Work machine and control method of work machine

Abstract

A wheel loader (100) is provided with a vehicle body (1), a travel direction detection unit (72), a rear direction detection unit (71), a brake unit (40), a cut-off valve (45), and a control system (26). The vehicle body (1) is capable of traveling. The rear direction detection unit (71) detects an object in a rear direction (one example of a prescribed direction) of the vehicle body (1). The brake unit (40) is capable of implementing an automatic brake that automatically brakes the vehicle body (1) and exerts a braking force, based on detection of the object by the rear direction detection unit (71). The cut-off valve (45) sets the brake unit (40) so that the brake unit (40) is capable of exerting or incapable of exerting the braking force based on the automatic brake. The control system (26) controls the cut-off valve (45) to set the brake unit (40) so that the brake unit (40) is capable of exerting the braking force when the vehicle body (1) is traveling in the rear direction, and to set the brake unit (40) so that the brake unit (40) is incapable of exerting the braking force when the vehicle body (1) is traveling in a direction other than the rear direction.

Description

TECHNICAL FIELD

[0001] The present application relates to a work machine and a control method of a work machine. BACKGROUND

[0002] In a wheel loader which is an example of a work machine, an automatic stop system which detects an obstacle behind and automatically stops is proposed (for example, refer to Patent Literature 1).

[0003] For example, in the wheel loader shown in Patent Literature 1, an area from the wheel loader to an object is divided into three areas of a first area, a second area, and a third area in order from a distance close to the object to a distance far from the object, and the brake is automatically operated and the vehicle is stopped in the third area which is closest to the wheel loader.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Utility Model Registration No. 3219005 (Japan) SUMMARY

[0007] However, if the automatic brake is operated and brakes in an unintended travel direction, work is sometimes hindered.

[0008] An object of the present disclosure is to provide a work machine and a control method of a work machine which can suppress misoperation by exerting a braking force based on an automatic brake only in an intended travel direction.

[0009] MEANS FOR SOLVING THE PROBLEM

[0010] The work machine according to the present mode has a vehicle body, a travel direction detection unit, an object detection unit, a brake unit, an implementation setting unit, and a control unit. The vehicle body is capable of traveling. The object detection unit detects an object in a prescribed direction of the vehicle body. The brake unit is capable of implementing an automatic brake which automatically brakes the vehicle body and exerts a braking force based on detection of the object by the object detection unit. The setting unit sets the brake unit so that the brake unit is capable of exerting or incapable of exerting the braking force based on the automatic brake. The control unit controls the setting unit to set the brake unit so that the brake unit is capable of exerting the braking force when the vehicle body is traveling in the prescribed direction, and to set the brake unit so that the brake unit is incapable of exerting the braking force when the vehicle body is traveling in a direction other than the prescribed direction.

[0011] The control method of the work machine according to another aspect includes a travel direction detection step, an object detection step, and a setting step. The travel direction detection step detects a travel direction of a vehicle body. The object detection step detects an object in a prescribed direction of the vehicle body. The setting step sets, in a case where the vehicle body is traveling in the prescribed direction, a brake force that can be exerted based on automatic braking of the vehicle body, and sets, in a case where the vehicle body is traveling in a direction other than the prescribed direction, a brake force that cannot be exerted.

[0012] Effects of Invention

[0013] According to the present disclosure, it is possible to provide a work machine and a control method of a work machine that can suppress misoperation by exerting a brake force based on automatic braking only in a desired travel direction. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a side view of a wheel loader according to an embodiment of the present disclosure.

[0015] Figure 2 is a block diagram showing a control system of the wheel loader of Figure 1

[0016] Figure 3 is a hydraulic circuit diagram showing a structure of a brake system of Figure 2

[0017] Figure 4 is a block diagram showing a structure of a detection system and a control system of Figure 2

[0018] Figure 5 is a side view for explaining automatic braking based on obstacle detection in the wheel loader of Figure 1

[0019] Figure 6 is a flowchart showing a control action of the wheel loader according to an embodiment in the present disclosure.

[0020] Figure 7 is a block diagram showing a structure of a drive system, a brake system, an operation system, an informing system, a detection system, and a controller of a wheel loader in a modified example of an embodiment of the present disclosure. DETAILED DESCRIPTION

[0021] A wheel loader as an example of a work machine according to the present disclosure will be described below with reference to the drawings.

[0022] (Outline of Wheel Loader)

[0023] Figure 1 ​​​​is a schematic view showing the structure of a wheel loader 100 (an example of a work machine) of the present embodiment. The wheel loader 100 of the present embodiment has a traveling body 2 and a work machine 3 on a vehicle body 1. The work machine 3 is arranged on the traveling body 2. The traveling body 2 is provided with a vehicle body frame 10, a pair of front wheels 4, a cab 5, an engine compartment 6, a pair of rear wheels 7, and a steering cylinder 9. In the following description, "front", "rear", "right", "left", "upper", and "lower" indicate directions based on a state in which the front is viewed from the driver's seat. In addition, "vehicle width direction" is synonymous with "left-right direction". In the following description, "front" indicates the direction toward the front of the vehicle, and "rear" indicates the direction toward the rear of the vehicle. Figure 1 In the following description, Z indicates the front-rear direction, Zf indicates the front direction, and Zb indicates the rear direction.

