Work vehicle

Abstract

The present invention improves travel operability in a work vehicle that performs automatic braking control of a brake device.　Provided is a work vehicle (100) comprising: a vehicle body (100A, 100B) that has traveling wheels (19); a brake device (20) that applies braking to the vehicle body; a controller (30) that performs automatic braking control for automatically controlling the braking of the brake device (20); and a cancel switch (4) that cancels the automatic braking control by the controller (30) when an operation is received. The controller (30) restores the automatic braking control when the elapsed time from when the cancel switch (4) received the operation reaches a preset restoration time.

Description

Work vehicle

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

[0002] As a background art in this technical field, Patent Document 1 describes a working machine that executes automatic braking control for automatically braking travel based on detection results of an obstacle. In the working machine described in Patent Document 1, an operator cancels the automatic braking control by operating a canceling device, and restores the canceled automatic braking control based on a forward / reverse switching signal (see the abstract).

[0003] Japanese Unexamined Patent Publication No. 2024-086279

[0004] When parking the vehicle in a narrow space, an operator needs to repeatedly turn the vehicle body back and forth while repeating forward and reverse travel with the automatic braking control canceled. In such a situation where forward and reverse travel are repeated many times, according to the prior art described in Patent Document 1, the automatic braking control is restored based on a forward / reverse switching signal, so the operator needs to operate the canceling device many times. Therefore, improving travel operability is an issue in the above-mentioned prior art.

[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.

[0006] In order to achieve the above object, one aspect of the present invention provides a work vehicle including: a vehicle body having traveling wheels; a brake device that applies braking to the vehicle body; a controller that performs automatic braking control for automatically controlling the braking of the brake device; and a release switch that releases the automatic braking control by the controller when an operation is received, wherein the controller restores the automatic braking control when an elapsed time from when the release switch received the operation reaches a preset restoration time.

[0007] According to the present invention, travel operability can be improved in a work vehicle that performs automatic braking control of a brake device. Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

[0008] This is a side view of a wheel loader according to an embodiment of the present invention. This is a block diagram showing the internal configuration of the wheel loader. This is a diagram showing an example of the interior of the driver's cab. This is a functional block diagram of the controller. This is a flowchart showing the control procedure of the controller. This is a flowchart showing the control procedure of the controller.

[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 bending 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 as to be rotatable 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 the left and right sides of the front frame 100A, and the remaining two wheels 19 are rear wheels 19B, located on 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 performing cargo handling operations, such as excavating work materials like 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 6 is provided at the rear of the rear frame 100B, above the counterweight 114, to detect the presence or absence of objects behind the vehicle (for example, obstacles or other vehicles). Note that the direction in which the object sensor 6 detects objects is not limited to the rear of the vehicle. The object may be located in front of or to the side of the vehicle.

[0015] The front work device 102 includes a lift arm 121 that is rotatably mounted vertically to the front frame 100A, a pair of left and right lift arm cylinders 16 that act as hydraulic cylinders to drive the lift arm 121, a bucket 123 that is rotatably mounted vertically to the tip of the lift arm 121, a bucket cylinder 17 that acts as a hydraulic cylinder to drive the bucket 123, and a bell crank 125 that is rotatably connected to the lift arm 121 and forms 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 rods of the pair of lift arm cylinders 16 extend, and rotates downward relative to the front frame 100A as the rods of the pair of lift arm cylinders 16 retract.

[0017] The bucket 123 rotates upward relative to the lift arm 121 and tilts backward toward the front frame 100A (tilt operation) when the rod of the bucket cylinder 17 extends, and rotates downward relative to the lift arm 121 and tilts forward (dump operation) when the rod of the bucket cylinder 17 retracts. As a result, the bucket 123 can scoop up and discharge (dump) the work material such as soil and minerals.

[0018] Furthermore, the bucket 123 can be replaced with various attachments, such as blades, and the wheel loader 100 can perform various tasks in addition to cargo handling using the bucket 123, such as snow removal and soil pushing.

[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 represent lines through which hydraulic fluid flows, and dotted lines represent electrical signal lines.

[0020] As shown in Figure 2, the wheel loader 100 is equipped with a controller 30 that controls the entire vehicle body. The controller 30 is located, for example, in the driver's cab 112. The controller 30 has a configuration in which a CPU, RAM, ROM, HDD, input I / F, and output I / F are connected to each other via a bus. In this hardware configuration, the CPU reads the calculation program (software) stored in a recording medium such as ROM, HDD, or optical disc, expands it onto RAM, and executes the expanded calculation program. The calculation program and hardware work together to realize the functions of the controller 30.

[0021] The input interface of the controller 30 is electrically connected to the following: 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.

