Braking system for a work vehicle

Abstract

The present application provides a braking system for a work vehicle. Without giving the passenger an obstacle to the manual driving of the work vehicle, a braking operation system for emergency stop required in the automatic travel of the work vehicle in an unattended state is provided in the braking system. The braking system for the work vehicle includes a brake pedal (40) disposed in a driving portion, a brake that brakes left and right rear wheels, a linkage mechanism (43) that links the brake pedal (40) and the brake to be able to operate in conjunction, and an electric brake operation device (100) that operates the brake according to an emergency stop command. The brake operation device (100) includes an operated body (101) that is linked to the brake pedal (40), an electric actuator (102) that operates the operated body (101), and a compromise portion (103) that allows the brake pedal (40) and the linkage mechanism (43) to follow the displacement of the brake pedal (40) with respect to the electric actuator (102) generated between the brake pedal (40) and the electric actuator (102) with the depression operation of the brake pedal (40).

Description

Technical Field

[0001] This invention relates to a braking system for work vehicles that includes a brake that brakes the wheels, tracks, and other traveling devices in conjunction with the operation of depressing the brake pedal. Background Technology

[0002] As a braking system for work vehicles, for example, it is configured to include left and right brake pedals, a parking brake lever, left and right brakes for braking the left and right rear wheels, a left and right linkage mechanism (left and right brake levers, etc.) that links the left and right brake pedals and left and right brakes together, an equalizer wire that links the parking brake lever and left and right brakes together, and an electronic hydraulic control braking device (automatic brake solenoid valve, etc.) that operates the brake on the inside of the turn in conjunction with a rotation operation of the steering wheel at a set angle or above. When the passenger performs any braking-related operation involving the left and right brake pedals, the parking brake lever, or the steering wheel, the corresponding brake is activated to brake the corresponding rear wheel (see, for example, Patent Document 1).

[0003] Patent Document 1: Japanese Patent Application Publication No. 2016-78612

[0004] In recent years, the automation of tractors and other work vehicles, utilizing satellite positioning systems such as GPS (Global Positioning System) and Navigation Satellite Systems (NSS), has developed, enabling them to operate autonomously. This automation further advances towards unmanned operation, allowing vehicles to travel automatically without human intervention. To achieve this, the work vehicle needs to possess the following function: to stop the vehicle in autonomous driving mode when abnormalities occur, such as discrepancies between the vehicle's speed and the target speed for autonomous driving, or deviations from the target driving path, due to malfunctions in the transmission control system, steering control system, or other control systems related to autonomous driving.

[0005] As a function to stop the operation of the work vehicle, since the work vehicle described in Patent Document 1 has a hydraulic continuously variable transmission that can decelerate to a stop state (zero speed state), it is conceivable that an automatic stop function can be provided to stop the operation of the work vehicle by controlling the hydraulic continuously variable transmission to decelerate to a stop state through the control operation of the transmission control system.

[0006] However, if only the above-mentioned automatic stop function is available, the vehicle will not be able to stop moving when unexpected abnormalities occur in the work vehicle, such as a drop in oil pressure in the hydraulic continuously variable transmission.

[0007] In other words, to achieve unmanned operation of the work vehicle, a braking system is required to quickly bring the vehicle to a stop in the event of unforeseen anomalies such as a drop in oil pressure. Furthermore, since work vehicles capable of autonomous operation are originally designed for manual driving by passengers, an emergency stopping system must be provided in a manner that does not impede the passengers' manual driving. Summary of the Invention

[0008] In view of this reality, the main objective of the present invention is to provide a braking system in the braking system that enables emergency stopping of the vehicle during automatic operation in an unmanned state, without hindering the passenger from manually driving the vehicle.

[0009] The first feature of this invention is that, in a braking system for a work vehicle, it comprises:

[0010] Brake pedal, which is located in the driver's area;

[0011] Brakes, which brake the traveling device;

[0012] The associated mechanism connects the brake pedal and the brake in a way that enables them to move together; and

[0013] An electrically operated braking device activates the aforementioned brakes upon receiving an emergency stop command.

[0014] The above-mentioned braking operating device has:

[0015] The operated body is connected to the aforementioned brake pedal or the aforementioned associated mechanism;

[0016] An electric actuator that operates the aforementioned operated body; and

[0017] The accommodative part allows the brake pedal and the associated mechanism to be displaced relative to the electric actuator during the braking operation of the brake pedal or the associated mechanism and the electric actuator.

[0018] According to this structure, for example, during the autonomous driving of a work vehicle in an unmanned state, if an unexpected anomaly occurs, such as a drop in oil pressure, an electric braking device activates the brakes via the brake pedal and the linkage mechanism, or only via the linkage mechanism, based on an emergency stop command given by the anomaly. This enables the work vehicle to be quickly brought to a stop while autonomously driving in an unmanned state.

[0019] Furthermore, unlike electronic hydraulic control brakes that operate the brakes using oil from a hydraulic pump driven by engine power, electric brakes can maintain the brakes even when the engine stops and the oil pressure drops. Therefore, for example, even if an unmanned work vehicle comes to an emergency stop on an incline leaning towards its direction of travel with the engine off, the vehicle can be kept in a braked stop.

[0020] Furthermore, when the passenger manually operates the brake pedal while driving the work vehicle, the accommodating part allows for smooth braking of the brakes that are linked to the pedal operation without being obstructed by the electric actuator.

[0021] That is, the braking system is equipped with an emergency stop braking system that can quickly brake and stop the vehicle when an abnormality occurs while the vehicle is driving automatically in an unmanned state, and can maintain the vehicle in a braked and stopped state even when the engine is stopped.

[0022] The second structural feature of the present invention is that,

[0023] The aforementioned braking operating device, through the operation of the aforementioned electric actuator, transitions between a non-operating state (no operation of the brake) and a maximum operating state (maximum operating amount of the brake).

[0024] The braking system used in the aforementioned work vehicle is equipped with a state detection sensor that detects the non-operating state and the maximum operating state of the aforementioned braking operation device.

[0025] Based on this structure, by utilizing the detection of the status detection sensor, it is easy to confirm the operation of the braking device before the work vehicle can drive automatically in an unmanned state, and to monitor the status of the braking device in the work vehicle while it is driving automatically in an unmanned state.

[0026] The third structural feature of the present invention is that,

[0027] The aforementioned electric actuator is an electric motor that outputs rotational power.

[0028] The aforementioned braking operating device includes a housing mounted on the fixed part of the vehicle body and a reduction gear set for reducing the rotational power from the aforementioned electric motor.

[0029] The electric motor and the reduction gear set are housed in the housing.

[0030] According to this structure, the electric motor, reduction gear set, and housing of the braking operating device can be integrally installed on the fixed part of the vehicle body. Moreover, after they are installed, by connecting the electric motor side to the brake pedal or associated mechanism via an operable body, the braking operating device can be assembled on the vehicle body in a state where the brake can be operated using the braking operating device.

[0031] That is, without making major changes to the structure of the vehicle body, the braking device can be easily assembled relative to the vehicle body, thereby enabling the subsequent addition of the braking device to the working vehicle.

[0032] As a result, it is easy to assemble the braking device relative to the vehicle body, and easy to perform maintenance such as replacement of the braking device in case of malfunctions.

[0033] The fourth structural feature of the present invention is that,

[0034] The aforementioned braking operating device includes a connecting pin that connects the outer peripheral side of the output gear in the aforementioned reduction gear set to the operated body via the aforementioned accommodating portion.

[0035] The aforementioned housing has a movement limiting part that restricts the movement range of the aforementioned connecting pin between a non-operating position where the brake is not operated and a maximum operating position where the brake's operating amount is maximized.

[0036] The range of movement of the aforementioned linkage pin is set such that the linkage pin moves across the range of the non-operating position and the maximum operating position, passing over an imaginary straight line, wherein the imaginary straight line is a straight line passing through the connection point of the operated body relative to the brake pedal or the linkage mechanism and the rotation center of the output gear.

[0037] According to this structure, when the brake is engaged by the braking device, firstly, the forward rotational power from the electric motor is transmitted to the output gear, which rotates in the braking direction. This causes the linkage pin to move in an arc from the non-operating position towards the maximum operating position. At this time, naturally, because the brake pedal is returned to the release position, the electric motor overcomes the force applied to the brake pedal to perform the braking operation within the first movement range of the linkage pin, from passing through the clearance area including the non-operating position to crossing an imaginary straight line. Therefore, within this first movement range, the closer the linkage pin is to the imaginary straight line, the heavier the load applied to the electric motor. On the other hand, the closer the linkage pin is to the imaginary straight line, the smaller the angle between the line connecting the linkage pin and the rotation center of the output gear and the operated body. Consequently, the force applied to the brake pedal is less likely to function as a force to return the linkage pin to the non-operating position, thus reducing the increase in load on the electric motor. Afterward, if the linkage pin crosses the imaginary straight line, the force applied to the brake pedal switches to a state that assists the braking operation performed by the electric motor. Therefore, within the second movement range of the connecting pin from crossing the imaginary straight line to reaching the maximum operating position, the closer the connecting pin is to the maximum operating position, the lighter the load applied to the electric motor. Furthermore, when the connecting pin reaches the maximum operating position, it is forced in the braking direction by the force applied to the brake pedal while its movement in the braking direction is restricted by the movement limiting part. Thus, for example, in the case of a motor malfunction or output gear damage when the connecting pin has crossed the imaginary straight line and reached the second movement range, the force applied to the brake pedal moves the connecting pin to the maximum operating position and maintains it there, thereby maintaining the brake in a braking state and keeping the work vehicle in a stopped state.

[0038] As a result, the load on the electric motor can be reduced during the braking operation of the brake by the braking device, and the vehicle can be kept in a stopped state regardless of electric motor failure, output gear damage, etc. when the vehicle is stopped by the operation of the braking device. Attached Figure Description

[0039] Figure 1 This is a diagram showing a simplified structure of an automated driving system.

[0040] Figure 2 This is a block diagram representing a simplified structure of an automated driving system.

[0041] Figure 3 This is a three-dimensional view taken from the upper left rear, showing the main structural components of the braking system.

[0042] Figure 4 This is a three-dimensional view taken from the upper right rear, showing the main structural components of the braking system.

[0043] Figure 5 It is a three-dimensional view showing the main structural parts around the brake pedal in the braking system.

[0044] Figure 6 This is a rear view showing the main parts of the structure surrounding the brake pedal in the braking system.

[0045] Figure 7 This is a perspective view taken from the upper right rear, showing the main structure of a braking system equipped with the electric braking operation device exemplified in the first embodiment.

