WORK MACHINE, BRAKING SYSTEM FOR A WORK MACHINE AND CONTROL METHOD FOR A WORK MACHINE

Abstract

An automatic braking control is implemented to automatically brake the vehicle. A control (26) limits the lifting operation of a work device (3) during the execution of the automatic braking control.

Description

TECHNICAL AREA

[0001] The present disclosure relates to a working machine, a braking system for a working machine and a control method for a working machine. STATE OF THE ART

[0002] The Japanese utility model with registration number 3219005 (patent document 1) discloses a collision prevention control for detecting a rear obstacle and automatically stopping the journey in a wheel loader, which is an example of a working machine.

[0003] In the wheel loader illustrated in patent document 1, the area from the wheel loader to the object is divided into three zones: a first zone, a second zone, and a third zone, in order of increasing distance from the object. The collision avoidance control system automatically applies the brakes to stop the vehicle if an obstacle is detected in the first zone, which is the closest to the wheel loader. LIST OF COUNTERPOINTS Patent Literature

[0004] Patent document 1: Japanese utility model registration number 3219005 BRIEF DESCRIPTION OF THE INVENTION Technical Problem

[0005] However, during work on a construction site, it can happen that the machine is in an unstable position. In such an unstable position, the machine's position becomes even more unstable if sudden braking is performed by the collision prevention control described in patent document 1.

[0006] One objective of the present disclosure is to provide a working machine, a braking system for a working machine and a control method for a working machine that are capable of maintaining a stable state even when braking is carried out by an automatic brake control. Solution to the problem

[0007] Both a working machine and a braking system for the working machine according to one aspect of the present disclosure perform automatic braking control for automatically braking the journey. Both a working machine and a braking system for a working machine according to one aspect of the present disclosure include a chassis, a working device mounted on the chassis, and a control system configured to limit a lifting operation of the working device during the execution of the automatic braking control.

[0008] Both a working machine and a braking system for the working machine according to another aspect of the present disclosure perform an automatic braking control for automatically braking the vehicle. Both a working machine and a braking system for a working machine according to another aspect of the present disclosure include a front frame, a rear frame pivotably coupled to the front frame, and a control configured to limit, during an execution of the automatic braking control, an operation to increase the pivot angle of the rear frame relative to the front frame.

[0009] In a control method for a working machine according to one aspect of the present disclosure, the working machine includes a chassis and a working device arranged on the chassis, and an automatic brake control is performed for automatically braking the machine. A control method for a working machine according to one aspect of the present disclosure includes a step for initiating the execution of an automatic brake control and a step for restricting a lifting operation of a working device during the execution of the automatic brake control.

[0010] In a control method for a working machine according to another aspect of the present disclosure, the working machine includes a front frame and a rear frame pivotably coupled to the front frame, and an automatic brake control is performed for automatically braking the journey. A control method for a working machine according to another aspect of the present disclosure includes a step for initiating the execution of an automatic brake control and a step for restricting an operation for increasing a pivot angle of a rear frame relative to a front frame during the execution of the automatic brake control. Advantageous effects of the invention

[0011] According to the present disclosure, it is possible to realize a working machine, a braking system for a working machine and a control method for a working machine that are able to maintain a stable state even when braking is carried out by an automatic brake control. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a side view showing a configuration of a wheel loader according to an embodiment of the present disclosure. Fig. Figure 2 is a block diagram showing a braking system for the wheel loader of Fig. 1 illustrates. Fig. 3 is a hydraulic circuit diagram showing a configuration of the brake device of Fig. 2 illustrated. Fig. 4 is a block diagram showing a configuration of an operating device, a detection device, and a control system in Fig. 2 illustrated. Fig. Figure 5 is a side view to illustrate the height H of the working implement in the wheel loader. Fig. Figure 6 is a top view to illustrate a swivel angle θ in the wheel loader. Fig. Figure 7 is a first flowchart illustrating a control method for a wheel loader according to an embodiment of the present disclosure. Fig. Figure 8 is a second flowchart illustrating the control procedure for the wheel loader according to the embodiment of the present disclosure. DESCRIPTION OF EXECUTION FORMS

[0012] The following describes embodiments of the present disclosure with reference to the drawings.

[0013] In the patent specification and the drawings, identical or corresponding components are designated with the same reference numerals, and redundant descriptions are not repeated. In the drawings, the configuration may be omitted or simplified to simplify the description. Furthermore, at least some of the embodiments and modifications may be combined arbitrarily. Configuration of the wheel loader 100

[0014] A configuration of a wheel loader 100 in the present embodiment is described with reference to Fig. 1 described.

[0015] Fig. Figure 1 is a side view showing a configuration of the wheel loader 100 (an example of a working machine) according to an embodiment of the present disclosure. As in Fig. As illustrated in Figure 1, the wheel loader 100 in the present embodiment comprises a vehicle body 1 and an object sensor 25a. The vehicle body 1 includes a chassis 2 and a working unit 3. The working unit 3 is mounted on the chassis 2. The chassis 2 includes a vehicle body frame 10, a pair of front tires 4, a cab 5, an engine compartment 6, a pair of rear tires 7, and a steering cylinder 9. The wheel loader 100 performs earthmoving and sand loading operations, or similar tasks, using the working unit 3.

[0016] In the following description, "front", "back", "right", "left", "up", and "down" indicate directions based on a situation where a driver seated in cab 5s in an operator seat is facing forward. Fig. 1. The forward-backward direction is indicated by Z, the forward direction is indicated by Zf, and the backward direction is indicated by Zb.

[0017] The vehicle body frame 10 is of the so-called articulated type (swivel type) and includes a front frame 11, a rear frame 12, and a coupling shaft section 13. The front frame 11 is arranged in the forward direction Zf of the rear frame 12. The coupling shaft section 13 is located in the center of the vehicle body frame 10 in the left-right direction (vehicle width direction) and pivotally couples the front frame 11 and the rear frame 12. The pair of front tires 4 are mounted on the left and right sides of the front frame 11. The pair of rear tires 7 are mounted on the left and right sides of the rear frame 12.

[0018] The working device 3 is driven by hydraulic oil from a working device pump (not illustrated). The working device 3 includes a boom 14, a bucket 15, a lifting cylinder 16, a bucket cylinder 17, and an angle lever 18. The boom 14 is attached to the front frame 11. The bucket 15 is attached to a distal end of the boom 14.

[0019] The lifting cylinder 16 and the bucket cylinder 17 are hydraulic cylinders. One end of the lifting cylinder 16 is attached to the front frame 11, and the other end is attached to the boom 14. The boom 14 pivots up and down by extending and retracting the lifting cylinder 16. One end of the bucket cylinder 17 is attached to the front frame 11, and the other end is connected to the bucket 15 via a bell crank 18. When the bucket cylinder 17 extends and retracts, the bucket 15 pivots up and down.

[0020] The cabin 5 is positioned on the rear frame 12. Inside the cabin 5 are the operator's seat 5s, on which the operator can sit, a steering wheel for steering, a lever for operating the implement 3, various switches, a display, and the like. The engine compartment 6 is located on the rear frame 12 in the reverse direction Zb of the cabin 5 and houses an engine 31 ( Fig. 2). Braking system for wheel loader 100

[0021] Next, with reference to Fig. 2 to 4 describe a braking system for the wheel loader 100 in the present embodiment.

