Work vehicle

Abstract

Provided is a work vehicle (1) with less heat load on a material accommodating unit, and with excellent mobility.　The present invention is provided with: a chassis (2); a motor (3) carried on the chassis; a travel apparatus (4) that supports the chassis so that the same can travel; a material accommodating unit (5) that accommodates work materials; and a radiator apparatus (10) for exchanging heat with external air to cool a coolant circulated through the motor. If the straight-advancing travel direction of the chassis serves as the front-rear direction, the motor is arranged forward of the material accommodating unit, across a ventilation chamber (20) through which the external air flows, and the radiator apparatus is disposed in the ventilation chamber.

Description

Work vehicle

[0001] The present invention relates to a work vehicle equipped with a material storage section.

[0002] A chemical sprayer vehicle that sprays chemicals in fields and orchards is known as a work vehicle equipped with a material storage section for storing work materials. The chemical sprayer vehicle disclosed in Patent Document 1 includes, from the front to the rear of the vehicle body, a seat for a driver, a chemical tank for storing the chemical, and an engine room that houses the motor, in that order.

[0003] Japanese Patent Publication No. 2023-109308

[0004] However, work vehicles with an engine compartment and a material storage compartment arranged vertically, such as the above-mentioned chemical sprayer vehicle, have a relatively long overall vehicle body length. Therefore, when turning, the vehicle must travel a larger route than usual to prevent the material storage compartment at the rear of the vehicle from getting caught in or coming into contact with obstacles near the center of the turn. To solve this mobility problem, one possible method is to position the material storage compartment as close to the engine compartment as possible, thereby shortening the overall vehicle body length. However, this method raises the risk of deformation or deterioration of the material storage compartment and deterioration of the work materials due to the effects of heat generated by high-temperature components such as the engine in the engine compartment.

[0005] The present invention has been made in consideration of the above problems, and has as its object to provide a work vehicle that imposes less thermal load on the material storage section and has excellent mobility.

[0006] The present invention employs the following technical means to achieve the above object.

[0007] A work vehicle according to one aspect of the present invention comprises a vehicle body, a prime mover mounted on the vehicle body, a traveling device that supports the vehicle body so that it can move, a material storage section that stores work materials, and a radiator device that cools the coolant circulated to the prime mover by heat exchange with external air, with the straight-ahead traveling direction of the vehicle body being the fore-and-aft direction.The prime mover is located in front of the material storage section, separated by an air vent through which the external air flows, and the radiator device is located in the air vent.

[0008] A cooling fan may be provided to send the outside air from the material storage section side to the motor side.

[0009] The radiator device may be provided with a cooling fan that sends the external air to the prime mover, the radiator device having a first ventilation surface portion arranged opposite the material storage section and a second ventilation surface portion arranged opposite the prime mover, and the cooling fan may be arranged adjacent to the second ventilation surface portion.

[0010] The vehicle may further include an oil cooler that cools hydraulic oil of each hydraulic device mounted on the vehicle body by heat exchange with the external air, and the oil cooler may be disposed in the ventilation chamber.

[0011] The radiator device may have a first ventilation surface portion arranged opposite the material storage section and a second ventilation surface portion arranged opposite the prime mover, and the oil cooler may be arranged adjacent to the first ventilation surface portion.

[0012] The vehicle may further include a cooling fan that sends the external air to the motor, the cooling fan being disposed adjacent to the second ventilation surface portion.

[0013] The vehicle may include a travel pump driven by the prime mover and discharging hydraulic oil, and a travel motor that drives the travel device using the hydraulic oil discharged from the travel pump, and the travel pump may be positioned adjacent to and in front of the prime mover.

[0014] The vehicle may further include an exhaust device that guides air discharged from the engine to the outside of the vehicle, the exhaust device being disposed adjacent to the front of the engine.

[0015] The vehicle may further include an air purifier that purifies air supplied to the motor, and the air purifier may be disposed in the ventilation chamber.

[0016] The vehicle may further include a spraying device that sprays the chemical solution around the vehicle body, and the material storage unit may be a chemical solution tank that stores the chemical solution.

[0017] The spray device may be provided with a spray pump that sprays the chemical solution from the spray device and a spray motor that provides rotational power to the spray device, and the spray pump and the spray motor may be arranged below the radiator device in the ventilation chamber.

[0018] The vehicle may include a bonnet that covers the prime mover and a body cover that covers the material storage section, and an air intake opening that communicates with the ventilation chamber may be provided between the butted ends of the bonnet and the body cover.

[0019] At least a portion of the air intake may be provided rearward of the ventilation chamber.

[0020] The butted end of the body cover may extend toward the inside of the hood.

[0021] According to the above-described work vehicle, the vehicle body can be made compact while suppressing the thermal load on the material storage section, thereby improving mobility.

[0022] 1 is a perspective view of a work vehicle of the present invention. FIG. 1 is a left side view of a work vehicle of the present invention. FIG. 2 is a top view of a work vehicle of the present invention. FIG. 3 is a front view of a work vehicle of the present invention. FIG. 4 is a left side schematic view showing the internal configuration of a work vehicle of the present invention. FIG. 5 is a top schematic view showing the internal configuration of a work vehicle of the present invention. FIG. 6 is a block diagram showing the internal configuration of a work vehicle of the present invention. FIG. 7 is a rear perspective view of the radiator device and its periphery. FIG. 8 is a view showing the trajectory of a work vehicle of the present invention when turning. FIG. 9 is a schematic configuration diagram of an adjustment device. FIG. 10 is a schematic configuration diagram of a control device. FIG. 11 is a view showing an example of a planned travel route. FIG. 12 is a view showing an example of a connection route in a planned travel route. FIG. 13 is a view showing another example of a connection route in a planned travel route. FIG. 14 is a view showing another example of a connection route in a planned travel route. FIG. 15 is a view showing another example of a connection route in a planned travel route.

[0023] An embodiment of the present invention will be described with reference to the drawings.

[0024] The work vehicle 1 of this embodiment is a chemical sprayer vehicle used to spray chemicals in agricultural fields such as fields and orchards. The work vehicle 1 of this embodiment is a type of autonomously traveling work vehicle that combines a remote control function for manual traveling using a remote control device RC and an autonomous traveling function for autonomous traveling based on the position information and obstacle detection information of the work vehicle 1. The work vehicle 1 according to the present invention is not limited to a chemical sprayer vehicle. For example, the work vehicle 1 according to the present invention may be an agricultural machine, construction machine, transport machine, utility vehicle, etc. that has a material storage section for storing work materials other than chemicals.

[0025] As shown in Figures 1 to 6, the work vehicle 1 of this embodiment comprises a vehicle body 2, a prime mover 3, a traveling device 4, a chemical tank 5 as a material storage section, a spraying device 6 as a work device, a bonnet 7, a bumper device 8, and an object sensor 9. As shown in Figures 5 and 6, the work vehicle 1 also comprises a radiator device 10, a cooling fan 11, an oil cooler 12, an exhaust device 13, an air purifier 14, and a control device 15. Furthermore, as shown in Figure 7, the work vehicle 1 also comprises a pump device 16, a traveling motor 17, a steering device 18, and a spraying motor 19.

[0026] Hereinafter, the longitudinal direction (direction indicated by arrows X1 and X2 in Figures 1 to 3), which is the straight-ahead traveling direction of the vehicle body 2, will be described as the front-to-rear direction, the width direction of the vehicle body 2 (direction indicated by arrows Y1 and Y2 in Figures 1, 3, and 4) as the left-to-right direction, and the height direction of the vehicle body 2 (direction indicated by arrows Z1 and Z2 in Figures 1, 2, and 4) as the up-to-down direction.

[0027] The vehicle body 2 is formed by combining metal plates and the like. As shown in Figures 1 to 3, the vehicle body 2 includes a vehicle body frame 2F. The vehicle body frame 2F has a frame structure that is long in the front-to-rear direction, and supports heavy objects such as the motor 3, chemical tank 5, and sprayer device 6 lined up in the front-to-rear direction.

[0028] As shown in Figure 6, a control box T1 and an oil tank T2 are provided on the right side of the body frame 2F. The control device 15 is housed in the control box T1. The detailed configuration of the control device 15 will be described later.

[0029] A fuel tank T3 and a battery box T4 are provided on the left side of the body frame 2F. The battery box T4 houses a charge-discharge battery such as a lithium-ion battery or a lead-acid battery, and supplies the power stored in the battery to electrically powered devices such as the cooling fan 11.

[0030] The prime mover 3 in this embodiment is a diesel engine. However, the prime mover 3 may be a hydrogen engine driven by the combustion energy of hydrogen gas, or an electric motor driven by electric power generated by a fuel cell or electric power charged in a battery from an external power source.

[0031] As shown in Figures 2, 3, 5, and 6, the prime mover 3 is provided in the front portion of the vehicle body 2. The prime mover 3 is supported in a position forward of the center between the front and rear of the vehicle on the upper portion of the body frame 2F. The prime mover 3 is covered by a bonnet 7. In other words, the prime mover 3 is stored inside the bonnet 7. A drive shaft is provided in the front portion of the prime mover 3.

[0032] The traveling devices 4 support the vehicle body 2 so that the vehicle body 2 can travel. As shown in Figures 1 to 4, the traveling devices 4 of this embodiment are wheels rotatably provided on the vehicle body 2, and include a pair of front wheels 4F provided on the left and right at the front of the vehicle body 2, and a pair of rear wheels 4R provided on the left and right at the rear of the vehicle body 2.

[0033] The front wheels 4F are provided below the engine 3 at the bottom of the body frame 2F. The rear wheels 4R are provided below the chemical tank 5 at the bottom of the body frame 2F. Note that, of the traveling device 4, either or both of the front wheels 4F and the rear wheels 4R may be crawlers.

