Work machine and work machine control method

Abstract

To provide a work machine capable of reducing alarms due to false detection.SOLUTION: A wheel loader 10 includes a vehicle body 1, a rear detection unit 71, an alarm system 61, and a controller 126. The rear detection unit 71 detects objects behind the vehicle body 1 and measures the distance to the objects rear of the vehicle body 1. The alarm system 61 notifies that the rear detection unit 71 has detected an object rear of the vehicle body 1. The controller 126 changes the notification by the alarm system 61 based on the changes of the distance to the object from the vehicle body 1 measured by the rear detection unit 71.SELECTED DRAWING: Figure 7

Description

[Technical Field]

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

[0002] 2. Description of the Related Art For a wheel loader, which is an example of a work machine, an automatic stopping system has been proposed that detects an obstacle behind the wheel loader and automatically stops the machine.

[0003] For example, in Non-Patent Document 1, a stereo camera is installed on a wheel loader, and if an obstacle is detected while the vehicle is moving backward, the foot brake is activated. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] "NIPPO / Development of Automatic Stop System for Wheel Loaders / Stereo Camera for Obstacle Detection" July 8, 2016, Page 3, Nikkan Kensetsu Kogyo Shimbun Online, Internet <url: https: www.decn.co.jp ?p="72204"> Summary of the Invention [Problem to be solved by the invention]

[0005] However, wheel loaders are sometimes used to shovel up piles of earth and sand, and in such cases, conventional automatic stop systems detect the ground as an obstacle when reversing and issue an obstacle alarm, which is cumbersome for 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 reduce alarms due to false detections. [Means for solving the problem]

[0007] The work machine according to this aspect includes a vehicle body, a rear detection unit, a tilt state detection unit, and a control unit. The rear detection unit detects objects behind the vehicle body. The tilt state detection unit detects the tilt state of the vehicle body. The control unit determines control corresponding to the detection by the rear detection unit based on the tilt state of the vehicle body detected by the tilt state detection unit.

[0008] The work machine according to this aspect includes a vehicle body, a rear detection unit, a first notification unit, and a control unit. The rear detection unit detects an object behind the vehicle body and measures the distance to the object behind the vehicle body. The first notification unit notifies the rear detection unit that an object has been detected behind the vehicle body. The control unit changes the notification by the first notification unit based on a change in the distance from the vehicle body to the object measured by the rear detection unit.

[0009] The control method for a work machine according to this aspect includes a rear detection step, a tilt state detection step, and a control step. The rear detection step detects an object rearward of the vehicle body. The tilt state detection step detects a tilt state of the vehicle body. The control step determines control corresponding to the detection in the rear detection step, based on the tilt state of the vehicle body detected in the tilt state detection step.

[0010] The method for controlling a work machine according to this aspect includes a rear detection step and a control step. The rear detection step detects an object behind the vehicle body and measures the distance to the object behind the vehicle body. The control step changes the notification that an object has been detected behind the vehicle body based on a change in the measured distance from the vehicle body to the object.

[0011] The work machine according to this aspect includes a vehicle body, a rear detection unit, and a control unit. The vehicle body has a traveling body and a work implement disposed in front of the traveling body. The rear detection unit detects objects behind the vehicle body. The control unit determines whether the work implement is in a scraping operation state when the traveling body is driven forward based on the operation of the work implement, and changes control to suppress approach to rear objects when reversing based on the determination of the scraping operation state.

[0012] The control method for a work machine according to this aspect includes a scraping-up determination step, a rear detection step, and a control step. The scraping-up determination step determines a scraping-up operation state based on the operation of the work implement when the vehicle body having the traveling body and the work implement is moving forward by driving the traveling body. The rear detection step detects an object behind the vehicle body. The control step changes control to suppress approach to the rear object when reversing based on the determination of the scraping-up operation state. [Effects of the Invention]

[0013] According to the present disclosure, it is possible to provide a work machine and a method for controlling a work machine that are capable of reducing alarms due to false detections. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a side view of a wheel loader according to a first embodiment of the present disclosure. [Figure 2] FIG. 2 is a block diagram showing the configuration of the drive system, braking system, operation system, notification system, and controller of the wheel loader of FIG. 1. [Figure 3] FIG. 3 is a block diagram showing the configuration of the controller in FIG. 2. [Figure 4] FIG. 2 is a side view illustrating an automatic braking function that is activated by detecting an obstacle in the wheel loader of FIG. 1. [Figure 5] FIG. 2 is a diagram for explaining the scraping operation performed by the wheel loader of FIG. 1. [Figure 6] FIG. 2 is a flow chart for explaining the control operation of the wheel loader of FIG. 1. [Figure 7] FIG. 10 is a block diagram showing the configurations of a drive system, a braking system, an operation system, a notification system, and a controller of a wheel loader according to a second embodiment of the present disclosure. [Figure 8] FIG. 8 is a block diagram showing the configuration of the controller in FIG. 7. [Figure 9] FIG. 2 is a diagram for explaining the scraping operation performed by the wheel loader of FIG. 1. [Figure 10] FIG. 8 is a flow chart for explaining the control operation of the wheel loader of FIG. 7. [Figure 11] FIG. 11 is a block diagram showing the configurations of a drive system, a braking system, an operation system, and a notification system of a wheel loader according to a third embodiment of the present disclosure. [Figure 12] FIG. 12 is a block diagram showing the configuration of the controller in FIG. 11. [Figure 13] 12 is a diagram showing the transition of the working state of the wheel loader of FIG. 11. [Figure 14] FIG. 12 is a flow chart for explaining the control operation of the wheel loader of FIG. 11. [Figure 15] FIG. 10 is a block diagram showing the configurations of a drive system, a braking system, an operation system, a notification system, and a controller of a wheel loader according to a modified example of an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0015] A wheel loader as an example of a work machine according to the present disclosure will be described below with reference to the drawings.

[0016] (Embodiment 1) <Configuration> (Outline of wheel loader) FIG. 1 is a schematic diagram showing the configuration of a wheel loader 10 (an example of a work machine) according to this embodiment. The wheel loader 10 according to this embodiment includes a vehicle body 1, a body frame 2, a work implement 3, a pair of front tires 4 (an example of wheels), a cab 5, an engine compartment 6, a pair of rear tires 7 (an example of wheels), and a steering cylinder 9. In the following description, the terms "front," "rear," "right," "left," "up," and "down" refer to directions based on a view forward from the driver's seat. Furthermore, the "vehicle width direction" and the "left-right direction" are synonymous. In FIG. 1, the front-to-rear direction is indicated by X, with Xf indicating the front direction and Xb indicating the rear direction. Furthermore, the body frame 2, the front tires 4, and the rear tires 7 correspond to an example of a traveling body.

[0017] The wheel loader 10 uses the work implement 3 to perform work such as loading earth and sand.

[0018] The body frame 2 is of a so-called articulated type and has a front frame 11, a rear frame 12, and a connecting shaft 13. The front frame 11 is disposed in front of the rear frame 12. The connecting shaft 13 is provided in the center in the vehicle width direction and connects the front frame 11 and the rear frame 12 to each other so that they can swing. A pair of front tires 4 are attached to the left and right of the front frame 11. Furthermore, a pair of rear tires 7 are attached to the left and right of the rear frame 12.

[0019] The work implement 3 is driven by hydraulic oil from a work implement pump (not shown). The work implement 3 is swingably attached to the front of the front frame 11. The work implement 3 has a boom 14, a bucket 15, a lift cylinder 16, a bucket cylinder 17 (an example of an actuator), and a bell crank 18 (an example of a sub-link).

[0020] The base end of the boom 14 is rotatably attached to the front of the front frame 11 by a boom pin 14a. The tip of the boom 14 is rotatably attached to the rear of the bucket 15. The rear of the bucket 15 is on the opposite side of the opening 15b. Between the base end and tip of the boom 14, the tip of a cylinder rod 16a of a lift cylinder 16 is rotatably attached. The cylinder body of the lift cylinder 16 is rotatably attached to the front frame 11.