[0022] Fig. Figure 2 is a block diagram showing the braking system for the wheel loader of Fig. 1 illustrates. Fig. 3 is a hydraulic circuit diagram showing a configuration of the brake device of Fig. 2 illustrated. Fig. 4 is a block diagram showing a configuration of an operating device, a detection device, and a control system in Fig. 2 illustrated.

[0023] As in Fig. As illustrated in Figure 2, the braking system for the wheel loader 100 includes a drive device 21, a braking device 22, an operating device 23, an operating unit 24, a detection device 25 and a control unit 26.

[0024] The drive unit 21 propels the wheel loader 100. The braking unit 22 brakes the wheel loader 100. The operating unit 23 is operated by an operator. The control unit 24 actuates both the implement 3 and the steering. The detection unit 25 detects a braking factor (an obstacle, a cliff, or the like) around the vehicle body 1, the position of the implement, a swivel angle, and the like. The control unit 26 actuates the drive unit 21, the braking unit 22, and the control unit 24 based on the operator's actuation of the operating unit 23 and the detection by the detection unit 25. Drive device 21

[0025] As in Fig. As illustrated in Figure 2, the drive device 21 includes a motor 31, an HST 32, a transfer case 33, an axle 34, the front tire 4 and the rear tire 7.

[0026] For example, the engine 31 is a diesel engine, and a driving force generated by the engine 31 drives a pump 32a of an HST (Hydro Static Transmission, hydrostatic transmission) 32.

[0027] The HST 32 includes pump 32a, motor 32b, and hydraulic circuit 32c. Pump 32a is, for example, a variable displacement swashplate pump, and the swashplate angle can be changed by a solenoid valve 32d. Pump 32a is driven by motor 31 to drain the hydraulic oil. The drained hydraulic oil is routed through hydraulic circuit 32b to motor 32c. Motor 32b is, for example, a swashplate pump, and the swashplate angle can be changed by a solenoid valve 32e.

[0028] The hydraulic circuit 32c connects the pump 32a and the motor 32b. The hydraulic circuit 32c comprises a first drive circuit 32c1 and a second drive circuit 32c2. When the hydraulic oil is directed from the pump 32a to the motor 32b via the first drive circuit 32c1, the motor 32b is driven in one direction (for example, forward). When the hydraulic oil is directed from the pump 32a to the motor 32b via the second drive circuit 32c2, the motor 32b is driven in the other direction (for example, reverse). The discharge direction of the hydraulic oil to the first drive circuit 32c1 or to the second drive circuit 32c2 can be changed by the solenoid valve 32d.

[0029] The transfer case 33 distributes the power of the engine 31 to the front and rear axles 34.

[0030] The pair of front tires 4 is connected to the front axle 34 and is rotated by the distributed power of the motor 31. The pair of rear tires 7 is connected to the rear axle 34 and is rotated by the distributed power of the motor 31. Brake device 22

[0031] The braking device 22 comprises a brake unit 40 and a shut-off valve 45. The brake unit 40 brakes the vehicle body 1 based on the actuation of a brake pedal 54 and performs automatic brake control of the vehicle body 1 based on a command from the control unit 26. The shut-off valve 45 puts the brake unit 40 into a state in which the braking force can be applied by the automatic brake control or cannot be applied.

[0032] The brake unit 40 includes a brake valve unit 41, brake circuits 42a and 42b (an example of a service brake), a parking brake 43, hydraulic oil supply channels 44a and 44b, an EPC (electric proportional valve) 46, a changeover valve unit 47 and a tank 48.

[0033] Accumulators, pumps and the like are connected to the hydraulic oil supply channels 44a and 44b and the hydraulic oil is supplied.

[0034] As in Fig. As illustrated in Figure 3, the brake valve unit 41 is actuated by a brake pedal 54, which will be described later. The brake valve unit 41 comprises a rear brake valve 41a and a front brake valve 41b. Both the rear brake valve 41a and the front brake valve 41b are three-position directional control valves with three ports.

[0035] The first port of the rear wheel brake valve 41a is connected to the hydraulic oil supply channel 44a via the accumulator 49a. A second port of the rear wheel brake valve 41a is connected to the tank 48. The third port of the rear wheel brake valve 41a is connected to the rear changeover valve 47a of the changeover valve unit 47.

[0036] In the first state, the rear brake valve 41a connects the first port to the third port, connects the hydraulic oil supply channel 44a to the rear changeover valve 47a, and supplies hydraulic oil to the rear changeover valve 47a. In the second state, the rear brake valve 41a closes all ports. In the third state, the rear brake valve 41a connects the second port to the third port and discharges the hydraulic oil between the rear changeover valve 47a and the rear brake valve 41a into the reservoir 48. In the second and third states, the rear brake valve 41a interrupts the hydraulic oil supply to the rear changeover valve 47a. The first port of the front brake valve 41b is connected to the hydraulic oil supply channel 44b via the accumulator 49b. The second port of the front brake valve 41b is connected to the reservoir 48.The third port of the front wheel brake valve 41b is connected to the front changeover valve 47b of the changeover valve unit 47.

[0037] In the first state, the front wheel brake valve 41b connects the first port to the third port, connects the hydraulic oil supply channel 44b to the front changeover valve 47b, and supplies hydraulic oil to the front changeover valve 47b. In the second state, the front wheel brake valve 41b closes all ports. In the third state, the front wheel brake valve 41b connects the second port to the third port and discharges the hydraulic oil between the front changeover valve 47b and the front wheel brake valve 41b into the reservoir 48. The front wheel brake valve 41b interrupts the supply of hydraulic oil to the front changeover valve 47b in both the second and third states.

[0038] The opening degrees of the rear wheel brake valve 41a and the front wheel brake valve 41b are adjusted according to the degree of actuation of the brake pedal 54, and the amount of hydraulic oil supplied to the changeover valve unit 47 is changed. For example, if the degree of actuation of the brake pedal 54 is large, the amount of hydraulic oil supplied to the changeover valve unit 47 by the rear wheel brake valve 41a and the front wheel brake valve 41b increases.

[0039] The brake circuit 42a is provided on the rear axle 34 ( Fig. 2) Brake circuit 42a is connected to the rear changeover valve 47a. Brake circuit 42b is provided on the front axle 34 ( Fig. 2) The brake circuit 42b is connected to the front changeover valve 47b.

[0040] Brake circuits 42a and 42b are hydraulic brakes. The braking force of brake circuit 42a increases when the quantity or pressure of the hydraulic oil supplied by the rear changeover valve 47a increases. The braking force of brake circuit 42b increases when the quantity or pressure of the hydraulic oil supplied by the front changeover valve 47b increases.

[0041] The shut-off valve 45 is connected to the hydraulic oil supply channel 44b. The shut-off valve 45 is a four-port solenoid valve and has two states: open and closed. The first port of the shut-off valve 45 is connected to the hydraulic oil supply channel 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 when open and is blocked when closed.

[0042] The shut-off valve 45 is opened and closed upon instruction from the controller 26. Specifically, the shut-off valve 45 enters an open state when activated by an opening command from the controller 26, and enters a closed state when deactivated by a closing command from the controller 26.

[0043] In the open position, the shut-off valve 45 connects the first port to the third port and directs the hydraulic oil from the hydraulic oil supply channel 44b to the EPC valve 46. Furthermore, in the open position, the shut-off valve 45 connects the fourth port, through which air flows, to the second port, which is connected to the tank 48.