[0034] As shown in Figure 6, rotational power is transmitted individually to the front wheels 4F and the rear wheels 4R from the travel motor 17. Also, as shown in Figure 7, the front wheels 4F and the rear wheels 4R are each steered individually by a steering cylinder 41, which will be described later. That is, the work vehicle 1 of this embodiment is a four-wheel drive vehicle in which the front wheels 4F and the rear wheels 4R are each driven independently, and is also a four-wheel steering vehicle in which the front wheels 4F and the rear wheels 4R are each steered independently. Note that the work vehicle 1 may also be a two-wheel drive vehicle in which only one of the front wheels 4F and the rear wheels 4R is used as the drive wheel. Also, the work vehicle 1 may be a two-wheel steering vehicle in which only one of the front wheels 4F and the rear wheels 4R is used as the steering wheel.

[0035] The chemical tank 5 is a container capable of holding a chemical solution as a work material. In this embodiment, the chemical tank 5 is made of a fiber-reinforced resin material reinforced with carbon fiber or glass fiber. However, the chemical tank 5 may be made of a synthetic resin material other than the fiber-reinforced resin material, or may be made of a metal material such as stainless steel, as long as the material has high heat resistance, impact resistance, and weather resistance.

[0036] As shown in FIGS. 1 to 3 , the chemical tank 5 is provided at the rear of the vehicle body 2. The chemical tank 5 is supported behind the prime mover 3 on the upper part of the vehicle body frame 2F. The chemical tank 5 is formed in a bullet shape that is long in the front-to-rear direction, and extends from the center between the front and rear of the vehicle body frame 2F to the rear end. As shown in FIGS. 5 and 6 , an air vent 20 that allows air outside the work vehicle 1 to circulate is provided between the prime mover 3 and the chemical tank 5. That is, the chemical tank 5 is located behind the prime mover 3, which is a heat-generating component, across the air vent 20. In other words, the prime mover 3 is located in front of the chemical tank 5, across the air vent 20. This significantly reduces the thermal impact on the chemical tank 5.

[0037] The spraying device 6 sprays the chemical liquid stored in the chemical tank 5 around the vehicle body 2. As shown in Figure 5, the spraying device 6 has a spray head 6A, a blower 6B, and a spray pump 6C. The spray head 6A sprays the chemical liquid from the chemical tank 5 to the outside. The blower 6B sends outside air to the spray head 6A. The spraying pump 6C supplies the chemical liquid from the chemical tank 5 to the spray head 6A and drives the blower 6B.

[0038] As shown in Figure 2, the spraying device 6 is disposed rearward of the rear wheels 4R at the rear of the vehicle body 2. The length (rear overhang) L1 from the rear wheels 4R to the rear end of the spraying device 6 (blower 6B) is set to be greater than the length (front overhang) L2 from the front wheels 4F to the front end of the vehicle body 2. That is, in the work vehicle 1 of this embodiment, the rear overhang portion rearward of the rear wheels 4R of the vehicle body 2 is configured to be shorter than the front overhang portion forward of the front wheels 4F of the vehicle body 2. Therefore, when turning, it is necessary to control the vehicle's travel so that the rear overhang portion does not come into contact with obstacles outside the travel route (travel trajectory).

[0039] As shown in Figures 1 to 3, the spray head 6A is provided at the rear of the vehicle body 2. The spray head 6A is supported at a position behind the liquid chemical tank 5 on the upper part of the vehicle body frame 2F. The spray head 6A has an air guide plate 21 and multiple spray nozzles 22. The air guide plate 21 redirects the air flow sent out from the blower 6B to the side or above the vehicle body 2. The spray nozzles 22 spray the liquid chemical in the form of a mist into the air flow redirected by the air guide plate 21.

[0040] As shown in Figures 5 and 6, the blower 6B is provided at the rear of the vehicle body 2. The blower 6B is supported at a position rearward of the spray head 6A on the upper part of the vehicle body frame 2F. The blower 6B has a blower fan 23. As shown in Figure 5, the driven shaft of the blower fan 23 is connected to the drive shaft of the spray pump 6C via a universal joint J1, and is driven by the rotational power of the spray pump 6C to blow air behind the work vehicle 1 toward the spray head 6A at the front.

[0041] The spray pump 6C is provided in a space below the radiator device 10 in the ventilation chamber 20. The suction side piping connection of the spray pump 6C is connected to the chemical liquid tank 5 through a water inlet pipe, and the outlet side piping connection is connected to the spray nozzle 22 through a water outlet pipe. The spray pump 6C has a driven shaft connected to the drive shaft of the spray motor 19 and is driven by the rotational power of the spray motor 19 to pressure-feed the chemical liquid from the chemical liquid tank 5 to the spray nozzle 22 and rotate the blower fan 23. This causes the chemical liquid from the chemical liquid tank 5 to be diffused to the sides and upward of the vehicle body 2.

[0042] The bonnet 7 is a cover that covers the engine 3, and is connected to and supported on the upper front part of the body frame 2F. The bonnet 7 in this embodiment is made of a material that is more weather resistant than the chemical tank 5. The bonnet 7 may be made of a synthetic resin material or a metal material such as a steel plate or a stainless steel plate, as long as the material has high heat resistance, impact resistance, and weather resistance.

[0043] The hood 7 is formed to a size that covers the area of ​​the vehicle body 2 forward of the chemical tank 5. That is, as shown in Figures 5 and 6, the hood 7 covers the prime mover 3 mounted on the front part of the vehicle body 2, as well as the radiator unit 10, cooling fan 11, oil cooler 12, exhaust unit 13, air purification unit 14, pump unit 16, etc. The hood 7 may be connected to the vehicle body frame 2F via a drive unit such as a hydraulic cylinder or an electric motor, and configured to be able to open and close automatically in response to instructions from the control unit 15.

[0044] As shown in Figures 1 to 3, the bonnet 7 is formed in a bullet shape extending forward from the front of the liquid chemical tank 5. As shown in Figures 2, 3, and 5, the bonnet 7 is arranged so that a portion of the rear edge 7E overlaps the front of the liquid chemical tank 5 from the outside. A gap 24 that communicates with the ventilation chamber 20 is defined between the rear edge 7E of the bonnet 7 and the front of the liquid chemical tank 5. The gap 24 is provided along the rear edge 7E of the bonnet 7 and communicates with the ventilation chamber 20. In other words, the gap 24 opens toward the rear. In this way, the gap 24 serves as an air intake for introducing external air into the ventilation chamber 20.

[0045] 1 to 3 , the left side surface 25 and the right side surface 26 of the bonnet 7 are formed so as to widen outward to the left and right from the front end to the rear end. The top surface 27 of the bonnet 7 is formed so as to extend obliquely upward from the front end to the rear end. Therefore, even if branches and leaves come into contact with the bonnet 7 from the front when traveling between trees in an orchard or the like, the branches and leaves can be smoothly deflected along the left side surface 25, right side surface 26, and top surface 27 to the outside and rear of the vehicle body 2.

[0046] The bumper device 8 is a protective device that protects the vehicle body 2 from collisions with obstacles and the like, and is provided by projecting from the front of the vehicle body 2. The bumper device 8 also functions as a contact detection device that detects when the vehicle 1 comes into contact with an obstacle while traveling. The detailed configuration of the bumper device 8 will be described later.

[0047] The object sensor 9 detects objects around the vehicle body 2. The object sensor 9 in this embodiment is a sensing device (LiDAR) that irradiates the surroundings with laser light and measures the distance and position of the object based on detection information of the reflected light. As shown in FIGS. 1 to 5 , the object sensor 9 is provided in the lower part of the bumper device 8. The detailed arrangement of the object sensor 9 will be described later. Note that, as long as the object sensor 9 can accurately detect objects around the vehicle body 2 while it is traveling, it may be a millimeter-wave radar that irradiates the surroundings with radio waves and measures the distance and position of the object based on detection information of the reflected waves, or a camera sensor that recognizes the distance and position of the object based on image information from a camera.

[0048] The radiator device 10 is a cooler that cools the coolant circulated through the engine 3 by heat exchange with external air. As shown in Figures 5 and 6, the radiator device 10 is provided in the front of the vehicle body 2. As shown in Figure 8, a support frame 10F, which serves as a mounting portion for the radiator device 10, is erected on the upper part of the vehicle body frame 2F and behind the engine 3. The radiator device 10 is connected to and supported by the support frame 10F. Partition walls 10P are provided on the left and right side edges of the support frame 10F. The partition walls 10P separate the space inside the hood 7 forward of the radiator device 10, i.e., the engine compartment 30 housing the engine 3, from the ventilation chamber 20.

[0049] 5 and 6, the radiator device 10 has a first ventilation surface portion 31 arranged opposite the liquid chemical tank 5, and a second ventilation surface portion 32 arranged opposite the engine 3. The radiator device 10 is placed in the ventilation chamber 20 with the first ventilation surface portion 31 facing the liquid chemical tank 5 (rearward) and the second ventilation surface portion 32 facing the engine 3 (forward).

[0050] The cooling fan 11 is driven by the rotational power of the prime mover 3 and sends outside air to the prime mover 3. The cooling fan 11 is provided in the front of the vehicle body 2. The cooling fan 11 is disposed adjacent to the second ventilation surface 32 (the ventilation surface on the prime mover 3 side) of the radiator device 10 in the ventilation chamber 20. Therefore, when the cooling fan 11 is operated, outside air from the work vehicle 1 is taken into the ventilation chamber 20 through the gap 24 in the rear edge 7E of the hood 7, and then sent to the prime mover 3 through the radiator device 10. This promotes cooling of the prime mover 3.

[0051] The oil cooler 12 is a cooler that cools the hydraulic oil of each hydraulic device mounted on the vehicle body 2 by heat exchange with external air. The oil cooler 12 is provided in the front part of the vehicle body 2. As shown in Figures 6 and 8, the oil cooler 12 includes a first oil cooler 12A and a second oil cooler 12B.