[0021] One end of the bell crank 18 is rotatably attached to the tip of the cylinder rod 17a of the bucket cylinder 17. The other end of the bell crank 18 is rotatably attached to the rear of the bucket 15. The bell crank 18 is rotatably supported between both ends by a bell crank support 14d near the center of the boom 14. The cylinder body of the bucket cylinder 17 is rotatably attached to the front frame 11. The extension and retraction force of the bucket cylinder 17 is converted into rotational motion by the bell crank and transmitted to the bucket 15.

[0022] The bucket 15 is rotatably attached to the tip of the boom 14 by a bucket pin 15a so that its opening faces forward. The bucket 15 rotates relative to the boom 14 by extension and contraction of the bucket cylinder 17, and performs a tilting operation (see arrow J) and a dumping operation (see arrow K). Here, the tilting operation of the bucket 15 refers to an operation in which the opening 15b and the claws 15c of the bucket 15 rotate toward the cab 5, thereby tilting the bucket. The dumping operation of the bucket 15 is the opposite of the tilting operation, and refers to an operation in which the opening 15b and the claws 15c of the bucket 15 rotate away from the cab 5, thereby tilting the bucket.

[0023] The cab 5 is mounted on the rear frame 12, and is equipped inside with a handle for steering, levers for operating the work implement 3, various display devices, etc. The engine room 6 is disposed on the rear frame 12 behind the cab 5, and houses an engine 31.

[0024] (Configuration for wheel loader control) FIG. 2 is a block diagram showing a configuration related to the control of the wheel loader 10 according to the present disclosure.

[0025] The wheel loader 10 has a drive system 21, a braking system 22, an operation system 23, a notification system 24, a detection system 25, and a controller 26 (an example of a control unit).

[0026] The drive system 21 drives the wheel loader 10. The braking system 22 brakes the wheel loader 10 while it is traveling. The operation system 23 is operated by an operator. The drive system 21 and braking system 22 operate based on the operation of the operation system 23 by the operator. The notification system 24 issues a notification to the operator based on the operation of the operation system 23 or the detection results by the detection system 25. The detection system 25 detects the tilt state of the vehicle body 1 and obstacles (an example of an object) behind the vehicle body 1. The controller 26 (an example of a control unit) operates the drive system 21, braking system 22, and notification system 24 based on the operation of the operation system 23 by the operator and the detection by the detection system 25.

[0027] (Drivetrain 21) The drivetrain 21 includes an engine 31 , an HST 32 , a transfer case 33 , an axle 34 , front tires 4 and rear tires 7 .

[0028] The engine 31 is, for example, a diesel engine, and the driving force generated by the engine 31 drives a pump 32 a of an HST (Hydro Static Transmission) 32 .

[0029] The HST 32 includes a pump 32a, a motor 32b, and a hydraulic circuit 32c connecting the pump 32a and the motor 32b. The pump 32a is a swash plate-type variable displacement pump, and the angle of the swash plate can be changed by a solenoid 32d. The pump 32a is driven by the engine 31 to discharge hydraulic oil. The discharged hydraulic oil is sent to the motor 32b through the hydraulic circuit 32c. The motor 32b is a swash plate-type motor, and the angle of the swash plate can be changed by a solenoid 32e. The hydraulic circuit 32c includes a first drive circuit 32c1 and a second drive circuit 32c2. The hydraulic oil is supplied from the pump 32a to the motor 32b via the first drive circuit 32c1, thereby driving the motor 32b in one direction (for example, the forward direction). Hydraulic oil is supplied from pump 32a to motor 32b via second drive circuit 32c2, thereby driving motor 32b in the other direction (for example, the reverse direction). The direction of hydraulic oil discharge to first drive circuit 32c1 or second drive circuit 32c2 can be changed by solenoid 32d.

[0030] The transfer 33 distributes the output from the engine 31 to the front and rear axles 34 .

[0031] A pair of front tires 4 are connected to the front axle 34, and rotate with the distributed power from the engine 31. A pair of rear tires 7 are connected to the rear axle 34, and rotate with the distributed power from the engine 31.

[0032] (Brake system 22) The braking system 22 includes a brake valve 41 , a service brake 42 , and a parking brake 43 .

[0033] The brake valve 41 is, for example, an EPC (Electric Proportional Valve) valve, and the amount of hydraulic oil sent to the service brake 42 can be adjusted by adjusting the opening degree.

[0034] The service brake 42 is provided on the axle 34. The service brake 42 is a hydraulic brake, and for example, when the opening of the brake valve 41 is large, the braking force becomes strong, and when the opening of the brake valve 41 is small, the braking force becomes weak.

[0035] As an automatic brake function, even if a brake pedal 54 (described later) is not operated, the brake valve 41 is driven by an instruction from the controller 26, and the service brake 42 is activated.

[0036] The parking brake 43 is provided on the transfer 33. As the parking brake 43, a wet multi-stage brake that can be switched between a braking state and a non-braking state, a disc brake, or the like can be used.

[0037] (Operation system 23) The operation system 23 has an accelerator 51, a FNR lever 52 (an example of an operation member), a parking switch 53, a brake pedal 54, a return switch 55, and an automatic brake release switch 56.

[0038] The accelerator 51 is provided in the cab 5. The operator sets the throttle opening by operating the accelerator 51. The accelerator 51 generates an opening signal indicating the accelerator operation amount and transmits it to the controller 26. The controller 26 controls the rotation speed of the engine 31 based on the transmitted signal.

[0039] When the accelerator 51 is turned off, the fuel supply to the engine 31 is stopped, the swash plates of the pump 32a and the motor 32b are controlled to provide resistance to the vehicle's movement, and a braking force (a weak braking force, described later) is generated due to internal inertia.

[0040] The FNR lever 52 is provided on the cab 5. The FNR lever 52 can be positioned for forward, neutral, or reverse. An operation signal indicating the position of the FNR lever 52 is sent to the controller 26, and the controller 26 controls the solenoid 32d to switch between forward and reverse.

[0041] The parking switch 53 is provided inside the cab 5 and is a switch that can be switched between an on and off state, and transmits a signal indicating the state to the controller 26. The controller 26 puts the parking brake 43 into a braking state or a non-braking state based on the transmitted signal.

[0042] The brake pedal 54 is provided inside the cab 5. The brake pedal 54 adjusts the opening of the brake valve 41. The brake pedal 54 also transmits the amount of operation to the controller 26.

[0043] The return switch 55 is operated by the operator to return the vehicle body 1 from a stopped state after the vehicle body 1 has been stopped by an automatic brake, which will be described later.

[0044] The automatic brake release switch 56 releases the automatic brake function and sets it so that the automatic brake function does not work.

[0045] (Hochi System 24) The notification system 24 includes an alarm device 61 (an example of a first notification unit), a function OFF notification lamp 62 (an example of a second notification unit), and an automatic brake activation notification lamp 63.

[0046] The warning device 61 issues a warning to the operator when an obstacle is detected behind the vehicle body 1 based on detection by a rear detection unit 71 of the detection system 25, which will be described later. The warning device 61 may have, for example, a lamp and turn on the lamp. Furthermore, instead of being limited to a lamp, the warning device 61 may have a speaker and emit a sound. Furthermore, the warning may be displayed on a display panel such as a monitor.

[0047] The function OFF notification lamp 62, for example, lights up to notify the operator when the automatic braking function has been suppressed or stopped at the discretion of the controller 26. The function OFF notification lamp 62 also lights up to notify the operator when the automatic braking release switch 56 has been operated at the discretion of the operator and the automatic braking function has been turned off. When the function OFF notification lamp 62 is off, this indicates that the automatic braking function can be activated. The function OFF notification lamp 62 does not have to be a lamp and may also emit a sound. The notification may also be displayed on a display panel, such as a monitor.

[0048] The automatic brake activation notification lamp 63 notifies the operator that the automatic brake is activated and that a recovery operation is required using the recovery switch 55. When the recovery switch 55 is operated to release the automatic brake, the automatic brake activation notification lamp 63 goes out.

[0049] The automatic brake activation notification lamp 63 does not have to be a lamp, but may emit a sound. The notification may also be displayed on a display panel such as a monitor.

[0050] As described above, the means for notifying the operator of information by the notification system 24 can be appropriately selected from lamps, sounds, monitors, etc.

[0051] (Detection System 25) As shown in FIG. 2, the detection system 25 has a rear detection unit 71 and a vehicle body angle sensor 72 (an example of a tilt state detection unit).