[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 according to the amount it is pressed. The parking switch 3 operates 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 releasing the automatic braking control of the brake 20, which will be described later. The release switch 4 may be a momentary switch or an alternate switch, for example. The forward / reverse lever 5 is a component for switching the wheel loader 100 to forward (F), neutral (N), or reverse (R). When the forward / reverse lever 5 is in the neutral position, the wheel loader 100 is unable to move under its own power.

[0024] The object sensor 6 is, for example, a millimeter-wave radar, LiDAR, or stereo camera. 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 figures, the wheel loader 100 is also equipped with a hydraulic pump that supplies 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 using 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 a 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 operation, 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 release time measurement 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 from the object (obstacle) detected by the object sensor 6.

[0040] The risk level determination unit 33 determines 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.

[0041] 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.

[0042] 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.

[0043] The release time measuring unit 43 measures release time, which is the elapsed time from when the release switch 4 is operated. Furthermore, if the release switch 4 is operated again while the release time is being measured (that is, while automatic braking control is being released), the release time measuring unit 43 resets the previously measured time and measures the release time again.

[0044] The traveling direction determination unit 44 determines the traveling direction of the wheel loader 100 based on the operation of the forward / backward lever 5.

[0045] The enable / release state determination unit 45 determines whether the automatic braking control is in an enabled state or in a released state. Specifically, the unit determines whether the automatic braking control is in an enabled state based on engine start information from the start information acquisition unit 31, vehicle speed determination information from the vehicle speed determination unit 41, release determination information (or return determination information) from the release operation determination unit 42, release time information from the release time measuring unit 43, and traveling direction information from the traveling direction determination unit 44.

[0046] The engine speed control unit 51 controls the rotation speed of the engine 15 based on engine start information from the start information acquisition unit 31 and risk determination results from the risk level determination unit 33. Specifically, when there is a high risk of collision, the engine speed control unit 51 performs control to reduce the rotation speed of the engine 15.

[0047] The solenoid valve control unit 52 controls opening and closing of the solenoid valve 10 based on risk determination results from the risk level determination unit 33 and enable / release determination results from the enable / release state determination unit 45. When the solenoid valve control unit 52 opens the solenoid valve 10, the brake 20 is automatically actuated to apply braking.

[0048] The alarm control output unit 53 issues various alarms to an operator via the notification device 26 based on risk determination results from the risk level determination unit 33 and enable / release determination results from the enable / release state determination unit 45.

[0049] 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.

[0050] (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).

[0051] (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 starting of the engine 15, 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.

[0052] (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 transitions 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 transitions to step S11 via P2.

[0053] (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 being activated automatically (when the process transitions to step S4 via P1), the brake 20 will become inactive, and the braking of 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 may be by sound or by screen display.

[0054] (Step S5) In step S5, the controller 30 (release time measurement unit 43) measures the release time, which is the elapsed time since the automatic braking control was released. The measurement of the release time may start from either when the release operation in step S3 is performed (when the release switch 4 is operated) or when the automatic braking control is released in step S4. Note that steps S4 and S5 do not necessarily have to be performed in this order.

[0055] In this embodiment, in step S5, if the release switch 4 is operated again (S8 / YES), the release time is reset to 0 and the elapsed time is remeasured. By remeasureing the release time, the operator can extend the time during which the automatic braking control is released, and it becomes possible to prevent the automatic braking control from being reactivated at an unintended time by the operator. Of course, the application of this configuration is optional.

[0056] (Step S6) In step S6, the controller 30 (release time measurement unit 43) updates the release time.

[0057] (Step S7) In step S7, the controller 30 (function activation determination unit 40) determines whether the release time exceeds a predetermined recovery time (for example, 30 seconds / hereinafter referred to as system time). If the release time does not exceed the system time (S7 / NO), the process proceeds to step S8. On the other hand, if the release time exceeds the system time (S7 / YES), the process proceeds to step S10.

[0058] In step S7, an example of setting the system time to 30 seconds is described, but this time is arbitrary. Preferably, the system time is set based on the time the operator works in the confined space. It may also be configured so that the administrator can arbitrarily change the system time setting to suit the work environment.

[0059] (Step S8) In step S8, the controller 30 (function activation determination unit 40) determines whether the release switch 4 has been operated based on the determination result from the release operation determination unit 42. That is, it determines whether the release switch 4 has been operated again. If the release switch 4 has been operated again (S8 / YES), the process transitions to step S5 (the measurement time is reset). On the other hand, if the release switch 4 has not been operated (S8 / NO), the process transitions to step S9.