[0052] 5 and 6 , the first oil cooler 12A is disposed adjacent to the first ventilation surface 31 of the radiator device 10. The first oil cooler 12A has a first ventilation surface 33 disposed facing the chemical tank 5 and a second ventilation surface 34 disposed facing the radiator device 10. The first oil cooler 12A is disposed in the ventilation chamber 20 with the first ventilation surface 33 facing the chemical tank 5 (rearward) and the second ventilation surface 34 facing the first ventilation surface 31 of the radiator device 10. Therefore, the outside air taken into the ventilation chamber 20 by the cooling fan 11 passes through the first oil cooler 12A and is then guided to the radiator device 10.

[0053] 6 and 8 , the second oil cooler 12B is disposed on the right side of the radiator device 10. The second oil cooler 12B has a first air permeable surface 35 disposed opposite the air intake port 7H opened in the right side surface 26 of the bonnet 7, and a second air permeable surface 36 disposed facing the interior space of the bonnet 7. The second oil cooler 12B is disposed in the air vent chamber 20 with the first air permeable surface 35 facing the air intake port 7H and the second air permeable surface 36 facing toward the center between the left and right sides of the bonnet 7 (to the left).

[0054] The second oil cooler 12B has an air intake fan 37. The air intake fan 37 is provided on the second air passage surface 36 (the air passage surface on the radiator device 10 side) of the second oil cooler 12B. Therefore, when the air intake fan 37 is operated, air outside the work vehicle 1 is taken into the air ventilation chamber 20 through the air intake port 7H and the second oil cooler 12B.

[0055] The exhaust device 13 is a muffler device that sends the combustion exhaust gas from the prime mover 3 to the outside of the work vehicle 1. The exhaust device 13 has a filter that removes particulate matter (PM) contained in the combustion exhaust gas. As shown in Figures 5 and 6, the exhaust device 13 is provided in the front part of the vehicle body 2. The exhaust device 13 is disposed adjacent to the front of the prime mover 3 inside the hood 7. The exhaust device 13 is connected to and supported at the upper front part of the prime mover 3.

[0056] The exhaust device 13 may have a catalyst carrier filter as the filter, which not only removes particulate matter but also purifies components contained in the combustion exhaust gas, such as hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx). Furthermore, if the prime mover 3 is an electric motor, the work vehicle 1 may be equipped, instead of the exhaust device 13, with a heat exhaust device that forcibly exhausts heat generated by the electric motor to the outside.

[0057] The air purifier 14 is a filter device that removes dust particles and the like from the air taken into the engine 3. The air purifier 14 is provided in the front part of the vehicle body 2. The air purifier 14 is disposed above and behind the radiator device 10 in the air vent chamber 20.

[0058] The pump device 16 is a hydrostatic continuously variable transmission (HST pump) that is driven by the rotational power of the prime mover 3 and discharges hydraulic oil to the travel motor 17 and the spray motor 19. As shown in Figure 7, the pump device 16 has a first pump section 16A as a travel pump that discharges hydraulic oil to the travel motor 17, and a second pump section 16B as a work pump that discharges hydraulic oil to the spray motor 19.

[0059] The first pump unit 16A and the second pump unit 16B are, for example, swash plate-type variable displacement axial pumps. The first pump unit 16A and the second pump unit 16B have pressure-receiving units whose swash plate angles change in response to the applied pilot pressure. The first pump unit 16A and the second pump unit 16B can change the hydraulic oil discharge amount (output) by changing the swash plate angles. The control device 15 changes the pilot pressure acting on the pressure-receiving unit of the first pump unit 16A and adjusts the output of the first pump unit 16A and the hydraulic oil discharge direction to adjust the rotation speed and rotation direction (forward or reverse) of the travel motor 17. The control device 15 also changes the pilot pressure acting on the pressure-receiving unit of the second pump unit 16B and adjusts the output of the second pump unit 16B to adjust the rotation speed of the spray motor 19.

[0060] 5 and 6, the pump device 16 is provided at the front of the vehicle body 2. The pump device 16 is supported at a position forward of the center between the front and rear of the upper part of the vehicle body frame 2F. The pump device 16 is disposed adjacent to and in front of the prime mover 3 inside the hood 7. The pump device 16 has a driven shaft connected to a drive shaft provided at the front of the prime mover 3, and is driven by the rotational power of the prime mover 3.

[0061] The travel motors 17 are hydraulic motors that hydraulically drive the travel devices 4. As shown in Fig. 6, the travel motors 17 include a front-wheel travel motor 17F and a rear-wheel travel motor 17R. The front-wheel travel motor 17F is provided in a position forward of the center between the front and rear of the lower part of the body frame 2F. The rear-wheel travel motor 17R is provided in a position rearward of the center between the front and rear of the lower part of the body frame 2F.

[0062] The steering device 18 is a device that adjusts the steering angle of the traveling device 4. As shown in Fig. 7 , the steering device 18 has a steering cylinder 41, a steering switching valve 42, a steering valve device 43, a steering pump 44, and an adjustment device 45.

[0063] The steering cylinders 41 are hydraulic cylinders that hydraulically steer the traveling device 4. The steering cylinders 41 include a front wheel steering cylinder 41F and a rear wheel steering cylinder 41R. As shown in Fig. 6, the front wheel steering cylinder 41F is provided in a position forward of the center between the front and rear of the lower part of the body frame 2F. The rear wheel steering cylinder 41R is provided in a position rearward of the center between the front and rear of the lower part of the body frame 2F.

[0064] The steering switching valve 42 is a direction switching valve that switches the flow direction of hydraulic oil to the rear wheel steering cylinder 41R. Specifically, the steering switching valve 42 is a switching valve that can be switched between three output positions: an anti-phase steering position (first position) that steers the rear wheel steering cylinder 41R in the anti-phase with the front wheel steering cylinder 41F; an in-phase steering position (second position) that steers the rear wheel steering cylinder 41R in the same phase as the front wheel steering cylinder 41F; and a two-wheel steering position (third position) that restricts steering of the rear wheel steering cylinder 41R. The steering switching valve 42 also has a flow rate adjustment mechanism that can adjust the hydraulic output to the rear wheel steering cylinder 41R in the in-phase steering position. The steering switching valve 42 is located rearward of the center between the front and rear of the lower part of the body frame 2F.

[0065] The steering valve device 43 is a pressure control valve (fully hydraulic power steering device) that adjusts the hydraulic pressure of the steering cylinder 41. The steering valve device 43 includes a front wheel steering valve device 43F and a rear wheel steering valve device 43R.

[0066] The front wheel steering valve device 43F adjusts the hydraulic oil pressure of the front wheel steering cylinder 41F. That is, the front wheel steering valve device 43F adjusts the pressure of the hydraulic oil supplied from the steering pump 44 to adjust the steering angle of the front wheels 4F. The rear wheel steering valve device 43R adjusts the hydraulic oil pressure of the rear wheel steering cylinder 41R. That is, the rear wheel steering valve device 43R adjusts the pressure of the hydraulic oil supplied from the steering pump 44 to adjust the steering angle of the rear wheels 4R.

[0067] The steering pump 44 is a hydraulic pump that is driven by the rotational power of the prime mover 3 and discharges hydraulic oil to the steering valve device 43. The steering pump 44 is provided in the front part of the vehicle body 2. The steering pump 44 is provided in a position on the vehicle body frame 2F that is forward and to the right of the prime mover 3 (to the right of the pump device 16).

[0068] The adjusting device 45 adjusts the hydraulic output of each of the front wheel steering valve device 43F and the rear wheel steering valve device 43R. The adjusting device 45 is provided in the front lower part of the vehicle body 2. The adjusting device 45 is provided in the lower part of the body frame 2F to the left of the control box T1 (toward the center of the vehicle body 2).

[0069] 10, the adjustment device 45 of this embodiment has a steering motor 45A and a gear device 45B. The steering motor 45A is an electric motor that is rotationally driven by electricity. The gear device 45B transmits the rotational power of the steering motor 45A to the input shafts of the front wheel steering valve device 43F and the rear wheel steering valve device 43R at different rotation ratios.

[0070] The gear device 45B has a front wheel gear 51, a rear wheel gear 52, and a pinion gear 53. The front wheel gear 51 is connected to the input shaft of the front wheel steering valve device 43F. The rear wheel gear 52 is connected to the input shaft of the rear wheel steering valve device 43R. The pinion gear 53 is connected to the drive shaft of the steering motor 45A.

[0071] The front wheel gear 51, rear wheel gear 52, and pinion gear 53 are all spur gears. The rear wheel gear 52 meshes with the front wheel gear 51. The front wheel gear 51 meshes with the pinion gear 53. Therefore, when the steering motor 45A is driven, the front wheel gear 51 and the rear wheel gear 52 rotate together, simultaneously driving the front wheel steering valve device 43F and the rear wheel steering valve device 43R.

[0072] The rotation ratio between the front wheel gear 51 and the rear wheel gear 52 is set to, for example, 2 / 1. In other words, the adjustment device 45 of this embodiment is configured so that the front wheel gear 51 rotates twice as fast as the rear wheel gear 52 by driving one steering motor 45A.

[0073] As described above, when the steering motor 45A is driven, the hydraulic output from the front wheel steering valve device 43F becomes higher than the hydraulic output from the rear wheel steering valve device 43R, driving the front wheel steering cylinder 41F more than the rear wheel steering cylinder 41R. As a result, the steering angle of the front wheels 4F is set to approximately twice the steering angle of the rear wheels 4R. The rotation ratio between the front wheel gear 51 and the rear wheel gear 52 is not limited to 2 / 1, and it is sufficient that the hydraulic output from the front wheel steering valve device 43F is set to be higher than the hydraulic output from the rear wheel steering valve device 43R.

[0074] In this way, when the steering device 18 turns the work vehicle 1 with the front wheels 4F and rear wheels 4R steered at opposite phases (4WS mode), the hydraulic output from the front wheel steering valve device 43F is set higher than the hydraulic output from the rear wheel steering valve device 43R, and the steering angle of the front wheels 4F is set at a ratio greater than the steering angle of the rear wheels 4R. This allows the turning radius of the work vehicle 1 to be smaller than when the steering angle of the front wheels 4F is set equal to or less than the steering angle of the rear wheels 4R, as shown in Figure 9 (the front wheels 4F shown by dashed lines in Figure 9 show a case where the steering angle is approximately the same as the steering angle of the rear wheels 4R). Furthermore, as the steering angle of the front wheels 4F is made larger than the steering angle of the rear wheels 4R, the turning center Q1 of the work vehicle 1 can be shifted toward the rear of the work vehicle 1 (toward the spraying device 6).