[0052] The rear detection unit 71 detects obstacles behind the vehicle body 1. The rear detection unit 71 is attached to the rear end of the vehicle body 1, for example, as shown in Fig. 1, but is not limited to the rear end.

[0053] The rear detection unit 71 has, for example, a millimeter-wave radar. The receiving antenna detects how millimeter-wave band radio waves emitted from a transmitting antenna are reflected off the surface of an obstacle and returned, allowing the distance to the object to be measured. The detection result by the rear detection unit 71 is transmitted to the controller 26, which can then detect that an obstacle is present within a predetermined range while reversing. Note that the device is not limited to millimeter-wave radar, and may be, for example, a camera.

[0054] The vehicle body angle sensor 72 detects the tilt state of the vehicle body 1. The vehicle body angle sensor 72 detects whether or not the vehicle body 1 is in a tilt state by detecting the angle of the vehicle body 1. Note that an IMU (Inertial Measurement Unit) may be used instead of the vehicle body angle sensor 72, and the tilt state of the wheel loader 10 may be determined based on images detected by cameras installed inside and outside the vehicle. Furthermore, any configuration may be used as long as it is capable of detecting the tilt state of the wheel loader 10, and the configuration is not limited to these.

[0055] (Controller 26) The controller 26 includes a processor such as a CPU (Central Processing Unit), a main memory including a non-volatile memory such as a ROM (Read Only Memory) and a volatile memory such as a RAM (Random Access Memory), and a storage. The controller 26 reads a program stored in the storage, loads it into the main memory, and executes predetermined processing in accordance with the program. The program may be distributed to the controller 26 via a network.

[0056] FIG. 3 is a block diagram showing the configuration of the controller 26.

[0057] The controller 26 has an automatic brake control determination unit 81, a brake instruction unit 82, and a notification instruction unit 83. Note that the controller 26 is not limited to being one, and a plurality of controllers may be provided, and the functions of the automatic brake control determination unit 81, the brake instruction unit 82, and the notification instruction unit 83 may also be provided separately among a plurality of controllers.

[0058] The automatic brake control determination unit 81 determines the control of the automatic brake. The automatic brake control determination unit 81 includes an obstacle determination unit 91, a tilt state determination unit 92, and a determination unit 93.

[0059] The obstacle determination unit 91 determines whether or not an obstacle is present when the vehicle is moving backward. The obstacle determination unit 91 detects that the front tire 4 or the rear tire 7 is rotating backward, or that the vehicle is moving backward because the FNR lever 52 is in the reverse position. When the obstacle determination unit 91 detects that the vehicle is moving backward, and receives detection information of an obstacle within a predetermined range from the rear detection unit 71 of the detection system 25, the obstacle determination unit 91 determines that an obstacle is present.

[0060] If the vehicle body angle sensor 72 detects that the tilt angle is equal to or greater than a predetermined angle (for example, 15°), the tilt state determination unit 92 determines that the vehicle body 1 is placed on an inclined surface that would cause the ground to be erroneously detected as an obstacle. The tilt angle θ (see FIG. 5, described later) is the angle at which the front side of the wheel loader 10 is raised above the horizontal.

[0061] The determination unit 93 determines automatic brake control based on the determination results of the obstacle determination unit 91 and the tilt state determination unit 92 .

[0062] When the obstacle determination unit 91 determines that an obstacle is present during reverse travel and the inclination state determination unit 92 determines that the inclination angle is less than a predetermined angle, the decision unit 93 determines to perform a first control that activates the automatic brakes and issues an alarm notifying the user of the presence of an obstacle, as shown in Fig. 4, which will be described later. This is because, since the inclination angle has been detected to be less than the predetermined angle, it can be determined that the wheel loader 10 is not performing work such as scraping, and that the detection of an obstacle is not a false detection.

[0063] Furthermore, if the obstacle determination unit 91 determines that an obstacle is present during reverse travel, but the inclination state determination unit 92 determines that the inclination angle is a predetermined angle or greater, the decision unit 93 determines to perform second control that does not activate the automatic brake and notifies the user that the automatic brake function has stopped. This is because, when the inclination angle is detected to be a predetermined angle or greater, it can be determined that the wheel loader 10 is performing work such as raking, and that the ground will be erroneously detected as an obstacle, as shown in Figure 5, which will be described later.

[0064] The brake instruction unit 82 controls the automatic brake based on the decision of either the first control or the second control by the decision unit 93. In this specification, automatic braking refers to automatically applying a braking force to the vehicle body 1 based on the determination results of the obstacle determination unit 91 and the tilt state determination unit 92, and is not limited to the braking force applied by the service brake 42, as will be described later.

[0065] The notification instruction unit 83 issues an operation instruction to the alarm device 61 or the function OFF notification lamp 62 based on the decision of the decision unit 93 on either the first control or the second control.

[0066] When the decision unit 93 decides to perform the first control, the brake instruction unit 82 stops the fuel supply to the engine 31 by turning off the accelerator 51. Then, the brake instruction unit 82 operates the brake valve 41 to drive the service brake 42 and stop the vehicle body 1. The notification instruction unit 83 activates the alarm device 61 to notify the operator of the presence of an obstacle and the activation of the automatic brake.

[0067] Fig. 4 is a diagram showing a state in which an obstacle S is detected while reversing and the vehicle body 1 is stopped. In the first control, the service brake 42 is activated with a preset brake force (which can also be considered as braking force) so that the vehicle body 1 stops in front of the obstacle S. In Fig. 4, the stopped vehicle body 1 is indicated by a two-dot chain line.

[0068] Note that automatic braking using a set braking force does not necessarily require braking the vehicle body 1 with the service brake 42 as described above, and may instead activate the parking brake 43. In this case, when the decision unit 93 decides to perform the first control, the brake command unit 82 stops the fuel supply to the engine 31 by turning off the accelerator 51. Then, the brake command unit 82 controls the parking brake 43 to brake the vehicle body 1.

[0069] When the decision unit 93 decides to perform the second control, the notification instruction unit 83 controls the function OFF notification lamp 62 to light up, and does not operate the brake valve 41 by the brake instruction unit 82 or the alarm device 61 by the notification instruction unit 83.

[0070] FIG. 5 is a diagram showing the wheel loader 10 performing raking work. As shown in FIG. 5, a mountain of earth and sand M has formed on the ground G, and the wheel loader 10 is positioned on its slope i. When raking, the wheel loader 10 goes up and down the slope i, and detects the ground G as an obstacle S every time it moves backward. Therefore, in this embodiment, when the angle θ detected by the vehicle body angle sensor 72 is equal to or greater than a predetermined angle, automatic braking is not performed even if an obstacle is detected, and control is performed so that the warning device 61 is not activated. The tilt angle θ is, for example, the angle formed between the horizontal line H and a line L connecting the axes of the front tires 4 and the rear tires 7.

[0071] This reduces false detections and improves work efficiency.

[0072] <Operation> Next, the control operation of the wheel loader 10 of this embodiment will be described.

[0073] FIG. 6 is a flow diagram showing the control operation of the wheel loader 10 of this embodiment.

[0074] First, in step S10 (an example of a rear detection step), the obstacle determination unit 91 of the controller 26 determines whether or not an obstacle has been detected when the vehicle body 1 is moving backward. The obstacle determination unit 91 determines that the vehicle body 1 is moving backward when the front tires 4 or the rear tires 7 are rotating backward or when the FNR lever 52 is in the reverse position. When the obstacle determination unit 91 detects that the vehicle is moving backward and receives detection information of an obstacle within a predetermined range from the rear detection unit 71 of the detection system 25, it determines that an obstacle is present.

[0075] If it is determined in step S10 that no obstacle is present, the controller 26 does not activate the automatic brakes in step S14, and the control ends. In step S14, the presence of an obstacle is not detected, and therefore the warning device 61 does not issue a warning.

[0076] In step S11 (an example of a tilt state detection step), if the tilt state determination unit 92 determines that the tilt angle θ is less than a predetermined threshold value (e.g., 15 degrees), the decision unit 93 decides to perform the first control, and the first control is performed in step S12.