[0060] (Step S9) In step S9, the controller 30 (function activation determination unit 40) determines whether or not the automatic braking control reset operation has been performed based on the determination result from the release operation determination unit 42. Specifically, the controller 30 checks whether the operator has operated the reset switch. If the operator has performed the reset operation (S9 / YES), the process transitions to step S10. On the other hand, if the operator has not performed the reset operation (S9 / NO), the process transitions to step S6 via P3.

[0061] Here, the release switch 4 can also be used as the reset switch. For example, the release switch 4 could be a momentary switch, so that pressing and releasing it immediately performs a reset operation, and pressing and holding it performs a reset operation. This allows the operator to reset to automatic braking control themselves according to the work site (the braking control of the brake can be freely set). As a result, operability for the operator is improved and work efficiency is increased.

[0062] 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.

[0063] 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.

[0064] (Step S10) In step S10, the controller 30 (function activation determination unit 40) returns the automatic braking control from a state where it is deactivated to a state where it is activated. In step S10, the controller 30 (alarm control output unit 53) notifies the operator via the notification device 26 that the automatic braking control has been restored.

[0065] (Step S11) In step S11, 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, which is whether the forward / reverse lever 5 is in forward, neutral, or reverse.

[0066] (Step S12) In step S12, 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 (S12 / YES), the process proceeds to step S13. On the other hand, if the vehicle speed exceeds a predetermined value and / or is not reverse (S12 / NO), i.e., neutral or forward, the process proceeds to step S3 via P1.

[0067] (Step S13) In step S13, the controller 30 (risk level determination unit 33) obtains object distance information from the object distance information acquisition unit 32.

[0068] (Step S14) In step S14, the controller 30 (risk level determination unit 33, engine speed control unit 51, solenoid valve control unit 52, alarm control output unit 53) determines whether there is a high risk of the wheel loader 100 colliding with an object behind it, based on the distance information of the object obtained from the object distance information acquisition unit 32 and the vehicle speed information from the vehicle speed sensor 7. If the risk is high (S14 / YES), the process proceeds to step S15. On the other hand, if the risk is not high (S14 / NO), the process proceeds to step S3 via P1.

[0069] (Step S15) In step S15, 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.

[0070] Furthermore, in step S15, the controller 30 (alarm control output unit 53) notifies the operator via the notification device 26 that automatic braking control is being performed.

[0071] As described above, this embodiment can achieve the following effects.

[0072] The wheel loader 100 according to this embodiment is equipped with a release switch 4 that releases the automatic braking control of the brake 20. The controller 30 starts measuring the release time (elapsed time) when the release switch 4 is operated, and when the release time reaches the system time (for example, 30 seconds), it restores the automatic braking control of the brake 20. 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.

[0073] Furthermore, the operator can manually activate (reset) the automatic braking control of the released brake 20 by manually operating 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 also functions as a reset switch, the number of parts can be reduced.

[0074] Furthermore, when the release switch 4 is operated while the automatic braking control is deactivated, the deactivation time being measured is reset and measurement resumes, effectively extending the deactivation time for the operator. This improves convenience.

[0075] 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.

[0076] 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.

[0077] 3 Parking switch (reset switch) 4 Release switch (release switch / reset switch) 14 Parking brake 19 Wheels (driving wheels) 20 Brakes (braking device) 26 Notification device 30 Controller 100 Wheel loader (work vehicle) 100A Front frame (vehicle body) 100B Rear frame (vehicle body)

Claims

1. A work vehicle comprising a vehicle body having running wheels, a brake device that applies braking to the vehicle body, a controller that performs automatic braking control to automatically control the braking of the brake device, and a release switch that releases the automatic braking control by the controller when it receives an operation, wherein the controller restores the automatic braking control when the elapsed time since the release switch received an operation reaches a preset recovery time.

2. A work vehicle according to claim 1, further comprising a reset switch that resets the automatic braking control by the controller when an operation is received, wherein the controller resets the automatic braking control when an operation is received by the reset switch, even if the elapsed time has not yet reached the reset time.

3. A work vehicle according to claim 1, wherein the controller, when the release switch is operated while the automatic braking control is released, restores the automatic braking control even if the elapsed time has not yet reached the restore time.

4. A work vehicle according to claim 1, comprising a parking brake and a parking switch that activates the parking brake when an operation is received, wherein the controller, when an operation is received by the parking switch, restores the automatic braking control even if the elapsed time has not yet reached the restore time.

5. A work vehicle according to claim 1, wherein the controller starts measuring the elapsed time from the time the release switch is operated during the automatic braking control, and when the release switch is operated during the release of the automatic braking control, it resets the elapsed time being measured and restarts the measurement.

6. A work vehicle according to claim 1, characterized in that it is equipped with a notification device that notifies that the controller has restored the automatic braking control.

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