[0044] In the closed position, the shut-off valve 45 connects the second port to the third port and discharges the hydraulic oil between the shut-off valve 45 and the EPC valve 46 into the tank 48. In the closed position, the shut-off valve 45 seals the first and fourth ports. Thus, in the closed position, the shut-off valve 45 stops the supply of hydraulic oil from the hydraulic oil supply channel 44b to the EPC valve 46.

[0045] In the present embodiment, the control unit 26 opens the shut-off valve 45 only when the vehicle body 1 is moving in reverse, for example. The reverse movement of the vehicle body 1 is determined by the control unit 26 based on the signal indicating the lever position in a direction-of-travel switching device 53 and the opening degree signal indicating the degree of deactivation of an accelerator pedal 55.

[0046] The EPC valve 46 is arranged in a flow path that connects the shut-off valve 45 and the changeover valve unit 47. The EPC valve 46 is a solenoid valve with 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 changeover valve unit 47.

[0047] In the open position, the EPC valve 46 connects the first port to the third port and supplies the hydraulic oil from the shut-off valve 45 to the changeover valve unit 47. The opening degree of the EPC valve 46 is adjusted based on a command from the controller 26. By adjusting the opening degree of the EPC valve 46, the amount of hydraulic oil supplied to the changeover valve unit 47 is changed.

[0048] When the EPC valve 46 is in the closed position, the first port is closed, the second and third ports are connected, and the hydraulic oil in the flow path from the EPC valve 46 to the changeover valve unit 47 is drained into the tank 48. Accordingly, when the EPC valve 46 is closed, it stops the supply of hydraulic oil from the shut-off valve 45 to the changeover valve unit 47.

[0049] In the present embodiment, the control unit 26 controls the EPC valve 46 to the open state when the wheel loader 100 is traveling in a predetermined direction (for example, the reverse direction Zb), and it is determined that the risk of a collision with an object in the direction of travel is high.

[0050] The changeover valve unit 47 comprises the rear changeover valve 47a and the front changeover valve 47b. The rear changeover valve 47a supplies hydraulic oil to the brake circuit 42a at a higher pressure than the hydraulic oil supplied via the rear brake valve 41a and the hydraulic oil supplied via the EPC valve 46. The front changeover valve 47b supplies hydraulic oil to the brake circuit 42b at a higher pressure than the hydraulic oil supplied via the front brake valve 41b and the hydraulic oil supplied via the EPC valve 46.

[0051] In such a configuration, even if the brake pedal 54 is not actuated and no hydraulic oil is supplied from the brake valve unit 41, the hydraulic oil is supplied to the brake circuits 42a and 42b by the rear changeover valve 47a and the front changeover valve 47b, and the automatic brake control is carried out when the shut-off valve 45 and the EPC valve 46 are opened by instruction from the control unit 26.

[0052] The brake, which is switched between braking and non-braking states by brake circuits 42a and 42b, is, for example, a wet solid disc brake. The wet solid disc brake primarily comprises a multitude of discs, a brake pad, a piston, and a spring. Each of the multiple discs is integrated with an output shaft to the front tire 4 or the rear tire 7. The brake pads alternate with the discs and are attached to a fixed element and do not rotate. The piston is actuated by the hydraulic pressure of the oil supplied to brake circuits 42a and 42b. When the piston is actuated, the brake pad is positioned between the multiple discs and pressed against them. This engages the wet solid disc brake.When the supply of hydraulic oil to brake circuits 42a and 42b is stopped, the piston is returned to its starting position by the spring's rebound force (restoring force), and the pressure between the plate and disc is released. This puts the wet solid disc brake into a non-braking state.

[0053] As in Fig. As illustrated in Figure 2, the parking brake 43 is provided in the transfer case 33. For example, a wet solid disc brake that can switch between a braking state and a non-braking state, a disc brake, or the like can be used as the parking brake 43. Operating device 23

[0054] The operating device 23 is operated by an operator in cabin 5 ( Fig. 1) The operating device 23 includes a work equipment operating unit 51, a steering operating unit 52, the direction switching device 53, the brake pedal 54, the accelerator pedal 55 and a parking switch 56.

[0055] The implement control unit 51 is located in the cab 5. The implement control unit 51 actuates an operation of the implement 3 and is, for example, a control lever operated by an operator. The degree of actuation of the implement control unit 51 is detected, for example, by a potentiometer, a Hall sensor (integrated circuit), or the like. When the implement control unit 51 is actuated, an operating signal indicating the degree of actuation of the implement control unit 51 is transmitted to the control unit 26. The control unit 26 transmits the operating signal as an operating command to the EPC valve 62 for the implement cylinders 16 and 17.

[0056] The steering control unit 52 is provided in the cabin 5. The steering control unit 52 includes a steering wheel, a joystick lever and the like, and changes a swivel angle θ (articulation angle: Fig. 6) of the rear frame 12 in relation to the front frame 11. The degree of actuation of the steering unit 52 is detected, for example, by a potentiometer, a Hall sensor, or the like. When the steering unit 52 is actuated, a steering operating angle is transmitted to the control unit 26. The control unit 26 sets the steering operating angle to the speed or target angle of the steering cylinder 9 and transmits the steering operating angle as a slewing operating command to the EPC valve 63 for the steering cylinder 9.

[0057] The direction-of-travel switching device 53 is located in the cab 5. The operator operates the direction-of-travel switching device 53 to set the direction of travel of the wheel loader 100. The direction-of-travel switching device 53 is, for example, an FNR lever. The FNR lever 53 can assume the forward (F), neutral (N), or reverse (R) position. An operating signal indicating the lever position of the FNR lever 53 is transmitted to the control unit 26, and the control unit 26 switches the direction of travel to forward, neutral, or reverse by controlling the solenoid valve 32d.

[0058] A potentiometer can be used as a position sensor to detect the lever position of the FNR lever 53, or a switch can be provided for each of the forward, reverse, and neutral positions. Furthermore, both the potentiometer and the switch can be designed to detect incorrect operation, even if one of the potentiometers or the switch is incorrectly actuated.

[0059] The brake pedal 54 is located in the cabin 5. The brake pedal 54 adjusts the opening degree of the rear wheel brake valve 41a and the front wheel brake valve 41b of the brake valve unit 41.

[0060] The accelerator pedal 55 is located in the cabin 5. The operator operates the accelerator pedal 55 to adjust the throttle valve opening degree. The accelerator pedal 55 generates an opening degree signal indicating the degree of actuation of the accelerator pedal and transmits this signal to the control unit 26. The control unit 26 controls the speed of the motor 31 based on the transmitted signal.

[0061] The parking switch 56 is located in cabin 5 and is a switch whose state can be toggled between on and off. It transmits a signal indicating its state to the control unit 26. Based on the transmitted signal, the control unit 26 engages or disengages the parking brake 43. Recognition device 25

[0062] The detection device 25 includes an object sensor 25a, a work tool position sensor 25b and a swivel angle sensor 25c.

[0063] The object sensor 25a detects factors (braking factors) that require braking, such as an object (obstacle) and a situation (including terrain such as a cliff) around the vehicle body 1. The object sensor 25a detects factors requiring braking, such as an object and a situation (including terrain such as a cliff), that are located in the direction of travel of the wheel loader 100. More precisely, the object sensor 25a is a rear detection unit that detects a factor requiring braking located in the reverse direction Zb of the vehicle body 1 when the wheel loader 100 is traveling in reverse direction Zb. Furthermore, the object sensor 25a is a front detection unit located in the forward direction Zf of the vehicle body 1 and detects a factor requiring braking when the wheel loader 100 is traveling in forward direction Zf.

