Work vehicles

Abstract

To improve the operability of a work vehicle that uses automatic braking control for its braking system. [Solution] In a work vehicle (100) comprising a vehicle body (100A, 100B) having running wheels (19), a distance sensor (6) for detecting the distance between the vehicle body and an obstacle, a brake device (20) for applying braking to the vehicle body, and a controller (30) that performs automatic braking control to automatically control the braking of the brake device based on the distance between the vehicle body and the obstacle detected by the distance sensor, the controller (30) performs a recovery control to restore automatic braking control if the distance between the vehicle body and the obstacle detected by the distance sensor becomes greater than a predetermined distance threshold while automatic braking control is deactivated.

Description

Technical Field

[0001] The present invention relates to a work vehicle that executes automatic braking control for automatically braking travel.

Background Art

[0002] As background art in this technical field, Patent Document 1 describes a work machine that executes automatic braking control for automatically braking travel based on an obstacle detection result. In the work machine described in Patent Document 1, an operator operates a canceling device to cancel the automatic braking control, and the canceled automatic braking control is restored based on a forward-reverse switching signal (see the abstract).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a scene where the vehicle is parked in a narrow place, the operator needs to repeatedly turn the vehicle body many times while repeating forward and reverse travel. In such a scene where forward and reverse travel is repeated many times, in the conventional technique described in Patent Document 1, the automatic braking control is restored based on the forward-reverse switching signal, so that it is necessary to operate the canceling device many times. Therefore, the above conventional technique has a problem of improving the operability of travel in which forward and reverse travel is repeated many times.

[0005] An object of the present invention is to improve travel operability in a work vehicle that performs automatic braking control of a brake device.

Means for Solving the Problems

[0006] To achieve the above objective, one aspect of the present invention provides a work vehicle comprising: a vehicle body having running wheels; a distance sensor for detecting the distance between the vehicle body and an obstacle; a braking device for applying braking to the vehicle body; and a controller for performing automatic braking control that automatically controls the braking of the braking device based on the distance between the vehicle body and the obstacle detected by the distance sensor, The controller is characterized in that, while the automatic braking control is deactivated, if the distance between the vehicle body and the obstacle detected by the distance sensor becomes greater than a predetermined distance threshold, it performs a recovery control to reactivate the automatic braking control. [Effects of the Invention]

[0007] According to the present invention, the operability of a work vehicle that performs automatic braking control of a brake system can be improved. Other problems, configurations, and effects will be clarified by the following description of embodiments. [Brief explanation of the drawing]

[0008] [Figure 1] This is a side view of a wheel loader according to an embodiment of the present invention. [Figure 2] This is a block diagram showing the internal structure of a wheel loader. [Figure 3] This is a diagram showing an example of the interior of a driver's cab. [Figure 4] This is a functional block diagram of the controller. [Figure 5] This is a flowchart showing the controller's control procedure. [Figure 6] This is a flowchart showing the controller's control procedure. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments of the work vehicle according to the present invention will be described using a wheel loader as an example. Figure 1 is a side view of a wheel loader 100 according to an embodiment of the present invention.

[0010] The wheel loader 100 is an articulated work vehicle that is steered by folding its body in the middle near its center. The front frame 100A, which is the front part of the body, and the rear frame 100B, which is the rear part of the body, are connected by a center joint 103 so that they can rotate freely in the left-right direction, and the front frame 100A bends in the left-right direction relative to the rear frame 100B.

[0011] The vehicle body is equipped with four wheels (running wheels) 19. Two of the wheels 19 are front wheels 19A, located on both the left and right sides of the front frame 100A, and the remaining two wheels 19 are rear wheels 19B, located on both the left and right sides of the rear frame 100B. Note that in Figure 1, only the front wheels 19A and rear wheels 19B located on the left side are shown.

[0012] A hydraulically driven front work device (cargo handling device) 102 is attached to the front of the front frame 100A for excavating work materials such as soil and minerals and loading them onto dump trucks or hoppers.