[0077] In the first control in step S12 (an example of a control step), in the controller 26, the brake instruction unit 82 stops the fuel supply to the engine 31. Then, the brake instruction unit 82 operates the brake valve 41 to drive the service brake 42 and stop the vehicle body 1. The notification instruction unit 83 activates the alarm device 61 to notify the operator of the presence of an obstacle and the activation of the automatic brake, and the control ends.

[0078] On the other hand, if it is determined in step S11 that the tilt angle θ is equal to or greater than the predetermined threshold value, the decision unit 93 decides to perform the second control, and the second control is performed in step S13.

[0079] In the second control in step S13 (an example of a control step), the notification instruction unit 83 does not activate the alarm device 61, but turns on the function OFF notification lamp 62, and the control ends. Note that the controller 26 does not control the brake valve 41.

[0080] As a result, in the case of an inclined state in which the ground G is detected as an obstacle, the automatic brake function and the warning device 61 can be stopped.

[0081] This reduces the number of alarms due to false detection.

[0082] In addition, since it is possible to disable the automatic brake function, it is possible to detect the ground during raking work and prevent the vehicle from being unable to descend from the mountain of earth and sand M.

[0083] Also, for example, if the first control is performed in step S12 and then terminated, and the control is started again, and if no obstacle is detected in step S10, the brake operation is stopped in step S14. In this way, even if an obstacle no longer exists during reverse travel, the automatic brake control can be performed appropriately. The same applies if an obstacle appears during reverse travel.

[0084] (Embodiment 2) Next, a wheel loader 10 according to a second embodiment of the present disclosure will be described.

[0085] <Configuration> The wheel loader 10 of the second embodiment does not have a vehicle body angle sensor 72, as compared to the first embodiment.

[0086] FIG. 7 is a block diagram showing the configuration of the drive system, braking system, operation system, notification system, and controller of the wheel loader according to the second embodiment. FIG. 8 is a block diagram showing the configuration of the controller 126 shown in FIG. 7.

[0087] The detection system 125 of the second embodiment has a rear detection unit 71 but does not have a vehicle body angle sensor 72.

[0088] Also, the automatic brake control determination unit 181 of the controller 126 in the second embodiment has a distance change determination unit 94 instead of the inclination state determination unit 92 of the automatic brake control determination unit 81 in the first embodiment.

[0089] The distance change determination unit 94 of the second embodiment determines the change in the distance to the object detected using the detection result from the rear detection unit 71. By using, for example, a millimeter-wave radar for the rear detection unit 71, the distance to the object can be measured.

[0090] Although the scooping operation of the wheel loader 10 has been described in FIG. 5, in the scooping operation, the up and down movement of the earth and sand mountain M is performed. FIG. 9 is a view showing the wheel loader 10 in a state lowered from the state of FIG. 5. In FIG. 5, the distance from the rear detection unit 71 to the ground G is indicated by d1, and in FIG. 9, the distance from the rear detection unit 71 to the ground G is indicated by d2. As shown in FIGS. 5 and 9, when the wheel loader 10 descends the earth and sand mountain M, the inclination becomes gentle, so the distance from the rear detection unit 71 to the ground G becomes longer as shown by d1 < d2.

[0091] The distance change determination unit 94 of the present embodiment determines whether the distance to the object determined as an obstacle by the obstacle determination unit 91 becomes longer during reverse travel.

[0092] When the obstacle determination unit 91 determines that an obstacle is present when reversing and determines that the distance to the obstacle increases when reversing, the decision unit 93 determines to perform second control that does not activate the automatic brake and notifies the user that the automatic brake function has stopped. This is because, since the distance to the obstacle increases when reversing, it can be determined that the wheel loader 10 is performing work such as raking, and that the ground is being erroneously detected as an obstacle. Note that it is not necessarily necessary to notify the user that the automatic brake function has stopped.

[0093] Furthermore, when the obstacle determination unit 91 determines that an obstacle is present when reversing and determines that the distance to the obstacle is not increasing while reversing, the decision unit 93 decides to perform the first control that activates the automatic brakes and issues an alarm notifying the presence of an obstacle. This is because the distance to the obstacle is not increasing, the wheel loader 10 is not performing work such as raking, and it can be determined that the detection of the obstacle is not a false detection.

[0094] <Operation> Next, the control operation of the wheel loader 10 according to the second embodiment will be described.

[0095] FIG. 10 is a flow diagram showing the control operation of the wheel loader 10 according to the second embodiment.

[0096] First, in step S10 (an example of a rearward detection step), the obstacle determination unit 91 of the controller 26 determines whether an obstacle has been detected when the vehicle body 1 is moving backward. The obstacle determination unit 91 determines that the vehicle body 1 is moving backward because the front tires 4 or the rear tires 7 are rotating backward or because the FNR lever 52 is in the reverse position. When the obstacle determination unit 91 detects that the vehicle is moving backward and receives detection information of an obstacle within a predetermined range from the rearward detection unit 71 of the detection system 125, the obstacle determination unit 91 determines that an obstacle is present. Note that if it is not determined that an obstacle is present in step S10, the controller 26 ends the control in step S14 without activating the automatic brake. Since the presence of an obstacle is not detected in step S14, the warning device 61 does not issue a warning.

[0097] Next, in step S111 (an example of a distance change determination step), the distance change determination unit 94 determines whether the distance to the obstacle is increasing during reverse travel using the obstacle determination unit 91. The distance change determination unit 94 compares the distance to the obstacle at a predetermined first point in time with the distance to the obstacle at a second point in time that is later than the first point in time, and determines that the distance to the obstacle is decreasing if the distance at the second point in time is greater than the distance at the first point in time.

[0098] In step S111, if the tilt state determination unit 92 determines that the distance to the obstacle has not increased, the decision unit 93 decides to perform the first control, and the first control is performed in step S12.

[0099] In the first control in step S12 (an example of a control step), in the controller 26, the brake instruction unit 82 stops the fuel supply to the engine 31. Then, the brake instruction unit 82 operates the brake valve 41 to drive the service brake 42 and stop the vehicle body 1. The notification instruction unit 83 activates the alarm device 61 to notify the operator of the presence of an obstacle and the activation of the automatic brake, and the control ends.

[0100] On the other hand, if the distance change determination unit 94 determines in step S111 that the distance to the obstacle has increased, the decision unit 93 decides to perform the second control, and the second control is performed in step S13.

[0101] In the second control in step S13 (an example of a control step), the notification instruction unit 83 does not activate the alarm device 61, but turns on the function OFF notification lamp 62, and the control ends. Note that the controller 26 does not control the brake valve 41.

[0102] This makes it possible to determine that the ground G has been detected as an obstacle, and the automatic brake function and the alarm device 61 can be stopped.

[0103] (Embodiment 3) Next, a wheel loader 10 according to a third embodiment of the present disclosure will be described.

[0104] In embodiment 1, when the inclination angle is equal to or greater than a predetermined threshold, it is determined that scraping work is being performed and the second control is carried out, but in embodiment 3, it is determined that scraping work is being performed based on the operation of the work machine 3, etc.

[0105] <Configuration> FIG. 11 is a block diagram showing a configuration relating to control of the wheel loader 10 according to the third embodiment.

[0106] In addition to the configuration of the drive system 21 of the first embodiment, a cylinder drive unit 35 is further provided in the drive system 221 of the wheel loader 10 of the third embodiment.

[0107] The cylinder drive unit 35 has a power take-off unit 35a, a work implement pump 35b, and a control valve 35c. The power take-off unit 35a is a PTO (Power Take Off) that takes output from the engine 31 and transmits it to the work implement pump 35b, for example, when the vehicle body 1 is stopped. The work implement pump 35b is driven by the power of the engine 31 and discharges hydraulic oil to the control valve 35c. The control valve 35c supplies the hydraulic oil supplied from the work implement pump 35b to the lift cylinder 16 (an example of a boom cylinder) and the bucket cylinder 17 based on commands from the controller 26.

[0108] Unlike the first embodiment, the detection system 225 of the wheel loader 10 of the third embodiment does not have a vehicle body angle sensor 72, but has a boom angle sensor 73 (an example of a work implement height detection unit) and a boom bottom pressure sensor 74 in addition to the rear detection unit 71.