[0024] The wheel loader 100 performs a sand loading work or the like using the work machine 3.

[0025] The vehicle body frame 10 is so-called articulated, and has a front frame 11, a rear frame 12, and a joint shaft portion 13. The front frame 11 is arranged in front of the rear frame 12. The joint shaft portion 13 is provided in the center in the vehicle width direction, and links the front frame 11 and the rear frame 12 so as to be swingable with respect to each other. The pair of front wheels 4 is attached to the left and right of the front frame 11. In addition, the pair of rear wheels 7 is attached to the left and right of the rear frame 12.

[0026] The work machine 3 is driven by hydraulic oil from a work machine pump not shown. The work machine 3 has a boom 14, a bucket 15, a lift cylinder 16, and a bucket cylinder 17. The boom 14 is attached to the front frame 11. The bucket 15 is attached to the front end of the boom 14.

[0027] The lift cylinder 16 and the bucket cylinder 17 are hydraulic cylinders. One end of the lift cylinder 16 is attached to the front frame 11, and the other end of the lift cylinder 16 is attached to the boom 14. The boom 14 swings up and down by extension and contraction of the lift cylinder 16. One end of the bucket cylinder 17 is attached to the front frame 11, and the other end of the bucket cylinder 17 is attached to the bucket 15 via a rocker arm 18. The bucket 15 swings up and down by extension and contraction of the bucket cylinder 17.

[0028] The cab 5 is placed on the rear frame 12, and is internally provided with a handle for steering device operation, or a lever for operating the work machine 3, various display devices, and the like. The engine compartment 6 is arranged on the rear side of the cab 5 and on the rear frame 12, and accommodates an engine 31.

[0029] Figure 2 is a block diagram showing the structure of the wheel loader 100.

[0030] The wheel loader 100 has a drive system 21, a brake system 22, an operation system 23, an informing system 24, a detection system 25, and a control system 26 (an example of a control portion).

[0031] The drive system 21 drives the wheel loader 100. The brake system 22 brakes the wheel loader 100. The operation system 23 is operated by an operator. The informing system 24 informs the operator based on a detection result of the detection system 25. The detection system 25 detects a traveling direction of the vehicle body 1 and an object in a rear direction of the vehicle body 1 (an example of a predetermined direction). The control system 26 operates the drive system 21, the brake system 22, and the informing system 24 based on an operation of the operation system 23 by the operator and a detection of the detection system 25.

[0032] (Drive system 21)

[0033] The drive system 21 has an engine 31, an HST 32, a transmission device 33, axles 34, front wheels 4, and rear wheels 7.

[0034] The engine 31 is, for example, a diesel engine, and a driving force generated by the engine 31 drives a pump 32a of an HST (Hydro Static Transmission) 32.

[0035] The HST 32 has the pump 32a, a motor 32b, and a hydraulic circuit 32c connecting the pump 32a and the motor 32b. The pump 32a is a skew plate-type variable capacity pump, and an angle of a skew plate can be changed by a solenoid 32d. The pump 32a discharges hydraulic oil by being driven by the engine 31. The discharged hydraulic oil is sent to the motor 32b through the hydraulic circuit 32c. The motor 32b is a skew plate-type pump, and an angle of a skew plate can be changed by a solenoid 32e. The hydraulic circuit 32c has a first drive circuit 32cl and a second drive circuit 32c2. The motor 32b is driven in one direction (for example, a forward direction) by supplying hydraulic oil from the pump 32a to the motor 32b via the first drive circuit 32cl. The motor 32b is driven in the other direction (for example, a backward direction) by supplying hydraulic oil from the pump 32a to the motor 32b via the second drive circuit 32c2. In addition, a discharge direction of the hydraulic oil to the first drive circuit 32cl or the second drive circuit 32c2 can be changed by the solenoid 32d.

[0036] The transmission device 33 distributes an output from the engine 31 to the front and rear axles 34.

[0037] A pair of front wheels 4 is connected to the front side axle 34 and rotates by the output from the engine 33 being distributed thereto. In addition, a pair of rear wheels 7 is connected to the rear side axle 34 and rotates by the output from the engine 33 being distributed thereto.

[0038] (brake system 22)

[0039] Figure 3 is a view of a hydraulic circuit of the brake system 22 of Figure 2 .

[0040] The brake system 22 has a brake portion 40 and a cut valve 45 (an example of a setting portion, an example of a cut valve). The brake portion 40 performs implementation of braking of the vehicle body 1 based on operation of a brake pedal 54 and implementation of automatic braking of the vehicle body 1 based on an instruction from a control system 26. The cut valve 45 makes the brake portion 40 into a state in which the brake portion 40 is able to exert or is unable to exert a braking force based on the automatic braking.

[0041] The brake portion 40 has a brake valve unit 41, brake circuits 42a, 42b (examples of service brakes), a parking brake 43 (refer to Figure 2 ), hydraulic oil supply lines 44a, 44b, an EPC (Electric Proportional Valve) valve 46 (an example of a regulating valve), a shuttle valve unit 47, and a reservoir 48.