[0075] Furthermore, when the steering device 18 is used to travel the work vehicle 1 with the front wheels 4F and rear wheels 4R steered at the same phase (crab mode), the hydraulic output from the front wheel steering valve device 43F and the hydraulic output from the rear wheel steering valve device 43R are made the same, so that the steering angle of the front wheels 4F is the same as the steering angle of the rear wheels 4R. When the steering motor 45A is driven, the hydraulic output from the front wheel steering valve device 43F becomes higher than the hydraulic output from the rear wheel steering valve device 43R, just as when the front wheels 4F and rear wheels 4R are steered in opposite phases. Therefore, in the work vehicle 1 of this embodiment, the hydraulic output to the rear wheel steering cylinder 41R is adjusted by the flow rate adjustment mechanism of the steering switch valve 42 to adjust the operating strokes of the front wheel steering cylinder 41F and the rear wheel steering cylinder 41R to be the same.

[0076] The spray motor 19 is a hydraulic motor that hydraulically applies rotational power to the spray device 6. As shown in Fig. 5, the spray motor 19 is arranged below the radiator device 10 in the ventilation chamber 20, aligned front to back with the spray pump 6C. The drive shaft of the spray motor 19 is connected to the driven shaft of the spray pump 6C, and the spray pump 6C is driven by the rotational power.

[0077] As described above, in the work vehicle 1 of this embodiment, not only the prime mover 3 but also the exhaust device 13 becomes hot due to the combustion exhaust gases from the prime mover 3, so these high-temperature parts are arranged in the prime mover compartment 30. On the other hand, parts such as the spray pump 6C, spray motor 19, radiator device 10, cooling fan 11, oil cooler 12, and air purifier 14 are arranged in the ventilation compartment 20 in consideration of cooling performance. Also, in the work vehicle 1 of this embodiment, in consideration of cooling capacity, the oil cooler 12 is divided into multiple parts (first oil cooler 12A, second oil cooler 12B), and each is arranged in a different position.

[0078] <Circuit configuration of hydraulic device> As shown in Figure 7, the pump device 16 has input / output ports that can supply hydraulic oil to two paths, and the travel motor 17 is connected to the input / output port of the first pump section 16A through a hydraulic oil pipe, and the spray motor 19 is connected to the input / output port of the second pump section 16B through a hydraulic oil pipe.

[0079] More specifically, the hydraulic oil pipe connected to the input / output port of the first pump unit 16A branches midway and is connected to the front wheel traveling motor 17F and the rear wheel traveling motor 17R. Therefore, the hydraulic oil discharged from the single first pump unit 16A is distributed to the front wheel traveling motor 17F and the rear wheel traveling motor 17R. In other words, the front wheel traveling motor 17F and the rear wheel traveling motor 17R are driven by hydraulic oil supplied from the common first pump unit 16A. Therefore, the hydraulic oil from the first pump unit 16A is appropriately distributed to the front wheel traveling motor 17F and the rear wheel traveling motor 17R according to the respective loads of the front wheel traveling motor 17F and the rear wheel traveling motor 17R.

[0080] The front wheel steering cylinder 41F is connected to a front wheel steering valve device 43F through a hydraulic oil pipe. The rear wheel steering cylinder 41R is connected to a steering changeover valve 42 through a hydraulic oil pipe. The steering changeover valve 42 is connected to a rear wheel steering valve device 43R through a hydraulic oil pipe.

[0081] Both the front wheel steering valve device 43F and the rear wheel steering valve device 43R are connected to a steering pump 44 and an oil tank T2 through hydraulic oil piping. The steering pump 44 is connected to the oil tank T2 through hydraulic oil piping. That is, the steering pump 44 circulates hydraulic oil between the oil tank T2 and the steering valve device 43.

[0082] <Control Device> The control device 15 is a processing circuit including one or more processors. The control device 15 is a controller for the vehicle 1 and performs various controls related to the vehicle 1. The control device 15 is connected to multiple devices mounted on the vehicle 1 via an on-board network such as CAN, ISOBUS, LIN, or FlexRay so that they can communicate with each other.

[0083] The control device 15 includes one or more memories, various analog circuits, various digital circuits, etc. The one or more memories store (memorize) software programs and various data to be executed by one or more processors. The control device 15 can read software programs from one or more memories using one or more processors and execute various processes based on the software programs. Note that the control device 15 may also be able to execute various processes based on predetermined logic circuits using one or more processors.

[0084] The processor is, for example, a central processing unit (CPU), a graphics processing unit (GPU), a digital signal processor (DSP), a field programmable gate array (FPGA), and an application specific integrated circuit (ASIC).

[0085] The control device 15 may execute various processes by having multiple physically separate processors work together, and the configuration is not limited to the above. In such a case, the multiple processors may be mounted on one or more computers physically separated from the vehicle 1, and these processors may be communicatively connected via a network such as an in-vehicle network, LAN, WAN, or the Internet. The software program may also be stored on a recording medium (non-volatile memory such as an HDD, SSD, CD-ROM, or DVD-ROM) communicatively connected to the control device 15, or on an external server device connected via the network, and installed into the memory from there.

[0086] 11 , the control device 15 has a travel control unit 61 and a spray control unit 62. The travel control unit 61 and the spray control unit 62 are, for example, software programs implemented in the control device 15.

[0087] The travel control unit 61 controls the travel operations of the work vehicle 1, such as moving forward, backward, turning, and stopping. The spray control unit 62 controls the spraying operation of the chemical solution by the spraying device 6. Note that the control device 15 in this embodiment is set to drive the spraying motor 19 at a constant rotation speed during the chemical solution spraying operation, but the rotation speed of the spraying motor 19 may be adjusted as appropriate depending on the usage environment, usage time, traveling position, etc.

[0088] The travel control unit 61 has a remote operation control unit 63, a steering switching control unit 64, a positioning control unit 65, an obstacle detection control unit 66, and a contact detection control unit 67. The remote operation control unit 63 acquires operation information from the remote control device RC, and sets various operations of the vehicle 1 based on that operation information.

[0089] The steering switching control unit 64 selectively switches the steering mode of the work vehicle 1 between three modes depending on the setting of the remote operation control unit 63: a 4WS mode in which the rear wheels 4R are steered in the opposite phase to the front wheels 4F, a 2WS mode in which only the front wheels 4F are steered, and a crab mode in which the rear wheels 4R are steered in the same phase as the front wheels 4F.

[0090] The positioning control unit 65 compares the position information of the vehicle 1 with pre-input map information of the field, and sets the travel route of the vehicle 1 by setting travel operations such as moving forward, backward, turning, and stopping of the vehicle 1 (in other words, causes the vehicle 1 to travel autonomously). The position information of the vehicle 1 is positioning information such as data indicated by latitude and longitude, or data indicated by coordinates (X-axis, Y-axis). The map information of the field includes a map M of the field (field map), for example, a pre-defined planned travel route N for automatic travel, and position information of trees such as fruit trees and crops in the field. The position information of the vehicle 1 and the map information of the field are data indicated by latitude and longitude, or data indicated by coordinates (X-axis, Y-axis). Therefore, the positioning control unit 65 sets the travel route of the vehicle 1 so that the vehicle 1 travels along the planned travel route N (so that the positional deviation and / or directional deviation between the vehicle body 2 and the planned travel route N is zero).

[0091] For example, the vehicle body 2 is provided with a detection device that detects its own position using a global positioning satellite system (GNSS), and the positioning control unit 65 acquires, as the position information of the vehicle 1, the position detected by the detection device, or a position obtained by correcting the detection device's own position to a predetermined position of the vehicle 1. In this embodiment, the positioning control unit 65 acquires, for example, the position of the center of the width of the spraying device 6 (particularly the blower 6B) (hereinafter referred to as vehicle body position VP shown in FIG. 3) as the position information of the vehicle 1. For example, the positioning control unit 65 corrects the position detected by the detection device based on a predetermined arithmetic expression stored in a recording medium, and acquires the vehicle body position VP. Note that the vehicle body position VP may also be the center of the width of the vehicle body 2 or the chemical tank 5, for example.

[0092] The method for acquiring the vehicle body position VP is not limited to the above-described method. For example, if the detection device has an inertial measurement unit (IMU) including an acceleration sensor, a gyro sensor, etc., the vehicle body position VP may be corrected using the roll angle, pitch angle, yaw angle, etc. of the vehicle body 2 detected by the IMU. The detection device may also be capable of detecting the orientation of the vehicle body 2 (vehicle body orientation VD).

[0093] The obstacle detection control unit 66 detects the approach of an obstacle based on the detection information from the object sensor 9 and executes a predetermined contact avoidance operation. When the object sensor 9 detects that an obstacle has approached within a predetermined distance from the vehicle body 2, the obstacle detection control unit 66 may perform the contact avoidance operation by changing the travel route in a direction that makes it possible to avoid contact with the obstacle, or by temporarily halting the travel of the vehicle 1.

[0094] The contact detection control unit 67 detects contact of an obstacle with the bumper device 8 based on detection information from the contact sensor 76, which will be described later, and executes a predetermined contact operation. In this embodiment, the contact detection control unit 67 stops the travel of the vehicle 1 as the contact operation when the contact sensor 76 detects that an obstacle has contacted the bumper device 8. Note that when contact of an obstacle with the bumper device 8 is detected as described above, the contact detection control unit 67 may execute an operation restriction mode that allows only predetermined operations (for example, operations to move the vehicle 1 in reverse) of the vehicle 1 to be operated by the remote control device RC.

[0095] As described above, the control device 15 can manually drive the vehicle 1 in response to the operation of the remote control device RC, or can autonomously drive the vehicle 1 based on the position information and obstacle detection information of the vehicle 1. Autonomous driving of the vehicle 1 will be described in detail below.