[0109] The boom angle sensor 73 detects the angle of the boom 14 and outputs the detected value to the controller 226 (an example of a control unit). The boom angle sensor 73 can be configured with a potentiometer, and is disposed on the boom pin 14a, for example.

[0110] As shown in FIG. 1, the angle of the boom 14 is the angle θ of a straight line Lb extending from the center of the boom pin 14a toward the center of the bucket pin 15a, relative to a horizontal line Lh extending forward from the center of the boom pin 14a. When the straight line Lb is horizontal, the boom angle is defined as 0°. When the straight line Lb is above the horizontal line Lh, the angle θ of the boom 14 is defined as a positive value. When the straight line Lb is below the horizontal line Lh, the angle θ of the boom 14 is defined as a negative value.

[0111] The boom angle sensor 73 may be a stroke sensor provided on the lift cylinder 16.

[0112] The boom bottom pressure sensor 74 is attached to the bottom side of the lift cylinder 16. Pressure is applied to the bottom side of the lift cylinder 16, causing the cylinder to extend and the boom 14 to rise. The boom bottom pressure sensor 74 detects the pressure (bottom pressure) of the hydraulic oil in the oil chamber on the cylinder bottom side of the lift cylinder 16. The boom bottom pressure sensor 74 sends the detected bottom pressure to the controller 226.

[0113] FIG. 12 is a block diagram showing the configuration of the controller 226.

[0114] The controller 226 differs from the controller 26 of the first embodiment in that it has a raking determination unit 95 instead of the tilt state determination unit 92. The raking determination unit 95 determines whether or not the work content of the wheel loader 10 when moving forward is raking work.

[0115] The raking-up determination unit 95 determines whether or not an excavation work state is being performed during forward movement, and after the determination that the excavation work state is being performed is maintained, determines whether or not an excavation work state is being performed.

[0116] 13 is a diagram showing the state transition of the work content. The raking determination unit 95 determines whether the work is in an excavation work state W1 or in a state other than excavation work W2.

[0117] The scraping determination unit 95 determines that the excavation work state W1 is in progress when the conditions A and B are met during forward movement.

[0118] The scrape-up determination unit 95 determines that the vehicle body 1 is traveling forward (forward state) based on whether the front tire 4 or rear tire 7 is rotating forward or the FNR lever 52 is in the forward position.

[0119] Condition (A) is that the boom bottom pressure, which is the value detected by the boom bottom pressure sensor 74, is equal to or greater than a first threshold value. The first threshold value is stored in the controller 226. When the boom bottom pressure is equal to or greater than a predetermined threshold value, it is determined that pressure is being applied to the lift cylinder 16. That is, during excavation, for example, pressure is applied to the lift cylinder 16 by loading earth and sand into the bucket 15, so by detecting the boom bottom pressure, it can be determined whether or not excavation work is being performed.

[0120] Condition (B) is that the angle θ of the boom 14, which is the value detected by the boom angle sensor 73, is equal to or less than a second threshold value. During excavation, the angle θ of the boom 14 is positioned below the horizontal position, so the second threshold value is preferably a negative value. The second threshold value is stored in the controller 226.

[0121] That is, when a pressure equal to or greater than a predetermined first threshold is applied to the lift cylinder 16 and the angle θ of the boom 14 drops to or below a predetermined second threshold, the state of the wheel loader 10 is determined to be in the excavation work state W1. When the scraping determination unit 95 determines that the wheel loader 10 is in the excavation work state W1, it sets the excavation flag to ON and sets the boom pressure reduction flag to OFF.

[0122] Next, the raking determination unit 95 determines whether the excavation work state W1 is in a raking work state W3 or a state W4 other than raking work. The raking determination unit 95 determines that the work is in a raking work state W3 when the excavation flag is ON and condition (C) is satisfied, and determines that the work is in a state W4 other than raking work when condition (C) is not satisfied.

[0123] Condition (C) is that the angle θ of the boom 14, which is the value detected by the boom angle sensor 73, is greater than a third threshold value. The third threshold value is, for example, a negative value. The third threshold value is set to a value greater than the second threshold value. The third threshold value is stored in the controller 226. The second threshold value indicates when the position of the bucket 15 is close to the tire contact surface. The second threshold value can be set to, for example, -40°. The third threshold value indicates when the boom 14 is positioned approximately halfway between the horizontal state and the state of the second threshold value. The third threshold value can be set to, for example, -20°. The third threshold value and the second threshold value are set so that the boom 14 at the third threshold value is rotated higher than the boom 14 at the second threshold value.

[0124] Conditions (B) and (C) are set based on the magnitude of the angle of boom 14, but are not limited to this and may be set based on the height of bucket 15 after detecting its position. The position of bucket 15 can be detected by a camera provided in cab 5, for example. The third threshold and the second threshold are set so that the height of bucket 15 at the third threshold is higher than the height of bucket 15 at the second threshold.

[0125] In this way, conditions (B) and (C) may be set based on the height of the work implement 3, and the height of the work implement 3 at the third threshold may be set higher than the height of the work implement 3 at the second threshold.

[0126] When the raking determination unit 95 determines that the raking operation state W3 is in, it sets the raking flag. Also, when the raking determination unit 95 determines that the excavation flag is ON and the condition (C) is not satisfied, it sets the raking flag to OFF.

[0127] Since the boom 14 is positioned higher during scraping compared to normal excavation, by detecting the angle θ of the boom 14 in the excavation work state W1, it is possible to distinguish between the scraping work state W3 and a state W4 other than scraping work.

[0128] If condition (D) or condition (E) is satisfied while the excavation flag is ON, the scraping determination unit 95 determines that the wheel loader 10 is in a state W2 other than excavation work and sets the excavation flag to OFF.

[0129] Condition (D) is that the boom bottom pressure reduction flag is ON. The boom bottom pressure reduction flag is set to ON when the value detected by the boom bottom pressure sensor 74 is lower for a predetermined time than a boom bottom pressure threshold value that is preset based on the angle θ of the boom 14. Here, the boom bottom pressure threshold value that is preset based on the angle θ of the boom 14 is stored in the controller 226.

[0130] In this way, when the boom bottom pressure becomes smaller than a threshold value set based on the boom angle for a predetermined period of time, the scraping determination unit 95 sets the boom pressure reduction flag to ON, determines that a transition has occurred to a state W2 other than excavation work, and sets the excavation flag to OFF.

[0131] Condition (E) is that the FNR lever 52 is in a position other than forward (F) (reverse (N) or neutral (N)). If the vehicle is not moving forward, the shoveling determination unit 95 determines that the vehicle is in a state W2 other than excavation work, and sets the excavation flag to OFF.

[0132] As described above, when the scraping determination unit 95 determines that the wheel loader 10 is in the excavation work state W1 by satisfying the conditions (A) and (B), and if the condition (C) is further satisfied while this determination is maintained, it determines that the wheel loader 10 is in the scraping work state W3 and sets the scraping flag to ON.

[0133] The determination unit 93 determines automatic brake control based on the determination results of the obstacle determination unit 91 and the determination results of the scraping-up determination unit 95.

[0134] When the raking determination unit 95 determines that raking work is not being performed (in FIG. 12, state W2 other than excavation work or state W4 other than raking work) and the obstacle determination unit 91 determines that an obstacle is present when moving backward, the decision unit 93 decides to perform first control that activates the automatic brakes and issues an alarm notifying the presence of an obstacle. This is because it can be determined that the wheel loader 10 is not performing raking work and that the detection of an obstacle is not a false detection.

[0135] Furthermore, if the obstacle determination unit 91 determines that an obstacle is present during reverse travel after the raking determination unit 95 determines that the vehicle is in the raking work state W3, the decision unit 93 determines to perform second control that does not activate the automatic brake and notifies the user that the automatic brake function has stopped. This is because it can be determined that the wheel loader 10 is performing raking work and that the ground is being erroneously detected as an obstacle.

[0136] <Operation> Next, the control operation of the wheel loader 10 according to the third embodiment will be described.

[0137] FIG. 14 is a flow diagram showing the control operation of the wheel loader 10 according to the third embodiment.

[0138] First, in step S210, the scraping determination unit 95 determines whether or not the vehicle body 1 is moving forward. The scraping determination unit 95 determines that the wheel loader 10 is traveling forward (forward state) based on whether the front tires 4 or rear tires 7 are rotating forward or the FNR lever 52 is in the forward position.