[0042] The hydraulic oil supply lines 44a, 44b have an accumulator or a pump connected thereto and are supplied with hydraulic oil.

[0043] The brake valve unit 41 is operated by the brake pedal 54 described later. As Figure 3 indicated, the brake valve unit 41 has 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.

[0044] The first port of the rear brake valve 41a is connected to the hydraulic oil supply line 44a via an accumulator 49a. In addition, the second port of the rear brake valve 41a is connected to the reservoir 48. The third port of the rear brake valve 41a is connected to a rear shuttle valve 47a of the shuttle valve unit 47.

[0045] The rear brake valve 41a connects the first port and the third port in the first state, connects the hydraulic oil supply line 44a and the rear spool valve 47a, and supplies hydraulic oil to the rear spool valve 47a. The rear brake valve 41a closes all the ports in the second state. The rear brake valve 41a connects the second port and the third port in the third state, and discharges hydraulic oil between the rear spool valve 47a and the rear brake valve 41a to the reservoir 48. The rear brake valve 41a stops the supply of hydraulic oil to the rear spool valve 47a in the second state and the third state.

[0046] The first port of the front brake valve 41b is connected to the hydraulic oil supply line 44b via the accumulator 49b. In addition, the second port of the front brake valve 41b is connected to the reservoir 48. The third port of the front brake valve 41b is connected to the front spool valve 47b of the spool valve unit 47.

[0047] The front brake valve 41b connects the first port and the third port in the first state, connects the hydraulic oil supply line 44b and the front spool valve 47b, and supplies hydraulic oil to the front spool valve 47b. The front brake valve 41b closes all the ports in the second state. The front brake valve 41b connects the second port and the third port in the third state, and discharges hydraulic oil between the front spool valve 47b and the front brake valve 41b to the reservoir 48. The front brake valve 41b stops the supply of hydraulic oil to the front spool valve 47b in the second state and the third state.

[0048] The opening degree of the rear brake valve 41a and the front brake valve 41b is adjusted according to the operation amount of the brake pedal 54, and the amount of hydraulic oil supplied to the spool valve unit 47 is changed. For example, in the case where the operation amount of the brake pedal 54 is large, the amount of hydraulic oil supplied to the spool valve unit 47 from the rear brake valve 41a and the front brake valve 41b becomes large.

[0049] The brake circuit 42a is provided on the rear side axle 34. The brake circuit 42a is connected to the rear spool valve 47a. The brake circuit 42b is provided on the front side axle 34. The brake circuit 42b is connected to the front spool valve 47b. The brake circuits 42a, 42b are hydraulic brakes. The more the amount of hydraulic oil supplied from the rear spool valve 47a or the greater the pressure, the stronger the brake force of the brake circuit 42a. The more the amount of hydraulic oil supplied from the front spool valve 47b or the greater the pressure, the stronger the brake force of the brake circuit 42b.

[0050] The stop valve 45 is connected to the hydraulic oil supply line 44b. The stop valve 45 has four valve ports and is an electromagnetic valve that takes two states of an open state and a closed state. The first valve port of the stop valve 45 is connected to the hydraulic oil supply line 44b. The second valve port of the stop valve 45 is connected to the oil reservoir 48. The third valve port of the stop valve is connected to the EPC valve 46. The fourth port of the stop valve 45 is in an air passage state in the open state and is blocked in the closed state.

[0051] The stop valve 45 is opened and closed based on an instruction from the control system 26. Specifically, the stop valve 45 becomes the open state when energized according to an open instruction from the control system 26 and becomes the closed state when energization is stopped according to a close instruction from the control system 26.

[0052] The stop valve 45 connects the first valve port and the third valve port in the open state and supplies hydraulic oil from the hydraulic oil supply line 44b to the EPC valve 46. In addition, the stop valve 45 connects the fourth valve port in the air passage state and the second valve port connected to the oil reservoir 48 in the closed state.

[0053] The stop valve 45 connects the second valve port and the third valve port in the closed state and discharges hydraulic oil between the stop valve 45 and the EPC valve to the oil reservoir 48. In addition, the stop valve 45 closes the first valve port and the fourth valve port in the closed state. Thus, the stop valve 45 stops the supply of hydraulic oil from the hydraulic oil supply line 44b to the EPC valve in the closed state.

[0054] In the present embodiment, the control system 26 causes the stop valve 45 to become the open state only when the vehicle body 1 is moving in the rear direction, for example. The movement of the vehicle body 1 in the rear direction is determined by the control system 26 based on the detection result of the travel direction detection portion 72.

[0055] The EPC valve 46 is disposed on a flow path connecting the stop valve 45 and the shuttle spool unit 47. The EPC valve 46 is an electromagnetic valve having three valve ports. The first valve port of the EPC valve 46 is connected to the stop valve 45. The second valve port of the EPC valve 46 is connected to the oil reservoir 48. The third valve port of the EPC valve 46 is connected to the shuttle spool unit 47.

