Working machine and control method for working machine

Abstract

To provide a work machine capable of improving work efficiency.SOLUTION: A wheel loader 100 is provided with a vehicle body 1, a traveling direction detecting part 72, a rear detecting part 71, a braking part 40, a shutoff valve 45, and a control system 26. The vehicle body 1 is able to travel. The rear detecting part 71 detects an object in a rear direction (one example of predetermined directions) of the vehicle body 1. The braking part 40 can exert a braking force by carrying out automatic brake automatically braking the vehicle body 1 based on detection of the object with the rear detecting part 71. The shutoff valve 45 sets the braking part 40 such that the brake force with the automatic brake can be exerted or cannot be exerted. The control system 26 sets the braking part 40 so as to exert the brake force when the vehicle 1 travels in the rear direction and sets the braking part 40 so as not to exert the brake force when the vehicle 1 travels in directions rather than the rear direction, through controlling the shutoff valve 45.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a work machine and a control method for a work machine.

Background Art

[0002] In a wheel loader which is an example of a work machine, an automatic stop system has been proposed that detects an obstacle behind and automatically stops (see, for example, Patent Document 1).

[0003] For example, in the wheel loader shown in Patent Document 1, the area from the wheel loader to an object is divided into three areas, a first area, a second area, and a third area, in the order of decreasing distance from the object, and the brake is automatically actuated in the third area where the distance from the wheel loader is the closest to stop the vehicle.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when the automatic brake is actuated and braking is performed in an unintended traveling direction, it may interfere with the work.

[0006] The present disclosure aims to provide a work machine and a control method for a work machine capable of suppressing malfunction by exerting braking force by an automatic brake only in a desired traveling direction.

Means for Solving the Problems

[0007] The work machine according to this aspect includes a vehicle body, a traveling direction detection unit, an object detection unit, a braking unit, an execution setting unit, and a control unit. The vehicle body is capable of traveling. The object detection unit detects an object in a predetermined direction of the vehicle body. The braking unit is capable of exerting a braking force by performing an automatic brake that automatically brakes the vehicle body based on the detection of the object by the object detection unit. The setting unit sets the braking unit so that the braking force by the automatic brake can or cannot be exerted. The control unit controls the setting unit and sets the braking unit so that the braking force can be exerted when the vehicle body is traveling in a predetermined direction, and sets the braking unit so that the braking force cannot be exerted when the vehicle body is traveling in a direction other than the predetermined direction.

[0008] The control method of the work machine according to another aspect includes a traveling direction detection step, an object detection step, and a setting step. The traveling direction detection step detects the traveling direction of the vehicle body. The object detection step detects an object in a predetermined direction of the vehicle body. The setting step sets so that the braking force can be exerted by performing an automatic brake that automatically brakes the vehicle body based on the detection of the object by the object detection step when the vehicle body is traveling in a predetermined direction, and sets so that the braking force cannot be exerted when the vehicle body is traveling in a direction other than the predetermined direction.

Effect of the Invention

[0009] According to the present disclosure, it is possible to provide a work machine and a control method of a work machine capable of suppressing malfunction by exerting the braking force by the automatic brake only in a desired traveling direction.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0011] A wheel loader as an example of a working machine according to the present disclosure will be described below with reference to the drawings.

[0012] (Overview of Wheel Loader) FIG. 1 is a schematic diagram showing the configuration of a wheel loader 100 (an example of a working machine) according to the present embodiment. The wheel loader 100 of the present embodiment has a traveling body 2 and a working machine 3 on a vehicle body 1. The working machine 3 is disposed on the traveling body 2. The traveling body 2 includes a vehicle body frame 10, a pair of front tires 4, a cab 5, an engine room 6, a pair of rear tires 7, and a steering cylinder 9. In the following description, “front”, “rear”, “right”, “left”, “up”, and “down” indicate directions based on the state of looking forward from the driver's seat. Also, “vehicle width direction” and “left - right direction” are synonymous. In FIG. 1, the front - rear direction is indicated by Z, the front direction is indicated by Zf, and the rear direction is indicated by Zb.

[0013] The wheel loader 100 performs earth - sand loading work and the like using the working machine 3.

[0014] The vehicle body frame 10 is of the so-called articulated type and has a front frame 11, a rear frame 12, and a connecting shaft portion 13. The front frame 11 is disposed in front of the rear frame 12. The connecting shaft portion 13 is provided at the center in the vehicle width direction and connects the front frame 11 and the rear frame 12 so as to be swingable relative to each other. A pair of front tires 4 are attached to the left and right of the front frame 11. Also, a pair of rear tires 7 are attached to the left and right of the rear frame 12.

[0015] The work implement 3 is driven by hydraulic oil from a work implement pump (not shown). The work implement 3 has a boom 14, a bucket 15, a lift cylinder 16, and a bucket cylinder 17. The boom 14 is mounted on the front frame 11. The bucket 15 is attached to the tip of the boom 14.