[0096] <Autonomous Driving> FIG. 12 shows an example of a planned driving route N. The planned driving route N is defined on a field map M showing the field, and is a route along which the vehicle 1 will travel between trees and crops in an orchard, etc. The planned driving route N is defined by a route definition unit provided in the control device 15 of the vehicle 1, an external server provided outside the vehicle 1, a management terminal (e.g., a personal computer) operated by a manager who manages the work performed by the vehicle 1, or the like. For example, the route definition unit is provided in the external server, and acquires the vehicle body position VP and position information of surrounding fruit trees, etc., when the vehicle 1 manually drives the field in response to operation of the remote control device RC. The route definition unit defines the planned driving route N based on this position information and the field map M stored in a database on the external server.

[0097] The route definition unit defines the planned driving route N while simulating the automatic driving of the work vehicle 1 and the spraying work by the spraying device 6. Specifically, the external server references the machine information of the work vehicle 1 stored in the database (e.g., information indicating the identification information, dimensional information, and specifications of the work vehicle 1) and defines the planned driving route N with the following goals in mind: (1) the spraying device 6 sprays the chemical solution on the fruit trees and crops in just the right amount; (2) there is no contact between the work vehicle 1 and the fruit trees, crops, or other obstacles; and (3) the work vehicle 1 avoids stopping due to turning operations or the like as much as possible. Note that these goals are merely examples, and at least one of them is emphasized. Furthermore, goals other than the above (1) to (3) may also be emphasized.

[0098] 12, the planned travel route N includes a plurality of work paths N1 defined between trees or crops in an orchard or the like, along which at least the spraying device 6 will spray the chemical solution. The plurality of work paths N1 are, for example, parallel, linear paths defined at a predetermined separation distance D. The spraying control unit 62 causes the spraying device 6 to perform a spraying operation of the chemical solution at least when the vehicle body position VP is located on the work path N1.

[0099] 12, the planned travel route N includes one or more connection routes N2 that connect multiple work routes N1. The connection route N2 is a generally curved route (or a route consisting of multiple consecutive straight lines) that connects one work route N1 to another work route N1, and is a route that the work vehicle 1 turns around. The spraying control unit 62 may or may not cause the spraying device 6 to perform a chemical spraying operation when the vehicle body position VP is located on the connection route N2. Whether or not to perform a spraying operation on the connection route N2 can be set appropriately by a management terminal or the like that is communicably connected to a server device or the like in which the route definition unit is provided.

[0100] In this embodiment, the case will be described in which the route definition unit defines a planned travel route N that includes multiple work routes N1 and connecting routes N2, but the planned travel route N only needs to include at least multiple work routes N1 and does not have to include connecting routes N2. In such a case, for example, when the work vehicle 1 moves from the currently traveling work route N1 to the next work route N1, the control device 15 controls the autonomous travel and sets a connecting route N2 that connects the currently traveling work route N1 with the next work route N1.

[0101] 13A to 13D are diagrams showing examples of connecting routes N2 on a planned travel route N. The route definition unit defines the connecting routes N2 shown in FIGS. 13A to 13D in accordance with the separation width D between adjacent work routes N1 and the minimum turning radius Rmin of the work vehicle 1. For example, the mechanical information of the work vehicle 1 stored in the database of the server device includes the minimum turning radius Rmin of the work vehicle 1 in 4WS mode. The route definition unit references the minimum turning radius Rmin in the database and defines the connecting route N2 based on this minimum turning radius Rmin and the separation width D between one work route N1 (first work route N1a) and another work route N1 (second work route N1b).

[0102] In this embodiment, the route definition unit defines a first connecting path N2a (see FIG. 13A) connecting the first working path N1a and the second working path N1b when the separation width D is equal to or greater than twice the minimum turning radius Rmin (D≧2×Rmin). Also, when the separation width D is equal to or greater than a predetermined value α times the minimum turning radius Rmin but less than twice the minimum turning radius Rmin (α×Rmin≦D<2×Rmin), the route definition unit defines a second connecting path N2b (see FIGS. 13B and 13C) connecting the first working path N1a and the second working path N1b. Then, when the separation width D is less than α times the minimum turning radius Rmin (D < α × Rmin), the route definition unit defines a third connecting path N2c (see Figure 13D) that connects the first work path N1a and the third work path N1c (the work path N1 where the second work path N1b is adjacent to the first work path N1a on the opposite side).

[0103] The predetermined value α can be calculated using the following formula (1) based on the above-mentioned predetermined angle θ, which is defined in advance. Note that the predetermined angle θ is defined as 45 degrees, for example. Note that the predetermined angle θ may be set appropriately by a management terminal or the like connected to a server device or the like in which the route definition unit is provided so as to be able to communicate with the server device or the like.

[0104] Predetermined value α=2×cosθ...Formula (1)

[0105] The first connection path N2a shown in Figure 13A is a path that connects the end of the first work path N1a and the start of the second work path N1b. The first connection path N2a turns from the end of the first work path N1a toward the start of the second work path N1b and aligns the orientation of the vehicle body 2 (vehicle body orientation VD) with the second work path N1b. In Figure 13A, the first connection path N2a turns 180 degrees from the end of the first work path N1a toward the start of the second work path N1b. The vehicle 1 travels along the first connection path N2a in either 2WS mode or 4WS mode depending on the separation width D.

[0106] The second connection path N2b shown in Figures 13B and 13C is a path that connects the terminal end of the first work path N1a and the starting end of the second work path N1b. In the example shown in Figures 13B and 13C, the second connection path N2b connects to a portion of the starting end of the second work path N1b closer to the terminal end. The second connection path N2b has a turning section N2b1 for turning the work vehicle 1 and a guidance section N2b2 for guiding (aligning) the work vehicle 1 onto the second work path N1b.

[0107] The swivel section N2b1 is a path that swivels from the end of the first work path N1a toward the start of the second work path N1b, aligning the orientation of the vehicle body 2 (vehicle body orientation VD) with the second work path N1b. In Figures 13B and 13C, the swivel section N2b1 shows a path that swivels 180 degrees from the end of the first work path N1a toward the start of the second work path N1b. The vehicle 1 travels on the swivel section N2b1 in 4WS mode.

[0108] 13B, the guidance section N2b2 includes a first section N2b21 that rotates a predetermined angle θ from the turning section N2b1 toward the second working path N1b, and a second section N2b22 that rotates from the first section N2b21 by the predetermined angle θ in the direction in which the second working path N1b extends. After traveling on the turning section N2b1 in 4WS mode, the work vehicle 1 travels on the first section N2b21 and the second section N2b22 while maintaining the 4WS mode.

[0109] 13C, the guiding portion N2b2 is a shift portion N2b3 that shifts and moves from the turning portion N2b1 in the direction in which the second working path N1b extends. After traveling on the turning portion N2b1 in 4WS mode, the vehicle 1 switches from the 4WS mode to the crab mode and travels on the shift portion N2b3.

[0110] Furthermore, if the work efficiency of the work vehicle 1 is to be prioritized, in a work vehicle 1 that can switch steering modes without stopping, the shift section N2b3 can be adopted as the guiding section N2b2, and in a work vehicle 1 that needs to stop to switch steering modes, the first part N2b21 and the second part N2b22 can be adopted as the guiding section N2b2.

[0111] The third connection path N2c shown in FIG. 13D is a path that connects the end of the first work path N1a and the start of the third work path N1c. The third connection path N2c is a path that turns from the end of the first work path N1a toward the start of the third work path N1c and aligns the orientation of the vehicle body 2 (vehicle body orientation VD) with the third work path N1c. In other words, the third connection path N2c shown in FIG. 13D connects every other work path N1. Furthermore, the turning section N2b1 is a path that turns 180 degrees from the end of the first work path N1a toward the start of the third work path N1c. The vehicle 1 travels along the third connection path N2c in 4WS mode.

[0112] The above-described connection route N2 is merely an example, and the first connection route N2a to the third connection route N2c may be combined as appropriate. In the above example, the route definition unit defines the connection route N2 based on the separation width D and the minimum turning radius Rmin, but this is not limited to this. The method of defining the planned travel route N by the route definition unit in the above example is merely an example, and other methods may also be applied.

[0113] <Bumper Device> As shown in Figures 14 and 15 , the bumper device 8 includes a bumper 71, a link mechanism 72 that connects the bumper 71 to the vehicle body 2 so that the bumper 71 can move in the longitudinal direction, a buffer spring 73 as a first buffer member that applies an elastic force to the bumper 71 against an external force when the external force acts on the bumper 71, a tension adjustment mechanism 74 that adjusts the tension of the buffer spring 73, a pad member 75 as a second buffer member that elastically contacts the bumper 71 when the external force acts on the bumper 71, a contact sensor 76 that detects the application of an external force to the bumper 71, a contact detector 77 that serves as a detection reference for the contact sensor 76, and a sensor bracket 78 that supports the object sensor 9.

[0114] The bumper 71 has a bumper main body 81 and a bumper bar 82. The bumper main body 81 is connected to the front of the vehicle body 2 so as to be movable back and forth. The bumper bar 82 is installed horizontally in front of the bumper main body 81. The bumper main body 81 has a bumper lower frame 81L extending in the left-right direction at the front of the vehicle body 2, and a pair of bumper side frames 81S extending upward from the left and right ends of the bumper lower frame 81L, respectively.

[0115] The bumper lower frame 81L has flat upper and lower portions and is formed in a generally flat plate shape that is long in the left-right direction. The bumper side frames 81S are formed by bending upward at a generally right angle from the left and right ends of the bumper lower frame 81L. The bumper side frames 81S are formed to extend diagonally forward and upward from the middle portion of the bumper.

[0116] The bumper bar 82 has a bumper front portion 82A extending in the left-right direction at the front of the vehicle body 2, and a pair of bumper end portions 82B extending diagonally outward toward the rear of the vehicle body 2 from the left and right ends of the bumper front portion 82A.