[0064] If the object sensor 25a is a rear detection unit, the rear detection unit 25a is, for example, mounted at the rear end of the vehicle body 1, as shown in Fig. Figure 1 illustrates the object sensor, but it can also be mounted in a position other than the rear end. For example, if the object sensor 25a is the front detection unit, the front detection unit 25a can be mounted on the cabin 5, the front frame 11, or other components.

[0065] The object sensor 25a, for example, is a LiDAR (Light Detection and Ranging) that emits laser light to capture information on an object. The object sensor 25a can also be a radar (Radio Detection and Ranging) that captures information on a target object by emitting radio waves. This radar could, for example, be a millimeter-wave radar that uses a receiving antenna to detect a condition in which a radio wave emitted by a transmitting antenna in a millimeter-wave band is reflected from the surface of an object and returns. The object sensor 25a can be a visual sensor, including a camera. The object sensor 25a can also be an infrared sensor.

[0066] Information detected by object sensor 25a is transmitted to the controller 26, which determines whether a braking factor (a factor that requires braking) exists in the direction of travel of the vehicle body 1. Furthermore, the controller 26 calculates a distance to the detected braking factor. Based on this distance, the controller 26 can determine whether there is a high risk (reach risk) that the vehicle body 1 will reach the braking factor (for example, collide with it).

[0067] The implement position sensor 25b is a sensor that detects the position of the implement 3. The implement position sensor 25b includes, for example, a boom angle sensor and a bucket angle sensor.

[0068] The boom angle sensor includes, for example, a rotary encoder provided on a boom bolt, which is a mounting section of the boom 14 to the chassis 2. The boom angle sensor detects an angle of the boom 14 with respect to the horizontal direction and generates a signal of the detected angle of the boom 14. The boom angle sensor outputs a signal about the angle of the boom 14 to the controller 26.

[0069] The blade angle sensor, for example, consists of a rotary encoder mounted on a support bolt, which is a rotating shaft of the deflection lever 18. The blade angle sensor detects the angle of the blade 15 relative to the boom 14 and generates a signal indicating the detected angle of the blade 15. The blade angle sensor outputs a signal about the angle of the blade 15 to the controller 26.

[0070] Instead of or in addition to the boom angle sensor and the bucket angle sensor, the implement position sensor 25b can be an angle sensor that detects the angle of the deflection lever 18 and an angle sensor that detects the angle of the connecting piece. The implement position sensor 25b is not limited to the rotary encoder described above and can be a stroke sensor, an IMU (Inertial Measurement Unit), a potentiometer, an optical sensor, or the like.

[0071] The swivel angle sensor 25c detects a swivel angle θ, which is an angle formed by the front frame 11 and the rear frame 12, and generates a signal of the detected swivel angle θ. The swivel angle sensor 25c outputs a signal of the swivel angle θ to the controller 26.

[0072] The swivel angle sensor 25c is, for example, attached to the steering cylinder 9. The swivel angle sensor 25c is, for example, a potentiometer and directly detects the swivel angle θ. Furthermore, the swivel angle sensor 25c can detect the stroke length of the steering cylinder 9. The controller 26 can calculate the swivel angle θ from the stroke length of the steering cylinder 9. Operating Unit 24

[0073] Operating unit 24 comprises steering cylinder 9, implement cylinders 16 and 17, EPC valves 62 and 63, and a hydraulic pump 61. Part of the drive power from motor 31 is transmitted to hydraulic pump 61. Hydraulic pump 61 is driven by the motor and operates implement cylinders 16 and 17 and steering cylinder 9 using the drained hydraulic oil. The hydraulic oil drained by hydraulic pump 61 is supplied to implement cylinders 16 and 17 and steering cylinder 9 via EPC valves 62 and 63.

[0074] Each of the EPC valves 62 and 63 is opened and closed based on an instruction from the controller 26. Specifically, each of the EPC valves 62 and 63 enters an open state when activated by an open command from the controller 26, and enters a closed state when deactivated by a close command from the controller 26.

[0075] In the open position, the EPC valve 62 connects the hydraulic pump 61 and the working tool cylinders 16 and 17, supplying hydraulic oil from the hydraulic pump 61 to the working tool cylinders 16 and 17. In the closed position, the EPC valve 62 stops the supply of hydraulic oil from the hydraulic pump 61 to the working tool cylinders 16 and 17.

[0076] In the open position, the EPC valve 63 connects the hydraulic pump 61 and the steering cylinder 9, supplying hydraulic oil from the hydraulic pump 61 to the steering cylinder 9. In the closed position, the EPC valve 62 stops the supply of hydraulic oil from the hydraulic pump 61 to the steering cylinder 9. Control 26

[0077] The controller 26 includes a processor, main memory, and storage. The processor is, for example, a CPU (Central Processing Unit). The main memory includes, for example, non-volatile memory, such as ROM (Read Only Memory), and volatile memory, such as RAM (Random Access Memory).

[0078] Both the control unit 26 and the operating device 23 can be mounted on the wheel loader 100 or located outside of and away from the wheel loader 100. If the control unit 26 and the operating device 23 are each located outside of and away from the wheel loader 100, they can each be wirelessly connected to the drive device 21, the brake device 22, the operating device 23, the object sensor 25a, etc. The control unit 26 can be stored on a server located away from the wheel loader 100. Furthermore, since the operating device 23 is separate from the wheel loader 100, the operator can operate the wheel loader 100 remotely without having to enter the cab 5 of the wheel loader 100.

[0079] The controller 26 reads a program stored in memory, extends the program in main memory, and executes a predetermined process according to the program. The controller 26 can be divided into a collision detection controller and a high-speed control (HST) controller. The collision detection controller and the HST controller can have different CPUs. Alternatively, the computer program can be distributed to the controller 26 via a network.

[0080] As in Fig. As illustrated in Figure 4, the control unit 26 includes an automatic brake control unit 27, a work tool position information acquisition unit 26A, a position determination unit 26B, a slew angle information acquisition unit 26C, a slew angle determination unit 26D, and a storage unit 26E. The automatic brake control unit 27 includes a direction of travel information acquisition unit 27A, a direction of travel determination unit 27B, an object information acquisition unit 27C, an object determination unit 27D, and an EPC valve control unit 27E.

[0081] The state (ON state) in which the automatic brake control is started means a state in which the control 26 can automatically control the opening and closing process of the EPC valve 46 based on the detection result of the direction switching device 53 and the detection result of the object sensor 25a.

[0082] When the automatic brake control unit 27 starts the automatic brake control, the direction information acquisition unit 27A detects the switching signal of the direction switching device 53. The direction information acquisition unit 27A outputs the detected switching signal of the direction switching device 53 to the direction determination unit 27B.

[0083] Upon detecting the switching signal of the direction-of-travel switching device 53, the direction-of-travel determination unit 27B determines, based on this signal, whether the direction of travel of the wheel loader 100 is a predetermined direction (for example, the reverse direction Zb). The direction-of-travel determination unit 27B outputs the result of this determination to the EPC valve control unit 27E.

[0084] Even in a stopped state, in which the wheels 4 and 7 are not rotating, the direction control unit 27B can determine that the vehicle body 1 is moving in the predetermined direction (reverse driving state) if the lever position of the direction switching device 53 is in a predetermined direction (for example, the reverse direction Zb).