[0016] The lift cylinder 16 and the bucket cylinder 17 are hydraulic cylinders. One end of the lift cylinder 16 is attached to the front frame 11, and the other end of the lift cylinder 16 is attached to the boom 14. By the expansion and contraction of the lift cylinder 16, the boom 14 swings up and down. One end of the bucket cylinder 17 is attached to the front frame 11, and the other end of the bucket cylinder 17 is attached to the bucket 15 via a bell crank 18. By the expansion and contraction of the bucket cylinder 17, the bucket 15 swings up and down.

[0017] The cab 5 is placed on the rear frame 12, and inside, there are arranged a steering wheel for steering operation, a lever for operating the work implement 3, various display devices, etc. The engine room 6 is located behind the cab 5 and on the rear frame 12, and the engine 31 is housed therein.

[0018] Figure 2 is a block diagram showing the configuration of the wheel loader 100.

[0019] The wheel loader 100 has a drive system 21, a braking system 22, an operating system 23, a notification system 24, a detection system 25, and a control system 26 (an example of a control unit).

[0020] The drive system 21 drives the wheel loader 100. The braking system 22 brakes the wheel loader 100. The operating system 23 is operated by an operator. The notification system 24 notifies the operator based on the detection result by the detection system 25. The detection system 25 detects the traveling direction of the vehicle body 1 and an object behind the vehicle body 1 (an example of a predetermined direction). The control system 26 operates the drive system 21, the braking system 22, and the notification system 24 based on the operation of the operator on the operating system 23 and the detection by the detection system 25.

[0021] (Drive system 21) The drive system 21 has an engine 31, an HST 32, a transfer 33, an axle 34, and front tires 4 and rear tires 7.

[0022] The engine 31 is, for example, a diesel engine, and the driving force generated by the engine 31 drives the pump 32a of the HST (Hydro Static Transmission) 32.

[0023] The HST32 has a pump 32a, a motor 32b, and a hydraulic circuit 32c that connects 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. When the pump 32a is driven by the engine 31, it discharges hydraulic oil. The discharged hydraulic oil is sent to the motor 32b through the hydraulic circuit 32c. The motor 32b is a swash plate pump, and the angle of the swash plate can be changed by a solenoid 32e. The hydraulic circuit 32c has a first drive circuit 32c1 and a second drive circuit 32c2. When hydraulic oil is supplied from the pump 32a to the motor 32b through the first drive circuit 32c1, the motor 32b is driven in one direction (for example, the forward direction). When hydraulic oil is supplied from the pump 32a to the motor 32b through the second drive circuit 32c2, the motor 32b is driven in the other direction (for example, the reverse direction). Note that the discharge direction of the hydraulic oil to the first drive circuit 32c1 or the second drive circuit 32c2 can be changed by the solenoid 32d.

[0024] The transfer 33 distributes the output from the engine 31 to the front and rear axles 34.

[0025] A pair of front tires 4 are connected to the front axle 34 and rotate by the output distributed from the engine 31. Also, a pair of rear tires 7 are connected to the rear axle 34 and rotate by the output distributed from the engine 31.

[0026] (Braking system 22) FIG. 3 is a diagram showing the hydraulic circuit of the braking system 22 in FIG. 2.

[0027] The braking system 22 has a braking unit 40 and a shut-off valve 45 (an example of a setting unit, an example of a shut-off valve). The braking unit 40 performs braking of the vehicle body 1 based on the operation of the brake pedal 54 and automatic braking of the vehicle body 1 based on a command from the control system 26. The shut-off valve 45 puts the braking unit 40 in a state where it can or cannot exert braking force by automatic braking.

[0028] The braking unit 40 includes a brake valve unit 41, brake circuits 42a and 42b (an example of a service brake), a parking brake 43 (see FIG. 2), hydraulic oil supply passages 44a and 44b, an EPC (Electric Proportional Valve) valve 46 (an example of a regulating valve), a shuttle valve unit 47, and a tank 48.

[0029] An accumulator, a pump, etc. are connected to the hydraulic oil supply passages 44a and 44b, and hydraulic oil is supplied.

[0030] The brake valve unit 41 is operated by a brake pedal 54, which will be described later. As shown in FIG. 3, the brake valve unit 41 includes a rear brake valve 41a and a front brake valve 41b. Each of the rear brake valve 41a and the front brake valve 41b is a three-position switching valve having three ports.

[0031] The first port of the rear brake valve 41a is connected to the hydraulic oil supply passage 44a via an accumulator 49a. The second port of the rear brake valve 41a is connected to the tank 48. The third port of the rear brake valve 41a is connected to the rear shuttle valve 47a of the shuttle valve unit 47.

[0032] In the first state, the rear brake valve 41a connects the first port and the third port, connects the hydraulic oil supply passage 44a and the rear shuttle valve 47a, and supplies hydraulic oil to the rear shuttle valve 47a. In the second state, the rear brake valve 41a closes all the ports. In the third state, the rear brake valve 41a connects the second port and the third port, and discharges the hydraulic oil between the rear shuttle valve 47a and the rear brake valve 41a to the tank 48. In the second and third states, the rear brake valve 41a stops the supply of hydraulic oil to the rear shuttle valve 47a.