[0056] The EPC valve 46 connects the first valve port and the third valve port in the open state and supplies hydraulic oil supplied from the stop valve 45 to the shuttle spool unit 47. The EPC valve 46 adjusts the opening degree based on an instruction from the control system 26, and changes the amount of hydraulic oil supplied to the shuttle spool unit 47.

[0057] The EPC valve 46 closes the first port in the closed state, connects the second port and the third port, and discharges hydraulic oil in the flow path from the EPC valve 46 to the shuttle valve unit 47 to the tank 48. Thus, the EPC valve 46 stops supply of hydraulic oil from the cut valve 45 to the shuttle valve unit 47 in the closed state.

[0058] The shuttle valve unit 47 has a rear shuttle valve 47a and a front shuttle valve 47b. The rear shuttle valve 47a supplies hydraulic oil of which pressure is greater between hydraulic oil supplied via the rear brake valve 41a and hydraulic oil supplied via the EPC valve 46 to the brake circuit 42a. The front shuttle valve 47b supplies hydraulic oil of which pressure is greater between hydraulic oil supplied via the front brake valve 41b and hydraulic oil supplied via the EPC valve 46 to the brake circuit 42b.

[0059] With such a configuration, even in a case where hydraulic oil is not supplied from the brake valve unit 41 by non-operation of the brake pedal 54, if the cut valve 45 and the EPC valve 46 become the open state 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, 42b, and control of automatic braking is implemented.

[0060] Figure 2 The illustrated parking brake 43 is provided on the conveyance device 33. As the parking brake 43, for example, a wet multi-stage brake or a disc brake, which can be switched to a braking state and a non-braking state, or the like can be used.

[0061] (Operation system 23)

[0062] As Figure 2 illustrated, the operation system 23 has an accelerator pedal 51, an FNR lever 52, a parking switch 53, a brake pedal 54, and a return switch 55.

[0063] The accelerator pedal 51 is provided in the cab 5. An operator operates the accelerator pedal 51 to set a throttle opening degree. The accelerator pedal 51 generates an opening degree signal indicating an accelerator pedal operation amount and transmits the same to the control system 26. The control system 26 controls a rotational speed of the engine 31 based on the transmitted signal.

[0064] The FNR lever 52 is provided in the cab 5. The FNR lever 52 can take a position of forward travel, neutral, or reverse travel. 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 forward travel or reverse travel.

[0065] The parking switch 53 is provided in the cab 5, is a switch capable of switching the state to ON and OFF, and sends a signal indicating the state to the control system 26. The control system 26 makes the parking brake 43 a braking state or a non-braking state based on the signal sent.

[0066] The brake pedal 54 is provided in the cab 5. The brake pedal 54 adjusts the opening degree of the rear brake valve 41a and the front brake valve 41b of the brake valve unit 41.

[0067] The return switch 55 is operated by the operator in order to return from the stopped state after the vehicle body 1 is stopped by the automatic brake described later.

[0068] (The informing system 24)

[0069] The informing system 24 has an alarm device 61 and an automatic brake operation notification lamp 63.

[0070] The alarm device 61 alarms the operator according to the instruction from the control system 26 in the case where the rear detection section 71 of the detection system 25 described later detects an object behind the vehicle body 1 at the time of backing up.

[0071] The alarm device 61 can have, for example, a lamp and make the lamp light. In addition, the alarm device 61 can have a speaker and sound a sound, not limited to a lamp. In addition, the alarm can be displayed on a display panel of a monitor or the like.

[0072] The automatic brake operation notification lamp 63 notifies the operator that the automatic brake is in an operation state and that the return operation based on the return switch 55 is required. In addition, the automatic brake operation notification lamp 63 is turned off if the automatic brake is released by operating the return switch 55.

[0073] In addition, the automatic brake operation notification lamp 63 can not be limited to a lamp, but can sound a sound. In addition, the notification can be displayed on a display panel of a monitor or the like.

[0074] The means of informing the operator of the information based on the informing system 24 described above can appropriately select a lamp, a sound, a monitor, or the like.

[0075] (The detection system 25)

[0076] Figure 3 is a block diagram indicating the structure of the detection system 25 and the control system 26.

[0077] The detection system 25 has a rear detection section 71 (an example of an object detection section) and a travel direction detection section 72.

[0078] The rear detection section 71 detects information on the state of the rear of the vehicle body 1. The rear detection section 71 is installed at the rear end of the vehicle body 1 as shown in FIG. 1, but is not limited to the rear end. Figure 1

[0079] The rear detection section 71 has 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 having the main radar 71a and the sub radar 71b, even if one of them malfunctions, the other can detect an object in the rear.

[0080] Each of the main radar 71a and the sub radar 71b uses a reception antenna to detect a case where a millimeter wave band wave emitted from a transmission antenna is reflected on the surface of an object and returns. 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 in the rear of the vehicle body 1. In addition, the control system 26 can calculate the distance to the detected object.

[0081] The travel direction detection section 72 detects information on the travel direction of the vehicle body 1. The control system 26 determines the travel direction of the vehicle body 1 based on information detected by the travel direction detection section 72. The travel direction detection section 72 has a rotation sensor 72a and an acceleration sensor 72b. The rotation sensor 72a detects the rotation direction of the front wheels 4 or the rear wheels 7. The acceleration sensor 72b detects the acceleration of the vehicle body 1.