[0046] Figure 8 This is a perspective view taken from the upper right front, showing the main structure of the electric braking operation device illustrated in the first embodiment.

[0047] Figure 9 This is a perspective view taken from the upper right rear, showing the main structure of the electric braking operation device illustrated in the first embodiment.

[0048] Figure 10 This is a right-side view showing the main parts of the structure of the electric braking operating device illustrated in the first embodiment.

[0049] Figure 11 This is a longitudinal sectional left-side view showing the main part of the electric braking operation device illustrated in the first embodiment in its non-operating state.

[0050] Figure 12 This is a longitudinal sectional left-side view showing the main part of the electric braking operating device illustrated in the first embodiment in its maximum operating state.

[0051] Figure 13 This is a longitudinal rear view showing the main part of the connection structure between the output gear and the operated body in the electric braking operating device illustrated in the first embodiment.

[0052] Figure 14 It is a graph showing the relationship between the operating amount, braking force, and operating load of the electric braking operating device illustrated in the first embodiment.

[0053] Figure 15 This is a longitudinal sectional left-side view showing the main components, such as the configuration of the emergency stop communication antenna that receives emergency stop commands from the emergency stop remote controller.

[0054] Figure 16This is a perspective view taken from the upper right rear, showing the main structure of the electric braking operation device illustrated in the second embodiment.

[0055] Figure 17 This is a front view showing the main parts of the structure of the electric braking operation device illustrated in the second embodiment.

[0056] Figure 18 This is a top view showing the main parts of the structure of the electric braking operation device illustrated in the third embodiment.

[0057] Figure 19 This is a perspective view taken from the upper right rear, showing the main structure of the electric braking operation device illustrated in the third embodiment.

[0058] Figure 20 This is a left-side view showing the main part of another embodiment of the electric braking operating device exemplified in the first embodiment, where the accommodating part is made of metal wire.

[0059] Figure 21 This is a left-side view showing the main part of another embodiment of the electric braking operating device exemplified in the first embodiment, where the accommodating part is composed of a linkage mechanism.

[0060] Figure 22 This is a perspective view showing the main parts of another embodiment of the electric braking operation device exemplified in the first embodiment, which includes a housing and the like arranged on the left front side of the driver's seat. Detailed Implementation

[0061] [First Implementation]

[0062] Hereinafter, as an example of a method for carrying out the present invention, a first embodiment of applying the braking system of the present invention for a work vehicle to a tractor, which is an example of a work vehicle, will be described based on the accompanying drawings.

[0063] Furthermore, the braking system for work vehicles of the present invention can be applied to passenger work vehicles other than tractors, such as passenger lawnmowers, passenger rice transplanters, combine harvesters, transport vehicles, wheel loaders, snowplows, etc.

[0064] like Figures 1-2As shown, the tractor 1 exemplified in this first embodiment is a vehicle configured to automatically travel in a field or the like, which is an example of a work site, via an automatic driving system for work vehicles. The automatic driving system includes an automatic driving unit 2 mounted on the tractor 1 and a portable communication terminal 3 configured to communicate with the automatic driving unit 2. For the portable communication terminal 3, a tablet-type personal computer or smartphone with a multi-touch display (e.g., an LCD panel) 4 that displays information related to automatic driving can be used.

[0065] like Figure 1 As shown, a rotary tiller 6, which is an example of an operating device, is connected to the rear of the tractor 1 via a three-point linkage mechanism 5, which can be raised, lowered, and rolled. Thus, the tractor 1 is configured as a rotary tiller.

[0066] In addition, it can replace the rotary tiller 6 and connect plows, disc harrows, tillers, core shovels, seeders, scattering devices, mowing devices and other operating devices to the rear of the tractor 1.

[0067] like Figures 1-4 As shown, the tractor 1 includes left and right front wheels 10 that function as a wheeled vehicle and can be driven and steered, left and right rear wheels 11 that can be driven, a cab 13 forming a riding-type driver's cab 12, an electronically controlled diesel engine (hereinafter referred to as the engine) with a common rail system 14, a transmission unit 15 that changes the speed of the power from the engine 14, a fully hydraulic power steering mechanism 16 that steers the left and right front wheels 10, a braking system 17 that brakes the left and right rear wheels 11, a working clutch that discontinuously transmits power to the rotary tiller 6, an electronically controlled clutch operating mechanism 19 that performs hydraulic operation of the working clutch, an electronically hydraulically controlled lifting drive mechanism 20 that lifts and lowers the rotary tiller 6, an electronically hydraulically controlled lateral sway drive mechanism 21 that drives the rotary tiller 6 in the lateral sway direction, an on-board control system 22 with various control units, a sensor unit 23 including various sensors that detect engine speed, vehicle speed, etc., and a positioning unit 24 that determines the current position and orientation of the tractor 1, etc.

[0068] Furthermore, an electronically controlled gasoline engine with an electronic speed governor or similar device can be used for engine 14. An electric power steering system with an electric motor or similar device can also be used for power steering mechanism 16.

[0069] like Figure 1 , Figures 3-4As shown, the driver's unit 12 includes a steering wheel 30 that can be manually steered by the front wheels 10 via the power steering mechanism 16, a passenger seat 31, a multi-touch LCD monitor that displays information related to autonomous driving, and various operating tools including a clutch pedal 33 and a gear lever.

[0070] like Figure 1 As shown, the cab 13 is supported in a vibration-damping manner by a front frame 34 located on the front side of the tractor 1 and a transmission unit 15 that also serves as a rear frame, via vibration-damping rubber or the like. The engine 14 is supported in a vibration-damping manner by the front frame 34. The engine 14 is covered by an engine cover 35 located on the front side of the tractor 1.

[0071] like Figure 2 As shown, the transmission unit 15 includes an electronically controlled continuously variable transmission (e.g., I-HMT) 36 that changes the speed of the power from the engine 14, and an electronically hydraulically controlled forward / reverse switching device 37 that switches the power changed by the continuously variable transmission 36 for forward and reverse use.

[0072] Furthermore, the continuously variable transmission (CVT) 36 can be replaced by an electronically hydraulically controlled stepped transmission in the transmission unit 15. The CVT 36 can also be a hydraulic mechanical CVT (HMT), a hydrostatic CVT (HST), or a belt CVT, etc.

[0073] like Figures 3-4 As shown, the braking system 17 includes: left and right brake pedals 40 and parking brake levers 41 located on the left and right sides of the driver's seat 12; left and right brakes 42 for braking the left and right rear wheels 11; a first linkage mechanism 43 that links the left and right brake pedals 40 and the left and right brakes 42 together; a second linkage mechanism 44 that links the parking brake lever 41 and the left and right brakes 42 together; and an electronic hydraulic control type first brake operation device 45 that operates the brake 42 on the inside of the turn in conjunction with steering operations at a set angle or higher on the left and right front wheels 10. When the passenger depresses either or both brake pedals 40, pulls the parking brake lever 41 to the braking position, or performs steering operations at a set angle or higher on the left and right front wheels 10 using the steering wheel 30, the braking system 17 activates the corresponding brake 42 to brake the corresponding rear wheel 11. Each brake 42 on the left and right sides has a force-applying component such as a compression spring inside, which applies force to restore the state of each brake 42 from the braking state of braking the rear wheel 11 to the released state of releasing the brake.

[0074] like Figure 2As shown, the vehicle control system 22 includes an engine control unit 22A for controlling the engine 14, a transmission control unit 22B for controlling the continuously variable transmission 36, forward / reverse switching device 37, etc., a steering control unit 22C for controlling the power steering mechanism 16, first braking operation device 45, etc., a work device control unit 22D for controlling work devices such as rotary tiller 6, an automatic driving control unit 22E for controlling automatic driving, and a non-volatile vehicle storage unit 22F for storing preset target driving paths for automatic driving. Each control unit 22A to 22E integrates electronic control units such as microcontrollers and various control programs. The automatic driving control unit 22E includes a display control module for controlling the operation of the aforementioned liquid crystal monitor, and is integrated into the liquid crystal monitor.

[0075] The sensor unit 23 includes a rotation sensor for detecting engine speed, a vehicle speed sensor for detecting the speed of the tractor 1, and a steering angle sensor for detecting the steering angle of the front wheels 10. In the tractor 1, the various control units 22A to 22E and the various sensors in the sensor unit 23 are connected via CAN (Controller Area Network) to communicate with each other.

[0076] like Figures 3-6 As shown, in the braking system 17, the left and right brake pedals 40 are arranged side-by-side on the lower front part of the right side of the driver's seat 12. The left and right brake pedals 40 are stressed by the left and right tension springs 46 in a manner that returns them to the released position. Each left and right brake pedal 40 has a shaft hole seat portion 40A supported by a rotating shaft 47 for pedal support extending in the left and right direction below the front of the steering wheel 30, a pedal arm portion 40B extending rearward and downward from the shaft hole seat portion 40A, and a pedal portion 40C mounted on the free end portion of the pedal arm portion 40B. The shaft hole seat portion 40A of the right brake pedal 40 rotates relative to the rotating shaft 47, and the right brake pedal 40 has an associated arm portion 40D extending forward and downward from the shaft hole seat portion 40A. The shaft hole seat portion 40A of the left brake pedal 40 rotates integrally with the associated arm 48 fixed to the left end of the rotating shaft 47 via the rotating shaft 47.

[0077] like Figures 3-4 As shown, the transmission unit 15 includes left and right brakes 42. Each left and right brake 42 has an operating shaft 49 protruding laterally outward from its front end toward the vehicle body, and an operating arm 50 fixed to the protruding end of the operating shaft 49, etc.

[0078] like Figures 3-6As shown, each of the left and right first linkage mechanisms 43 has a shaft hole seat member 52 rotatably supported on a left or right fixed shaft 51 extending in the left-right direction below the rotation shaft 47, a first linkage rod 53 in the vertical direction formed by a linkage arm 40D or linkage arm 48 extending over the right brake pedal 40 and a first arm 52A of the shaft hole seat member 52, and a second linkage rod 54 in the front-back direction formed by a second arm 52B extending over the shaft hole seat member 52 and an operating arm 50 of the brake 42. The left first linkage mechanism 43 includes the aforementioned rotation shaft 47 and linkage arm 48. That is, the left and right first linkage mechanisms 43 are configured as a rod linkage type that links the left and right brake pedals 40 to the left and right brakes 42 via the first linkage rod 53, the second linkage rod 54, etc.