[0033] The first port of the front brake valve 41b is connected to the hydraulic oil supply passage 44b via the accumulator 49b. Also, the second port of the front brake valve 41b is connected to the tank 48. The third port of the front brake valve 41b is connected to the front shuttle valve 47b of the shuttle valve unit 47.

[0034] In the first state, the front brake valve 41b connects the first port and the third port, connects the hydraulic oil supply passage 44b and the front shuttle valve 47b, and supplies hydraulic oil to the front shuttle valve 47b. In the second state, the front brake valve 41b closes all the ports. In the third state, the front brake valve 41b connects the second port and the third port, and discharges the hydraulic oil between the front shuttle valve 47b and the front brake valve 41b to the tank 48. In the second and third states, the front brake valve 41b stops the supply of hydraulic oil to the front shuttle valve 47b.

[0035] The opening degrees of the rear brake valve 41a and the front brake valve 41b are adjusted according to the operation amount of the brake pedal 54, and the amount of hydraulic oil supplied to the shuttle valve unit 47 is changed. For example, when the operation amount of the brake pedal 54 is large, the amount of hydraulic oil supplied from the rear brake valve 41a and the front brake valve 41b to the shuttle valve unit 47 increases.

[0036] The brake circuit 42a is provided on the rear axle 34. The brake circuit 42a is connected to the rear shuttle valve 47a. The brake circuit 42b is provided on the front axle 34. The brake circuit 42b is connected to the front shuttle valve 47b. The brake circuits 42a and 42b are hydraulic brakes. The greater the amount or pressure of the hydraulic oil supplied from the rear shuttle valve 47a to the brake circuit 42a, the stronger the braking force. The greater the amount or pressure of the hydraulic oil supplied from the front shuttle valve 47b to the brake circuit 42b, the stronger the braking force.

[0037] The shut-off valve 45 is connected to the hydraulic oil supply passage 44b. The shut-off valve 45 has four ports and is a solenoid valve that takes two states: an open state and a closed state. The first port of the shut-off valve 45 is connected to the hydraulic oil supply passage 44b. The second port of the shut-off valve 45 is connected to the tank 48. The third port of the shut-off valve 45 is connected to the EPC valve 46. The fourth port of the shut-off valve 45 allows air to pass through in the open state and is shielded in the closed state.

[0038] The shut-off valve 45 is opened and closed based on an instruction from the control system 26. Specifically, the shut-off valve 45 assumes an open state when it is energized by an open command from the control system 26, and assumes a closed state when the energization is stopped by a close command from the control system 26.

[0039] In the open state, the shut-off valve 45 connects the first port and the third port, and supplies hydraulic oil from the hydraulic oil supply passage 44b to the EPC valve 46. Also, in the open state, the shut-off valve 45 connects the fourth port through which air passes and the second port connected to the tank 48.

[0040] In the closed state, the shut-off valve 45 connects the second port and the third port, and discharges the hydraulic oil between the shut-off valve 45 and the EPC valve to the tank 48. Also, in the closed state, the shut-off valve 45 closes the first port and the fourth port. Thereby, the shut-off valve 45 stops the supply of hydraulic oil from the hydraulic oil supply passage 44b to the EPC valve 46 in the closed state.

[0041] In the present embodiment, the control system 26 opens the shut-off valve 45 only when the vehicle body 1 is traveling backward, for example. The control system 26 makes a determination based on the detection result of the traveling direction detection unit 72 regarding the backward movement of the vehicle body 1.

[0042] The EPC valve 46 is disposed in the flow path connecting the shut-off valve 45 and the shuttle valve unit 47. The EPC valve 46 is a solenoid valve having three ports. The first port of the EPC valve 46 is connected to the shut-off valve 45. The second port of the EPC valve 46 is connected to the tank 48. The third port of the EPC valve 46 is connected to the shuttle valve unit 47.

[0043] In the open state, the EPC valve 46 connects the first port and the third port, and supplies the hydraulic oil supplied from the shut-off valve 45 to the shuttle valve unit 47. The opening degree of the EPC valve 46 is adjusted based on an instruction from the control system 26, and the amount of hydraulic oil supplied to the shuttle valve unit 47 is changed.

[0044] In the closed state, the first port of the EPC valve 46 is closed, the second port and the third port are connected, and the hydraulic oil in the flow path from the EPC valve 46 to the shuttle valve unit 47 is discharged to the tank 48. Thereby, the EPC valve 46 stops the supply of hydraulic oil from the shut-off valve 45 to the shuttle valve unit 47 in the closed state.