[0139] If it is determined in step S210 that the wheel loader 10 is in the forward movement state, then in step S220 the scraping determination unit 95 determines whether or not the wheel loader 10 is in the excavation work state W1. The scraping determination unit 95 determines that the wheel loader 10 is in the excavation work state W1 when condition (A) based on the boom bottom pressure and condition (B) based on the boom angle are satisfied.

[0140] If it is determined in step S220 that conditions (A) and (B) are satisfied and the excavation operation state is W1, the raking determination unit 95 sets the excavation flag to ON, and control proceeds to step S230.

[0141] In step S230, the raking determination unit 95 determines whether or not the wheel loader 10 is in the raking work state W3. The raking determination unit 95 determines that the wheel loader 10 is in the raking work state W3 when the excavation flag is set to ON and condition (C) based on the boom angle is satisfied.

[0142] In step S230, if it is determined that the condition (C) is satisfied and the state is the scraping operation state W3, the scraping determination unit 95 sets the scraping flag to ON, and control proceeds to step S240.

[0143] In step S240, the obstacle determining unit 91 determines whether or not the wheel loader 10 is in a reverse state. The obstacle determining unit 91 determines that the wheel loader 10 is traveling backward (in a reverse state) either because the front tires 4 or the rear tires 7 are rotating rearward, or because the FNR lever 52 is in the reverse position.

[0144] If it is determined in step S240 that the vehicle is in reverse, control proceeds to step S250.

[0145] In step S250, the obstacle determiner 91 determines whether an obstacle is present. When the obstacle determiner 91 receives detection information of an obstacle within a predetermined range from the rear detector 71 of the detection system 225, the obstacle determiner 91 determines that an obstacle is present.

[0146] If it is determined in step S250 that an obstacle is present, the decision unit 93 decides to perform the second control, and the second control is performed in step S260.

[0147] In the second control in step S260 (an example of a control step), the notification instruction unit 83 does not activate the alarm device 61, but turns on the function OFF notification lamp 62, and the control ends. Note that the controller 26 does not control the brake valve 41.

[0148] This makes it possible to determine that the ground G has been detected as an obstacle, and the automatic brake function and the alarm device 61 can be stopped.

[0149] On the other hand, if it is determined in step S210 that the wheel loader 10 is not in a forward traveling state, control proceeds to step S270. In step S270, the obstacle determination unit 91 determines whether or not the wheel loader 10 is in a reverse traveling state. The obstacle determination unit 91 determines that the wheel loader 10 is traveling backward (reverse traveling state) either because the front tires 4 or the rear tires 7 are rotating rearward, or because the FNR lever 52 is in the reverse position.

[0150] If it is determined in step S270 that the vehicle is in reverse, control proceeds to step S280. In step S280, the obstacle determination unit 91 determines whether an obstacle is present. When the obstacle determination unit 91 receives detection information of an obstacle within a predetermined range from the rear detection unit 71 of the detection system 225, the obstacle determination unit 91 determines that an obstacle is present.

[0151] If it is determined in step S280 that an obstacle is present, the decision unit 93 decides to perform the first control, and the first control is performed in step S290.

[0152] In the first control in step S280 (an example of a control step), in the controller 26, the brake instruction unit 82 stops the fuel supply to the engine 31. Then, the brake instruction unit 82 operates the brake valve 41 to drive the service brake 42 and stop the vehicle body 1. The notification instruction unit 83 activates the alarm device 61 to notify the operator of the presence of an obstacle and the activation of the automatic brake, and the control ends.

[0153] If it is not determined in step S220 that excavation work is being performed, the control ends without operating the braking system 22 and the notification system 24. If it is not determined in step S230 that shoveling work is being performed, the control ends without operating the braking system 22 and the notification system 24. If it is not determined in step S240 that the vehicle is in reverse, the control ends without operating the braking system 22 and the notification system 24. If an obstacle is not detected in step S250, the control ends without operating the braking system 22 and the notification system 24.

[0154] Furthermore, if it is determined in step S270 that the vehicle is not in reverse, the control ends without operating the braking system 22 and the notification system 24. Also, if no obstacle is detected in step S280, the control ends without operating the braking system 22 and the notification system 24.

[0155] <Features> (1) The wheel loader 10 (an example of a work machine) of this embodiment includes a vehicle body 1, a rear detection unit 71, a vehicle body angle sensor 72 (an example of a tilt state detection unit), and a controller 26 (an example of a control unit). The rear detection unit 71 detects obstacles (an example of objects) behind the vehicle body 1. The vehicle body angle sensor 72 detects the tilt state of the vehicle body 1. The controller 26 determines control corresponding to the detection of the rear detection unit 71, based on the tilt state of the vehicle body 1 detected by the vehicle body angle sensor 72.

[0156] As a result, when the vehicle body 1 is placed on an inclined surface, for example, for raking work, it is possible to prevent the ground surface G from being detected as an obstacle, thereby preventing erroneous detection of an obstacle. Note that the control corresponding to the detection by the rear detection unit 71 can also be said to be control that suppresses approach to a rear obstacle S (an example of an object) when reversing.

[0157] (2) The wheel loader 10 (an example of a work machine) of this embodiment further includes an alarm device 61 (an example of a first alarm unit). The alarm device 61 issues an alarm when the rear detection unit 71 detects an obstacle (an example of an object) behind the vehicle body 1. Control corresponding to rear detection by the rear detection unit 71 includes stopping the alarm by the alarm device 61.

[0158] This makes it possible to prevent the ground G from being erroneously detected as an obstacle and an alarm being issued to notify the presence of the obstacle.

[0159] (3) The wheel loader 10 (an example of a work machine) of this embodiment includes a vehicle body 1, a rear detection unit 71, an alarm device 61 (an example of a first alarm unit), and a controller 126 (an example of a control unit). The rear detection unit 71 detects an object behind the vehicle body 1 and measures the distance to the object behind the vehicle body 1. The alarm device 61 issues an alarm that the rear detection unit 71 has detected an object behind the vehicle body 1. The controller 126 changes the alarm issued by the alarm device 61 based on a change in the distance from the vehicle body 1 to the object measured by the rear detection unit 71.

[0160] This makes it possible to prevent the ground G from being detected as an obstacle when the wheel loader 10 is performing work such as raking, thereby preventing erroneous detection of an obstacle. As a result, it is possible to, for example, stop the alarm from the alarm device 61, thereby reducing the number of alarms due to erroneous detection.

[0161] (4) In the wheel loader 10 (an example of a work machine) of this embodiment, the rear detection unit 71 detects objects behind the vehicle body 1 when the vehicle body 1 is moving in reverse. The rear detection unit 71 detects that the vehicle is moving in reverse when the front tires 4 or rear tires 7 (an example of a wheel) provided on the vehicle body 1 are rotating rearward or when the FNR lever 52 (an example of an operating member) which can set the vehicle body 1 to move forward or backward is set to the reverse position.

[0162] This makes it possible to detect that the vehicle body 1 is moving backward.

[0163] (5) In the wheel loader 10 (an example of a work machine) of this embodiment, the control corresponding to detection by the rear detection unit 71 includes automatic braking, which automatically brakes the vehicle body 1 when the rear detection unit 71 detects an obstacle (an example of an object), and stopping the automatic braking.

[0164] This prevents the ground G from being mistakenly detected as an obstacle S, which would cause the automatic brake to operate and stop the vehicle body 1.

[0165] (6) In the wheel loader 10 (an example of a work machine) of this embodiment, when the rear detection unit 71 detects an obstacle (an example of an object) behind the vehicle body 1, the controller 26 (an example of a control unit) causes the warning device 61 to issue an alert of the obstacle detection if the inclination of the vehicle body 1 is less than a predetermined threshold, and causes the warning device 61 (an example of a first alert unit) to stop issuing an alert if the inclination of the vehicle body 1 is equal to or greater than the predetermined threshold.

[0166] This makes it possible to prevent the ground G from being erroneously detected as an obstacle and an alarm from being issued when the vehicle body 1 is placed on an inclined position, for example, during raking work.