[0085] When the automatic brake control unit 27 initiates automatic brake control, the object information acquisition unit 27C acquires the detection result from the object sensor 25a. The object information acquisition unit 27C outputs the acquired detection result from the object sensor 25a to the object determination unit 27D. Based on a detection result from the object sensor 25a, the object determination unit 27D determines whether there is a high risk (reach risk) that the vehicle body 1 will reach a braking force (for example, collide with an object) and outputs a determination result to the EPC valve control unit 27E.

[0086] The EPC valve control unit 27E controls the opening and closing process of the EPC valve 46 based on the determination result of the direction-of-travel determination unit 27B and the determination result of the object-detection unit 27D during the execution of the automatic brake control. More precisely, during the execution of the automatic brake control, the EPC valve control unit 27E issues an opening command (command stream) to the EPC valve 46, so that the EPC valve 46 is brought into the open state when the EPC valve control unit 27E, for example, detects the determination result from the direction-of-travel determination unit 27B that the direction of travel is reverse Zb, and detects the determination result from the object-detection unit 27D that there is a high risk that the vehicle body 1 will reach the braking factor. The electromagnet of the EPC valve 46 is actuated based on the command current, so that the EPC valve 46 is opened.

[0087] When the EPC valve 46 is opened, the hydraulic oil from the rear changeover valve 47a and the front changeover valve 47b is supplied to the brake circuits 42a and 42b and the braking process is carried out.

[0088] The ON state means that braking force is applied through brake circuits 42a and 42b. An example of an ON state is when a plate is placed and pressed between multiple discs in a wet disc brake system. Conversely, an OFF state means that braking force is not applied through brake circuits 42a and 42b. An example of an OFF state is when a plate is not pressed between multiple discs in a wet disc brake system.

[0089] The opening degree of the EPC valve 46 is set by a command stream issued from the EPC valve control unit 27E to the EPC valve 46. In this example, the command stream is preset to a predetermined value. The command stream can be adjusted based on the distance to the detected braking factor. For example, the EPC valve control unit 27E can calculate a deceleration to stop before the braking factor from the detected distances and can send an opening command (command stream) to the EPC valve 46 to achieve an opening degree at which the deceleration occurs.

[0090] As described above, the controller 26 executes the automatic brake control to automatically decelerate the vehicle (stop or slow down) based on the detection of the braking force in the direction of travel. During automatic brake control, the controller 26 automatically controls the vehicle's movement via the brake device 22 based on the detection of the braking force by the object sensor 25a. As a result, the automatic brake control is executed and braking force is applied, even if the brake pedal 54 is not pressed by the operator, and the vehicle body 1 can be stopped before reaching the braking force.

[0091] During the execution of the automatic brake control, the control unit 26 restricts at least one of the lifting process of the working device 3 and the process of increasing the swivel angle θ. More precisely, the control unit 26 restricts the lifting process of the working device 3 such that the lifting of the working device 3 is limited to a certain height H1 ( Fig. 5) based on the position detection of the work device 3. If the height of the work device 3 exceeds the limit height H1 ( Fig. 5) If the height reaches a level equal to or lower than a predetermined height H2, the control system 26 stops or slows down the lifting process of the work device 3 without receiving an operating command from the operator to raise the work device 3 above the predetermined height H2.

[0092] Furthermore, the control 26 limits the process of increasing the swivel angle θ of the rear frame 12 in relation to the front frame 11, so that the swivel angle θ ( Fig. 6) lies within the limitation angle. If the swivel angle θ reaches a predetermined angle that is smaller than the limitation angle, the control 26 stops or slows down the process of increasing the swivel angle θ of the rear frame 12 relative to the front frame 11 without receiving the operator's command to increase the swivel angle θ from the predetermined angle.

[0093] The implement position information acquisition unit 26A acquires a signal relating to implement position information from the implement operating unit 51 or the implement position sensor 25b. The implement position information acquisition unit 26A outputs a signal regarding the acquired implement position information to the position information unit 26B. The position determination unit 26B calculates the height of the implement 3 based on the implement position information. In calculating the height of the implement 3, the position determination unit 26B refers to the dimensions and other parameters of each part of the implement 3, which were previously stored in the storage unit 26E. The position determination unit 26B determines whether the calculated height of the implement 3 has reached a predetermined height H2.When this determination is made, the position determination unit 26B refers to the predetermined height H2, which was previously stored in the storage unit 26E.

[0094] When the position control unit 26B determines that the height of the work tool 3 has reached the predetermined height H2, the position control unit 26B issues a limit command to the EPC valve control unit 27E to limit the lifting operation of the work tool 3. More precisely, when the position control unit 26B determines that the height of the work tool 3 has reached the predetermined height H2, the position control unit 26B issues a limit command to the EPC valve control unit 27E to stop or slow down the lifting operation of the work tool 3.

[0095] When the EPC valve control unit 27E detects the limit command from the position detection unit 26B, the EPC valve control unit 27E outputs a command current value to the EPC valve 62 based on the limit command. When the EPC valve control unit 27E detects the limit command from the position detection unit 26B to stop the lifting operation of the work tool 3, the EPC valve control unit 27E controls the EPC valve 62 so that it is in the closed position. More precisely, the EPC valve control unit 27E outputs a command current to the EPC valve 62 to close the EPC valve 62. However, if the EPC valve 62 does not go into the open state and remains in the closed state unless the command current value of the opening command is entered, the EPC valve control unit 27E does not need to output the command current value to the EPC valve 62.When the EPC valve control unit 27E receives a restriction command from the position determination unit 26B to slow down the lifting process of the working device 3, the EPC valve control unit 27E further controls the EPC valve 62 so that the opening degree of the EPC valve 62 is reduced.

[0096] As described above, during the execution of the automatic brake control, the lifting process of the work device 3 is limited so that the height of the work device 3, based on the position detection of the work device 3, is within the limitation height H1.

[0097] The yaw angle information acquisition unit 26C acquires a signal relating to yaw angle information from the steering operating unit 52 or the yaw angle sensor 25c. The yaw angle information acquisition unit 26C outputs a signal regarding the acquired yaw angle information to the yaw angle determination unit 26D. The yaw angle determination unit 26D calculates the yaw angle θ based on the yaw angle information. The yaw angle determination unit 26D determines whether the calculated yaw angle θ has reached a predetermined angle. If this determination is made, the yaw angle determination unit 26D refers to a predetermined angle that was previously stored in the storage unit 26E.

[0098] When the swivel angle determination unit 26D determines that the swivel angle θ has reached the predetermined angle, the swivel angle determination unit 26D issues a restriction command to the EPC valve control unit 27E to restrict an operation to increase the swivel angle θ of the rear frame 12 relative to the front frame 11. More precisely, when the swivel angle determination unit 26D determines that the swivel angle θ has reached the predetermined angle, the swivel angle determination unit 26D issues a restriction command to the EPC valve control unit 27E to stop or slow down the operation to increase the swivel angle θ of the rear frame 12 relative to the front frame 11.

[0099] When the EPC valve control unit 27E receives the limit command from the swivel angle determination unit 26D, the EPC valve control unit 27E outputs a command current value to the EPC valve 63 based on the limit command. When the EPC valve control unit 27E detects the limit command from the swivel angle determination unit 26D to stop the process of increasing the swivel angle θ, the EPC valve control unit 27E controls the EPC valve 63 to close. More precisely, the EPC valve control unit 27E outputs a command current to the EPC valve 63 to close it. However, if the EPC valve 63 does not go into the open state and remains in the closed state unless the command current value of the opening command is entered, the EPC valve control unit 27E does not need to output the command current value to the EPC valve 63.When the EPC valve control unit 27E receives the restriction command to slow down the process of increasing the swivel angle θ from the swivel angle determination unit 26D, the EPC valve control unit 27E further controls the EPC valve 63 in such a way that the opening degree of the EPC valve 63 is reduced.