[0013] The rear frame 100B is provided with a driver's cab 112 where the operator sits, a machine room 113 that houses the equipment necessary for driving the wheel loader 100, and a counterweight 114 that maintains balance with the front working device 102 to prevent the vehicle body from tilting. In the rear frame 100B, the driver's cab 112 is located at the front, the counterweight 114 is located at the rear, and the machine room 113 is located between the driver's cab 112 and the counterweight 114.

[0014] An object sensor (distance sensor) 6 is provided at the rear of the rear frame 100B, above the counterweight 114, to detect the presence or absence of an object behind the vehicle (for example, an obstacle or another vehicle) and the distance between the object and the vehicle (hereinafter referred to as the first distance, as appropriate). Note that the direction in which the object sensor 6 detects an object is not limited to the rear of the vehicle. The object may be in front of or to the side of the vehicle.

[0015] The front working device 102 includes a lift arm 121 mounted on the front frame 100A so as to be rotatable in the vertical direction, a pair of left and right lift arm cylinders 16 as hydraulic cylinders for driving the lift arm 121, a bucket 123 mounted on the tip of the lift arm 121 so as to be rotatable in the vertical direction, a bucket cylinder 17 as a hydraulic cylinder for driving the bucket 123, and a bell crank 125 rotatably connected to the lift arm 121 and constituting a link mechanism between the bucket 123 and the bucket cylinder 17.

[0016] The lift arm 121 rotates upward relative to the front frame 100A as the respective rods of the pair of lift arm cylinders 16 extend, and rotates downward relative to the front frame 100A as the respective rods of the pair of lift arm cylinders 16 retract.

[0017] As the rod of the bucket cylinder 17 extends, the bucket 123 rotates upward relative to the lift arm 121 and tilts backward toward the front frame 100A (tilt operation), and as the rod of the bucket cylinder 17 retracts, the bucket 123 rotates downward relative to the lift arm 121 and tilts forward (dump operation). Thereby, the bucket 123 can scoop and discharge (unload) work objects such as earth, sand, and minerals.

[0018] The bucket 123 can be replaced with various attachments such as a blade, and the wheel loader 100 can perform various works such as snow removal work and earth pushing work in addition to cargo handling work using the bucket 123.

[0019] Next, the internal configuration of the wheel loader 100 will be described. Figure 2 is a block diagram showing the internal configuration of the wheel loader 100. In Figure 2, solid lines are lines through which hydraulic fluid flows, and dotted lines are electric signal lines.

[0020] As shown in Figure 2, the wheel loader 100 includes a controller 30 that controls the entire vehicle body. The controller 30 is provided, for example, inside the cab 112. The controller 30 has a configuration in which a CPU, a RAM, a ROM, an HDD, an input I / F, and an output I / F are connected to one another via a bus. In such a hardware configuration, the CPU reads out an arithmetic program (software) stored in a recording medium such as the ROM, the HDD, or an optical disk, develops the arithmetic program on the RAM, and executes the developed arithmetic program, whereby the arithmetic program and the hardware cooperate to realize the functions of the controller 30.

[0021] To the input I / F of the controller 30, the starting device 1, the accelerator pedal 2, the parking switch 3, the release switch 4, the forward-reverse lever 5, the object sensor 6, and the vehicle speed sensor 7 are electrically connected.

[0022] The starting device 1 is an engine key switch for starting the engine 15. The accelerator pedal 2 adjusts the rotational speed of the engine 15 in accordance with the depression amount. The parking switch 3 activates and releases the parking brake 14. The parking brake 14 brakes the rotation of the propeller shaft 21 when the parking switch 3 is operated.

[0023] The release switch 4 is a switch for canceling automatic braking control of the brake 20 described later. The release switch 4 may be, for example, a momentary switch or an alternate switch. The forward-reverse lever 5 is a member for switching the wheel loader 100 to any one of forward (F), neutral (N), and reverse (R). When the forward-reverse lever 5 is in the neutral position, the wheel loader 100 enters a state in which self-propulsion is not possible.

[0024] The object sensor 6 is, for example, a millimeter-wave radar, LiDAR, a stereo camera, or the like. The vehicle speed sensor 7 detects the rotational speed of the propeller shaft 21. The vehicle speed of the wheel loader 100 is calculated from the rotational speed of the propeller shaft 21.

[0025] The output interface of the controller 30 is electrically connected to the engine 15, the solenoid valve 10, the notification device 26, and the parking brake 14.