[0079] With the above structure, if only the right brake pedal 40 is depressed, the operating force is transmitted to the operating arm 50 of the right brake 42 via the first linkage mechanism 43 on the right side. This switches the braking system 17 to a right-side braking state, where the right rear wheel 11 is braked by the right brake 42. Subsequently, if the right brake pedal 40 is depressed, the system switches from the right-side braking state to the depressed state.

[0080] If only the left brake pedal 40 is engaged, the operating force is transmitted via the first linkage mechanism 43 on the left to the operating arm 50 of the left brake 42, thereby switching the braking system 17 to a left-side braking state where the left rear wheel 11 is braked by the left brake 42. Subsequently, if the engagement of the left brake pedal 40 is released, the system switches from the left-side braking state to the released state.

[0081] If both left and right brake pedals 40 are depressed, the operating force is transmitted via the first linkage mechanism 43 to the operating arms 50 of the left and right brakes 42, thereby switching the braking system 17 to a braking state where the left and right rear wheels 11 are braked by the left and right brakes 42. Afterwards, if the depressing of the left and right brake pedals 40 is released, the braking state switches to a released state.

[0082] Therefore, when the passenger manually drives the tractor 1, the passenger can operate the steering wheel 30 in the turning direction while simultaneously depressing the brake pedal 40 on the inside of the turn, thereby reducing the turning radius of the tractor 1 during braking and turning. Alternatively, the passenger can depress both the left and right brake pedals 40, thereby maintaining the tractor 1 in a forward posture while braking and decelerating or stopping it.

[0083] like Figures 5-6As shown, the braking system 17 has a connection mechanism 55 that can switch between an engaged state connecting the left and right brake pedals 40 and a disengaged state releasing the connection. The connection mechanism 55 includes an operating lever 56 supported on the right brake pedal 40 and movable in the left and right directions; a compression spring 57 that applies force to the left end of the operating lever 56 protruding towards the left brake pedal 40; and a guide plate 58 that guides the guided portion 56A of the operating lever 56. A J-shaped guide hole 58a is formed in the guide plate 58, guiding the guided portion 56A of the operating lever 56 throughout both the engaged and disengaged positions. A through hole 40E is formed in the left brake pedal 40, into which the left end of the operating lever 56 is inserted when the guided portion 56A of the operating lever 56 is in the engaged position (see reference). Figure 8 , Figures 11-12 ).

[0084] With the above structure, if the operating lever 56 is operated with the guided portion 56A of the operating lever 56 in the connected position, the left end of the operating lever 56 is inserted into the through hole 40E of the left brake pedal 40. This switches the connecting mechanism 55 to a connected state connecting the left and right brake pedals 40, and this connected state is maintained by the compression spring 57. If the operating lever 56 is operated with the guided portion 56A of the operating lever 56 in the released position, the left end of the operating lever 56 is pulled out from the through hole 40E of the left brake pedal 40. This switches the connecting mechanism 55 to a released state releasing the connection between the left and right brake pedals 40, and this released state is maintained by the compression spring 57.

[0085] Therefore, when the passenger is manually driving the tractor 1 in the field, the passenger operates the lever 56 to switch the coupling mechanism 55 to the disengaged state, thereby enabling braking and turning necessary when driving in the field. Alternatively, when the passenger is manually driving the tractor 1 outside the field, the passenger operates the lever 56 to switch the coupling mechanism 55 to the engaged state, thereby avoiding concerns about braking and turning unnecessary when driving outside the field.

[0086] In the braking system 17, the parking brake lever 41 is located near the left side of the seat 31 in the driver's compartment 12. The parking brake lever 41 is configured to be a two-position switchable type, that is, it is switched to and held in two positions: the upper braking position, which switches the left and right brakes 42 to the braking state, and the lower release position, which switches them to the release state.

[0087] like Figures 3-4As shown, the second linkage mechanism 44 for the parking brake includes left and right control cables 59, an equalizer unit 60 connecting one end of the inner cable of the left and right control cables 59 to the parking brake lever 41, and left and right chain link plates 61 and left and right linkage pins 62 connecting the other end of the left and right inner cables to the operating arms 50 of the left and right brakes 42. That is, the second linkage mechanism 44 is configured as a cable linkage, meaning that the parking brake lever 41 is linked to the left and right brakes 42 via the left and right control cables 59, etc. The left and right chain link plates 61 have elongated holes through which the linkage pins 62, which are fixed to the left and right operating arms 50, pass. These elongated holes function as accommodative parts to allow displacement of the left and right operating arms 50 relative to the left and right chain link plates 61 as the left and right brake pedals 40 are depressed.

[0088] With the above structure, if the parking brake lever 41 is pulled up from the lower release position to the upper brake position and held in the brake position, the operating force is transmitted to the operating arms 50 of the left and right brakes 42 via the second linkage mechanism 44. This switches the braking system 17 to a parking brake state, where the left and right rear wheels 11 are braked by the left and right brakes 42 and this braking state is maintained. Then, if the parking brake lever 41 is pressed down from the upper brake position to the lower release position and held in the release position, the parking brake state switches to the released state.

[0089] like Figure 5 As shown, in the left and right first linkage mechanisms 43, an elongated hole 53a with vertical length is formed at the lower end of each first linkage rod 53, and the linkage pin 63 fixed to the first arm portion 52A of the shaft hole seat component 52 passes through the elongated hole 53a. Figures 3-5 As shown, when the left and right brakes 42 are switched from a released state to a parking brake state by pulling up the parking brake lever 41, the left and right first linkage mechanisms 43 are linked to this switch. Simultaneously, the left and right second linkage levers 54 are pulled rearward, and the second arms 52B of the left and right shaft hole seat components 52 swing rearward. Linked to this swinging displacement, the first arms 52A of the left and right shaft hole seat components 52 swing upward. At this time, the elongated holes 53a of each first linkage lever 53 function as accommodating parts, allowing the left and right first arms 52A to swing upward relative to the left and right first linkage levers 53. This avoids the reduced operability caused by the left and right brake pedals 40 becoming heavier when the left and right brakes 42 are switched to the parking brake state by pulling up the parking brake lever 41.

[0090] like Figures 3-6As shown, in the braking system 17, the first braking operating device 45 includes an automatic braking hydraulic unit 64 equipped with two hydraulic cylinders and two solenoid valves corresponding to the left and right brakes 42, a pair of push-pull linkages 65 pushed and pulled by the hydraulic unit 64, a pair of crank arms 66 that swing about a longitudinal axis in conjunction with the pair of push-pull linkages 65, left and right control cables 67 extending from the pair of crank arms 66 toward the left and right shaft hole seat members 52, and left and right chain link plates 68 and left and right connecting pins 69 connecting the front ends of the inner cables 67A of the left and right control cables 67 to the third arm portions 52C of the left and right shaft hole seat members 52. Oil supplied to the hydraulic unit 64 by a hydraulic pump driven by power from the engine 14 is supplied. The left and right chain link plates 68 have elongated holes 68a through which the connecting pins 69 fixed to the left and right third arms 52C pass. The elongated holes 68a function as accommodating parts to allow the left and right third arms 52C to swing relative to the left and right chain link plates 68 as the left and right brake pedals 40 are depressed or the parking brake lever 41 is pulled up.

[0091] like Figure 2 As shown, the braking system 17 includes a steering control unit 22C. When the automatic braking mode is selected by operating the automatic braking selection switch provided on the driver's side 12, the steering control unit 22C controls the operation of the hydraulic unit 64 in the first braking operation device 45 based on the detection of the steering angle sensor, and performs automatic braking control to operate the left and right brakes 42. During automatic braking control, when the steering angle of the left and right front wheels 10 is less than the set angle, the steering control unit 22C maintains each solenoid valve of the hydraulic unit 64 in the discharge state, thereby maintaining the left and right hydraulic cylinders in the contracted state and maintaining the left and right brakes 42 in the released state. Moreover, if the steering angle of the left and right front wheels 10 is greater than or equal to the set angle, the solenoid valve corresponding to the inner rear wheel 11 is switched to the supply state, thereby extending the hydraulic cylinder corresponding to the inner rear wheel 11 and switching the inner brake 42 to the braking state.

[0092] With the above structure, during manual driving in automatic braking mode, when the steering angle of the left and right front wheels 10 based on the steering wheel 30 rotation is less than a set angle, the braking system 17 maintains the left and right brakes 42 in a released state via the first braking operation device 45. Thus, the turning state of the tractor 1 is maintained as a normal turning state where the tractor 1 turns with a turning radius corresponding to the steering angle of the left and right front wheels 10. Furthermore, if the steering angle of the left and right front wheels 10 based on the steering wheel 30 rotation becomes a set angle or higher, the first braking operation device 45 switches the brake 42 on the inside of the turn to a braking state. Thus, the turning state of the tractor 1 is switched to a braking turning state where the tractor 1 turns with a turning radius smaller than that in the normal turning state. Afterwards, if the steering angle of the left and right front wheels 10 based on the steering wheel 30 rotation is less than the set angle, the first braking operation device 45 switches the left and right brakes 42 in a released state. Thus, the turning state of the tractor 1 switches back to the aforementioned normal turning state.

[0093] That is, by selecting the automatic braking mode during manual driving, when the left and right front wheels 10 are turned to a angle above the set angle, even if the driver does not depress the brake pedal 40 on the inside of the turn, the braking system 17 automatically switches the turning state of the tractor 1 to normal turning state and braking turning state based on whether the left and right front wheels 10 are below or above the set angle. As a result, the driver can easily perform turning operations to make small turns of the tractor 1 simply by turning the steering wheel 30.

[0094] like Figure 5 As shown, in each of the left and right first linkage mechanisms 43, as described above, an elongated hole 53a is formed at the lower end of the first linkage rod 53, which functions as a accommodating part. Thus, even when the left and right brake pedals 40 are connected by the linkage mechanism 55, when the left and right front wheels 10 are turned to a set angle or higher, the first brake operation device 45 can activate the brake 42 on the inside of the turn, thereby switching the turning radius of the tractor 1 to a braking turn state.

[0095] The positioning unit 24 includes a satellite navigation device that uses GPS (Global Positioning System), an example of a Navigation Satellite System (NSS), to determine the current position and orientation of the tractor 1, and an inertial measurement unit (IMU) that uses a three-axis gyroscope and three-directional accelerometers to determine the attitude and orientation of the tractor 1. For GPS-based positioning methods, there are DGPS (Differential GPS) and RTK-GPS (Real-Time Kinematic GPS). In this embodiment, RTK-GPS, suitable for positioning moving objects, is used. Therefore, as... Figure 1 As shown, a base station 73 capable of positioning using RTK-GPS is set up at a known location around the field.