[0117] The bumper front portion 82A is installed laterally between the upper ends of the left and right bumper side frames 81S of the bumper main body 81. The bumper front portion 82A is located forward of the front end of the hood 7. The bumper end portions 82B are formed to extend from the left and right ends of the bumper front portion 82A toward the outer surfaces of the front wheels 4F. This allows the work vehicle 1 to avoid the bumper end portions 82B coming into contact with obstacles outside the paths of the front wheels 4F when turning along a predetermined travel route.

[0118] As shown in FIG. 2 , the vertical distance H1 from the road surface S to the bumper bar 82 (bumper height) is set to be approximately the same as the vertical distance H2 from the road surface S to the top vertices of the front wheels 4F (front wheel height). As shown in FIG. 3 , the left-right width W1 of the bumper bar 82 (bumper width) is set to be greater than the left-right width W2 of the hood 7 and smaller than the distance W3 between the outer surfaces of the left and right front wheels 4F (outer width between the left and right front wheels 4F). The bumper height H1 and bumper width W1 are set appropriately in accordance with regulations of the destination country, etc. Therefore, for example, the bumper height H1 may be set to be lower than the front wheel height H2. Furthermore, the bumper width W1 may be set to be greater than the outer width W2 between the left and right front wheels 4F.

[0119] 15 , the link mechanism 72 is a parallel link mechanism that moves the bumper 71 in the longitudinal direction, and has a pair of link frames 83, 84 that are aligned parallel to each other in the longitudinal direction. Both link frames 83, 84 are disposed above the bumper main body 81 and connect the bumper main body 81 to the vehicle frame 2F. The link frames 83, 84 include a first link frame 83 on the front side and a second link frame 84 on the rear side.

[0120] The first link frame 83 is a generally L-shaped plate having a front frame portion 83F extending vertically and an upper frame portion 83U extending rearward from the upper end of the front frame portion 83F. The upper frame portion 83U of the first link frame 83 is pivotally supported to the vehicle body frame 2F at a central position between the front and rear, and the front frame portion 83F is pivotally supported to the bumper side frame 81S of the bumper main body 81 at a lower end position.

[0121] The second link frame 84 is a generally L-shaped plate, and has a rear frame portion 84E that extends vertically alongside the front frame portion 83F of the first link frame 83, and a lower frame portion 84L that extends downward and forward from the lower end of the rear frame portion 84E. The second link frame 84 is pivotally supported at its upper end to the vehicle body frame 2F by the rear frame portion 84E, and at its front end to the bumper side frame 81S of the bumper main body 81 by the lower frame portion 84L.

[0122] The rear frame portion 84E of the second link frame 84 is pivotally supported on the body frame 2F at a position adjacent to and below the connection portion (proximal end connection portion) P1 between the upper frame portion 83U of the first link frame 83 and the body frame 2F. In other words, the rear frame portion 84E and the upper frame portion 83U are pivotally supported side by side, one above the other, on the body frame 2F.

[0123] The lower frame portion 84L of the second link frame 84 is pivotally supported to the bumper body 81 at a position adjacent to and below the connection portion (tip connection portion) P2 between the front frame portion 83F of the first link frame 83 and the bumper body 81. In other words, the lower frame portion 84L and the front frame portion 83F are pivotally supported side by side, one above the other, on the bumper body 81. Therefore, when an external force acts on the bumper bar 82 from the front, the bumper 71 moves rearward and downward while maintaining the basic posture it had before the external force was applied.

[0124] The buffer springs 73 are disposed rearward of the bumper 71. A pair of buffer springs 73 are provided on the left and right outer sides of the body frame 2F, sandwiching the body frame 2F. The buffer springs 73 are tension coil springs, and a first end 73A of each buffer spring 73 is engaged with the rear end (upper frame rear end) 83E of the upper frame portion 83U of the first link frame 83, and a second end 73B of each buffer spring 73 is engaged with the body frame 2F via the tension adjustment mechanism 74. That is, the buffer springs 73 apply a predetermined tension between the upper frame rear end 83E of the first link frame 83 and the tension adjustment mechanism 74. As a result, the first link frame 83 is constantly biased to swing about the base end connecting portion P1 in a direction that moves the tip end connecting portion P2 forward of the vehicle body 2. That is, the buffer springs 73 constantly press and bias the bumper 71 in a direction that moves the bumper 71 forward. Therefore, when the bumper 71 is pushed rearward by an external force, the buffer spring 73 applies an elastic force to the bumper 71 against the external force.

[0125] The bumper device 8 may be provided with a spring member (for example, a torsion spring) at the base end connecting portion P1 that urges the first link frame 83 to swing as described above, instead of the buffer spring 73. In this case, as with the bumper device 8 having the buffer spring 73, when the bumper 71 is pushed rearward by an external force, an elastic force can be applied to the bumper 71 against the external force.

[0126] The tension adjustment mechanism 74 has a connecting bolt 85, a bolt receiving frame 86, and an adjustment nut 87. The tension adjustment mechanism 74 is provided on each of the left and right outer surfaces of the body frame 2F. The bolt receiving frame 86 is connected to and supported by the outer surface of the body frame 2F.

[0127] The connecting bolt 85 is inserted into the bolt receiving frame 86 from above. The adjusting nut 87 is threadedly connected to the connecting bolt 85 from below the bolt receiving frame 86. The second end 73B of the buffer spring 73 is engaged with the upper end of the connecting bolt 85. Therefore, by changing the fastening position of the adjusting nut 87 relative to the connecting bolt 85, the length of the buffer spring 73 is changed, and the tensile force thereof is also changed. In this way, the tension adjustment mechanism 74 can adjust the tensile force of the buffer spring 73 by adjusting the length of the buffer spring 73 using the adjusting nut 87.

[0128] The pad member 75 is disposed in the center between the left and right sides of the front portion of the vehicle body frame 2F. The pad member 75 is positioned at a vertical height that contacts the bumper bar 82 from behind when the bumper 71 moves rearward and downward. At least the contact portion of the pad member 75 with the bumper bar 82 is formed of an elastic material such as natural rubber or silicone resin. Therefore, when the bumper bar 82 is pushed rearward by an external force and contacts the pad member 75, the pad member 75 applies an elastic force to the bumper bar 82 against the external force. Note that the pad member 75 may include a spring member (e.g., a compression coil spring) instead of or in addition to the elastic material, which applies an elastic force to the bumper 71 against the external force when the bumper bar 82 is pushed rearward by an external force and contacts the pad member 75. Even with this configuration, the same effects as those of the pad member 75 are achieved.

[0129] The contact sensor 76 is disposed in the front of the body frame 2F. In this embodiment, the contact sensor 76 is disposed in a position offset to one side of the left-right center at the front of the body frame 2F. The contact sensor 76 is disposed in a position where it can detect that an external force has acted on the bumper 71 when the bumper 71 moves from a reference position to a first position rearward. The pad member 75 is disposed in a position where it will come into contact with the bumper 71 when the bumper 71 moves from the first position to a second position further rearward. In other words, the contact sensor 76 is disposed in a position where it can detect that an external force has acted on the bumper 71 before the bumper bar 82 comes into contact with the pad member 75 as described above.

[0130] The contact sensor 76 is an on / off switch that is turned on or off when the contact detector 77 comes into contact with a detection portion. The contact sensor 76 may be any sensor that can detect the application of an external force to the bumper 71, and may be, for example, a proximity sensor that is turned on or off when the contact detector 77 approaches a predetermined position. Alternatively, the contact sensor 76 may be configured to detect contact or proximity of a member different from the contact detector 77 (such as the first link frame 83, the second link frame 84, or the bumper main body 81).

[0131] The contact detector 77 is a plate piece that is pivotally supported on one of the left and right side surfaces of the body frame 2F in a flush state. The contact detector 77 is pivotally connected to the front frame portion 83F of the second link frame 84 at a position that is eccentric toward the outer periphery of the pivotal support portion with the body frame 2F. The detection portion of the contact sensor 76 is located rearward of the rear end edge of the contact detector 77. Therefore, if an external force acts on the bumper 71 and the second link frame 84 swings rearward about the upper end of the rear frame portion 84E as a fulcrum, the contact detector 77 will swing rearward in conjunction with this, about the pivotal support portion with the body frame 2F as a fulcrum. As a result, the rear end edge of the contact detector 77 comes into contact with the detection portion of the contact sensor 76.

[0132] At this time, the contact detector 77 comes into contact with the detecting portion before the bumper bar 82 comes into contact with the pad member 75. In other words, when the bumper 71 is pushed and moves rearward and downward, the contact detector 77 is configured to come into contact with the detecting portion of the contact sensor 76 before the bumper bar 82 comes into contact with the pad member 75. This allows the contact sensor 76 to detect that an external force has acted on the bumper 71 before the bumper bar 82 comes into contact with the pad member 75.

[0133] The sensor bracket 78 is connected and supported to the lower part of the bumper main body 81. The object sensor 9 is attached to the sensor bracket 78. That is, the object sensor 9 is provided below the bumper 71 on the vehicle body 2 side. Therefore, when the bumper 71 is pushed rearward by an external force, the object sensor 9 also moves rearward in conjunction with the bumper 71. In this way, the object sensor 9 of this embodiment is configured to move rearward together with the bumper 71 when an external force acts on the bumper 71.

[0134] The sensor bracket 78 has an upper bracket plate 78U disposed above the object sensor 9, a lower bracket plate 78L disposed below the object sensor 9, and bracket side plates 78S connecting the left and right side edges of the upper bracket plate 78U and the lower bracket plate 78L to each other. The object sensor 9 is supported and fixed on the upper surface of the lower bracket plate 78L.

[0135] The bracket upper plate 78U extends out to the left and right beyond the object sensor 9 and functions as a protective frame that protects the object sensor 9. Specifically, the bracket upper plate 78U is formed in a plate shape that is wider left and right than the object sensor 9 and also wider front to back, and covers the entire object sensor 9 when viewed from above. This prevents obstacles from coming into direct contact with the object sensor 9 while driving. It can also protect the object sensor 9 from mud splashes and flying stones from above.