[0026] The driving force from the engine 15 mounted on the wheel loader 100 is reduced by the transmission 13 and transmitted to the front and rear axles 18 via the propeller shaft 21. The driving force transmitted to the axles 18 is then transmitted to the left and right wheels 19 (19A, 19B), which are the running gear, via a differential and final reduction gear (not shown) within the axles 18, causing the wheel loader 100 to move.

[0027] Although not shown in the diagram, the wheel loader 100 is also equipped with a hydraulic pump for supplying hydraulic fluid and a hydraulic fluid storage unit. The hydraulic pump is driven by the engine 15, and the hydraulic fluid supplied from the hydraulic pump operates the front working device 102 (lift arm cylinder 16, bucket cylinder 17).

[0028] Multiple operating levers 8 are provided inside the driver's cab 112. By operating these operating levers 8, hydraulic fluid is supplied to the lift arm cylinder 16 and the bucket cylinder 17, and the front work device 102 is displaced to a predetermined position (see Figure 3).

[0029] The wheel loader 100 brakes the wheels 19 with a brake 20. The brake 20 is, for example, a wet disc brake. The brake 20 is housed in a case on the axle 18. When hydraulic fluid is supplied to the brake 20 via the brake valve 12, the brake 20 generates a braking force corresponding to the pressure of the hydraulic fluid. The wheel loader 100 is equipped with a hydraulic source (not shown) that supplies hydraulic fluid to the brake 20.

[0030] The brake valve 12 is a pressure reducing valve that reduces the hydraulic fluid supplied from the hydraulic source to a pressure corresponding to the compression force of the spring. When the operator presses the brake pedal 11, the brake valve 12 reduces the pressure of the hydraulic fluid supplied from the hydraulic source to a pressure corresponding to the pressing force (amount of pressing) of the brake pedal 11. The brake valve 12 reduces the pressure of the hydraulic fluid so that the higher the compression force of the spring, that is, the greater the pressing force of the brake pedal 11, the higher the pressure of the hydraulic fluid supplied to the brake 20. In this embodiment, the brake 20 is equipped with a function to automatically apply the brakes (details will be described later).

[0031] Next, the internal configuration of the driver's cab 112 will be described. Figure 3 shows an example of the interior of the driver's cab 112.

[0032] As shown in Figure 3, the driver's cab 112 is equipped with a starting device 1, a steering wheel 28 for steering, an accelerator pedal 2, a brake pedal 11, a parking switch 3, a release switch 4, a forward / reverse lever 5, a notification device 26, and an operating lever 8.

[0033] The steering wheel 28 is used to steer the wheel loader 100. The notification device 26 displays the travel speed of the wheel loader 100 detected by the vehicle speed sensor 7. The notification device 26 also displays the control status of the brake 20. Specifically, the notification device 26 indicates whether the automatic braking control of the brake 20 is enabled, released, or restored (details will be described later). The notification device 26 is, for example, an LCD panel, but other notification means such as a speaker can be used.

[0034] The controller 30 performs automatic braking control of the brake 20. While the automatic braking control of the brake 20 is in effect, the controller 30 controls the movement of the wheel loader 100 to prevent collision with an object. Therefore, if there is a possibility of collision, the wheel loader 100 will stop automatically.

[0035] On the other hand, while the automatic braking control is deactivated, the controller 30 does not perform automatic braking control of the brake 20. That is, during this time, the operator presses the brake pedal 11 to apply the brakes to the wheel loader 100.

[0036] Figure 4 is a functional block diagram of the controller 30. As shown in Figure 4, the controller 30 includes a start information acquisition unit 31, an object distance information acquisition unit 32, a risk level determination unit 33, a function validity determination unit 40, an engine speed control unit 51, a solenoid valve control unit 52, and an alarm control output unit 53.

[0037] The function activation determination unit 40 determines whether or not to enable automatic braking control, and includes a vehicle speed determination unit 41, a release operation determination unit 42, a return condition determination unit 43, a driving direction determination unit 44, and an activation / deactivation state determination unit 45.

[0038] The starting information acquisition unit 31 monitors the operation of the starting device 1 and acquires starting information (engine starting information) for the engine 15.