[0096] like Figures 1-2 As shown, both tractor 1 and base station 73 are equipped with receivers from GPS satellite 74 (see reference). Figure 1 The positioning unit 24 includes GPS antennas 75 and 76 that transmit radio waves, and communication modules 77 and 78 that enable wireless communication of various data, including positioning data between the tractor 1 and the base station 73. Thus, the satellite navigation device of the positioning unit 24 can accurately determine the current position and orientation of the tractor 1 based on positioning data received from the GPS satellite 74 by the GPS antenna 75 on the tractor side and the GPS antenna 76 on the base station side. Alternatively, the positioning unit 24, equipped with a satellite navigation device and an inertial measurement unit, can accurately determine the current position, orientation, and attitude angles (yaw angle, side yaw angle, and longitudinal yaw angle) of the tractor 1.

[0097] In this tractor 1, the inertial measurement unit 24, GPS antenna 75, and communication module 77 are included in... Figure 1 The antenna unit 79 shown is located in the upper left and right center positions of the front surface side of the cab 13.

[0098] like Figure 2As shown, the portable communication terminal 3 includes: a terminal control unit 80 that integrates an electronic control unit such as a microcontroller and various control programs, and a communication module 81 that can wirelessly communicate with the communication module 77 on the tractor side, including various data such as positioning data. The terminal control unit 80 includes a display control unit 80A that controls the operation of the display unit 4, a driving path generation unit 80B that generates a target driving path for automatic driving, and a non-volatile terminal storage unit 80C that stores the target driving path generated by the driving path generation unit 80B.

[0099] The target travel path includes not only multiple work path sections arranged in parallel at constant intervals corresponding to the working width of the tractor 1, and multiple non-work turning path sections that connect the ends and beginnings of adjacent work path sections in the order of travel, but also appropriate engine speed, appropriate vehicle speed, the direction of travel of the tractor 1, and the front wheel steering angle in the turning path section, which are set according to the driving mode of the tractor 1 in the various travel path sections.

[0100] When the driving mode selection switch located on the driver unit 12 is operated to select the automatic mode, and all conditions for starting automatic driving are met, the automatic driving control unit 22E switches the driving mode of the tractor 1 from manual mode to automatic mode. After the automatic driving control unit 22E switches the driving mode of the tractor 1 to automatic mode, and the user issues the start command for automatic driving by operating the display unit 4 of the portable communication terminal 3, automatic driving control begins, in which the tractor 1 automatically drives along the target driving path while using the positioning unit 24 to obtain the current position of the tractor 1.

[0101] The automatic driving control based on the automatic driving control unit 22E includes automatic engine control processing that sends control commands related to the engine 14 for automatic driving to the engine control unit 22A, automatic transmission control processing that sends control commands related to the continuously variable transmission 36, forward / reverse switching device 37, etc., to the transmission control unit 22B, automatic steering control processing that sends control commands related to steering for automatic driving to the steering control unit 22C, and automatic operation control processing that sends control commands related to the rotary tiller 6 and other operating devices to the operating device control unit 22D.

[0102] In the automatic control processing for the engine, the automatic driving control unit 22E sends an engine start command based on the establishment command of the engine start condition to start the engine 14, an engine stop command based on the establishment command of the engine stop condition to stop the engine 14, and an engine speed change command based on the appropriate engine speed included in the target driving path to the engine control unit 22A.

[0103] In the automatic control processing for transmission, the automatic driving control unit 22E sends transmission operation commands to the transmission control unit 22B, such as transmission operation commands that instruct the continuously variable transmission 36 to perform transmission operation based on the appropriate vehicle speed included in the target driving path, forward and backward switching commands that instruct the forward and backward switching device 37 to perform forward and backward switching operation based on the direction of travel of the tractor 1 included in the target driving path, and neutral switching commands that instruct the forward and backward switching device 37 to switch to a neutral state based on the stopping position of the tractor 1 included in the target driving path.

[0104] In the automatic control processing for steering, the automatic driving control unit 22E sends steering control commands, such as those instructing the left and right front wheels 10 to the steering control unit 22C, based on the front wheel steering angle included in the target driving path.

[0105] In the automatic control processing for operation, the automatic driving control unit 22E sends operation start commands, which instruct the rotary tiller 6 to switch to the operation state based on the operation start location included in the target driving path, and operation stop commands, which instruct the rotary tiller 6 to switch to the non-operation state based on the operation stop location included in the target driving path, to the operation device control unit 22D.

[0106] The engine control unit 22A executes various control commands related to the engine 14 sent from the automatic driving control unit 22E through the above-mentioned automatic engine control processing, such as automatic engine start control to automatically start the engine 14, automatic engine stop control to automatically stop the engine 14, and automatic engine speed change control to automatically change the engine speed.

[0107] The transmission control unit 22B executes various control commands related to the continuously variable transmission 36, forward / reverse switching device 37, etc., sent from the automatic driving control unit 22E through the automatic control processing for transmission, and performs automatic transmission control to control the operation of the continuously variable transmission 36 to make the speed of the tractor 1 appropriate, automatic forward / reverse switching control to control the operation of the forward / reverse switching device 37 to switch the direction of travel of the tractor 1, and automatic stop control to neutralize the forward / reverse switching device 37 and stop the tractor 1 from moving.

[0108] The steering control unit 22C executes automatic steering control of the left and right front wheels 10 by controlling the working steering of the power steering mechanism 16, and automatic braking and turning control of the first braking operation device 45 to operate and the brake 42 on the inside of the turn when the left and right front wheels 10 are steered to a set angle or above.

[0109] The work device control unit 22D executes various control commands related to the rotary tiller 6 sent from the automatic travel control unit 22E via the aforementioned automatic control processing for work. These commands include automatic work start control, which lowers the rotary tiller 6 to the working height and initiates its operation by controlling the lifting drive mechanism 20 and the clutch operating mechanism 19; and automatic work stop control, which stops the rotary tiller 6 and raises it to a non-working height. Furthermore, in the working state where the work device control unit 22D lowers the rotary tiller 6 to the working height and initiates its operation, the work device control unit 22D performs automatic tillage depth maintenance control, which controls the lifting drive mechanism 20 to maintain the tillage depth of the rotary tiller 6 at a set depth, based on the detection of the tillage depth by the tillage depth sensor of the rotary tiller 6. It also performs automatic sway angle maintenance control, which controls the sway direction drive mechanism 21 to maintain the tilt posture of the rotary tiller 6 in the sway direction at a set posture (e.g., a horizontal posture), based on the detection of the accelerometer (tilt sensor) of the inertial measurement device that detects the sway angle of the tractor 1.

[0110] Thus, the tractor 1 is equipped with an automatic driving unit 2, which, through a power steering mechanism 16, a clutch operating mechanism 19, a lifting drive mechanism 20, a side sway drive mechanism 21, an on-board control system 22, a sensor unit 23, a positioning unit 24, and a communication module 77, enables the tractor 1 to automatically travel along the target driving path while appropriately controlling the operation of the rotary tiller 6.

[0111] The automatic driving control based on the automatic driving control unit 22E includes emergency stop processing, which causes the tractor 1 to stop urgently when any of the emergency stop conditions are met, and emergency stop reporting processing, which reports the emergency stop. In the emergency stop processing, the automatic driving control unit 22E sends an emergency stop command to the engine control unit 22A and the steering control unit 22C, etc. In the emergency stop reporting processing, the automatic driving control unit 22E activates the reporting devices 83 (see reference 83) such as the emergency stop indicator lights on the vehicle body. Figure 2The engine control unit 22A, based on the emergency stop command from the automatic driving control unit 22E, performs emergency engine stop control to bring the engine 14 to an emergency stop. The steering control unit 22C, based on the emergency stop command from the automatic driving control unit 22E, performs emergency driving stop control to bring the tractor 1 to a stop by engaging the left and right brakes 42. The portable communication terminal 3, based on the emergency stop report command from the automatic driving control unit 22E, performs emergency stop report processing, such as switching the display screen of the display unit 4 to emergency stop report mode. The conditions for emergency stop include, for example, a decrease in engine speed below a set lower limit, and emergency stop via the portable communication terminal 3 or the emergency stop remote control 90 (see reference). Figure 2 The acquisition of emergency stop commands sent from the portable communication terminal 3 or the emergency stop remote control 90 by human operation, or abnormalities in the transmission control unit 22B, etc.

[0112] like Figure 2 , Figures 7-12 As shown, the braking system 17 includes an electrically operated second brake operating device 100. During emergency driving stop control of the steering control unit 22C, which corresponds to an emergency stop command from the automatic driving control unit 22E, this second brake operating device 100 activates the left and right brakes 42. The second brake operating device 100 is located near the right side of the right brake pedal 40 in the driver's compartment 12. The second brake operating device 100 includes: an operable body 101 connected to the right brake pedal 40, an electric actuator 102 for operating the operable body 101 in a forward and backward direction, and a accommodating part 103 that allows displacement of the right brake pedal 40 and other components relative to the electric actuator 102 between the right brake pedal 40 and the electric actuator 102 as the brake pedal 40 is depressed.

[0113] The second braking operating device 100 is described in detail, such as Figures 8-12As shown, the operated body 101 includes: a first component 104 and a second component 105 connected to the pedal arm 40B of the brake pedal 40 on the right side; a shock absorber 107 connected to the second component 105 via a connecting pin 106 extending laterally, which can swing vertically; and a chain link plate 108 connected to the shock absorber 107, which can be adjusted in position in the front-rear direction. Furthermore, an elongated hole 108a, which functions as a accommodating portion 103, is formed in the chain link plate 108. The electric actuator 102 uses an electric motor with a worm gear reducer 102A. The electric motor 102 is switched between a first operating state (outputting forward rotation power), a second operating state (outputting reverse rotation power), and an operating stop state (stopping rotation power output) by the control operation of the steering control unit 22C. Between the operated body 101 and the worm gear reducer 102A of the electric motor 102, there is a reduction gear set 111 that further reduces the power from the worm gear reducer 102A by having a small-diameter input gear 109 and a large-diameter output gear 110, and a connecting pin 112 that connects the outer peripheral side of the output gear 110 in the reduction gear set 111 to the operated body 101 via a accommodating portion 103. The connecting pin 112 is fixed to the outer peripheral side of the output gear 110 in a state where it passes through the elongated hole 108a of the chain link plate 108. The connecting pin 112 is moved from the non-operating position (refer to) where the right brake pedal 40 (right brake 42) is not operated by the forward rotation power from the electric motor 102. Figures 8-11 The maximum operating position is achieved by moving the brake pedal 40 (right brake 42) to the right side (see reference). Figure 12 The linkage pin 112 moves from the maximum operating position to the non-operating position via reverse power from the electric motor 102. The non-operating position of the linkage pin 112 is set such that when the right brake pedal 40 is in the depressed / released position, the linkage pin 112 is located at the front end of the elongated hole 101a. Thus, when the right brake pedal 40 is depressed, the forward movement of the operating body 101 relative to the linkage pin 112 caused by this operation is permitted by the elongated hole 108a of the link plate 108. A first limit switch 113 is provided in the non-operating position of the linkage pin 112 to detect when the linkage pin 112 has reached the non-operating position. A second limit switch 114 is provided in the maximum operating position of the linkage pin 112 to detect when the linkage pin 112 has reached the maximum operating position.