[0100] As described above, during the execution of the automatic brake control, the process of increasing the swivel angle θ of the rear frame 12 in relation to the front frame 11 is limited so that the swivel angle θ is within the limiting angle. Control method for wheel loader 100

[0101] Next, with reference to the Fig. 4, Fig. 7 and Fig. 8 a control method for the wheel loader 100 according to the present embodiment is described.

[0102] Fig. 7 and Fig. Figure 8 represents a first and a second flowchart, respectively, illustrating a control method for a wheel loader according to an embodiment of the present disclosure. First, a method for controlling the height of the working implement 3 is described such that it remains within the limit height H1 during the execution of the automatic braking control.

[0103] As in Fig. 4 and Fig. As illustrated in section 7, the automatic brake control is started by the operator's action (step S1: Fig. 7) The operator initiates the automatic brake control, for example, by inserting a key into a key switch on the wheel loader 100 to switch the wheel loader 100 from the OFF state to the ON state. When the automatic brake control unit 27 receives the start information for the automatic brake control, the automatic brake control unit 27 starts the automatic brake control accordingly.

[0104] When the automatic brake control is started, the automatic brake control unit 27 outputs an automatic brake control start signal to the implement position information acquisition unit 26A. When the implement position information acquisition unit 26A detects the start signal, it acquires a signal relating to the implement position information from the implement operating unit 51 or the implement position sensor 25b (step S2A: Fig. 7).

[0105] The work tool position information acquisition unit 26A outputs a signal regarding the acquired work tool position information to the position information unit 26B. The position determination unit 26B calculates the height of the work tool 3 based on the work tool position information. When calculating the height of the work tool 3, the position determination unit 26B refers to the dimensions and similar information of each part of the work tool 3, which were previously stored in the storage unit 26E. The position determination unit 26B determines whether the calculated height of the work tool 3 has reached a predetermined height H2 (step S3A: Fig. 7) When this determination is made, the position determination unit 26B refers to the predetermined height H2, which was previously stored in the storage unit 26E.

[0106] If the position determination unit 26B determines that the height of the work tool 3 has not reached the predetermined height H2, step S2A to acquire the work tool position information and step S3A to determine whether the calculated height of the work tool 3 has reached the predetermined height H2 are repeated.

[0107] Conversely, if the position determination unit 26B determines that the height of the work tool 3 has reached the predetermined height H2, the position determination unit 26B issues a restriction command to the EPC valve control unit 27E to restrict the lifting operation of the work tool 3. More precisely, if the position determination unit 26B determines that the height of the work tool 3 has reached the predetermined height H2, the position determination unit 26B issues a restriction command to the EPC valve control unit 27E to stop or slow down the lifting operation of the work tool 3.

[0108] When the EPC valve control unit 27E receives the restriction command from the position control unit 26B, the EPC valve control unit 27E controls the EPC valve 62 based on the restriction command. If the EPC valve control unit 27E receives a restriction command from the position control unit 26B to stop the lifting operation of the work tool 3, the EPC valve control unit 27E controls the EPC valve 62 so that it is in the closed position. If the EPC valve control unit 27E receives a restriction command from the position control unit 26B to slow down the lifting operation of the work tool 3, the EPC valve control unit 27E further controls the EPC valve 62 so that the opening degree of the EPC valve 62 is reduced.

[0109] As described above, during the execution of the automatic brake control, the control unit 26 corrects the operator's input to limit the lifting operation of the work device 3 (step S4A: Fig. 7) This means that when the height of the work tool 3 reaches the predetermined height H2, the control unit 26 stops or slows down the lifting process of the work tool 3 without receiving an operating command from the operator to raise the work tool 3 above the predetermined height. Accordingly, the height of the work tool 3 is controlled during the execution of the automatic braking control to remain within the limit height H1.

[0110] The operator then cancels the correction of the process by stopping the wheel loader 100 (step S5: Fig. 7) The wheel loader 100 can be stopped, for example, by operating a key switch.

[0111] Next, a method for controlling the swivel angle θ is described so that it lies within the limit angle during the execution of the automatic brake control.

[0112] As in Fig. 4 and Fig. As illustrated in section 8, the automatic brake control is started by the operator's action (step S1: Fig. 8) The operator initiates the automatic brake control, for example, by inserting a key into a key switch on the wheel loader 100 to switch the wheel loader 100 from the OFF state to the ON state. When the automatic brake control unit 27 receives the start information for the automatic brake control, the automatic brake control unit 27 starts the automatic brake control accordingly.

[0113] When the automatic brake control is started, the automatic brake control unit 27 outputs an automatic brake control start signal to the swashplate information acquisition unit 26C. Upon acquiring the start signal, the swashplate information acquisition unit 26C acquires a signal relating to the swashplate information from the steering actuation unit 52 or the swashplate sensor 25c (step S2B: Fig. 8).

[0114] The pan angle information acquisition unit 26C outputs a signal regarding the acquired pan angle information to the pan angle determination unit 26D. The pan angle determination unit 26D calculates the pan angle θ based on the pan angle information. The pan angle determination unit 26D determines whether the calculated pan angle θ has reached a predetermined angle (step S3B: Fig. 8) When this determination is made, the swivel angle determination unit 26D refers to a predetermined angle that was previously stored in the storage unit 26E.

[0115] If the swivel angle determination unit 26D determines that the swivel angle θ has not reached the predetermined angle, step S2B to acquire the swivel angle information and step S3B to determine whether the calculated swivel angle θ has reached the predetermined angle are repeated.

[0116] Conversely, if the swivel angle determination unit 26D determines that the swivel angle θ has reached the predetermined angle, the swivel angle determination unit 26D issues a limit command to the EPC valve control unit 27E to limit the swivel angle θ. More precisely, if the swivel angle determination unit 26D determines that the swivel angle θ has reached the predetermined angle, the swivel angle determination unit 26D issues a limit command to the EPC valve control unit 27E to stop or slow down the process of increasing the swivel angle θ of the rear frame 12 relative to the front frame 11.

[0117] When the EPC valve control unit 27E receives the restriction command from the swivel angle determination unit 26D, the EPC valve control unit 27E controls the EPC valve 63 based on the restriction command. If the EPC valve control unit 27E receives the restriction command from the swivel angle determination unit 26D to stop the swivel angle θ increase operation, the EPC valve control unit 27E controls the EPC valve 63 to close. Furthermore, if the EPC valve control unit 27E receives the restriction command from the swivel angle determination unit 26D to slow down the swivel angle θ increase operation, the EPC valve control unit 27E controls the EPC valve 63 to decrease its opening degree.

[0118] As described above, during the execution of the automatic brake control, the control unit 26 corrects the operator's input to limit the process of increasing the swivel angle θ of the rear frame 12 relative to the front frame 11 (step S4B: Fig. 8) That is, when the swivel angle θ reaches the predetermined angle, the control unit 26 stops or slows down the process of increasing the swivel angle θ of the rear frame 12 relative to the front frame 11, without receiving the operator's command to increase the swivel angle θ from the predetermined angle. As a result, the swivel angle θ is controlled to remain within the limit angle during the execution of the automatic braking control.