[0039] The object distance information acquisition unit 32 acquires distance information (first distance) to the object (obstacle) detected by the object sensor 6.

[0040] The risk level determination unit 33 calculates the level of risk of the wheel loader 100 colliding with an object based on the distance information acquired by the object distance information acquisition unit 32 and the vehicle speed of the wheel loader 100 detected by the vehicle speed sensor 7. Specifically, the risk level determination unit 33 compares the magnitude of a distance threshold calculated according to the vehicle speed detected by the vehicle speed sensor 7, or a second distance obtained by adding a predetermined margin distance to the distance threshold, with the first distance detected by the object sensor 6 to determine the level of risk of the wheel loader 100 colliding with an object.

[0041] Here, the distance threshold is the braking distance of the wheel loader 100 according to the vehicle speed. The distance threshold is set to increase as the vehicle speed detected by the vehicle speed sensor 7 increases. The second distance is the braking distance plus a predetermined margin distance, which is a distance that allows for safety. The predetermined margin distance may take into account the control speed of the controller 30 and other disturbance factors.

[0042] In this embodiment, the risk of collision is divided into five levels, from Level 1, the lowest, to Level 5, the highest. Specifically, Level 1 is "very low risk of collision (no object is present within the detection range of the object sensor 6)", Level 2 is "low risk of collision", Level 3 is "high risk of collision", Level 4 is "very high risk of collision", and Level 5 is "a collision is imminent, so the brakes are applied automatically". The levels are set according to the risk of collision.

[0043] The risk level determination unit 33 then determines which of the five levels the current risk falls into, based on the comparison of the magnitudes of the distances described above. Note that there may be multiple risk levels.

[0044] The vehicle speed determination unit 41 determines whether the vehicle speed of the wheel loader 100 detected by the vehicle speed sensor 7 exceeds a predetermined value.

[0045] The release operation determination unit 42 determines whether the automatic braking control has been released based on the operation of the release switch 4. Furthermore, if a return operation is performed using the release switch 4 or the parking switch 3, as described later, the release operation determination unit 42 determines whether the automatic braking control has been released again based on the return operation of the release switch 4 or the parking switch 3.

[0046] The return condition determination unit 43 determines whether the collision risk is high or low based on the risk level (levels 1 to 5) calculated by the risk level determination unit 33. More specifically, the return condition determination unit 43 determines whether the collision risk is high or low in step S7 of Figure 5, which will be described later, then determines whether the collision risk is low or low in step S10, and further determines that the collision risk has transitioned in the order of steps S7 and S10. Based on these determination results, the return condition determination unit 43 determines whether the brake 20 can be returned to automatic braking control (whether or not to execute return control).

[0047] The travel direction determination unit 44 determines the travel direction of the wheel loader 100 based on the operation of the forward / reverse lever 5.

[0048] The Enabled / Disabled State Determination Unit 45 determines whether the automatic braking control is enabled or disabled. Specifically, it determines whether the automatic braking control is enabled or disabled based on the engine start information from the Start Information Acquisition Unit 31, the vehicle speed determination information from the Vehicle Speed ​​Determination Unit 41, the disabling determination information (or return determination information) from the Disabling Operation Determination Unit 42, the determination result from the Return Condition Determination Unit 43, and the driving direction determination information from the Driving Direction Determination Unit 44.

[0049] The engine speed control unit 51 controls the rotational speed of the engine 15 based on engine start information from the start information acquisition unit 31 and the risk determination result from the risk level determination unit 33. Specifically, if the risk of collision is high, the engine speed control unit 51 controls the rotational speed of the engine 15 to decrease.

[0050] The solenoid valve control unit 52 controls the opening and closing of the solenoid valve 10 based on the risk determination result from the risk level determination unit 33 and the effective / deactivated determination result from the effective / deactivated state determination unit 45. When the solenoid valve control unit 52 opens the solenoid valve 10, the brake 20 is automatically deactivated.

[0051] The alarm control output unit 53 issues various alarms to the operator via the notification device 26 based on the risk determination result from the risk level determination unit 33 and the valid / deactivation determination result from the valid / deactivation status determination unit 45.