[0045] The shuttle valve unit 47 includes a rear shuttle valve 47a and a front shuttle valve 47b. The rear shuttle valve 47a supplies the hydraulic oil with the higher pressure among the hydraulic oil supplied via the rear brake valve 41a and the hydraulic oil supplied via the EPC valve 46 to the brake circuit 42a. The front shuttle valve 47b supplies the hydraulic oil with the higher pressure among the hydraulic oil supplied via the front brake valve 41b and the hydraulic oil supplied via the EPC valve 46 to the brake circuit 42b.

[0046] With such a configuration, even when the brake pedal 54 is not operated and no hydraulic oil is supplied from the brake valve unit 41, when the shut-off valve 45 and the EPC valve 46 are opened according to an instruction from the control system 26, hydraulic oil is supplied from the rear shuttle valve 47a and the front shuttle valve 47b to the brake circuits 42a and 42b, and automatic brake control is performed.

[0047] The parking brake 43 shown in Fig. 2 is provided on the transfer 33. As the parking brake 43, for example, a wet multi-stage brake or a disk brake that can be switched between a braking state and a non-braking state can be used.

[0048] (Operating system 23) As shown in Fig. 2, the operating system 23 includes an accelerator 51, an FNR lever 52, a parking switch 53, a brake pedal 54, and a return switch 55.

[0049] The accelerator 51 is provided in the cab 5. The operator operates the accelerator 51 to set the throttle opening. The accelerator 51 generates an opening signal indicating the accelerator operation amount and transmits it to the control system 26. The control system 26 controls the rotational speed of the engine 31 based on the transmitted signal.

[0050] The FNR lever 52 is provided in the cab 5. The FNR lever 52 can take positions for forward, neutral, or reverse. An operation signal indicating the position of the FNR lever 52 is transmitted to the control system 26, and the control system 26 controls the solenoid 32d to switch between forward and reverse.

[0051] The parking switch 53 is provided in the cab 5 and is a switch that can be switched between on and off states, and transmits a signal indicating its state to the control system 26. The control system 26 sets the parking brake 43 to a braking state or a non-braking state based on the transmitted signal.

[0052] The brake pedal 54 is provided in the cab 5. The brake pedal 54 adjusts the opening degrees of the rear brake valve 41a and the front brake valve 41b of the brake valve unit 41.

[0053] The return switch 55 is operated by the operator to return from the stopped state after the vehicle body 1 has stopped by the automatic brake described later.

[0054] (Notification system 24) The notification system 24 includes an alarm device 61 and an automatic brake operation notification lamp 63.

[0055] When the rear detection unit 71 of the detection system 25 described later detects an object behind the vehicle body 1 during reverse travel, the alarm device 61 gives an alarm to the operator according to an instruction from the control system 26.

[0056] The alarm device 61 may have, for example, a lamp and turn on the lamp. Also, not limited to the lamp, the alarm device 61 may have a speaker and make a sound. Further, an alarm may be displayed on a display panel such as a monitor.

[0057] The automatic brake operation notification lamp 63 notifies the operator that the automatic brake is in an operating state and that a return operation by the return switch 55 is required. When the return switch 55 is operated to release the automatic brake, the automatic brake operation notification lamp 63 turns off.

[0058] Note that the automatic brake operation notification lamp 63 is not limited to a lamp and may make a sound. Further, a notification may be displayed on a display panel such as a monitor.

[0059] As described above, the means for notifying the operator by the notification system 24 can be appropriately selected such as a lamp, a sound, a monitor, etc.

[0060] (Detection system 25) FIG. 3 is a block diagram showing the configurations of the detection system 25 and the control system 26.

[0061] The detection system 25 includes a rear detection unit 71 (an example of an object detection unit) and a traveling direction detection unit 72.

[0062] The rear detection unit 71 detects information regarding the state behind the vehicle body 1. The rear detection unit 71 is attached to the rear end of the vehicle body 1 as shown in FIG. 1, for example, but is not limited to the rear end.

[0063] The rear detection unit 71 includes a main radar 71a and a sub-radar 71b. The main radar 71a and the sub-radar 71b are, for example, millimeter-wave radars. By providing the main radar 71a and the sub-radar 71b, even when one of them fails, the other can detect an object behind.

[0064] Each of the main radar 71a and the sub-radar 71b detects, with a receiving antenna, the state in which millimeter-wave radio waves emitted from a transmitting antenna are reflected from the surface of an object and return. Information detected by the main radar 71a and the sub-radar 71b is transmitted to the control system 26, and the control system 26 can determine whether there is an object behind the vehicle body 1. Further, the control system 26 may calculate the distance to the detected object.

[0065] The traveling direction detection unit 72 detects information regarding the traveling direction of the vehicle body 1. The control system 26 determines the traveling direction of the vehicle body 1 based on the information detected by the traveling direction detection unit 72. The traveling direction detection unit 72 includes a rotation sensor 72a and an acceleration sensor 72b. The rotation sensor 72a detects the rotation direction of the front tire 4 or the rear tire 7. The acceleration sensor 72b detects the acceleration of the vehicle body 1.

[0066] Based on the information of the rotation sensor 72a and the acceleration sensor 72b, it is possible to determine whether the vehicle body 1 is in a state of moving forward, stopping, or moving backward.