[0114] In emergency driving stop control, the steering control unit 22C performs forward power output processing by switching the electric motor 102 from the working stop state to the first working state and outputting forward rotational force from the electric motor 102, based on the emergency stop command from the automatic driving control unit 22E, and rotational power output stop processing by switching the electric motor 102 from the first working state to the working stop state based on the detection of the second limit switch 114 and stopping the output of rotational power from the electric motor 102.

[0115] With the above structure, when the tractor 1 is driving automatically in an unmanned state, if any condition for emergency stop is met and an emergency stop command is sent from the automatic driving control unit 22E, the steering control unit 22C will process forward rotation power output according to the emergency stop command. At this time, if the left and right brake pedals 40 are connected by the connecting mechanism 55, the connecting pin 112 moves from the non-operating position to the maximum operating position by means of the forward rotation power from the electric motor 102, and in conjunction with this movement, the left and right brake pedals 40 are pulled from the depressed release position to the depressed limit position against the action of the left and right tension springs 46. Thus, the forward rotation power from the electric motor 102 is transmitted to the operating arms 50 of the left and right brakes 42 via the left and right brake pedals 40 and the left and right first connecting mechanisms 43, and the left and right brakes 42 switch from the release state to the braking state against the action of the internal force-applying components. As a result, the tractor 1, which is driving automatically in an unmanned state, can be quickly braked to a stop.

[0116] Furthermore, if the linkage pin 112 reaches the maximum operating position, the steering control unit 22C stops the rotational power output based on the detection of the second limit switch 114, thereby stopping the output of forward rotational power from the electric motor 102. Thus, the linkage pin 112 stops moving at the maximum operating position, and is maintained at the maximum operating position by the action of the worm gear reducer 102A. Consequently, the movement of the left and right brake pedals 40 in the release direction is prevented by the action of the left and right tension springs 46. As a result, the left and right brakes 42 can be maintained in a braking state, and the tractor 1 can be maintained in a braked stopped state.

[0117] Furthermore, since the left and right brake pedals 40 and the left and right first linkage mechanisms 43 are highly reliable components that are unlikely to malfunction even when frequently used during manual driving by the passenger, the linkage structure will not be complicated by the dedicated linkage mechanism formed by the brakes 42 extending from the second brake operating device 100 to the left and right, and the tractor 1 can be reliably stopped when unattended.

[0118] Furthermore, unlike the first brake operating device 45, which operates the left and right brakes 42 via an electronically controlled hydraulic pump powered by the engine, the second brake operating device 100 can maintain the left and right brakes 42 in a braking state even when the engine 14 stops and the hydraulic pressure drops. Therefore, even if the engine control unit 22A performs emergency engine stop control to bring the engine 14 to an emergency stop according to an emergency stop command from the automatic travel control unit 22E, the tractor 1 can be maintained in a braked stop state. As a result, even if the emergency stop position of the tractor 1 is on an inclined surface tilted towards the direction of travel, the risk of the tractor 1 unexpectedly sliding down is avoided.

[0119] Furthermore, when the passenger manually drives the tractor 1 and operates the right or left / right brake pedal 40, the accommodating part 103 enables the smooth braking operation of the right or left / right brake 42, which is linked to the operation of the pedal, without being obstructed by the electric motor 102.

[0120] Furthermore, since the second braking operation device 100 is located on the right side of the driver's compartment 12, which is less frequently used when getting on and off the vehicle due to the presence of numerous operating tools such as the left and right brake pedals 40 and accelerator pedals, it can prevent the reduced ease of getting on and off the vehicle from the left side of the driver's compartment 12, which is more frequently used when getting on and off the vehicle.

[0121] That is, the braking system 17 is equipped with an emergency stop braking system that does not obstruct the passenger's manual driving of the tractor 1 or the passenger's getting on and off the left side of the driver's seat 12. This system enables the tractor 1 to be quickly braked to a stop in the event of an abnormality while the tractor 1 is automatically driving in an unmanned state, and can maintain the tractor 1 in a braked stop state even when the engine is stopped.

[0122] After the aforementioned emergency stop procedure, if power is restored via the key switch on the driver's unit 12, the automatic driving control unit 22E performs an emergency stop release procedure. During this procedure, the automatic driving control unit 22E sends an emergency stop release command to the engine control unit 22A. The engine control unit 22A then allows the engine 14 to start based on the emergency stop release command from the automatic driving control unit 22E.

[0123] As described above, the second braking operation device 100 has a second component 105 connected to the right brake pedal 40, and a shock absorber 107 connected to the second component 105 via a connecting pin 106. Therefore, when the tractor 1 is braked to a stop by operating the left and right brakes 42 via the second braking operation device 100, the connection between the second component 105 on the brake pedal side and the shock absorber 107 on the electric motor side can be released by pulling out the connecting pin 106. Consequently, the left and right brake pedals 40 are restored from their depressed position to their released position by the action of the left and right tension springs 46. Furthermore, the left and right brakes 42 are restored from the braking state to the released state by the action of their internal force-applying components.

[0124] That is, when the tractor 1 is brought to an emergency stop via the aforementioned emergency stop control operation, after the power is turned off by operating the key switch, the connecting pin 106 is pulled out, disconnecting the second component 105 on the brake pedal side of the operated body 101 from the shock absorber 107 on the electric motor side. Furthermore, after this disconnection, the power is restored by operating the key switch, thereby enabling the passenger to manually drive the tractor 1. As a result, the tractor 1 can be moved to a safe location, repair shop, etc., by the passenger's manual driving.

[0125] By the way, if Figure 13 As shown, the linkage pin 112 of the second braking operating device 100 is secured to the outer periphery of the output gear 110 by a nut 115, making it removable. The output gear 110 has a shaft hole seat 110A that supports the linkage pin 112 at its fixed location. The shaft hole seat 110A and the head 112A of the linkage pin 112 together restrict the left-right displacement of the link plate 108 located between them.

[0126] With the above structure, when the tractor 1 is braked to a stop by operating the left and right brakes 42 caused by operating the second brake operating device 100, the fixing of the connecting pin 112, which is secured by the nut 115, to the output gear 110 is released, and the connecting pin 112 is pulled out from the output gear 110, thereby releasing the connection between the output gear 110 of the reduction gear set 111 and the operated body 101. In this way, similar to the case described above where the connection between the second component 105 on the brake pedal side and the shock absorber 107 on the electric motor side in the operated body 101 is released by pulling out the connecting pin 106, the left and right brake pedals 40 are restored from the depressed position to the released position by the action of the left and right tension springs 46. Furthermore, the left and right brakes 42 are restored from the braking state to the released state by the action of the internal force-applying components.

[0127] That is, even if the tractor 1 is brought to an emergency stop via the aforementioned emergency stop control operation, after turning off the power by operating the key switch and disengaging the output gear 110 of the reduction gear set 111 from the operated body 101 by pulling out the linkage pin 112, the passenger can manually drive the tractor 1 by operating the key switch again after this disengagement. As a result, the tractor 1 can be moved to a safe location, repair shop, etc., by the passenger's manual driving.

[0128] like Figures 8-12 As shown, through the operation of the electric motor 102, the connecting pin 112 moves to the non-operating position (see reference). Figures 8-11 ) and maximum operating position (refer to Figure 12 The movement causes the second braking operating device 100 to transition between a non-operating state (no operation of the left and right brakes 42) and a maximum operating state (maximum operation of the left and right brakes 42). This transition can be detected by the aforementioned first limit switch 113 and second limit switch 114. That is, the first limit switch 113 and second limit switch 114 function as state detection sensors for detecting the non-operating state and the maximum operating state of the second braking operating device 100.

[0129] As a result, by utilizing the detection of the first limit switch 113 and the second limit switch 114, it is easy to confirm the operation of the second braking operation device 100 before the tractor 1 is driven automatically in an unmanned state, and to monitor the status of the second braking operation device 100 in the tractor 1 during automatic driving in an unmanned state.

[0130] like Figures 7-13 As shown, the second braking operating device 100 has a housing 116 mounted on the base plate (an example of a vehicle body fixing part) 38 of the driver's compartment 12. The housing 116 includes: a base plate 117 that is bolted to the base plate 38 for removability; a left housing 118 bolted to the base plate 38 and the base plate 117; a first support plate 119 fused to the inner side of the left housing 118; a second support plate 120 mounted at predetermined intervals to the side wall of the left housing 118; and a right housing 121 bolted to the left housing 118. The housing 116 forms a receiving space between the left housing 118 and the right housing 121.

[0131] Within the housing 116, three stepped bolts 122 extending to the right from the side wall of the left housing 118 are fixed to the left housing 118. A second support plate 120 is mounted to the side wall of the left housing 118 via these stepped bolts 122. The stepped bolt 122 located at the center of the side wall serves as a pivot 123 supporting the output gear 110 for rotation. On the side wall of the left housing 118, guide holes 118a for the guide pins 112 in both the non-operating and maximum operating positions are formed in an arc shape centered on the pivot 123. An electric motor 102 is mounted on the first support plate 119 using three bolts 124. An input gear 109, meshing with the output gear 110, is mounted on the output shaft of the worm gear reducer 102A in the electric motor 102. The second support plate 120 is configured such that one end functions as a first blocking part 120A to block the linkage pin 112 from reaching the non-operating position, and the other end functions as a second blocking part 120B to block the linkage pin 112 from reaching the maximum operating position. Furthermore, a first limit switch 113 is installed at one end of the second support plate 120, and a second limit switch 114 is installed at the other end of the second support plate 120.