[0052] Next, the braking control of the brake 20 by the controller 30 will be described. Figures 5 and 6 are flowcharts showing the control processing procedure of the controller 30. The controller 30 starts processing, for example, when the engine 15 starts.

[0053] (Step S1) In step S1, the controller 30 (function activation determination unit 40) acquires start information. Specifically, the activation / deactivation state determination unit 45 acquires engine start information from the start information acquisition unit 31. The start information acquired in step S1 may include information confirming that there are no problems with the operation of the equipment related to the automatic braking control of the brake 20 (for example, that there are no malfunctions in the solenoid valve 10 or the brake valve 12).

[0054] (Step S2) In step S2, the controller 30 (function activation determination unit 40) activates automatic braking control based on the acquired start information. Specifically, the controller 30 activates automatic braking control on the condition that the engine 15 has started. In addition to the engine 15 starting, the condition for activating automatic braking control may also include that there are no problems with the operation of the equipment related to the automatic braking control of the brake 20, as described above.

[0055] (Step S3) In step S3, the controller 30 (release operation determination unit 42) determines whether or not the release switch 4 has been operated. If the release switch 4 has been operated (S3 / YES), the process proceeds to step S4. This makes it possible to release the automatic braking control by operator operation. On the other hand, if the release switch 4 has not been operated (S3 / NO), the process proceeds to step S12 via P2.

[0056] (Step S4) In step S4, the controller 30 (function activation determination unit 40) releases the automatic braking control. Therefore, while the automatic braking control is released, the brake 20 will only be activated when the operator depresses the brake pedal 11. Consequently, if the automatic braking control is released while the brake 20 is automatically activated (when the process transitions to step S4 via P1), the brake 20 will become inactive, and the brakes on the wheel loader 100 will be released. At this time, the controller 30 (alarm control output unit 53) outputs information to the notification device 26 indicating that the automatic braking control has been released, and notifies the operator via the notification device 26. The method of notification is arbitrary; it can be by sound or screen display.

[0057] (Step S5) In step S5, the controller 30 (release operation determination unit 42) determines whether or not a reset operation for automatic braking control has been performed. Specifically, the controller 30 checks whether the operator has operated the reset switch. If the operator has performed the reset operation (S5 / YES), the process transitions to step S11 via P3. On the other hand, if the operator has not performed the reset operation (S5 / NO), the process transitions to step S6.

[0058] Here, the release switch 4 can also be used as the reset switch. For example, the release switch 4 could be a momentary switch; pressing and releasing it immediately would perform a reset operation, while pressing and holding it would perform a reset operation. This allows the operator to reset to automatic braking control themselves according to the work site (the braking control of the brakes can be freely set). As a result, operability for the operator is improved, and work efficiency is increased.

[0059] Alternatively, instead of using the release switch 4 as an input means for the reset operation, the parking switch 3 may also be used as a reset switch. When an operator changes, the parking brake 14 is usually applied, so before the change, the parking brake 14 will be activated by the parking switch 3. Therefore, by using the operation of the parking switch 3 as a reset operation, the automatic braking control can always be restored when an operator changes. Thus, unexpected events that would occur while the automatic braking control is disengaged can be prevented.

[0060] Of course, a dedicated reset switch may be provided to return to automatic braking control, and the controller 30 may determine that a reset operation has been performed when this reset switch is operated.

[0061] (Step S6) In step S6, the controller 30 (risk level determination unit 33) acquires object distance information (first distance) from the object distance information acquisition unit 32.

[0062] (Step S7) In step S7, the controller 30 (risk level determination unit 33) compares the distance information of the object (first distance) obtained from the object distance information acquisition unit 32 with a distance threshold calculated based on the vehicle speed information from the vehicle speed sensor 7, or a second distance obtained by adding a margin to that distance threshold, to calculate the risk level of the wheel loader 100 colliding with an object behind it. Then, the controller 30 (return condition determination unit 43) determines whether there is a high risk of the wheel loader 100 colliding with an object based on the calculated risk level. If the collision risk is high (S7 / YES), the process proceeds to step S8. On the other hand, if the collision risk is not high (S7 / NO), the process proceeds to step S5.