[0136] The bracket upper plate 78U is fixed to and overlaps the underside of the bumper lower frame 81L, with its front edge coinciding with the front edge of the bumper lower frame 81L when viewed from above and its rear portion extending rearward beyond the rear edge of the bumper lower frame 81L. The bumper lower frame 81L is disposed rearward of the bumper front portion 82A of the bumper bar 82. Therefore, the bracket upper plate 78U is also disposed rearward of the bumper front portion 82A.

[0137] The bracket lower plate 78L extends out to the left and right beyond the object sensor 9 and functions as a protective frame that protects the object sensor 9. Specifically, the bracket lower plate 78L is formed in a plate shape that is wider left and right than the object sensor 9 and also wider front to back, and covers the entire object sensor 9 when viewed from below. This prevents obstacles from coming into direct contact with the object sensor 9 while driving. It can also protect the object sensor 9 from mud splashes and flying stones from below.

[0138] The lower bracket plate 78L is disposed below the upper bracket plate 78U with its front edge coinciding with the front edge of the lower bumper frame 81L when viewed from below and its rear portion extending rearward beyond the rear edge of the lower bumper frame 81L. Therefore, like the upper bracket plate 78U, the lower bracket plate 78L is also disposed rearward of the front bumper portion 82A.

[0139] A space 88 capable of accommodating the object sensor 9 is defined between the upper and lower bracket plates 78L and 78U. The object sensor 9 is supported at a position near the front of the upper surface of the lower bracket plate 78L in the space 88. Therefore, even when the bumper 71 moves forward or backward, the object sensor 9 is always located rearward and below the bumper front portion 82A.

[0140] The bracket side plate 78S has a notch 89 that connects the outside of the sensor bracket 78 to the space 88. The notch 89 is an opening large enough to expose almost the entire object sensor 9 to the outside in a side view, and extends rearward from the front edge of the bracket side plate 78S. This allows the object sensor 9 to detect objects in a wide range in front of the vehicle body 2. The object sensor 9 of this embodiment is configured to be able to detect objects within an angular range of 137.5 degrees to the left and 137.5 degrees to the right of the front of the vehicle body 2.

[0141] <First Modification> In the work vehicle 1 of the above embodiment, the chemical liquid tank 5 is provided so as to be exposed to the outside, but as shown in Figures 16 and 17 , the work vehicle 1 may also be provided with a body cover 90 that covers the chemical liquid tank 5. In more detail, the work vehicle 1 of the first modification is provided with the body cover 90 lined up behind the hood 7. The body cover 90 is connected to and supported on the upper rear side of the body frame 2F. The body cover 90 may be connected to the body frame 2F via a drive device such as a hydraulic cylinder or an electric motor, and configured to be able to open and close automatically in response to commands from the control device 15.

[0142] The body cover 90 is made of a material and has a thickness that can thermally and physically protect the liquid chemical tank 5. The body cover 90 is made of a material that is more weather resistant than the liquid chemical tank 5. The body cover 90 may be made of a synthetic resin material or a metal material such as a steel plate or a stainless steel plate, as long as the material has high heat resistance, impact resistance, and weather resistance.

[0143] The body cover 90 is formed to a size that covers almost the entire top surface and both left and right side surfaces of the liquid chemical tank 5. The body cover 90 is arranged such that a portion of the front edge 90E overlaps the rear edge 7E of the bonnet 7 from the inside. In other words, the front edge 90E of the body cover 90, which is the end that butts against the bonnet 7, extends toward the inside of the rear edge 7E of the bonnet 7.

[0144] A gap 91 that communicates with the ventilation chamber 20 is defined between the front edge 90E of the body cover 90 and the rear edge 7E of the bonnet 7. The gap 91 is provided along the rear edge 7E of the bonnet 7 and communicates with the ventilation chamber 20. Therefore, when the cooling fan 11 is operated, air outside the work vehicle 1 flows from rear to front along the surface of the body cover 90 and is introduced into the ventilation chamber 20 through the gap 91. In this way, the gap 91 serves as an air intake for introducing outside air into the ventilation chamber 20.

[0145] At least a portion of gap 91 is located rearward of ventilation chamber 20. As a result, air outside of work vehicle 1 is introduced into ventilation chamber 20 from the chemical solution tank 5 side (rear) through gap 91, and flows smoothly toward motor 3 side (front).

[0146] The body cover 90 has a rear end plate 92. The rear end plate 92 extends in the left-right direction (the direction intersecting the front-rear direction) in front of the spray head 6A. Therefore, the chemical solution sprayed from the spray head 6A is smoothly dispersed toward the side of the vehicle body 2 along the rear end plate 92 together with the air blown by the blower 6B.

[0147] The body cover 90 has a first sloped surface 90A and a second sloped surface 90B. The first sloped surface 90A extends diagonally forward and outward from the side edge of the rear end plate 92. The second sloped surface 90B extends diagonally forward and upward from the upper edge of the rear end plate 92. Therefore, the chemical solution sprayed from the spray head 6A is diffused diagonally forward of the vehicle body 2 along the first sloped surface 90A and the second sloped surface 90B together with the air blown out from the blower 6B.

[0148] The body cover 90 has a side cover 93 and an upper cover 94. The side cover 93 covers the side of the chemical solution tank 5. The side cover 93 is removably attached to the vehicle body 2 or the upper cover 94. The side cover 93 has a first protrusion 95. The first protrusion 95 protrudes outward in the left-right direction of the vehicle body 2 and extends upward from the front to the rear along the side surface of the side cover 93. Therefore, even if branches or leaves come into contact with the side cover 93 from the front while driving, the branches or leaves can be smoothly deflected along the first protrusion 95 toward the rear and upper side of the vehicle body 2.

[0149] The upper cover 94 covers the top of the chemical solution tank 5. The upper cover 94 has a second protrusion 96. The second protrusion 96 protrudes above the vehicle body 2 and is formed so as to widen outward in the left-right direction of the vehicle body 2 as it moves from the front to the rear along the upper surface of the upper cover 94. Therefore, even if branches or leaves come into contact with the upper cover 94 from the front while driving, the branches or leaves can be smoothly deflected along the second protrusion 96 to the rear outward in the left-right direction of the vehicle body 2.

[0150] <Second Modification> The work vehicle 1 in the above embodiment has an adjustment device 45 that operates two steering valve devices 43 (front wheel steering valve device 43F, rear wheel steering valve device 43R) with one steering motor 45A, but as shown in Figure 18, the work vehicle 1 may have an adjustment device 100 that operates two steering valve devices 43 (front wheel steering valve device 43F, rear wheel steering valve device 43R) with two steering motors 101F, 101R, respectively.

[0151] More specifically, the adjustment device 100 of the second modified example includes a front wheel steering motor 101F, a rear wheel steering motor 101R, and a gear device 102. Both the front wheel steering motor 101F and the rear wheel steering motor 101R are electric motors that are driven to rotate by electricity. When the front wheel steering motor 101F and the rear wheel steering motor 101R are driven at the same rotation speed, the gear device 102 transmits the rotational power of each steering motor 101F, 101R to the input shafts of the corresponding steering valve devices 43F, 43R at different rotation ratios.

[0152] The gear device 102 has a front wheel gear 103, a rear wheel gear 104, a first pinion gear 105, and a second pinion gear 106. The front wheel gear 103 is connected to the input shaft of the front wheel steering valve device 43F. The rear wheel gear 104 is connected to the input shaft of the rear wheel steering valve device 43R. The first pinion gear 105 is connected to the drive shaft of the front wheel steering motor 101F. The second pinion gear 106 is connected to the drive shaft of the rear wheel steering motor 101R.

[0153] The front wheel gear 103, rear wheel gear 104, first pinion gear 105, and second pinion gear 106 are all spur gears. The front wheel gear 103 meshes with the first pinion gear 105. The rear wheel gear 104 meshes with the second pinion gear 106. The front wheel gear 103 and the rear wheel gear 104 do not mesh with each other and rotate independently. Therefore, when the front wheel steering motor 101F is operated, the front wheel gear 103 rotates, driving the front wheel steering valve device 43F. On the other hand, when the rear wheel steering motor 101R is operated, the rear wheel gear 104 rotates, driving the rear wheel steering valve device 43R. At this time, the control device 15 controls the operation of the front wheel steering motor 101F and the operation of the rear wheel steering motor 101R separately to steer the front wheels 4F and the rear wheels 4R.

[0154] The first pinion gear 105 and the second pinion gear 106 are the same gear, and when the front wheel steering motor 101F and the rear wheel steering motor 101R are driven at the same rotation speed, the rotation ratio between the two gears 105 and 106 is set to, for example, 1 / 1. On the other hand, the rotation ratio between the front wheel gear 103 and the rear wheel gear 104 is set to, for example, 2 / 1. In other words, the adjustment device 100 of the second modified example is configured so that the front wheel gear 103 rotates twice as fast as the rear wheel gear 104 by driving the front wheel steering motor 101F and the rear wheel steering motor 101R at the same rotation speed.

[0155] As described above, when the front wheel steering motor 101F and the rear wheel steering motor 101R are driven at the same rotation speed, the hydraulic output from the front wheel steering valve device 43F becomes higher than the hydraulic output from the rear wheel steering valve device 43R, driving the front wheel steering cylinder 41F more than the rear wheel steering cylinder 41R. As a result, the steering angle of the front wheels 4F is set to approximately twice the steering angle of the rear wheels 4R.

[0156] In this way, when the steering device 18 turns the front wheels 4F and rear wheels 4R with steering angles in opposite phases (4WS mode), it sets the hydraulic output from the front wheel steering valve device 43F higher than the hydraulic output from the rear wheel steering valve device 43R, so that the steering angle of the front wheels 4F is greater than the steering angle of the rear wheels 4R. This achieves the same effects as the work vehicle 1 of the above embodiment. Furthermore, the steering angle of the front wheels 4F can be set to approximately twice the steering angle of the rear wheels 4R without having to individually control the operation of the front wheel steering motor 101F and the rear wheel steering motor 101R.