[0132] With the above structure, the electric motor 102, the reduction gear set 111, the first limit switch 113, and the second limit switch 114 are housed in the housing 116 of the second brake operating device 100. Thus, the housing 116, the electric motor 102, the reduction gear set 111, the first limit switch 113, and the second limit switch 114 can be detachably mounted on the base plate 38 as an integrated drive unit. Furthermore, after installing this drive unit, the operated body 101 connected to the right brake pedal 40 is connected to the output gear 110 on the drive unit side via the accommodating part 103 and the connecting pin 112, so that the operated body 101 can be operated by the electric motor 102. Therefore, the second brake operating device 100 can be assembled on the driving unit 12 in a state where the left and right brakes 42 can be operated by the second brake operating device 100.

[0133] That is, the second brake operating device 100 can be easily assembled relative to the driver unit 12 without making major changes to the structure of the driver unit 12, thereby enabling subsequent addition of the second brake operating device 100 to the tractor 1. As a result, the assembly of the second brake operating device 100 to the tractor 1 becomes easy, and maintenance such as replacing the second brake operating device 100 in case of malfunction is easy.

[0134] Furthermore, when the aforementioned connecting pin 112 is removed to enable manual driving of the tractor 1 in an emergency stop, the right housing 121 can be removed from the second brake operating device 100 by releasing the bolt connection between the right housing 121 and the left housing 118. This allows for a significant opening of the right side of the housing 116, facilitating the operation of removing the nut 115 for the connecting pin 112.

[0135] like Figures 10-12 As shown, the first blocking portion 120A and the second blocking portion 120B of the second support plate 120 function as movement limiting portions that restrict the movement range of the linkage pin 112 between the non-operating position and the maximum operating position. The movement range of the linkage pin 112 is set such that the linkage pin 112 crosses the imaginary straight line L1 and extends throughout the range of movement between the non-operating position and the maximum operating position, wherein the imaginary straight line L1 passes through the connection point of the operated body 101 relative to the brake pedal 40 on the right side, i.e., the connecting pin 106, and the rotation center of the output gear 110, i.e., the support shaft 123.

[0136] With the above structure, when the second braking operating device 100 operates the left and right brakes 42, firstly, the forward rotational power from the electric motor 102 is transmitted to the output gear 110, thereby causing the output gear 110 to rotate in the braking direction, and thus the connecting pin 112 moves while tracing an arc from the non-operating position to the maximum operating position. At this time, as Figure 14As shown, the braking force A of the left and right brakes 42 increases according to the amount of movement of the connecting pin 112 from passing through the clearance region including the non-operating position to reaching the maximum operating position. On the other hand, regarding the operating load B applied to the electric motor 102, as the braking force A of the left and right brakes 42 increases, the reaction force generated inside the left and right brakes 42 from each friction plate and other components increases, and the left and right brake pedals 40 are forceped by the tension of the left and right tension springs 46 to be restored to the released position. Therefore, in the first range of movement of the connecting pin 112 from passing through the clearance region to crossing the imaginary straight line L1, the closer the connecting pin 112 is to the imaginary straight line L1, the heavier the operating load B applied to the electric motor 102. Conversely, as the linkage pin 112 approaches the imaginary straight line L1, the angle θ between the connecting line L2 linking the linkage pin 112 and the rotation center of the output gear 110 and the operated body 101 becomes smaller. Consequently, the reaction force from the left and right brakes 42 and the tension force from the left and right tension springs 46 applied to the left and right brake pedals 40 are less effective as forces to return the linkage pin 112 to the non-operating position, thus reducing the increase in the operating load B applied to the electric motor 102. Subsequently, if the linkage pin 112 crosses the imaginary straight line L1, the reaction force from the left and right brakes 42 and the tension force from the left and right tension springs 46 switch to assisting the braking operation performed by the electric motor 102 on the left and right brakes 42. Therefore, in the second movement range of the linkage pin 112 from crossing the imaginary straight line L1 to reaching the maximum operating position, the further the linkage pin 112 moves away from the imaginary straight line L1 and closer to the maximum operating position, the lighter the operating load B applied to the electric motor 102. Furthermore, when the linkage pin 112 reaches its maximum operating position, and its movement in the braking direction is restricted by the second blocking part 120B, it is subjected to a braking force by the reaction force from the left and right brakes 42 and the tension force from the left and right tension springs 46. Therefore, even if, for example, damage occurs to the worm gear reducer 102A in the electric motor 102 or the output gear 110 when the linkage pin 112 crosses the imaginary straight line L1 and reaches the second movement range, the linkage pin 112 moves to its maximum operating position and remains there due to the reaction force from the left and right brakes 42 and the tension force from the left and right tension springs 46. This allows the left and right brakes 42 to be maintained in a braking state, thereby keeping the tractor 1 in a stopped state.

[0137] As a result, the operating load applied to the electric motor 102 can be reduced during the braking operation performed by the brakes 42 on the left and right sides of the second braking operation device 100, and the tractor 1 can be maintained in a braked and stopped state regardless of damage to the worm gear reducer 102A in the electric motor 102, damage to the output gear 110, etc., when the tractor 1 is braked and stopped by the operation of the second braking operation device 100.

[0138] like Figures 8-10 As shown, the first component 104 and the second component 105 are bolted together so that they clamp the pedal arm 40B of the right brake pedal 40, thereby connecting the operating body 101 to the right brake pedal 40. Thus, without performing the connection process on the right brake pedal 40 to the operating body 101, the operating body 101 can be connected to the right brake pedal 40.

[0139] like Figure 2 , Figure 15 As shown, in this tractor 1, an emergency stop communication antenna 91 for receiving emergency stop commands sent from the emergency stop remote control 90 is provided inside the cab 13. This allows for a shorter antenna cable from the communication antenna 91 to the LCD monitor. An antenna support member 39 is provided on the upper right rear side of the cab 13. A first communication antenna 91A extending forward from the support member 39 and a second communication antenna 91B extending downward from the support member 39 are mounted on the support member 39 as the emergency stop communication antenna 91. By using two communication antennas 91A and 91B with different directions as the emergency stop communication antenna 91, the emergency stop communication antenna 91 can be positioned inside the cab 13, and the receiving sensitivity of the communication antenna 91 can be improved.

[0140] Furthermore, the communication antenna 91 for emergency stop may consist of only either the first communication antenna 91A or the second communication antenna 91B. Additionally, to improve the receiving sensitivity of the communication antenna 91 for emergency stop, it may be mounted outside the driver's cab 13.

[0141] [Second Implementation]

[0142] Hereinafter, as an example of a method for implementing the present invention, a second embodiment of the braking system for a work vehicle of the present invention, which differs from the first embodiment, will be described based on the accompanying drawings.

[0143] Furthermore, since the braking system illustrated in this second embodiment differs from the braking system illustrated in the first embodiment only in the structure of the second braking operating device, only the structure of the second braking operating device will be described.

[0144] like Figures 16-17 As shown, the second braking operation device 130 illustrated in this second embodiment includes left and right operated bodies 131 connected to the first linkage rod 53 in the left and right first linkage mechanism 43, left and right electric actuators 132 that operate the left and right operated bodies 131 in the up and down direction, and accommodating portions 133 that allow the left and right first linkage mechanism 43 and the left and right electric actuators 132 to be displaced relative to the left and right electric actuators 132 as the left and right brake pedals 40 are depressed.

[0145] Each of the left and right operable bodies 131 has an upper end portion 131A and a lower end portion 131B with through holes for the passage of the first linkage rod 53, a middle portion 131C extending across the upper and lower ends 131A and 131B, and an arm portion 131D extending laterally from the middle portion 131C. In each of the left and right operable bodies 131, the upper end portion 131A is supported by the first linkage rod 53. The lower end portion 131B is fixed to the first linkage rod 53 using a nut 134. The arm portion 131D is linked to the depressing operation of the corresponding brake pedal 40, and moves across a lower limit position corresponding to the depressing release position of the brake pedal 40 and an upper limit position corresponding to the depressing limit position of the brake pedal 40. A through hole 131a for association with the electric actuator 132 is formed in the arm portion 131D.

[0146] The left and right electric actuators 132 employ electric cylinders having a cylinder portion 132A arranged parallel to and adjacent to the corresponding first linkage 53, and a motor portion 132B that extends and retracts the cylinder portion 132A. The left and right electric cylinders 132 are switched by the control of the steering control unit 22C to a first operating state in which the motor portion 132B outputs forward rotational power to extend the cylinder portion 132A, a second operating state in which the motor portion 132B outputs reverse rotational power to retract the cylinder portion 132A, and a working stop state in which the extension and retraction of the cylinder portion 132A is stopped by the output of the motor portion 132B stopping rotational power.

[0147] The left and right electric cylinders 132 have connecting portions 132C formed at their lower ends. These connecting portions 132C are supported by left and right fixed shafts 51, which support the shaft hole seat members 52 of the left and right first linkage mechanisms 43, via left and right support brackets 135. Each left and right support bracket 135 has: an L-shaped lower bracket portion 135A, which is bolted to the arm portion 51A of the fixed shaft 51 while being blocked by the fixed shaft 51; and a U-shaped upper bracket portion 135B, which is connected to the upper end of the lower bracket portion 135A. Furthermore, the connecting portions 132C of the electric cylinders 132 are connected to the upper bracket portion 135B via left and right long connecting pins 136.

[0148] In each of the left and right electric cylinders 132, the cylinder portion 132A has an associate rod 137 extending upward from its upper part to associate the cylinder portion 132A with the arm portion 131D of the operated body 131. The associate rod 137 has: an externally threaded portion 137A, which is detachably screwed into and connected to the cylinder portion 132A; a large-diameter contact portion 137B, which contacts the arm portion 131D of the operated body 131 from below; and an associate portion 137C, which is associated with the operated body 131 by passing through a through hole 131a in the arm portion 131D. The cylinder portion 132A is extended and retracted by rotational power from the motor portion 132B, thereby moving the contact portion 137B to a non-operating position set below the lower limit position of the arm portion 131D, and to a maximum operating position that pushes the arm portion 131D upward to the upper limit position. The linkage 137C functions as the aforementioned accommodating part 133 by having a vertical length that allows movement from the lower limit position to the upper limit position of the arm 131D in conjunction with the depressing operation of the brake pedal 40. Thus, when the left or right brake pedal 40 is depressed, the upward movement of the operated body 131 relative to the linkage 137C caused by the operation is permitted by the accommodating vertical length of the linkage 137C. The left and right electric cylinders 132 have internal sensors that detect the arrival of the contact part 137B at the non-operating position and the maximum operating position based on the amount of extension and retraction of the cylinder 132A via the rotational power from the motor 132B.