[0082] From the information of the rotation sensor 72a and the acceleration sensor 72b, it can be determined which of advancing, stopping, or retreating the vehicle body 1 is in.

[0083] (Control system 26)

[0084] The control system 26 has a perception controller 80 and a body controller 90.

[0085] ​Each of the perception controller 80 and the body controller 90 includes a processor such as a CPU (Central Processing Unit), a main memory including a nonvolatile memory such as a ROM (Read Only Memory) and a volatile memory such as a RAM (Random Access Memory), and a storage. The perception controller 80 and the body controller 90 read a program stored in the storage and expand in the main memory, and execute a prescribed process according to the program. In addition, in the present embodiment, although it is described that each of the perception controller 80 and the body controller 90 has a CPU, it can be that the perception controller 80 and the body controller 90 as a whole have one CPU. Further, the program can be distributed to the perception controller 80 and the body controller 90 via a network.

[0086] The perception controller 80 detects the presence of an object based on information detected by the rear detection section 71. The body controller 90 implements control of automatic braking based on the detection result of the perception controller 80. In a case where the vehicle body 1 is advancing, the body controller 90 sets the brake system 22 to be unable to exert a braking force based on automatic braking.

[0087] The perception controller 80 has a rear information acquisition section 81 and an object determination section 82.

[0088] The rear information acquisition section 81 acquires information about the rear detected by the main radar 71a and the sub radar 71b of the rear detection section 71. The object determination section 82 determines whether there is an object in the rear based on the acquired information about the rear. The determination result of the object determination section 82 is transmitted to the EPC valve command section 94 described later. Figure 5 is a view indicating a state in which there is an object M in the rear of the wheel loader 100.

[0089] The body controller 90 has a travel direction information acquisition section 91, a travel direction determination section 92, a cut-off valve command section 93, an EPC valve command section 94, and a notification system command section 95.

[0090] The travel direction information acquisition section 91 acquires detection information based on the rotation sensor 72a and the acceleration sensor 72b.

[0091] The travel direction determination unit 92 determines the travel direction of the vehicle body 1 based on the acquired detection information. In the present embodiment, since the control of automatic braking is implemented when an object is detected behind in the case of backing up, the travel direction determination unit 92 determines whether the vehicle body 1 is backing up based on the information of the rotation sensor 72a and the acceleration sensor 72b. In addition, for the determination of the travel direction, not only the detection results of the rotation sensor 72a and the acceleration sensor 72b, but also the position of the FNR lever 52 can be combined to determine whether the vehicle body 1 is in the backing-up state. For example, even if the front wheels 4 and the rear wheels 7 are in a stopped state in which they are not rotating, in the case where the FNR lever 52 is in the position for backing up, it can be determined that the vehicle body 1 is in the backing-up state. As a position detection sensor that detects the position of the FNR lever 52, a potentiometer can be provided, or a switch can be provided for each of the forward position, the backward position, and the neutral position. Furthermore, both the potentiometer and the switch can be provided so that the vehicle body 1 can be detected even if one of them is malfunctioning.

[0092] In the case where the vehicle body 1 is determined to be backing up by the travel direction determination unit 92, the cut valve command unit 93 issues an open command to the cut valve 45. Thus, the cut valve 45 is energized, and the cut valve 45 becomes in the open state, and hydraulic oil is supplied from the hydraulic oil supply line 44b to the EPC valve 46, and becomes in a state in which the braking force is exerted when automatic braking is implemented. On the other hand, in the case where the vehicle body 1 is determined to be advancing by the travel direction determination unit 92, the cut valve command unit 93 issues a close command to the cut valve 45. In the case where the close command is issued, since the cut valve 45 becomes in a non-energized state, the closed state, hydraulic oil is not supplied to the EPC valve.

[0093] In the case where the vehicle body 1 is determined to be backing up by the travel direction determination unit 92, in the case where it is determined by the object determination unit 82 that there is an object behind the vehicle body 1, the EPC valve command unit 94 issues an open command to the EPC valve 46. The opening degree of the EPC valve 46 can be preset, or can be adjusted based on the distance to the detected object. For example, the deceleration at which the vehicle body 1 stops in the vicinity of the object can be calculated from the detected distance to the object, and the EPC valve command unit 94 issues an open command to the EPC valve 46 so that the EPC valve 46 becomes in an opening degree at which the deceleration is exerted.