[0067] (Control system 26) The control system 26 includes a detection controller 80 and a vehicle body controller 90.

[0068] Each of the detection controller 80 and the vehicle body controller 90 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 detection controller 80 and the vehicle body controller 90 read out a program stored in the storage, expand it in the main memory, and execute predetermined processing according to the program. In the present embodiment, although it is described that each of the detection controller 80 and the vehicle body controller 90 has a CPU, the detection controller 80 and the vehicle body controller 90 may have one CPU in total. Further, the program may be distributed to the detection controller 80 and the vehicle body controller 90 via a network.

[0069] The detection controller 80 detects the presence of an object based on the information detected by the rear detection unit 71. The vehicle body controller 90 controls the automatic brake based on the detection result of the detection controller 80. When the vehicle body 1 is moving forward, the vehicle body controller 90 sets the braking system 22 so that the braking force by the automatic brake cannot be exerted.

[0070] The detection controller 80 includes a rear information acquisition unit 81 and an object determination unit 82.

[0071] The rear information acquisition unit 81 acquires information regarding the rear detected by the main radar 71a and the sub-radar 71b of the rear detection unit 71. The object determination unit 82 determines whether or not there is an object in the rear based on the acquired information regarding the rear. The determination result by the object determination unit 82 is transmitted to an EPC valve command unit 94 described later. FIG. 5 is a diagram showing a state in which an object M exists behind the wheel loader 100.

[0072] The vehicle body controller 90 includes a traveling direction information acquisition unit 91, a traveling direction determination unit 92, a shut-off valve command unit 93, an EPC valve command unit 94, and a notification system command unit 95.

[0073] The traveling direction information acquisition unit 91 acquires detection information from the rotation sensor 72a and the acceleration sensor 72b.

[0074] The traveling direction determination unit 92 determines the traveling direction of the vehicle body 1 based on the acquired detection information. In the present embodiment, since automatic brake control is performed when an object is detected rearward during reverse travel, the traveling direction determination unit 92 determines whether the vehicle body 1 is traveling in reverse based on the information of the rotation sensor 72a and the acceleration sensor 72b. Note that for the determination of the traveling direction, not only the detection results of the rotation sensor 72a and the acceleration sensor 72b but also the fact that the FNR lever 52 is in the reverse position may be combined. For example, even in a stopped state where the front tires 4 and the rear tires 7 are not rotating, if the FNR lever 52 is in the reverse position, it may be determined that the vehicle body 1 is in a reverse state. As a position detection sensor for detecting the position of the FNR lever 52, a potentiometer may be provided, or switches may be provided for each of the forward position, the reverse position, and the neutral position. Further, both may be provided so that even if one of the potentiometer and the switch is misoperated, it can be detected.

[0075] When the traveling direction determination unit 92 determines that the vehicle body 1 is traveling in reverse, the shut-off valve command unit 93 issues an open command to the shut-off valve 45. As a result, the shut-off valve 45 is energized, the shut-off valve 45 becomes an open state, hydraulic oil is supplied from the hydraulic oil supply passage 44b to the EPC valve 46, and a braking force is exerted when the automatic brake is performed. On the other hand, when the traveling direction determination unit 92 determines that the vehicle body 1 is traveling forward, the shut-off valve command unit 93 issues a close command to the shut-off valve 45. When the close command is transmitted, the shut-off valve 45 becomes a non-energized state and a closed state, so that hydraulic oil is not supplied to the EPC valve 46.

[0076] When the traveling direction determination unit 92 determines that the vehicle body 1 is moving backward and the object determination unit 82 determines that there is an object behind the vehicle body 1, the EPC valve command unit 94 issues an opening command. The opening degree of the EPC valve 46 may be preset or adjusted based on the distance to the detected object. For example, the deceleration for stopping in front of the detected object is calculated from the distance to the detected object, and the EPC valve command unit 94 may send an opening command to the EPC valve 46 so that the opening degree is such that the deceleration is exerted.

[0077] Based on the opening command, the solenoid of the EPC valve 46 is operated to be in an open state, and hydraulic oil is supplied from the EPC valve 46 to the rear shuttle valve 47a and the front shuttle valve 47b. In the rear shuttle valve 47a, the hydraulic oil with the higher pressure among the hydraulic oil from the rear brake valve 41a and the hydraulic oil from the EPC valve 46 is supplied to the brake circuit 42a, and braking force is exerted. Also, in the front shuttle valve 47b, the hydraulic oil with the higher pressure among the hydraulic oil from the front brake valve 41b and the hydraulic oil from the EPC valve 46 is supplied to the brake circuit 42a, and braking force is exerted. Thereby, even when the operator does not operate the brake pedal 54, automatic braking is performed and braking force is exerted, and the vehicle body 1 can be stopped in front of the object M as shown in FIG. 5. The stopped vehicle body 1 is indicated by a two-dot chain line.