[0149] The second braking operation device 130 moves its contact portion 137B between a non-operating position and a maximum operating position through the operation of the left and right electric cylinders 132. This transitions between a non-operating state (where the left and right brakes 42 are not operated) and a maximum operating state (where the operating amount of the left and right brakes 42 is at its maximum). Furthermore, this transition can be detected by the aforementioned internal sensors. That is, the internal sensors of each electric cylinder 132 function as state detection sensors to detect the non-operating state and the maximum operating state of the second braking operation device 130.

[0150] With the above structure, when the tractor 1 equipped with the second braking operation device 130 is driving automatically in an unmanned state, and an emergency stop command is sent from the automatic driving control unit 22E when any condition for emergency stop is met, the steering control unit 22C performs forward rotation power output processing according to the emergency stop command. Then, in the left and right electric cylinders 132, the motor part 132B outputs forward rotation power, the cylinder part 132A extends due to this forward rotation power, and the contact part 137B of the linkage rod 137 moves from the non-operating position to the maximum operating position. As a result, the arm part 131D of the left and right operated bodies 131 is pushed upward from the lower limit position to the upper limit position, and the left and right first linkage rods 53 move upward. Furthermore, through this movement, even if the left and right brake pedals 40 are not connected by the connecting mechanism 55, the left and right brake pedals 40 are pulled from the depressed release position to the depressed limit position against the tension of the left and right tension springs 46, and the left and right brakes 42 switch from the released state to the braking state against the action of the internal force-applying components. As a result, the tractor 1, which is driving automatically in an unmanned state, can be quickly braked to a stop.

[0151] Furthermore, if the contact portion 137B reaches the maximum operating position, the steering control unit 22C stops the rotational power output based on the detection of internal sensors. As a result, because the motor portion 132B in the left and right electric cylinders 132 stops outputting rotational power, and with this output stopping, the cylinder portion 132A stops extending and retracting, so the contact portion 137B of the linkage 137 is maintained in the maximum operating position. Therefore, the arms 131D of the left and right operated bodies 131 are maintained in the upper limit position, and the downward movement of the left and right first linkages 53 is prevented. Moreover, by preventing this movement, the left and right brake pedals 40 are maintained in the depressed limit position, and the left and right brakes 42 are maintained in the braking state. As a result, the tractor 1 can be maintained in a braked and stopped state.

[0152] Furthermore, when the passenger manually operates the tractor 1 and presses either or both of the left and right brake pedals 40, the accommodating part 133 enables the braking operation of either or both of the left and right brakes 42, which are linked to the pressing operation, to be performed smoothly without being obstructed by the left and right electric cylinders 132.

[0153] That is, the braking system 17 is equipped with an emergency stop braking system that, without hindering the passenger's manual driving of the tractor 1, enables the tractor 1 to be quickly braked to a stop in the event of an abnormality in the tractor 1 which is automatically driving in an unmanned state, and can maintain the tractor 1 in a braked stop state even when the engine is stopped.

[0154] As described above, since the second braking operating device 130 independently operates the left and right first linkage rods 53 via the left and right electric cylinders 132, it can also serve as the first braking operating device 45 for braking and turning. This simplifies the structure by having the second braking operating device 130 also function as the first braking operating device 45.

[0155] On the other hand, when the tractor 1 is brought to a stop by operating the left and right brakes 42 through the operation of the second brake operating device 130, the left and right electric cylinders 132 can be removed from between the left and right operated bodies 131 and the left and right support brackets 135 by pulling out the left and right connecting pins 136 that connect the connecting part 132C of the left and right electric cylinders 132 to the upper bracket part 135B of the left and right support brackets 135. As a result, the left and right brake pedals 40 are returned from the depressed position to the released position by the action of the left and right tension springs 46. Furthermore, the left and right brakes 42 are returned from the braking state to the released state by the action of the internal force-applying components.

[0156] That is, when the tractor 1 is brought to an emergency stop via the aforementioned emergency stop control operation, after turning off the power by operating the key switch, the left and right connecting pins 136 are pulled out, and the left and right electric cylinders 132 are removed from between the left and right operated bodies 131 and the left and right support brackets 135. Furthermore, after this removal, the power can be turned back on by operating the key switch, allowing the passenger to manually drive the tractor 1. As a result, the tractor 1 can be moved to a safe location, repair shop, etc., by the passenger's manual driving.

[0157] [Third Implementation Method]

[0158] Hereinafter, as an example of a method for implementing the present invention, a third embodiment of the braking system for a work vehicle of the present invention, which differs from the first and second embodiments, will be described based on the accompanying drawings.

[0159] Furthermore, since the braking system illustrated in this third embodiment differs from the braking systems illustrated in the first and second embodiments only in the structure of the second braking operating device, only the structure of the second braking operating device will be described.

[0160] like Figures 18-19As shown, the braking system 17 includes an electrically operated second brake operating device 140, which operates the left and right brakes 42 during emergency driving stop control by the steering control unit 22C based on an emergency stop command from the automatic driving control unit 22E. The second brake operating device 140 is located near the right side of the right brake pedal 40 in the driver's compartment 12. The second brake operating device 140 includes: an operable body 141 connected to the right brake pedal 40, an electric actuator 142 for operating the operable body 141 in a forward and backward direction, and a accommodating part 143 that allows displacement of the right brake pedal 40 and other components relative to the electric actuator 142 between the right brake pedal 40 and the electric actuator 142 as the brake pedal 40 is depressed.

[0161] In the second braking operation device 140, the operated body 141 has a first component 144 connected to the pedal arm 40B of the right brake pedal 40, and a square tube-shaped second component 146 connected to the first component 144 via a first connecting pin 145 extending vertically, which can swing left and right. Moreover, the second component 146 has elongated holes 146a that are long in the front-rear direction and function as a accommodating part 143, and left and right recesses 146b that allow the second component 146 to swing left and right relative to the first component 144.

[0162] The electric actuator 142 employs an electric cylinder having a cylinder portion 142A that is oscillating in the up-and-down direction and associated with a second component 146 via a left-right extending connecting pin 147, and a motor portion 142B that extends and retracts the cylinder portion 142A. A connecting portion 142C is formed at the motor portion side end (front end) of the electric cylinder 142. Furthermore, this connecting portion 142C is oscillating in the up-and-down direction and associated with a support portion 38A of the base plate 38 via a left-right extending second connecting pin 148. The electric cylinder 142 is switched between a first operating state (motor portion 142B outputting forward rotational power to retract the cylinder portion 142A), a second operating state (motor portion 142B outputting reverse rotational power to extend the cylinder portion 142A), and a stop operating state (motor portion 142B outputting power to stop rotation, stopping the extension and retraction of the cylinder portion 142A).

[0163] The linkage pin 147 connects the second component 146 of the operated body 141 to the cylinder portion 142A of the electric cylinder 142 via the accommodating portion 143. The cylinder portion 142A retracts due to the forward rotational force from the motor portion 142B, thereby moving the linkage pin 147 from the non-operating position (where the right brake pedal 40 is not operated) to the maximum operating position (where the operation amount of the right brake pedal 40 (right brake 42) is maximized). The cylinder portion 142A extends due to the reverse rotational force from the motor portion 142B, thereby moving the linkage pin 147 from the maximum operating position to the non-operating position. The non-operating position of the linkage pin 147 is set such that when the right brake pedal 40 is in the depress / release position, the linkage pin 147 is located at the front end of the left and right elongated holes 146a. Therefore, when the right brake pedal 40 is depressed, the forward movement of the operated body 141 relative to the connecting pin 147 caused by this operation is permitted by the accommodating elongated holes 146a on the left and right sides of the second component 146. The electric cylinder 142 has an internal sensor that detects the arrival of the connecting pin 147 to the non-operating position and the maximum operating position based on the amount of extension and retraction of the cylinder 142A generated by the rotational power from the motor 142B.

[0164] The second braking operating device 140 moves the connecting pin 147 between a non-operating position and a maximum operating position through the operation of the electric cylinder 142, transitioning between a non-operating state where the left and right brakes 42 are not operated and a maximum operating state where the operating amount of the left and right brakes 42 is at its maximum. Furthermore, this transition can be detected by the aforementioned internal sensor. That is, the internal sensor of the electric cylinder 142 functions as a state detection sensor for detecting the non-operating state and the maximum operating state of the second braking operating device 140.

[0165] With the above structure, when the tractor 1 equipped with the second braking operation device 140 is driving automatically in an unmanned state, and an emergency stop command is sent from the automatic driving control unit 22E when any condition for emergency stop is met, the steering control unit 22C performs forward rotation power output processing according to the emergency stop command. Then, in the electric cylinder 142, the motor unit 142B outputs forward rotation power, the cylinder unit 142A retracts due to this forward rotation power, and the linkage pin 147 moves from the non-operating position to the maximum operating position. At this time, if the left and right brake pedals 40 are connected via the connecting mechanism 55, the movement of the left and right brake pedals 40 and the linkage pin 147 is linked, overcoming the tension of the left and right tension springs 46 and being pulled from the released position to the maximum position. Thus, the operating force of the electric cylinder 142 is transmitted to the operating arms 50 of the left and right brake 42 via the left and right brake pedals 40 and the left and right first linkage mechanisms 43, and the left and right brake 42 overcome the action of the internal force-applying components and switch from the released state to the braking state. As a result, the tractor 1, which is driving automatically in an unmanned state, can be quickly braked to a stop.

[0166] Furthermore, if the linkage pin 147 reaches its maximum operating position, the steering control unit 22C stops the rotational power output based on the detection of internal sensors. Thus, because the motor unit 142B in the electric cylinder 142 stops outputting rotational power, and with this output ceasing, the cylinder unit 142A stops extending and retracting, so the linkage pin 147 is maintained at its maximum operating position. Consequently, the left and right brake pedals 40 are maintained at their maximum depressed positions, and the left and right brakes 42 are maintained in a braking state. As a result, the tractor 1 can be maintained in a braked and stopped state.

[0167] Furthermore, when the passenger manually operates the tractor 1 and presses the right or left / right brake pedal 40, the accommodating part 143 enables the right or left / right brake 42, which is linked to the pressing operation, to be smoothly operated without being obstructed by the left or right electric cylinders 142.

[0168] As described above, since the second braking operation device 140 is located on the right side of the driver's compartment 12, which is less frequently used when getting on and off the vehicle due to the presence of numerous operating tools such as left and right brake pedals 40 and accelerator pedals, it can prevent the reduced ease of getting on and off the vehicle from the left side of the driver's compartment 12, which is more frequently used when getting on and off the vehicle.

[0169] That is, the braking system 17 is equipped with an emergency stop braking system that does not obstruct the passenger's manual driving of the tractor 1 or the passenger's getting on and off the left side of the driver's seat 12. This system enables the tractor 1 to be quickly braked to a stop in the event of an abnormality while the tractor 1 is driving automatically in an unmanned state, and can maintain the tractor 1 in a braked stop state even when the engine is stopped.

