the operation of the work implement 3.

[0109] (F)

[0110] In the above embodiment, the wheel loader 10 includes the pair of lift cylinders 16, but the present invention is not limited to this. The wheel loader 10 may include one or more lift cylinders 16.

[0111] (G)

[0112] In the above embodiment, the wheel loader 10 has been described as an example of the work machine, but examples of the work machine include, in addition to the wheel loader, a hydraulic excavator and a backhoe loader that include wheels.

[0113] (H)

[0114] In the above embodiment, the wheel loader 10 includes the HST 32 as a transmission, but the present invention is not limited to this. As a transmission, for example, a hydro mechanical transmission (HMT), a torque converter (T / C), or the like can be used.

[0115] The work machine and the control method for the work machine of the present disclosure have an effect that can easily stabilize behavior during travel, and are useful for, for example, a wheel loader and the like.

Claims

1. A work machine comprising:a work machine body configured to travel;a work implement attached to the work machine body;a damping unit configured to damp vibration of the work implement;a vibration information detection sensor configured to detect information regarding vibration of the work machine body; anda controller configured to control the damping unit based on the information regarding vibration detected by the vibration information detection sensor.

2. The work machine according to claim 1, whereinthe controller is configured to switch the damping unit betweena first state in which a function of damping vibration of the work implement is exerted anda second state in which a function of damping vibration of the work implement is not exerted, andthe controller is configured to switch the damping unit to the first state upon determining that the work machine body is vibrating based on the information regarding vibration.

3. The work machine according to claim 2, further comprising:a hydraulic cylinder that drives the work implement,the damping unit includingan on-off valve, andan accumulator connected to the hydraulic cylinder via the on-off valve,the damping unit being in the first state when the on-off valve is in an open state,the damping unit being in the second state when the on-off valve is in a closed state, andthe controller being configured to control the on-off valve based on the information regarding vibration.

4. The work machine according to claim 2, whereinthe information regarding vibration is acceleration generated in the work machine body, andthe controller is configured to determine that the work machine body is vibrating when at least one ofan amplitude of the acceleration being larger than a predetermined threshold anda frequency of the acceleration being larger than a predetermined threshold is satisfied.

5. The work machine according to claim 2, whereinthe information regarding vibration is a pitch angle generated in the work machine body, andthe controller is configured to determine that the work machine body is vibrating when at least one ofan amplitude of the pitch angle being larger than a predetermined threshold anda frequency of the pitch angle being larger than a predetermined threshold is satisfied.

6. A control method for a work machine including a work machine body configured to travel and a work implement attached to the work machine body, the control method comprising:acquiring information regarding vibration of the work machine body; andcontrolling a damping unit that damps vibration of the work implement based on the information regarding vibration.

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