[0119] The operator then cancels the correction of the process by stopping the wheel loader 100 (step S5: Fig. 8) The wheel loader 100 can be stopped, for example, by activating a key switch. The wheel loader 100 can be stopped, for example, when its vehicle speed is 0 (zero).

[0120] At the in Fig. 7 and Fig. The automatic brake control is carried out as follows, as illustrated in the 8 illustrated control methods.

[0121] As in Fig. As illustrated in Figure 4, the direction information acquisition unit 27A detects the switching signal of the direction switching device 53 when the automatic brake control is started. The direction information acquisition unit 27A outputs the detected switching signal of the direction switching device 53 to the direction determination unit 27B.

[0122] Upon detecting the switching signal of the direction-of-travel switching device 53, the direction-of-travel determination unit 27B determines, based on this signal, whether the direction of travel of the wheel loader 100 is a predetermined direction (for example, the reverse direction Zb). The direction-of-travel determination unit 27B outputs the result of this determination to the EPC valve control unit 27E.

[0123] When the automatic brake control unit 27 initiates automatic brake control, the object information acquisition unit 27C acquires the detection result from the object sensor 25a. The object information acquisition unit 27C outputs the acquired detection result from the object sensor 25a to the object determination unit 27D. Based on the detection result from the object sensor 25a and similar information, the object determination unit 27D determines whether there is a high risk that the vehicle body 1 will reach the braking factor and outputs the determination result to the EPC valve control unit 27E.

[0124] The EPC valve control unit 27E controls the opening and closing process of the EPC valve 46 based on the determination result of the direction-of-travel determination unit 27B and the determination result of the object-detection unit 27D during the execution of the automatic brake control. More precisely, during the execution of the automatic brake control, the EPC valve control unit 27E issues an opening command (command stream) to the EPC valve 46, so that the EPC valve 46 is brought into the open state when the EPC valve control unit 27E, for example, detects the determination result from the direction-of-travel determination unit 27B that the direction of travel is reverse Zb, and detects the determination result from the object-detection unit 27D that there is a high risk that the vehicle body 1 will reach the braking factor. The electromagnet of the EPC valve 46 is actuated based on the command current, so that the EPC valve 46 is opened.When the EPC valve 46 is opened, the hydraulic oil from the rear changeover valve 47a and the front changeover valve 47b is supplied to the brake circuits 42a and 42b and the braking process is carried out. Effects

[0125] The effects of the present embodiment will be described next. During operation on a construction site, a work machine such as the wheel loader 100 frequently assumes an unstable position. In such an unstable position, the wheel loader 100 becomes even more unstable if the automatic brake control initiates sudden braking. In particular, when the work attachment 3 of the wheel loader 100 is loaded and in a raised position, the wheel loader 100's center of gravity is high, thus increasing its instability.

[0126] In contrast, the present revelation is limited, as in Fig. 4 and Fig. Figure 7 illustrates how the control system 26 manages the lifting process of the work implement 3 during the execution of the automatic braking control. Therefore, the wheel loader 100 is prevented from being in an unstable state during the execution of the automatic braking control, and a stable state can be maintained.

[0127] As in Fig. 4 and Fig. As illustrated in Figure 7, during automatic braking control, the control unit 26 limits the lifting operation of the implement 3 so that, based on the implement 3's position detection, the lifting of the implement 3 remains within the limited height H1. Thus, the wheel loader 100 can be kept in a stable state even during automatic braking control. During automatic braking control, the control unit 26 can completely prevent the operation of the implement 3.

[0128] As in Fig. 4 and Fig. Figure 7 illustrates that the control system 26 stops or slows down the lifting process of the work implement 3 when its height reaches the predetermined height H2, without receiving an operating command from the operator to raise the work implement 3 above the predetermined height H2. Accordingly, the wheel loader 100 can be held in a stable state during the execution of the automatic braking control, regardless of any action taken by the operator.

[0129] As in Fig. As illustrated in Figure 4, during the execution of the automatic braking control, the control unit 26 limits the lifting operation of the implement 3, while the vehicle is automatically braked by the braking device 22, based on the determined risk that the wheel loader 100 will reach the braking threshold (risk of collision with an obstacle or the like). Thus, the wheel loader 100 can be kept in a stable state even during the execution of the automatic braking control.

[0130] Furthermore, the position of the wheel loader 100 in an unstable position, in which the rear frame 12 pivots in relation to the front frame 11 during work on a construction site, becomes even more unstable if sudden braking is carried out by the automatic brake control.

[0131] In contrast, the present revelation is limited, as in Fig. 4 and Fig. Figure 8 illustrates that the control unit 26 performs a process to increase the pivot angle θ of the rear frame 12 relative to the front frame 11 during the execution of the automatic braking control. This prevents the wheel loader 100 from being in an unstable state during the execution of the automatic braking control, and a stable state can be maintained.

[0132] As in Fig. 4 and Fig. As illustrated in Figure 8, the control unit 26 further limits the process of increasing the swivel angle θ of the rear frame 12 relative to the front frame 11, so that the swivel angle θ lies within the limiting angle. Thus, the wheel loader 100 can be kept in a stable state even during the execution of the automatic brake control.

[0133] As in Fig. 4 and Fig. Figure 8 illustrates that the control system 26 stops or slows down the process of increasing the slew angle θ of the rear frame 12 relative to the front frame 11 when the slew angle θ reaches the predetermined angle, without receiving an operating command from the operator to increase the slew angle θ from the predetermined angle. Accordingly, the wheel loader 100 can be held in a stable state during the execution of the automatic braking control, regardless of any action taken by the operator.

[0134] As in Fig.As illustrated in Figure 4, during the execution of the automatic braking control, the control unit 26 limits the process of increasing the swivel angle θ while the vehicle is automatically braked by the braking device 22, based on the determined risk of the wheel loader 100 reaching the braking factor (risk of collision with an obstacle or the like). Thus, the wheel loader 100 can be kept in a stable state even during the execution of the automatic braking control.

[0135] Although the braking process of the automatic brake control was described above for the case where a braking factor in the reverse direction of the vehicle body 1 is present when the wheel loader 100 is moving backward, the braking process of the automatic brake control in the present disclosure is similarly applicable to the case where a braking factor in the forward direction of the vehicle body 1 is present when the wheel loader 100 is moving forward. In this case, if the wheel loader 100 is moving forward and the risk of reaching the braking factor in the forward direction is high, the automatic brake control determines that a braking command is required, and the braking process is executed. Attachments

[0136] The above description includes the following features. Annex 1

[0137] A working machine configured to perform automatic brake control for automatic braking while driving, the working machine comprising: a chassis; a working implement mounted on the chassis; and a control configured to limit any lifting operation of the working implement during the execution of the automatic brake control. Appendix 2

[0138] Working machine according to Annex 1, wherein the control system limits the lifting process of the working device so that the lifting of the working device is based on the position detection of the working device within a limited height. Appendix 3

[0139] Working machine according to Annex 1 or 2, wherein the control, when a height of the working equipment reaches a predetermined height, stops or slows down the lifting process of the working equipment without receiving an operating command from an operator to raise the working equipment above the predetermined height. Appendix 4

[0140] Working machine according to one of Annexes 1 to 3, further comprising: an object sensor configured to detect a braking factor located in a direction of travel of the working machine; and a braking device configured to brake the travel, wherein the control, during the execution of the automatic braking control, automatically brakes the travel by means of the braking device, based on a determination result of a risk that the braking factor detected by the working machine and the object sensor will be reached, and limits the lifting operation of the working machine. Appendix 5