[0063] For example, in step S7, if the collision risk level falls under levels 1 to 3 as described above, the controller 30 determines NO. On the other hand, if it falls under levels 4 to 5, the controller 30 determines YES.

[0064] (Step S8) In step S8, the same process as in step S5 is performed. That is, the controller 30 checks whether the operator has operated the reset switch. If the operator has performed the reset operation (S8 / YES), the process transitions to step S11 via P3. On the other hand, if the operator has not performed the reset operation (S8 / NO), the process transitions to step S9.

[0065] (Step S9) In step S9, the same process as in step S6 is performed. That is, the controller 30 obtains the object distance information (first distance) from the object distance information acquisition unit 32.

[0066] (Step S10) In step S10, similar to step S7, the controller 30 (risk level determination unit 33, return condition determination unit 43) compares the distance information of the object (first distance) obtained from the object distance information acquisition unit 32 with a distance threshold calculated based on the vehicle speed information from the vehicle speed sensor 7, or a second distance obtained by adding a margin to that distance threshold, to determine whether the risk of the wheel loader 100 colliding with an object behind it is low or not. If the collision risk is low (S10 / YES), the process proceeds to step S11. On the other hand, if the collision risk is not low (S10 / NO), the process proceeds to step S8.

[0067] For example, in step S10, if the collision risk level falls under levels 1 or 2 as described above, the controller 30 determines YES. On the other hand, if it falls under levels 3 to 5, the controller 30 determines NO.

[0068] By performing the process in step S10, if the state in which the first distance is greater than the distance threshold or the second distance continues for a certain period of time, the brake 20 can be returned to automatic braking control. In addition, in the process in step S10, the controller 30 may not only determine whether the level of collision risk is low, but also whether the state of low collision risk has continued for a certain period of time.

[0069] (Step S11) In step S11, the controller 30 (enabled / deactivated state determination unit 45) restores the automatic braking control from a deactivated state to an enabled state (restore control). In step S11, the controller 30 (alarm control output unit 53) notifies the operator via the notification device 26 that the automatic braking control has been restored.

[0070] Thus, in this embodiment, the controller 30, through the determination processes in steps S7 and S10, returns to automatic braking control if the conditions are met that, after the automatic braking control is released (S4), the collision risk becomes high-risk (S7 / YES), and subsequently, the collision risk becomes low-risk (S10 / YES).

[0071] The reasons for this are: (1) Since situations in which the automatic braking control is to be deactivated are expected to be narrow parking spaces, etc., from the perspective of operability, it is necessary to deactivate the automatic braking control when the risk of collision is high, and (2) it is preferable to reactivate the automatic braking control once the work in the narrow space is completed and the risk of collision is low.

[0072] (Step S12) In step S12, the controller 30 (vehicle speed determination unit 41, driving direction determination unit 44) acquires vehicle speed information and driving direction information. Specifically, the controller 30 (vehicle speed determination unit 41) acquires vehicle speed information detected by the vehicle speed sensor 7, and the controller 30 (driving direction determination unit 44) acquires driving direction information, indicating whether the forward / reverse lever 5 is in the forward, neutral, or reverse position.

[0073] (Step S13) In step S13, the controller 30 (vehicle speed determination unit 41, travel direction determination unit 44) determines whether the vehicle speed is below a predetermined value and whether the travel direction is reverse. If the vehicle speed is below a predetermined value and the travel direction is reverse (S13 / YES), the process proceeds to step S14. On the other hand, if the vehicle speed exceeds a predetermined value and / or the travel direction is not reverse (S13 / NO), i.e., neutral or forward, the process proceeds to step S3 via P1.

[0074] (Step S14) In step S14, the controller 30 (risk level determination unit 33) acquires object distance information (first distance) from the object distance information acquisition unit 32.

[0075] (Step S15) In step S15, the controller 30 (risk level determination unit 33, engine speed control unit 51, solenoid valve control unit 52, alarm control output unit 53) compares the distance information of the object (first distance) obtained from the object distance information acquisition unit 32 with a distance threshold calculated based on the vehicle speed information from the vehicle speed sensor 7, or a second distance obtained by adding a margin to that distance threshold, to determine whether the risk of the wheel loader 100 colliding with an object behind it is greater than or equal to a predetermined risk. If the collision risk is greater than or equal to the predetermined risk (S15 / YES), the process proceeds to step S16. On the other hand, if the collision risk is less than the predetermined risk (S15 / NO), the process proceeds to step S3 via P1.