[0078] On the other hand, when the shut-off valve 45 is closed, since hydraulic oil is not supplied to the EPC valve 46, even if the EPC valve 46 is accidentally opened due to malfunction, hydraulic oil is not supplied from the EPC valve 46 to the shuttle valve unit 47. Therefore, even if automatic braking is performed, braking force is not exerted. Thereby, for example, even if automatic braking is performed during forward movement due to malfunction, since braking force is not exerted, the vehicle body 1 does not stop and the work is not hindered.

[0079] Even when the braking force by the automatic brake is not exerted, when the operator operates the brake pedal 54 and hydraulic oil is supplied from the brake valve unit 41 to the shuttle valve unit 47, the brake circuits 42a and 42b are activated.

[0080] When the notification system command unit 95 issues an open command from the shut-off valve command unit 93 and an open command from the EPC valve command unit 94, it issues a lighting command to the automatic brake operation notification lamp 63 and a drive command to the alarm device 61. When the operator operates the return switch 55 and the automatic brake is released, the notification system command unit 95 issues a light-off instruction to the automatic brake operation notification lamp 63 and a stop command to the alarm device 61.

[0081] <Operation> Next, the control operation of the wheel loader 100 according to the present embodiment will be described.

[0082] FIG. 6 is a flowchart showing the control operation of the wheel loader 100 according to the present embodiment.

[0083] First, in step S10, the traveling direction information acquisition unit 91 acquires the detection information of the traveling direction detection unit 72.

[0084] Next, in step S20 (an example of a traveling direction detection step), the traveling direction determination unit 92 determines whether the traveling direction of the vehicle body 1 is in reverse based on the acquired detection information.

[0085] If it is determined in step S20 that the traveling direction is in reverse, in step S30 (an example of a setting step), the shut-off valve command unit 93 transmits an open command to the shut-off valve 45. As a result, the shut-off valve 45 is energized, the shut-off valve 45 becomes an open state, and hydraulic oil is supplied to the EPC valve 46.

[0086] On the other hand, when it is determined in step S20 that the traveling direction is forward instead of backward, in step S40 (an example of a setting step), the shut-off valve command unit 93 transmits a close command to the shut-off valve 45, and the control ends. As a result, the shut-off valve 45 becomes de-energized, and the shut-off valve 45 closes. Note that if the current open / closed state of the shut-off valve 45 is known, it is not necessary to transmit a command in the same state as the current one. For example, if the shut-off valve 45 is currently in the closed state, it is not necessary to transmit a close command again.

[0087] Next, in step S50 (an example of an object detection step) following step S30, when the object determination unit 82 determines that there is an object behind the vehicle body 1, the control proceeds to step S60. On the other hand, when the object determination unit 82 determines in step S50 that there is no object behind the vehicle body 1, the control ends.

[0088] Next, in step S60, the EPC valve command unit 94 transmits an open command to the EPC valve 46. As a result, the solenoid of the EPC valve 46 is operated to be in the open state, and hydraulic oil is supplied from the EPC valve 46 to the brake circuits 42a and 42b via the rear shuttle valve 47a and the front shuttle valve 47b, and the braking force by the automatic brake is exerted.

[0089] Next, in step S70, the notification system command unit 95 transmits a fall command to the automatic brake operation notification lamp 63 and transmits a notification command to the alarm device 61. As a result, the automatic brake operation notification lamp 63 lights up, and an alarm by the alarm device 61 is notified.

[0090] As described above, when the vehicle body 1 is traveling backward and an object M is detected behind it, the vehicle body 1 can be stopped in front of the object M by the automatic brake (see FIG. 5). On the other hand, when the vehicle body 1 is traveling forward, since the shut-off valve 45 is closed and hydraulic oil is not supplied to the EPC valve 46, even if the automatic brake is implemented due to a malfunction, the braking force is not exerted, and the stop of the vehicle body 1 can be suppressed.

[0091] <Features> (1) The wheel loader 100 (an example of a work machine) of this embodiment includes a vehicle body 1, a traveling direction detection unit 72, a rear detection unit 71 (an example of an object detection unit), a braking unit 40, a shut-off valve 45 (an example of a setting unit), and a control system 26 (an example of a control unit). The vehicle body 1 is capable of traveling. The rear detection unit 71 detects an object in the rear direction (an example of a predetermined direction) of the vehicle body 1. The braking unit 40 is capable of exerting a braking force by performing an automatic brake that automatically brakes the vehicle body 1 based on the detection of an object by the rear detection unit 71. The shut-off valve 45 sets the braking unit 40 so that the braking force by the automatic brake can be exerted or cannot be exerted. The control system 26 controls the shut-off valve 45 to set the braking unit 40 so that the braking force can be exerted when the vehicle body 1 is traveling in the rear direction, and sets the braking unit 40 so that the braking force cannot be exerted when the vehicle body 1 is traveling in a direction other than the rear direction.