[0167] (7) In the wheel loader 10 (an example of a work machine) of this embodiment, when the rear detection unit 71 detects an obstacle (an example of an object) behind the vehicle body 1, the controller 26 (an example of a control unit) activates the automatic brakes if the inclination of the vehicle body 1 is less than a predetermined threshold, and stops the automatic brakes if the inclination of the vehicle body 1 is equal to or greater than the predetermined threshold.

[0168] This makes it possible to prevent the vehicle body 1 from being stopped by the automatic brake being activated when the vehicle body is placed on an inclined position due to, for example, scraping work.

[0169] (8) The wheel loader 10 (an example of a work machine) of this embodiment further includes a function-off notification lamp 62 (an example of a second notification unit). The function-off notification lamp 62 notifies the operator that the automatic brake has been stopped. When the controller 26 (an example of a control unit) has suppressed or stopped the automatic brake, the controller 26 notifies the operator by means of the function-off notification lamp 62. This allows the operator to recognize that automatic braking is being suppressed or stopped.

[0170] (9) In the wheel loader 10 (an example of a work machine) of this embodiment, the predetermined threshold value of the inclination is 15°.

[0171] This allows the vehicle body 1 to detect that it is placed on a steep slope such as a construction site.

[0172] (10) In the wheel loader 10 (an example of a work machine) of this embodiment, the controller 126 (an example of a control unit) changes the notification by the warning device 61 (an example of a first notification unit) when the distance to the object at a second point in time that is later than the first point in time becomes greater than the distance to the object at a first point in time.

[0173] When the distance to the detected object increases in this way, it can be determined that the wheel loader 10 is performing, for example, raking work.

[0174] (11) In the wheel loader 10 (an example of a work machine) of this embodiment, the controller 126 (an example of a control unit) stops the automatic brake that automatically brakes the vehicle body 1 when changing the notification by the warning device 61 (an example of a first notification unit).

[0175] This prevents the ground G from being mistakenly detected as an obstacle S, which would cause the automatic brake to operate and stop the vehicle body 1.

[0176] (12) The wheel loader 10 (an example of a work machine) of this embodiment includes a body frame 2 (an example of a main body frame), a boom 14, a bucket 15, a bucket cylinder 17 (an example of an actuator), and a bell crank 18 (an example of a sub-link). The boom 14 is attached to the front of the body frame 2 so that it can swing. The bucket 15 is connected to the boom 14 so that an opening 15b faces forward, and is driven relative to the boom 14. The bucket cylinder 17 drives the bucket 15. The bell crank 18 is attached to the boom 14, and transmits the driving force of the bucket cylinder 17 to the bucket 15.

[0177] This reduces the number of alarms caused by false detections that would otherwise occur when the ground G is mistakenly detected as an obstacle S and the alarm device 61 is activated when performing raking work or the like in a wheel loader 10 having a front loading configuration.

[0178] (13) The control method for the wheel loader 10 (an example of a work machine) of this embodiment includes step S10 (an example of a rear detection step), step S11 (an example of a tilt state detection step), and steps S12 and S13 (an example of a control step). Step S10 detects an obstacle (an example of an object) behind the vehicle body 1. Step S11 detects the tilt state of the vehicle body 1. Steps S12 and S13 determine control corresponding to the detection of step S10 based on the tilt state of the vehicle body 1 detected in step S11.

[0179] This makes it possible to prevent the ground G from being detected as an obstacle when the vehicle body 1 is placed on an inclined surface, for example, during raking work, thereby preventing erroneous detection of an obstacle.

[0180] (14) The control method for the wheel loader 10 (an example of a work machine) of this embodiment includes step S10 (an example of a rear detection step), step S111 (an example of a distance change determination step), and steps S12 and S13 (an example of a control step). Step S10 detects an obstacle (an example of an object) behind the vehicle body 1. Step S11 determines a change in the measured distance from the vehicle body 1 to the obstacle. Steps S12 and S13 change the notification that an object has been detected behind the vehicle body 1, based on the change in distance detected in step S111.

[0181] (15) The wheel loader 10 (an example of a work machine) of this embodiment includes a vehicle body 1, a rear detection unit 71, and a controller 226 (an example of a control unit). The vehicle body 1 has a body frame 2, front tires 4 and rear tires 7 (an example of a traveling body), and a work implement 3 arranged in front of the body frame 2. The rear detection unit 71 detects obstacles (an example of an object) behind the vehicle body 1. The controller 226 (an example of a control unit) determines that a shoveling operation is in progress based on the operation of the work implement 3 when the traveling body is driven forward, and changes control to suppress approach to objects behind when reversing based on the determination that the shoveling operation is in progress.

[0182] This makes it possible to prevent the ground G from being detected as an obstacle when the vehicle body 1 is placed on an inclined surface during scraping work, thereby preventing erroneous detection of an obstacle.

[0183] (16) In the wheel loader 10 (an example of a work machine) of this embodiment, the work implement 3 has a boom 14, a bucket 15, and a lift cylinder 16 (an example of a boom cylinder). The boom 14 is swingably attached to the front of the body frame 2. The bucket 15 is connected to the boom 14 so that its opening faces forward, and is driven relative to the boom 14. The lift cylinder 16 drives the boom 14. The wheel loader 10 further includes a boom bottom pressure sensor 74 and a boom angle sensor 73 (an example of a work implement height detection unit). The boom bottom pressure sensor 74 detects the bottom pressure of the lift cylinder 16. The boom angle sensor 73 detects the angle θ of the boom 14. The controller 226 determines whether or not the work implement 3 is in a lifting operation state based on the bottom pressure of the lift cylinder 16 and the height of the work implement 3.

[0184] In this way, by detecting the angle θ of the boom 14 and the bottom pressure of the lift cylinder 16, it is possible to determine whether or not the wheel loader 10 is in a scraping operation state.

[0185] (17) In the wheel loader 10 (an example of a work machine) of this embodiment, the controller determines that the work is in an excavation state when the bottom pressure of the lift cylinder 16 (an example of a boom cylinder) is equal to or greater than a first threshold value and the height of the work implement 3 is equal to or less than a second threshold value, and determines that the work is in a scraping state when the height of the work implement 3 is greater than a third threshold value while the controller is determining that the work is in an excavation state. The second and third threshold values ​​are set so that the height of the work implement 3 at the third threshold value is higher than the height of the work implement 3 at the second threshold value.

[0186] In this way, by detecting the height of the work implement 3 and the bottom pressure of the lift cylinder 16, it is possible to determine whether the wheel loader 10 is in an excavation operation state, and once it has been determined that the wheel loader is in an excavation operation state, it is possible to determine whether the excavation operation is a scraping operation or not based on the height of the work implement 3. This is because, since the height of the work implement 3 is higher during scraping compared to normal excavation, when in an excavation operation state, it is possible to distinguish between a scraping operation state and a state other than scraping operation.

[0187] (18) The wheel loader 10 (an example of a work machine) of this embodiment has a boom angle sensor 73 that detects the angle of the boom 14. The second threshold value and the third threshold value are set as angles of the boom 14.

[0188] In this way, by detecting the angle of the boom 14 and the bottom pressure of the lift cylinder 16, it is possible to determine whether the wheel loader 10 is in an excavation operation state, and once it has been determined that the wheel loader is in an excavation operation state, it is possible to determine whether the excavation operation is a scraping operation state based on the angle of the boom 14. This is because, since the boom 14 rotates upward when scraping compared to normal excavation, it is possible to distinguish between a scraping operation state and a state other than scraping operation when the wheel loader is in an excavation operation state.

[0189] (19) In the wheel loader 10 (an example of a work machine) of this embodiment, the controller 226 (an example of a control unit) determines whether or not an excavation operation is in progress when the vehicle is moving forward. The controller 226 detects that the vehicle is moving forward when the front tires 4 (an example of a wheel) or the rear tires 7 (an example of a wheel) are rotating forward or when the FNR lever 52 (an example of an operating member), which can set the vehicle body 1 to move forward or backward, is set to the forward position.

[0190] This makes it possible to detect the forward movement of the vehicle body 1.

[0191] (20) The wheel loader 10 (an example of a work machine) of this embodiment is further provided with an alarm device 61 (an example of a first alarm unit). The alarm device 61 issues an alarm when the rear detection unit 71 detects an obstacle (an example of an object) behind the vehicle body 1. Control to prevent the vehicle from approaching the rear obstacle S (an example of an object) when reversing includes stopping the alarm by the alarm device 61.