[0076] For example, in step S15, if the collision risk level corresponds to level 5 as described above, the controller 30 determines YES. On the other hand, if it corresponds to levels 1 to 4, the controller 30 determines No.

[0077] (Step S16) In step S16, the controller 30 (solenoid valve control unit 52) ​​performs braking on the wheel loader 100. Specifically, the solenoid valve control unit 52 opens the solenoid valve 10 and activates the brake 20. This applies braking to the axle 18, stopping the movement of the wheel loader 100. After the automatic braking control is performed, the process transitions to step S3 via P1.

[0078] Furthermore, in step S16, the controller 30 (alarm control output unit 53) notifies the operator via the notification device 26 that automatic braking control is being performed.

[0079] As described above, this embodiment can achieve the following effects.

[0080] The wheel loader 100 according to this embodiment is equipped with an object sensor 6 (distance sensor). The controller 30 performs automatic braking control of the brake 20 based on the distance between the vehicle and the obstacle detected by the object sensor 6. In this case, if the distance between the vehicle and the obstacle detected by the object sensor 6 becomes greater than a predetermined distance threshold while the automatic braking control is released, the controller 30 is configured to restore the automatic braking control of the brake 20 (execute restoration control). Therefore, when parking in a narrow space, the operator can maneuver the vehicle without having to operate the release switch 4 repeatedly each time the forward / reverse lever 5 is operated. Thus, the operability related to driving is improved.

[0081] Furthermore, in this embodiment, while the automatic braking control of the brake 20 is deactivated, if the distance between the vehicle and the obstacle increases from below a distance threshold to above a distance threshold, the controller 30 is configured to reactivate the automatic braking control of the brake 20. Therefore, when the vehicle is close to an obstacle, i.e., when the risk of collision is high, the controller 30 maintains the deactivation of the automatic braking control, thereby improving work efficiency such as maneuvering to a narrower position. Also, when the vehicle has moved away from an obstacle and the work is completed, i.e., when the risk of collision is low, the controller 30 can reactivate the automatic braking control. Therefore, it offers high convenience.

[0082] Furthermore, in this case, even if the automatic braking control is released when the distance between the vehicle and the obstacle is greater than the distance threshold, the automatic braking control will not be reactivated immediately. Instead, the automatic braking control will be reactivated only after the distance between the vehicle and the obstacle falls below the distance threshold, and then increases again when the distance between the vehicle and the obstacle exceeds the distance threshold. This configuration allows the system to control the vehicle according to the operator's intentions, even when the operator releases the automatic braking control while away from the obstacle.

[0083] Furthermore, while the automatic braking control of the brake 20 is deactivated, if the distance between the vehicle and the obstacle increases from below a distance threshold to above a distance threshold, the controller 30 maintains the deactivated state of the automatic braking control of the brake 20 until the distance between the vehicle and the obstacle exceeds a second distance threshold, which is the distance threshold plus a predetermined distance. When the distance between the vehicle and the obstacle exceeds the second distance threshold, the controller 30 reactivates the automatic braking control of the brake 20. This configuration makes the transition between operation and completion of operation smoother and prevents unintended reactivation of the automatic braking control.

[0084] Furthermore, the automatic braking control of the released brake 20 can be restored (enabled) by accepting the operator's operation of the release switch 4 or the parking switch 3 (reset switch), thus further improving operability. In addition, since the release switch 4 or the parking switch 3 is also used as a reset switch, the number of parts can be reduced.

[0085] Furthermore, since the operator is notified of the enabled / disabled / reset status of the automatic braking control of the brake 20 via the notification device 26, it becomes easier for the operator to recognize the braking control status of the brake 20, which is convenient.