[0094] The solenoid of the EPC valve 46 based on the open command is operated to be in the open state, and hydraulic oil is supplied from the EPC valve 46 to the rear spool valve 47a and the front spool valve 47b. In the rear spool valve 47a, the hydraulic oil from the rear brake valve 41a and the hydraulic oil from the EPC valve 46, one of which has a higher pressure, is supplied to the brake circuit 42a, and a braking force is exerted. Also, in the front spool valve 47b, the hydraulic oil from the front brake valve 41b and the hydraulic oil from the EPC valve 46, one of which has a higher pressure, is supplied to the brake circuit 42a, and a braking force is exerted. Thus, even in a case where the operator does not perform an operation of the brake pedal 54, automatic braking can be implemented and a braking force can be exerted, and the vehicle body 1 can be stopped in front of the object M as shown in FIG. 6. The vehicle body 1 in the stopped state is indicated by a double-dotted line. Figure 5

[0095] On the other hand, in a state where the shut-off valve 45 is closed, since no hydraulic oil is supplied to the EPC valve 46, even if the EPC valve 46 becomes in the open state due to a malfunction, no hydraulic oil is supplied from the EPC valve 46 to the spool valve unit 47. Therefore, even if automatic braking is implemented, no braking force is exerted. Thus, even in a case where automatic braking is implemented at the time of forward travel due to a malfunction, for example, since no braking force is exerted, the vehicle body 1 is not stopped, and work is not hindered.

[0096] In addition, even in a case where no braking force based on automatic braking is exerted, if the operator operates the brake pedal 54, hydraulic oil is supplied from the brake valve unit 41 to the spool valve unit 47, and the brake circuits 42a and 42b operate.

[0097] In a case where an open command is performed from the shut-off valve command section 93 and an open command is performed from the EPC valve command section 94, the notification system command section 95 performs a lighting command to the automatic braking operation notification lamp 63 and a driving command to the alarm device 61. In addition, if the operator operates the return switch 55 and automatic braking is released, the notification system command section 95 performs a lighting-out instruction to the automatic braking operation notification lamp 63 and a stop command to the alarm device 61.

[0098] <Operation>

[0099] Next, a control operation of the wheel loader 100 of the present embodiment will be described.

[0100] Figure 6 is a flowchart indicating the control operation of the wheel loader 100 of the present embodiment.

[0101] First, in Step S10, the travel direction information acquisition section 91 acquires detection information of the travel direction detection section 72.

[0102] ​Next, in step S20 (an example of a travel direction detection step), the travel direction determination section 92 determines whether the travel direction of the vehicle body 1 is reverse based on the acquired detection information.

[0103] In the case where it is determined in step S20 that the travel direction is reverse, in step S30 (an example of a setting step), the cut valve command section 93 sends an open command to the cut valve 45. Thereby, the cut valve 45 is energized, the cut valve 45 becomes an open state, and hydraulic oil is supplied to the EPC valve 46.

[0104] On the other hand, in the case where it is determined in step S20 that the travel direction is not reverse but forward, in step S40 (an example of a setting step), the cut valve command section 93 sends a close command to the cut valve 45, and the control ends. Thereby, the cut valve 45 becomes a non-energized state, and the cut valve 45 becomes a closed state. In addition, in the case where the open / close state of the cut valve 45 at present is known, the same command as the present state can not be sent. For example, in the case where the cut valve 45 is in a closed state at present, a close command can not be sent again.

[0105] In step S50 (an example of an object detection step) following step S30, in the case where the object determination section 82 determines that an object exists behind the vehicle body 1, the control proceeds to step S60. On the other hand, in the case where the object determination section 82 determines that no object exists behind the vehicle body 1 in step S50, the control ends.

[0106] Next, in step S60, the EPC valve command section 94 sends an open command to the EPC valve 46. Thereby, the solenoid of the EPC valve 46 is operated, becomes an open state, and hydraulic oil is supplied from the EPC valve 46 to the brake circuits 42a, 42b via the rear spool valve 47a and the front spool valve 47b, and a brake force based on automatic braking is exerted.

[0107] Next, in step S70, the notification system command section 95 sends a light-on command to the automatic brake operation notification lamp 63 and a notification command to the alarm device 61. Thereby, the automatic brake operation notification lamp 63 is lighted, and the alarm of the alarm device 61 is notified.

[0108] As described above, in the case where an object M is detected behind in a state where the vehicle body 1 is traveling in the rearward direction, the vehicle body 1 can be stopped in the vicinity of the object M by automatic braking (refer to FIG. 6). Figure 5 On the other hand, in a state where the vehicle body 1 is traveling in the forward direction, since the cut valve 45 is closed and hydraulic oil is not supplied to the EPC valve 46, even in the case where automatic braking is performed due to a malfunction, a brake force can not be exerted and the stop of the vehicle body 1 can be suppressed.

[0109] <FEATURE>

[0110] (1) The wheel loader 100 (one example of a work machine) of the present embodiment is provided with a vehicle body 1, a travel direction detection section 72, a rear detection section 71 (one example of an object detection section), a brake section 40, a stop valve 45 (one example of a setting section), and a control system 26 (one example of a control section). The vehicle body 1 is capable of traveling. The rear detection section 71 detects an object in a rear direction (one example of a prescribed direction) of the vehicle body 1. The brake section 40 is capable of implementing an automatic brake that automatically brakes the vehicle body 1 and exerting a brake force in accordance with detection of the object by the object detection section. The stop valve 45 sets the brake section 40 so that the brake section 40 is capable of exerting or incapable of exerting the brake force based on the automatic brake. The control system 26 controls the stop valve 45, and sets the brake section 40 so that the brake section 40 is capable of exerting the brake force in a case where the vehicle body 1 is traveling in the rear direction, and sets the brake section 40 so that the brake section 40 is incapable of exerting the brake force in a case where the vehicle body 1 is traveling in a direction other than the rear direction.