[0092] Thereby, only when traveling backward, the braking force by the automatic brake is exerted when an object is detected. Therefore, when traveling in a direction other than the rear direction (forward), even if the control of the automatic brake is performed due to a malfunction, the braking force cannot be exerted. For this reason, malfunctions can be suppressed and the braking force by the automatic brake can be exerted only in the desired traveling direction.

[0093] (2) In the wheel loader 100 of this embodiment, when the vehicle body 1 is traveling in the rear direction, the control system 26 controls the braking unit 40 to perform an automatic brake when an object is detected by the rear detection unit 71.

[0094] Thereby, when an object is detected in the rear direction, the vehicle body 1 can be automatically stopped.

[0095] (3) In the wheel loader 100 according to this embodiment, the braking unit 40 includes brake circuits 42a and 42b (an example of a service brake) and an EPC valve 46 (an example of a regulating valve). The EPC valve 46 can adjust the supply amount of hydraulic oil to the brake circuits 42a and 42b.

[0096] Thereby, an automatic brake can be implemented by the brake circuits 42a and 42b which are service brakes.

[0097] (4) In the wheel loader 100 according to this embodiment, the shut-off valve 45 can cut off the supply of hydraulic oil to the EPC valve 46. The control system 26 controls the shut-off valve 45 to cut off the supply of hydraulic oil to the EPC valve 46, thereby setting the braking unit 40 so that braking force cannot be exerted, and supplying hydraulic oil to the EPC valve 46 to set the braking unit 40 so that braking force can be exerted.

[0098] Thereby, by opening and closing the shut-off valve 45, it is possible to set whether the braking force by the automatic brake can be exerted or not.

[0099] (5) In the wheel loader 100 according to this embodiment, the traveling direction detection unit 72 includes at least one of a rotation sensor 72a, an acceleration sensor 72b, and a position detection sensor (not shown). The rotation sensor 72a detects the rotation of the front tire 4 (an example of a wheel) or the rear tire 7 (an example of a wheel) of the traveling body 2. The acceleration sensor 72b detects the acceleration of the traveling body 2. The position detection sensor detects the position of the FNR lever 52. The control system 26 determines the traveling direction of the vehicle body 1 based on the detection by the rotation sensor 72a, the acceleration sensor 72b, or the position detection sensor.

[0100] Thereby, the traveling direction of the vehicle body can be determined.

[0101] (6) In the wheel loader 100 according to the present embodiment, the braking unit 40 includes a rear shuttle valve 47a and a front shuttle valve 47b, and a rear brake valve 41a and a front brake valve 41b. The rear shuttle valve 47a and the front shuttle valve 47b supply hydraulic oil to the brake circuits 42a and 42b. The rear brake valve 41a and the front brake valve 41b adjust the flow rate of the hydraulic oil discharged to the rear shuttle valve 47a and the front shuttle valve 47b based on the operation of the brake pedal 54. The EPC valve 46 supplies hydraulic oil to the rear shuttle valve 47a and the front shuttle valve 47b. The rear shuttle valve 47a and the front shuttle valve 47b supply the hydraulic oil with the higher pressure among the hydraulic oil supplied from the EPC valve 46 and the hydraulic oil supplied from the rear brake valve 41a and the front brake valve 41b to the brake circuits 42a and 42b.

[0102] Accordingly, when the operator operates the brake pedal 54, when the pressure of the hydraulic oil from the brake pedal 54 is high, braking can be performed by operating the brake pedal 54.

[0103] (7) The wheel loader 100 according to the present embodiment further includes a work implement 3, a front frame 11, and a rear frame 12. The work implement 3 is attached to the front frame 11. The rear frame 12 is rotatably attached to the front frame 11. Accordingly, in the wheel loader, malfunction can be suppressed and the braking force by the automatic brake can be exerted only in the desired traveling direction.

[0104] (8) The control method of the wheel loader 100 according to this embodiment includes step S20 (an example of a traveling direction detection step), step S50 (an example of an object detection step), and steps S30 and S40 (an example of a setting step). Step S20 detects the traveling direction of the vehicle body 1. Step S50 detects an object in the rear direction (an example of a predetermined direction) of the vehicle body 1. Steps S30 and S40 are configured to enable the braking force by implementing an automatic brake that automatically brakes the vehicle body 1 based on the detection of the object in step S50 when the vehicle body 1 is traveling in the rear direction, and to set the automatic brake so that the braking force cannot be exerted and the automatic brake cannot be implemented when the vehicle body 1 is traveling in a direction other than the rear direction.

[0105] As a result, the braking force by the automatic brake is exerted only when traveling backward, so that in a direction other than the rear direction (forward), even if the control of the automatic brake is performed due to a malfunction, the braking force cannot be exerted. Therefore, it is possible to suppress malfunctions and exert the braking force by the automatic brake only in the desired traveling direction.

[0106] <Other Embodiments> As described above, one embodiment of the present invention has been described. However, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the gist of the invention.

[0107] (A) In the above embodiment, the traveling direction detection unit 72 has the main radar 71a and the sub-radar 71b, but it is not limited to a radar, and for example, a camera or the like may be used. When it is detected by the rear detection unit 71 that there is an object in the rear during reverse travel, the automatic brake is executed.