[0141] A working machine configured to perform automatic brake control for automatic braking of the journey, the working machine including: a front frame; a rear frame pivotally coupled to the front frame; and a control configured to restrict an operation to increase a pivot angle of the rear frame relative to the front frame during the execution of the automatic brake control. Appendix 6

[0142] Working machine according to Annex 5, wherein the control system limits the process of increasing the swivel angle of the rear frame in relation to the front frame in such a way that the swivel angle is within a limiting angle. Appendix 7

[0143] Working machine according to Annex 5 or 6, wherein the control, when the swivel angle reaches a predetermined angle, stops or slows down the process of increasing the swivel angle of the rear frame relative to the front frame without receiving an operating command from an operator to increase the swivel angle from the predetermined angle. Appendix 8

[0144] Working machine according to any one of Annexes 5 to 7, further comprising: an object sensor configured to detect a braking factor located in a direction of travel of the working machine; and a braking device configured to brake the travel, wherein, during the execution of the automatic braking control, the control automatically brakes the travel by means of the braking device, based on a determination result of a risk that the braking factor detected by the working machine and the object sensor will be reached, and limits the process of increasing the swivel angle. Appendix 9

[0145] A braking system for a working machine configured to perform automatic brake control for automatic braking of the journey, wherein the braking system includes: a chassis; a working implement mounted on the chassis; and a control configured to limit a lifting operation of the working implement during the execution of the automatic brake control. Appendix 10

[0146] A braking system for a work machine configured to perform automatic brake control for automatic braking of the journey, wherein the braking system includes: a front frame; a rear frame pivotally coupled to the front frame; and a control configured to limit an operation to increase a pivot angle of the rear frame relative to the front frame during the execution of the automatic brake control. Annex 11

[0147] A control method for a working machine which includes a chassis and a working device arranged on the chassis and is configured to perform an automatic brake control for automatic braking of the journey, wherein the control method includes: initiating the execution of the automatic brake control; and restricting a lifting operation of the working device during the execution of the automatic brake control. Appendix 12

[0148] A control method for a working machine comprising a front frame and a rear frame pivotably coupled to the front frame and configured to perform automatic brake control for automatic braking of the journey, wherein the control method includes: initiating the execution of the automatic brake control; and restricting an operation to increase a pivot angle of the rear frame relative to the front frame during the execution of the automatic brake control.

[0149] It is understood that the embodiments disclosed herein are in every respect illustrative and not limiting. The scope of protection of the present invention is defined by the terms of the claims and not by the foregoing description and is intended to include all modifications within the scope and meaning that correspond to the content of the claims. Reference symbol list

[0150] 1 Vehicle body, 2 Chassis, 3 Working implement, 4 Front tires, 5 Cab, 5s Driver's seat, 6 Engine compartment, 7 Rear tires, 9 Steering cylinder, 10 Vehicle body frame, 11 Front frame, 12 Rear frame, 13 Coupling shaft section, 14 Boom, 15 Bucket, 16 Lifting cylinder, 17 Bucket cylinder, 18 Deflection lever, 21 Drive device, 22 Brake device, 23 Operating device, 24 Operating unit, 25 Detection device, 25a Object sensor, 25b Working implement position sensor, 25c Slew angle sensor, 26 Control, 26A Working implement position information unit, 26B Position determination unit, 26C Slew angle information acquisition unit, 26D Slew angle determination unit, 26E Storage unit, 27 Automatic brake control unit, 27A Travel direction information acquisition unit, 27B Direction of travel determination unit, 27C Object information acquisition unit, 27D Object identification unit, 27E Valve control unit, 31 Motor, 32a Pump, 32b Motor, 32c1 First drive circuit,32c2 Second drive circuit, 32c Hydraulic circuit, 32d, 32e Solenoid valve, 33 Transfer case, 34 Axle, 40 Brake unit, 41 Brake valve unit, 41a Rear wheel brake valve, 41b Front wheel brake valve, 42a, 42b Brake circuit, 43 Parking brake, 44a, 44b Hydraulic oil supply channel, 45 Shut-off valve, 46, 62, 63 EPC valve, 47 Changeover valve unit, 47a Rear changeover valve, 47b Front changeover valve, 48 Tank, 49a, 49b Pressure accumulator, 51 Implement control unit, 52 Steering control unit, 53 Direction of travel switch, 54 Brake pedal, 55 Accelerator pedal, 56 Parking switch, 61 Hydraulic pump, 100 Wheel loader

Claims

[1] Working machine configured to perform automatic brake control for automatic braking of the journey, the working machine comprising: a chassis; a work device mounted on the chassis and a control system configured to perform a lifting operation of the work equipment to restrict during the execution of the automatic brake control. [2] Working machine according to claim 1, wherein the control limits the lifting process of the working device such that the lifting of the working device is based on the position detection of the working device within a limited height. [3] Working machine according to claim 1, wherein the control, when a height of the working device reaches a predetermined height, stops or slows down the lifting process of the working device without receiving an operating command from an operator to lift the working device above the predetermined height. [4] Working machine according to claim 1, further comprising: an object sensor configured to detect a braking factor located in one direction of travel of the working machine; and a braking device configured to slow the movement, wherein the control system automatically slows the movement through the braking device during the execution of the automatic braking control, based on a determination result of a risk that the braking factor detected by the working machine and the object sensor will be reached, and the lifting operation limited to the work equipment. [5] Working machine configured to perform automatic brake control for automatic braking of the journey, the working machine comprising: a front frame; a rear frame that is pivotally coupled to the front frame; and a control that is configured to limit an operation to increase a pivot angle of the rear frame relative to the front frame during the execution of the automatic brake control. [6] Working machine according to claim 5, wherein the control limits the process for increasing the swivel angle of the rear frame in relation to the front frame such that the swivel angle is within a limiting angle. [7] Working machine according to claim 5, wherein, when the swivel angle reaches a predetermined angle, the control stops or slows down the process of increasing the swivel angle of the rear frame relative to the front frame without receiving an operating command from an operator to increase the swivel angle from the predetermined angle. [8] Working machine according to claim 5, further comprising: an object sensor configured to detect a braking factor, which is located in one direction of travel of the working machine; and a braking device configured to slow the movement, wherein during the execution of the automatic braking control the control automatically slows the movement by means of the braking device, based on a determination result of a risk that the braking factor detected by the working machine and the object sensor will be reached, and limits the process to increasing the swivel angle. [9] Braking system for a working machine which is configured to perform automatic brake control for automatic braking of the journey, wherein the braking system comprises: a chassis; a work device mounted on the chassis and a control system configured to limit the lifting operation of the work equipment during the execution of the automatic braking control. [10] Braking system for a working machine configured to perform automatic brake control for automatic braking of the journey, wherein the braking system comprises: a front frame; a rear frame that is pivotally coupled to the front frame; and a control that is configured to limit an operation to increase a pivot angle of the rear frame relative to the front frame during the execution of the automatic brake control. [11] Control method for a working machine which includes a chassis and a working device arranged on the chassis and is configured to perform automatic brake control for automatic braking of the journey, wherein the control method comprises: Starting the execution of the automatic brake control and Limiting the lifting operation of the work equipment during the execution of the automatic brake control. [12] Control method for a working machine which includes a front frame and a rear frame pivotably coupled to the front frame and is configured to perform automatic brake control for automatic braking of the journey, wherein the control method comprises: Starting the execution of the automatic brake control and Restricting a process to increase the swivel angle of the rear frame relative to the front frame during the execution of automatic brake control.

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