[0192] This makes it possible to prevent the ground G from being erroneously detected as an obstacle and an alarm being issued.

[0193] (twenty one) The control method for the wheel loader 10 (an example of a work machine) of this embodiment includes steps S220 and S230 (an example of a scraping-up determination step), steps S250 and S280 (an example of a rear detection step), and steps S260 and S290 (an example of a control step). S220 and S230 determine the scraping-up operation state based on the operation of the work implement 3 when the vehicle main body 1, which has a traveling body and a work implement 3, moves forward by driving the traveling body. Steps S250 and S280 detect an obstacle (an example of an object) behind the vehicle main body 1. Steps S260 and S290 change the control to suppress approach to the rear obstacle S (an example of an object) when moving backward, based on the determination of the scraping-up operation state.

[0194] This makes it possible to prevent the ground G from being detected as an obstacle when the vehicle body 1 is placed on an inclined surface during scraping work, thereby preventing erroneous detection of an obstacle.

[0195] <Other embodiments> Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the gist of the invention.

[0196] (A) In the above embodiment, the automatic braking function is stopped as shown in the second control of step S13. However, this is not limited to stopping the automatic braking function. The opening of the brake valve 41 may be set smaller than in the first control to apply a weaker braking force than during the automatic braking. This weaker braking corresponds to an example of suppressing the automatic braking. In this case, the suppression of the automatic braking may be notified by the function OFF notification lamp 62.

[0197] Note that the weak braking force may be generated by controlling when the operator turns off the accelerator 51, instead of adjusting the opening of the brake valve 41. When the operator turns off the accelerator 51, the fuel supply to the engine 31 is stopped, and the swash plates of the pump 32a and the motor 32b are controlled to provide resistance to traveling, thereby applying a weak braking force. In other words, the brake command unit 82 may stop the fuel supply to the engine 31 and control the swash plates of the pump 32a and the motor 32b to provide resistance to traveling.

[0198] Furthermore, a weak braking force may be applied not only when the accelerator is released but also when the FNR lever 52 is operated to the neutral position. When the FNR lever 52 is in the neutral position, the controller 26 controls the solenoids 32d and 32e to move the swash plates of the pump 32a and the motor 32b so as to provide resistance to traveling. In other words, the brake command unit 82 may stop the fuel supply to the engine 31 and control the swash plates of the pump 32a and the motor 32b so as to provide resistance to traveling.

[0199] This generates a weak braking force. Note that a stronger braking force can be obtained in neutral than by simply releasing the accelerator 51.

[0200] (B) In the above embodiment, the HST 32 is used in the drivetrain 21, but this is not limited to an HST and a torque converter may also be used. Fig. 15 is a block diagram showing a configuration in which the drivetrain 21 is provided with a torque converter 132 and a transmission 133. The driving force from the engine 31 is transmitted to the transmission 133 via the torque converter 132. The transmission 133 changes the speed of the rotational driving force of the engine 31 transmitted via the torque converter 132 and transmits it to the axle 34. The transmission 133 is provided with a parking brake 43.

[0201] In the case of a torque converter, to generate the weak braking force described in (A) above, the opening of the brake valve 41 may be set small in the same manner as above. Also, although the braking force will be weaker than with an HST, it is also possible to simply control the accelerator 51 to an off state. Note that, to generate a set braking force, the opening of the brake valve 41 may be increased or the parking brake 43 may be used, as in the above embodiment.

[0202] Furthermore, instead of HST, HMT (Hydro Mechanical Transmission) may be used.

[0203] (C) In the above embodiment, in the second control, the automatic brake is not activated and the warning device 61 is not activated either, but for example, only the warning device 61 may be activated. Also, only the automatic brake may be activated, or both the automatic brake and the warning device 61 may be activated. When both are activated, the second control, unlike the first control, suppresses the braking force of the automatic brake and the magnitude of the warning of the warning device 61, etc.

[0204] (D) Although the wheel loader 10 in the above embodiment has an automatic braking function, it does not have to have an automatic braking function. In this case, in the first control, the automatic braking does not operate, and the warning device 61 operates. In addition, in the second control, the warning device 61 does not operate.

[0205] (E) In the above embodiment, as an example of changing the notification by the alarm device 61, the second control stops the alarm by the alarm device 61, but this is not limiting, and the volume of the alarm may be reduced or the output form of the alarm may be changed. Changing the output form of the alarm means, for example, changing the notification by sound to notification by light.

[0206] (F) The braking force can be controlled by appropriately applying the service brake 42, the parking brake 43, or other means for changing the braking force.

[0207] (G) In the above-described third embodiment, if it is determined in step S210 that the scraping work state W3 is present, an obstacle is detected in step S214 and then the second control is performed in step S215, but obstacle detection in step S214 does not have to be provided. If the second control is to reduce the magnitude of the automatic brake or alarm, obstacle detection is necessary, but if the automatic brake function and alarm are simply stopped and the function OFF notification lamp 62 is turned on, this can be performed after the scraping work state is determined, regardless of whether an obstacle is detected or not.

[0208] (H) In the above-described first embodiment, after an obstacle is detected in step S10, it is determined in step S11 whether the tilt angle is equal to or greater than a predetermined threshold value. However, step S11 may be performed before step S10.

[0209] (I) The wheel loader of the above embodiment may be operated by an operator on board, or may be operated unmanned.

[0210] (J) In the above embodiment, a wheel loader has been used as an example of a work machine, but the present invention is not limited to this and may be a forklift or the like. [Industrial Applicability]

[0211] The work machine and work machine control method disclosed herein have the effect of reducing alarms due to false detection, and are useful as bulldozers, wheel loaders, etc. [Explanation of symbols]

[0212] 1: Vehicle body 10: Wheel loader 26: Controller 71: Rear detection unit 72: Body angle sensor< / url:>

Claims

1. The vehicle body, a rear detection unit that detects an object behind the vehicle body and measures a distance between the object and the vehicle body; a first notification unit that notifies that an object has been detected behind the vehicle body by the rear detection unit; a control unit that determines, during reverse driving, that an object is present based on detection by the rear detection unit, and stops the alarm by the first notification unit, reduces the volume of the alarm, or changes the output format of the alarm when the distance from the vehicle body to the object measured by the rear detection unit at a second time point after the first time point changes so that the distance from the vehicle body to the object measured by the rear detection unit at a first time point becomes larger than the distance from the vehicle body to the object measured by the rear detection unit at the first time point. Work machinery.

2. The control unit detects that the vehicle is moving backward when the wheels mounted on the vehicle body are rotating backward or when an operating member capable of setting the vehicle body to move forward or backward is set to a reverse position, and when it detects that the vehicle is moving backward, it determines that an object is present when it receives object detection information from the rear detection unit.

2. The work machine according to claim 1.

3. the control unit, when moving backward, determines that an object is present based on the detection by the rear detection unit, and when the distance from the vehicle body to the object has changed so that it is greater at the second time point than at the first time point, reduces the braking force of an automatic brake that automatically brakes the vehicle body, or stops the automatic brake.

2. The work machine according to claim 1.

4. Further provided is a second notification unit that notifies the suppression of the braking force of the automatic brake or the stop of the automatic brake, When the braking force of the automatic brake is reduced or the automatic brake is stopped, the control unit notifies the operator by the second notification unit.

4. The work machine according to claim 3.

5. A rear detection step of detecting an object behind the vehicle body and measuring a distance to the object behind the vehicle body when reversing; a distance change determination step of determining whether or not a distance has changed such that a distance from the vehicle body to the object measured in the rearward detection step at a second time point after the first time point becomes larger than a distance from the vehicle body to the object measured in the rearward detection step at a first time point while the vehicle is moving backward; and a control step of stopping an alarm that is issued when it is determined that an object is present based on the detection of the object in the rear detection step, suppressing the volume of the alarm, or changing the output form of the alarm, when it is determined in the distance change determination step that the distance has changed so that the distance from the vehicle body to the object measured in the rear detection step at the second time point that is later than the first time point is greater than the distance from the vehicle body to the object measured in the rear detection step. A method for controlling a work machine.

Images