[0111] Thus, since the brake force based on the automatic brake is exerted only when traveling in the rear direction and when an object is detected, the brake force cannot be exerted even if the control of the automatic brake is implemented due to a malfunction in a direction other than the rear direction (forward travel). Therefore, it is possible to suppress malfunctions and to exert the brake force based on the automatic brake only in a desired travel direction. (2)

[0113] In the wheel loader 100 of the present embodiment, the control system 26 controls the brake section 40 to implement the automatic brake when an object is detected by the rear detection section 71 in a case where the vehicle body 1 is traveling in the rear direction.

[0114] Thus, it is possible to automatically stop the vehicle body 1 when an object is detected in the rear direction. (3)

[0116] In the wheel loader 100 of the present embodiment, the brake section 40 has brake circuits 42a, 42b (one example of a service brake) and an EPC valve 46 (one example of a regulating valve). The EPC valve 46 is capable of adjusting the amount of supply of hydraulic oil to the brake circuits 42a, 42b.

[0117] Thus, the automatic brake can be implemented by the brake circuits 42a, 42b as service brakes. (4)

[0119] In the wheel loader 100 of the present embodiment, the stop valve 45 is capable of cutting off supply of hydraulic oil to the EPC valve 46. The control system 26 controls the stop valve 45 to set the brake portion 40 to be incapable of exerting braking force by cutting off supply of hydraulic oil to the EPC valve 46, and to set the brake portion 40 to be capable of exerting braking force by supplying hydraulic oil to the EPC valve 46.

[0120] Thus, by opening and closing of the stop valve 45, it is possible to set the brake portion 40 to be capable of or incapable of exerting braking force based on automatic braking. (5)

[0122] In the wheel loader 100 of the present embodiment, the travel direction detection portion 72 has at least one of a rotation sensor 72a, an acceleration sensor 72b, and a position detection sensor (not shown). The rotation sensor 72a detects rotation of the front wheel 4 (an example of a wheel) or the rear wheel 7 (an example of a wheel) of the traveling body 2. The acceleration sensor 72b detects acceleration of the traveling body 2. The position detection sensor detects the position of the FNR lever 52. The control system 26 determines the travel direction of the vehicle body 1 based on detection by the rotation sensor 72a, the acceleration sensor 72b, or the position detection sensor.

[0123] Thus, it is possible to determine the travel direction of the vehicle body. (6)

[0125] In the wheel loader 100 of the present embodiment, the brake portion 40 has a rear spool valve 47a and a front spool valve 47b, a rear brake valve 41a and a front brake valve 41b. The rear spool valve 47a and the front spool valve 47b supply hydraulic oil to the brake circuits 42a, 42b. The rear brake valve 41a and the front brake valve 41b adjust the flow rate of hydraulic oil discharged to the rear spool valve 47a and the front spool valve 47b based on operation of the brake pedal 54. The EPC valve 46 supplies hydraulic oil to the rear spool valve 47a and the front spool valve 47b. The rear spool valve 47a and the front spool valve 47b supply, to the brake circuits 42a, 42b, the higher one in pressure between 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.

[0126] Thus, in the case where the operator operates the brake pedal 54, when the pressure of hydraulic oil from the brake pedal 54 is high, it is possible to brake in accordance with operation of the brake pedal 54. (7)

[0128] The wheel loader 100 of the present embodiment further has the work machine 3, the front vehicle frame 11, and the rear vehicle frame 12. The work machine 3 is mounted on the front vehicle frame 11. The rear vehicle frame 12 is swingably mounted on the front vehicle frame 11.

[0129] Thus, in the wheel loader, it is possible to suppress malfunction and exert the braking force based on automatic braking only in the desired direction of travel. (8)

[0131] The control method of the wheel loader 100 of the present embodiment has a step S20 (an example of a travel direction detection step), a step S50 (an example of an object detection step), and steps S30, S40 (examples of setting steps). The step S20 detects the travel direction of the vehicle body 1. The step S50 detects an object in the rear direction of the vehicle body 1 (an example of a predetermined direction). In a case where the vehicle body 1 is traveling in the rear direction, the steps S30, S40 are set to the braking force that enables implementation of automatic braking that automatically brakes the vehicle body 1 based on the detection of the object of the step S50, and in a case where the vehicle body 1 is traveling in a direction other than the rear direction, the steps S30, S40 are set to the braking force that does not enable implementation of automatic braking and further does not exert the braking force.

[0132] Thus, since the braking force based on automatic braking is exerted only when an object is detected while traveling in the rear direction, in a direction other than the rear direction (forward travel), the braking force cannot be exerted even if the control of automatic braking is implemented due to malfunction. Thus, it is possible to suppress malfunction and exert the braking force based on automatic braking only in the desired direction of travel.

[0133] <Other Embodiments>

[0134] The above describes one embodiment of the present application, but the present application is not limited to the above-described embodiment and various modifications can be made within the scope of the gist of the present application.