[0086] Furthermore, in this embodiment, even if the distance between the vehicle and the obstacle exceeds a distance threshold while the automatic braking control of the brake 20 is released, the controller 30 maintains the released state of automatic braking control until the state in which the distance between the vehicle and the obstacle is greater than the distance threshold continues for a predetermined time. When the state in which the distance between the vehicle and the obstacle is greater than the distance threshold continues for a predetermined time, the controller 30 restores the automatic braking control of the brake 20. In other words, the automatic braking control of the brake 20 is restored when the state in which the collision risk is low continues for a predetermined time in step S10. This configuration prevents the automatic braking control from being restored unintentionally by the operator, further improving operability.

[0087] Furthermore, since the distance threshold is set to increase as the vehicle speed detected by the vehicle speed sensor 7 increases, collision risk can be determined with high accuracy, and the timing for resuming automatic braking control is also optimized.

[0088] Furthermore, the present invention is not limited to wheel loaders. It can be applied to any self-propelled work vehicle. For example, it may be applied to hydraulic excavators, forklifts, and the like. [Explanation of Symbols]

[0089] 3. Parking switch (reset switch) 4. Release switch (Release switch / Reset switch) 6. Object Sensor (Distance Sensor) 7. Vehicle speed sensor 14. Parking brake 19. Wheels (running wheels) 20. Brakes (Brake System) 26. Notification device 30 controllers 100 Wheel Loader (Work Vehicle) 100A Front frame (body) 100B Rear frame (body)

Claims

1. A work vehicle comprising a body having wheels, a distance sensor for detecting the distance between the body and an obstacle, a braking device for applying the brakes to the body, and a controller for automatic braking control that automatically controls the braking of the braking device based on the distance between the body and the obstacle detected by the distance sensor, The aforementioned controller, If, while the automatic braking control is deactivated, the distance between the vehicle body and the obstacle detected by the distance sensor exceeds a predetermined distance threshold, a recovery control is executed to reactivate the automatic braking control. A work vehicle characterized by the following features.

2. In the work vehicle described in claim 1, The recovery control by the controller is This control restores the automatic braking control when, while the automatic braking control is deactivated, the distance between the vehicle and the obstacle increases from a state where it was below the distance threshold to a state where it was above the distance threshold. A work vehicle characterized by the following features.

3. In the work vehicle described in claim 2, The recovery control by the controller is While the automatic braking control is deactivated, even if the distance between the vehicle and the obstacle increases from being below the distance threshold to exceeding the distance threshold, the deactivated state of the automatic braking control is maintained until the distance between the vehicle and the obstacle exceeds a second distance threshold greater than the distance threshold. If the distance between the vehicle and the obstacle exceeds the second distance threshold, the automatic braking control is reactivated. A work vehicle characterized by the following features.

4. In the work vehicle described in claim 1, The system includes a reset switch that resets the automatic braking control by the controller when an operation is received, The recovery control by the controller is If the reset switch is activated while the automatic braking control is deactivated, the control will reactivate the automatic braking control even if the distance between the vehicle and the obstacle is below the distance threshold. A work vehicle characterized by the following features.

5. In the work vehicle described in claim 1, The system includes a release switch that releases the automatic braking control by the controller when an operation is received during the automatic braking control, The recovery control by the controller is When the release switch is activated while the automatic braking control is deactivated, the control is to reactivate the automatic braking control even if the distance between the vehicle body and the obstacle is below the distance threshold. A work vehicle characterized by the following features.

6. In the work vehicle described in claim 1, It comprises a parking brake and a parking switch that activates the parking brake when an operation is received, The recovery control by the controller is When the automatic braking control is deactivated and the parking switch is operated, the control is to reactivate the automatic braking control even if the distance between the vehicle body and the obstacle is below the distance threshold. A work vehicle characterized by the following features.

7. In the work vehicle described in claim 1, The controller is equipped with a notification device that notifies that the automatic braking control has been restored. A work vehicle characterized by the following features.

8. In the work vehicle described in claim 1, The recovery control by the controller is When the automatic braking control is restored, the control is restored only after a predetermined period of time has passed during which the distance between the vehicle body and the obstacle is greater than the distance threshold. A work vehicle characterized by the following features.

9. In the work vehicle described in claim 1, The vehicle further includes a vehicle speed sensor that detects the vehicle speed of the vehicle body, The distance threshold is set to increase as the vehicle speed detected by the vehicle speed sensor increases. A work vehicle characterized by the following features.

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