[0170] On the other hand, when the tractor 1 is braked to a stop by operating the left and right brakes 42 through the operation of the second brake operating device 140, by releasing the anti-disengagement mechanism of the β pin or the like on the connecting pin 147, the connecting pin 147 is pulled out from the cylinder portion 142A of the electric cylinder 142, thereby releasing the connection between the second component 146 of the operated body 141 and the cylinder portion 142A of the electric cylinder 142. As a result, the left and right brake pedals 40 are restored from the depressed position to the released position by the action of the left and right tension springs 46. Furthermore, the left and right brakes 42 are restored from the braking state to the released state by the action of the internal force-applying components.

[0171] That is, when the tractor 1 is brought to an emergency stop via the aforementioned emergency stop control operation, after turning off the power by operating the key switch, the linkage pin 147 is pulled out to disengage the operated body 141 from the electric cylinder 142. Furthermore, after this disengagement, the power can be restored by operating the key switch, allowing the passenger to manually drive the tractor 1. As a result, the tractor 1 can be moved to a safe location, repair shop, etc., by the passenger's manual driving.

[0172] [Other Implementation Methods]

[0173] Other embodiments of the present invention will be described.

[0174] Furthermore, the structures of the embodiments described below are not limited to individual applications, but can also be combined with the structures of other embodiments.

[0175] (1) Other representative implementations related to the structure of the work vehicle are described below.

[0176] For example, as a driving device, the work vehicle can also be configured as a half track, having left and right front wheels 10 and left and right tracks that replace the left and right rear wheels 11.

[0177] For example, as a driving device, the work vehicle can also be configured as a fully tracked vehicle, with left and right tracks to replace the left and right front wheels 10 and the left and right rear wheels 11.

[0178] For example, the work vehicle may also be configured to replace the cab 13 with a protective frame extending upward from the tractor 1.

[0179] (2) The braking system 17 may also be configured as having a single brake 42 for braking the left and right driving devices 11, and a single brake pedal 40 that is linked to the brake 42 via a linkage mechanism 43.

[0180] (3) Figure 20 As shown, the electric braking operating device 100 illustrated in the first embodiment can also be configured to have a wire 126 from the connecting pin 106 to the chain link plate 108 instead of the shock absorber 107 in the operated body 101.

[0181] In this structure, when the passenger manually operates the tractor 1 and depresses the right or left / right brake pedal 40, the wire 126 loosens, and the accommodating part 103 functions as a braking part that allows the braking operation of the right or left / right brake 42 linked to the depressing operation.

[0182] Therefore, the braking operation of the right or left brake 42, which is linked to the depressing operation of the right or left brake pedal 40, can be performed smoothly without being obstructed by the left or right electric motors 102. Furthermore, by enabling the metal wire 126 to function as a accommodating part 103 in this way, it is possible to eliminate the need for... Figures 8-12 The elongated hole 108a required for the brake operating device 100 shown is formed on the chain link plate 108. Furthermore, because it is possible to prevent the chain link plate 108 from moving in conjunction with the depressing operation of the right or left brake pedal 40 towards the front of the vehicle body relative to the linkage pin 112, concerns about the chain link plate 108 coming into contact with other objects closer to the front of the vehicle body than the linkage pin 112 can be avoided.

[0183] (4) Figure 21 As shown, the electric braking operating device 100 illustrated in the first embodiment can also be configured to have a linkage mechanism 127 capable of bending in the up and down directions, replacing the shock absorber 107 and chain link plate 108 in the operated body 101.

[0184] In this structure, the linkage mechanism 127 includes: a first link plate 127A, which is supported on the connecting pin 106 and can swing vertically; a second link plate 127B, which is supported on the connecting pin 112 and can swing vertically; and a left-right connecting pin 127C, which connects the front end of the first link plate 127A to the rear end of the second link plate 127B. Thus, in this structure, when the passenger manually operates the tractor 1 and depresses the right or left brake pedal 40, the linkage mechanism 127 bends downward, and the accommodating part 103 functions as a braking part that allows the braking operation of the right or left brake 42 linked to the depressing operation.

[0185] Therefore, the braking operation of the right or left brake 42, which is linked to the depressing operation of the right or left brake pedal 40, can be performed smoothly without being obstructed by the left or right electric motors 102. Furthermore, by enabling the linkage mechanism 127 to function as a accommodating part 103 in this way, the need for… Figures 8-12 The elongated hole 108a required for the brake operating device 100 shown is formed during the time when the second link plate 127B, etc., is formed. Furthermore, since it is possible to prevent the linkage mechanism 127 from moving in conjunction with the depressing operation of the right or left brake pedal 40 towards the front of the vehicle body relative to the linkage pin 112 when the depressing operation is performed, concerns about the linkage mechanism 127 coming into contact with other objects near the front of the vehicle body relative to the linkage pin 112 can be avoided.

[0186] (5) Figure 22 As shown, the electric brake operating device 100 illustrated in the first embodiment can also be configured such that the housing 116 of the brake operating device 100 and the linkage pin 112 are arranged on the left front side of the driving unit 12, and the brake operating device 100 has a metal wire 128 from the brake pedal 40 on the right side to the linkage pin 112 and a plurality of guide wheels 129 for pushing and pulling the metal wire 128. The metal wire 128 also serves as the operated body 101 and the accommodating part 103.

[0187] In this structure, since the second braking operation device 100 is not located on the right side of the driver's unit 12, which is equipped with a large number of operating tools such as left and right brake pedals 40 and accelerator pedal, but on the left side of the driver's unit 12, the concern that the second braking operation device 100 may obstruct the operation of the left and right brake pedals 40, accelerator pedal, etc. can be avoided when the passenger manually drives the tractor 1.

[0188] Furthermore, when the right or left / right brake pedal 40 is depressed during manual driving, the metal wire 128 loosens, allowing the right or left / right brake 42, which is linked to the depressing operation, to engage. Thus, the braking operation of the right or left / right brake 42, which is linked to the depressing operation of the right or left brake pedal 40, can be performed smoothly without obstruction from the left or right electric motors 102.

[0189] Furthermore, the brake operating device 100 illustrated in this other embodiment may also be configured to replace the wire 128 and the plurality of guide wheels 129 with a control cable from the brake pedal 40 on the right side to the associated pin 112.

[0190] (6) The electric braking operation device 100 illustrated in the first embodiment may, for example, have a linkage pin 112 connected to the chain link plate 108 of the operated body 101, and an arc-shaped elongated hole formed in the output gear 110 of the reduction gear set 111, which functions as a accommodating part 103.

[0191] (7) The electric brake operating device 100 illustrated in the first embodiment and the electric brake operating device 140 illustrated in the third embodiment may also be configured such that the operated body 101, 141 is connected to the first linkage rod 53 of the left brake pedal 40 or the linkage mechanism 43 of either the left or right side.

[0192] (8) The electric braking operation device 130 illustrated in the second embodiment may also be configured such that the left and right operated bodies 131 are connected to the left and right brake pedals 40.

[0193] (9) For the state detection sensors 113 and 114, for example, a first non-contact switch that detects the arrival of the associated pin 112 to the non-operating position and a second non-contact switch that detects the arrival of the associated pin 112 to the maximum operating position can be used.

[0194] (10) The housing 116 may be configured to not have a base plate 117, but instead have a left housing 118 that is detachably connected to the fixing part of the vehicle body by bolts, and a right housing 121 that is connected to the left housing 118 by bolts.

[0195] (11) The housing 116 may also be configured to be installed on a fixed part of the vehicle body, such as the front frame 34 or the cab frame, other than the base plate 38.

[0196] Industrial availability

[0197] The braking system for work vehicles involved in this invention can be applied to work vehicles such as tractors, passenger lawnmowers, passenger rice transplanters, combine harvesters, transport vehicles, wheel loaders, and snowplows.

[0198] Explanation of reference numerals in the attached figures:

[0199] 11…Travel mechanism (left and right rear wheels); 12…Driver unit; 38…Fixed part (base plate); 40…Brake pedal; 42…Brake; 43…Linking mechanism; 100…Electric brake operating device; 101…Operated body; 102…Electric actuator (electric motor); 103…Accommodation part (elongated hole); 110…Output gear; 111…Reduction gear set; 112…Linking pin; 113…Status detection sensor; 114…Status detection sensor; 116…Housing housing; 120A…Movement restriction part; 120B…Movement restriction part; 130…Electric brake operating device; 131…Operated body; 132…Electric actuator (electric cylinder); 133…Accommodation part (linking part); 140…Electric brake operating device; 141…Operated body; 142…Electric actuator (electric cylinder); 143…Accommodation part (elongated hole); L1…Imaginary straight line.

Claims

1. A braking system for a work vehicle, wherein, have: Brake pedal, which is located in the driver's area; Brakes, which brake the traveling device; An associated mechanism that links the brake pedal to the brake in a manner that enables them to move together; and An electrically operated braking device that activates the brake in response to an emergency stop command. The braking operation device has: The operated body is connected to the brake pedal or the associated mechanism; An electric actuator that operates the operated body; and The accommodative section allows for displacement of the brake pedal and the associated mechanism relative to the electric actuator relative to the electric actuator during the braking pedal depressing operation, either between the brake pedal or between the associated mechanism and the electric actuator.

2. The braking system for a work vehicle according to claim 1, wherein, The braking operating device, through the operation of the electric actuator, transitions between a non-operating state (no braking) and a maximum operating state (maximum braking). The braking system for the work vehicle includes a state detection sensor that detects the non-operating state and the maximum operating state of the braking operation device.

3. The braking system for a work vehicle according to claim 1 or 2, wherein, The electric actuator is an electric motor that outputs rotational power. The braking operation device includes a housing mounted on a fixed part of the vehicle body and a reduction gear set for reducing the rotational power from the electric motor. The electric motor and the reduction gear set are housed in the housing.

4. The braking system for a work vehicle according to claim 3, wherein, The braking operating device has an association pin that connects the outer peripheral side of the output gear in the reduction gear set to the operated body via the accommodating part. The housing has a movement limiting portion that restricts the movement range of the associated pin between a non-operating position where the brake is not operated and a maximum operating position where the brake's operating amount is maximized. The movement range of the connecting pin is set such that the connecting pin crosses an imaginary straight line and extends throughout the range between the non-operating position and the maximum operating position. The imaginary straight line is a straight line passing through the connection point of the operated body relative to the brake pedal or the associated mechanism and the rotation center of the output gear.

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