[0108] (B) In the above-described embodiment, the HST 32 is used in the drive system 21, but it is not limited to the HST, and a torque converter may be used instead. FIG. 7 is a block diagram showing a configuration in which a torque converter 132 and a transmission 133 are provided in the drive system 21. The driving force from the engine 31 is transmitted to the transmission 133 via the torque converter 132. The transmission 133 shifts the rotational driving force of the engine 31 transmitted via the torque converter 132 and transmits it to the axle 34. A parking brake 43 is provided in the transmission 133.

[0109] Further, not only the HST but also an HMT (Hydro Mechanical Transmission) may be used.

[0110] (C) The wheel loader according to the above-described embodiment may be operated by an operator boarding it, or may be operated unmanned.

[0111] (D) In the above-described embodiment, a wheel loader has been described as an example of the working machine, but it is not limited to the wheel loader, and a hydraulic excavator or the like may be used.

Industrial Applicability

[0112] According to the working machine and the control method of the working machine of the present invention, it is possible to exhibit an effect of improving the working efficiency and is useful as a wheel loader or the like.

Explanation of Signs

[0113] 1: Vehicle body 26: Control system 40: Braking unit 45: Shut-off valve 71: Rear detection unit 72: Travel direction detection unit 100: Wheel loader

Claims

1. A travelable vehicle body, A travel direction detection unit that detects the travel direction of the vehicle body, An object detection unit that detects an object in a predetermined direction of the vehicle body, A braking unit capable of exerting braking force by performing an automatic brake that automatically brakes the vehicle body based on the detection of the object by the object detection unit, A setting unit that sets the braking unit so that the braking force by the automatic brake can be exerted or cannot be exerted, A control unit that controls the setting unit based on the travel direction by the travel direction detection unit, and includes: The braking unit is A service brake, An adjustment valve capable of adjusting the supply amount of hydraulic oil to the service brake, and has: The setting unit is It has a shut-off valve capable of shutting off the supply of the hydraulic oil to the adjustment valve, When the vehicle body is traveling in the predetermined direction, the control unit controls the shut-off valve to an open state and supplies the hydraulic oil to the adjustment valve, thereby controlling the setting unit so that the braking unit can exert the braking force. When the vehicle body is traveling in a direction other than the predetermined direction, the control unit controls the shut-off valve to a closed state and shuts off the supply of the hydraulic oil to the adjustment valve, thereby controlling the setting unit so that the braking unit cannot exert the braking force. A working machine.

2. When the vehicle body is traveling in the predetermined direction and the object is detected by the object detection unit, the control unit controls the braking unit to perform the automatic brake. The working machine according to claim 1.

3. The predetermined direction is the rear direction. The working machine according to claim 1 or 2.

4. The travel direction detection unit is It has at least one of a rotation sensor that detects the rotation of the wheels of the vehicle body, an acceleration sensor that detects the acceleration of the vehicle body, or a position detection sensor that detects the position of the FNR lever. The control unit determines the traveling direction of the vehicle body based on the detection by the rotation sensor, the acceleration sensor, or the position detection sensor. The working machine according to any one of claims 1 to 3.

5. The braking unit A shuttle valve that supplies hydraulic oil to the service brake, A brake valve that adjusts the flow rate of the hydraulic oil discharged to the shuttle valve based on the operation of the brake pedal, and further includes The regulating valve supplies hydraulic oil to the shuttle valve, The shuttle valve supplies the service brake with the hydraulic oil having the higher pressure among the hydraulic oil supplied from the regulating valve and the hydraulic oil supplied from the brake valve. The working machine according to claim 1.

6. The working machine is a wheel loader, A working implement, A front frame to which the working implement is attached, A rear frame rotatably connected to the front frame, and further includes The working machine according to any one of claims 1 to 5.

7. A vehicle body, a braking unit capable of exerting braking force by implementing an automatic brake for automatically braking the vehicle body, and a setting unit for setting the braking unit so that the braking force by the automatic brake can be exerted or cannot be exerted. The braking unit has a service brake and a regulating valve capable of adjusting the supply amount of hydraulic oil to the service brake. The setting unit has a shut-off valve capable of shutting off the supply of the hydraulic oil to the regulating valve. A control method for a working machine, A traveling direction detection step of detecting the traveling direction of the vehicle body, An object detection step of detecting an object in a predetermined direction of the vehicle body; When the vehicle body is traveling in the predetermined direction, the shut-off valve is controlled to an open state, and the setting unit is controlled so that the braking unit can exert the braking force by performing the automatic brake based on the detection of the object in the object detection step by supplying the hydraulic oil to the regulating valve. When the vehicle body is traveling in a direction other than the predetermined direction, the shut-off valve is controlled to a closed state, and the setting unit is controlled so that the braking unit cannot exert the braking force by shutting off the supply of the hydraulic oil to the regulating valve. A setting step; A control method for a working machine.

Images