[0135] (A)

[0136] In the above-described embodiment, the rear detection portion 71 has the main radar 71a and the sub radar 71b, but it can not be limited to a radar and can be, for example, a camera or the like. In a case where it is detected by the rear detection portion 71 that there is an object behind when backing up, automatic braking is performed.

[0137] (B)

[0138] In the above-described embodiment, the HST 32 is used in the drive system 21, but it can not be limited to the HST and can be a torque converter. Figure 7 is a block diagram that shows a structure in which the torque converter 132 and the 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 speed changes the rotational driving force of the engine 31 transmitted via the torque converter 132 and transmits it to the axle 34. The parking brake 43 is provided in the transmission 133.

[0139] Moreover, not limited to HST, HMT (Hydro Mechanical Transmission) can also be used.

[0140] (C)

[0141] The wheel loader of the above-described embodiment can be either manned or unmanned.

[0142] (D)

[0143] In the above-described embodiment, a wheel loader is described as an example of a work machine, but it can also be not limited to a wheel loader, and can also be a hydraulic excavator or the like.

[0144] Industrial applicability

[0145] The work machine and the control method of the work machine according to the present application exert an effect of being able to improve work efficiency, and are useful for a wheel loader or the like.

[0146] Label explanation

[0147] 1: Vehicle main body

[0148] 26: Control system

[0149] 40: Brake

[0150] 45: Stop valve

[0151] 71: Rear detection unit

[0152] 72: Travel direction detection unit

[0153] 100: Wheel loader

Claims

1. A work machine, comprising: a vehicle body that is capable of traveling; a travel direction detection unit that detects a travel direction of the vehicle body; an object detection unit that detects an object in a prescribed direction of the vehicle body; a braking unit that is capable of implementing automatic braking of the vehicle body and exerting a braking force based on detection of the object by the object detection unit; a setting unit that sets the braking unit so that the braking unit is capable of exerting or incapable of exerting the braking force based on the automatic braking; and a control unit that controls the setting unit based on the travel direction detected by the travel direction detection unit, the control unit controlling the setting unit so that the braking unit is capable of exerting the braking force when the vehicle body is traveling in the prescribed direction and so that the braking unit is incapable of exerting the braking force when the vehicle body is traveling in a direction other than the prescribed direction.

2. The work machine according to claim 1, wherein the control unit controls the braking unit so that the automatic braking is implemented when the object is detected by the object detection unit when the vehicle body is traveling in the prescribed direction.

3. The work machine according to claim 1 or 2, wherein the prescribed direction is a rear direction.

4. The work machine according to claim 1 or 2, wherein the braking unit has: a service brake; and a regulating valve that is capable of adjusting an amount of supply of hydraulic oil to the service brake.

5. The work machine according to claim 4, wherein the setting unit has: a cut-off valve that is capable of cutting off supply of the hydraulic oil to the regulating valve, the control unit controlling the setting unit so that the braking unit is incapable of exerting the braking force by controlling the cut-off valve to a closed state to cut off supply of the hydraulic oil to the regulating valve when the vehicle body is traveling in a direction other than the prescribed direction and so that the braking unit is capable of exerting the braking force by controlling the setting unit so that the hydraulic oil is supplied to the regulating valve when the vehicle body is traveling in the prescribed direction.

6. The work machine according to claim 1 or 2, wherein the travel direction detection unit has at least one of a rotation sensor that detects rotation of a wheel of the vehicle body, an acceleration sensor that detects acceleration of the vehicle body, or a position detection sensor that detects a position of an FNR lever, the control unit determining the travel direction of the vehicle body based on detection by the rotation sensor, the acceleration sensor, or the position detection sensor.

7. The work machine according to claim 4, wherein the braking unit further has: a shuttle slide valve that supplies hydraulic oil to the service brake; and a brake valve that adjusts a flow rate of hydraulic oil discharged to the shuttle slide valve based on operation of a brake pedal, the regulating valve supplying hydraulic oil to the shuttle slide valve. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The shuttle slide valve supplies the service brake with one of the hydraulic oil supplied from the regulating valve and the hydraulic oil supplied from the brake valve that has a higher pressure.

8. The work machine according to claim 1 or 2, wherein The work machine is a wheel loader, and further includes: a work machine; a front vehicle frame on which the work machine is mounted; and a rear vehicle frame swingably coupled to the front vehicle frame.

9. A control method of a work machine including a vehicle main body, a brake portion capable of implementing automatic braking of the vehicle main body and exerting a braking force, and a setting portion that sets the brake portion so that the brake portion can exert or cannot exert the braking force based on the automatic braking, the control method including: a travel direction detection step of detecting a travel direction of the vehicle main body; an object detection step of detecting an object in a prescribed direction of the vehicle main body; and a setting step of, when the vehicle main body is traveling in the prescribed direction, controlling the setting portion so that the brake portion can exert the braking force based on implementation of the automatic braking based on the detection of the object in the object detection step, and when the vehicle main body is traveling in a direction other than the prescribed direction, controlling the setting portion so that the brake portion cannot exert the braking force. ​

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