[0157] Furthermore, when the steering device 18 is used to travel the work vehicle 1 with the front wheels 4F and rear wheels 4R steered at the same phase (crab mode), the hydraulic output from the front wheel steering valve device 43F and the hydraulic output from the rear wheel steering valve device 43R are made equal to make the steering angle of the front wheels 4F the same as the steering angle of the rear wheels 4R. At this time, the control device 15 makes the rotation speed of the front wheel steering motor 101F lower than the rotation speed of the rear wheel steering motor 101R, adjusting the hydraulic outputs from both steering valve devices 43F, 43R to be the same. This adjusts the operating strokes of the front wheel steering cylinder 41F and the rear wheel steering cylinder 41R to be the same.

[0158] <Third Modification> The work vehicle 1 in the above embodiment is configured to drive the front wheel steering cylinder 41F and the rear wheel steering cylinder 41R by operating the steering valve device 43 with the steering motor 45A (electric motor), but instead of the steering motor 45A and the steering valve device 43, the front wheel steering cylinder 41F and the rear wheel steering cylinder 41R may be driven by a proportional control valve that can freely adjust the discharge pressure of the hydraulic oil.

[0159] The present invention provides a work vehicle 1 described in the following items.

[0160] (Item A1) A work vehicle 1 comprising a vehicle body 2, a prime mover 3 mounted on the vehicle body 2, a traveling device 4 that supports the vehicle body 2 so that it can travel, a material storage section 5 that stores work materials, and a radiator device 10 that cools the coolant circulated to the prime mover 3 by heat exchange with external air, with the direction of straight-ahead travel of the vehicle body 2 being the fore-and-aft direction, the prime mover 3 is located in front of the material storage section 5 across an air vent 20 through which the external air flows, and the radiator device 10 is located in the air vent 20.

[0161] According to the work vehicle 1 according to item A1, the air flowing through the ventilation chamber 20 and the radiator device 10 can prevent the heat generated by the engine 3 from being transmitted to the material storage section 5, thereby reducing the thermal load on the material storage section 5. This makes it possible to make the vehicle body 2 more compact, contributing to improved mobility.

[0162] Furthermore, with the work vehicle 1 according to item A1, the coolant circulating between the radiator device 10 and the engine 3 is appropriately cooled by the air flowing through the ventilation chamber 20, so the engine 3 can be cooled more efficiently. This further reduces the thermal load on the material storage section 5.

[0163] (Item A2) The work vehicle 1 according to Item A1, further comprising a cooling fan 11 that sends the outside air from the material storage section 5 side to the prime mover 3 side.

[0164] According to the work vehicle 1 according to item A2, the material storage section 5 can be cooled more efficiently by the outside air, and the hot air generated by the motor 3 can be reliably prevented from flowing toward the material storage section 5. This further reduces the thermal load on the material storage section 5.

[0165] (Item A3) The work vehicle 1 described in Item A1 or A2 is equipped with a cooling fan 11 that sends the outside air to the prime mover 3, the radiator device 10 having a first ventilation surface 31 arranged opposite the material storage section 5 and a second ventilation surface 32 arranged opposite the prime mover 3, and the cooling fan 11 is arranged adjacent to the second ventilation surface 32.

[0166] According to the work vehicle 1 according to item A3, the air that has passed through the radiator device 10 can be more reliably blown to the engine 3, which further contributes to cooling the engine 3. This further reduces the thermal load on the material storage section 5.

[0167] (Item A4) The work vehicle 1 according to any one of Items A1 to A3, further comprising an oil cooler 12 that cools hydraulic oil of each hydraulic device mounted on the vehicle body 2 by heat exchange with the outside air, the oil cooler 12 being arranged in the ventilation chamber 20.

[0168] With the work vehicle 1 according to item A4, the air flowing through the ventilation chamber 20, the radiator unit 10, and the oil cooler 12 can more reliably prevent the heat generated by the prime mover 3 from being transmitted to the material storage unit 5, further reducing the thermal load on the material storage unit 5. Moreover, with this vehicle, the air flowing through the ventilation chamber 20 can appropriately cool the hydraulic oil circulating between the oil cooler 12 and each hydraulic device, maintaining stable operation of each hydraulic device. This further improves mobility.

[0169] (Item A5) The work vehicle 1 described in Item A4, wherein the radiator device 10 has a first ventilation surface portion 31 arranged opposite the material storage section 5 and a second ventilation surface portion 32 arranged opposite the prime mover 3, and the oil cooler 12 is arranged adjacent to the first ventilation surface portion 31.

[0170] According to the work vehicle 1 according to item A5, the coolant is cooled more efficiently by the air that has passed through the oil cooler 12, which further contributes to cooling the prime mover 3. This further reduces the thermal load on the material storage section 5.

[0171] (Item A6) The work vehicle 1 according to Item A5, further comprising a cooling fan 11 that sends the outside air to the motor 3, the cooling fan 11 being disposed adjacent to the second ventilation surface portion 32.

[0172] With the work vehicle 1 according to item A6, the air flowing through the ventilation chamber 20 can be more reliably sent to the oil cooler 12, so the hydraulic oil is cooled more efficiently, further contributing to maintaining the operational stability of each hydraulic device. This further improves mobility.

[0173] (Item A7) The work vehicle 1 according to any one of Items A1 to A6, comprising: a travel pump 16A driven by the prime mover 3 and discharging hydraulic oil; and a travel motor 17 that drives the travel device 4 with the hydraulic oil discharged from the travel pump 16A, wherein the travel pump 16A is disposed adjacent to and in front of the prime mover 3.

[0174] According to the work vehicle 1 according to item A7, the relatively large prime mover 3 can be disposed behind the travel pump 16A, making it possible to make the front part of the vehicle body 2 compact. This further improves mobility.

[0175] (Item A8) The work vehicle 1 according to any one of Items A1 to A7, further comprising an exhaust device 13 that guides air discharged from the engine 3 to the outside of the vehicle, the exhaust device 13 being disposed adjacent to and in front of the engine 3.

[0176] According to the work vehicle 1 relating to item A8, in addition to the heat generated by the engine 3, the heat generated by the exhaust device 13 can be prevented from being transmitted to the material storage section 5, thereby further reducing the thermal load on the material storage section 5.

[0177] (Item A9) The work vehicle 1 according to any one of Items A1 to A8, further comprising an air purification device 14 that purifies the air supplied to the motor 3, the air purification device 14 being disposed in the ventilation chamber 20.

[0178] According to the work vehicle 1 according to item A9, the temperature of the air supplied from the air purifier 14 to the engine 3 can be kept low, thereby maintaining a stable output of the engine 3. This further improves mobility.

[0179] (Item A10) The work vehicle 1 according to any one of Items A1 to A9, further comprising a spraying device 6 that sprays a chemical solution around the vehicle body 2, and the material storage section 5 is a chemical solution tank that stores the chemical solution.

[0180] The work vehicle 1 according to item A10 is a chemical spray vehicle equipped with a material storage section 5 serving as a chemical tank and a spraying device 6. As with the work vehicle 1 according to item A1 above, this work vehicle 1 can reduce the thermal load on the material storage section (chemical tank) 5 while making the vehicle body 2 more compact. This improves mobility.

[0181] Furthermore, with the work vehicle 1 according to item A10 above, the thermal load on the material storage section 5 is reduced, thereby preventing the chemical solution stored in the material storage section 5 from being altered by the radiant heat and ultraviolet rays, and also preventing the adverse effects that may occur when high-temperature chemical solution is sprayed on crops or soil.

[0182] (Item A11) A work vehicle 1 described in Item A10, which is equipped with a spray pump 6C that sprays the chemical solution from the spray device 6, and a spray motor 19 that provides rotational power to the spray device 6, and the spray pump 6C and the spray motor 19 are arranged below the radiator device 10 in the ventilation chamber 20.

[0183] In the work vehicle 1 (chemical sprayer vehicle) according to item A11, the spray pump 6C and the spray motor 19 are cooled by the air flowing through the ventilation chamber 20, so that they can maintain stable operation, thereby further improving mobility.

[0184] (Item A12) A work vehicle 1 described in any one of Items A1 to A11, which is provided with a bonnet 7 that covers the prime mover 3 and a body cover 90 that covers the material storage section 5, and an air intake 91 that leads to the ventilation chamber 20 is provided between the butt ends 7E, 90E of the bonnet 7 and the body cover 90.

[0185] According to the work vehicle 1 relating to item A12, the air introduced into the ventilation chamber 20 from the air intake 91 acts as a wall, separating the location of the prime mover 3 from the location of the material storage section 5, thereby effectively reducing the thermal load on the material storage section 5.

[0186] (Item A13) The work vehicle 1 according to Item A12, wherein at least a portion of the air intake 91 is provided rearward of the ventilation chamber 20.

[0187] With the work vehicle 1 according to item A13, the outside air is smoothly guided along the surface of the body cover 90 from the rear into the gap 91, so that cool air can be efficiently introduced into the ventilation chamber 20. This effectively reduces the thermal load on the material storage section 5.

[0188] (Item A14) The work vehicle 1 according to Item A13, wherein the butt end 90E of the body cover 90 extends toward the inside of the hood 7.

[0189] With the work vehicle 1 according to item A14, the outside air introduced into the gap 91 as described above is smoothly guided along the butt end 90E of the body cover 90 into the ventilation chamber 20, allowing cool air to be introduced more efficiently into the ventilation chamber 20. This makes it possible to reduce the thermal load on the material storage section 5 even more effectively.

[0190] (Item A15) A work vehicle 1 comprising a vehicle body 2, a prime mover 3 mounted on the vehicle body 2, a traveling device 4 that supports the vehicle body 2 so that it can travel, a chemical solution tank 5 that stores a chemical solution, a spraying device 6 that sprays the chemical solution around the vehicle body 2, and a body cover 90 that covers the chemical solution tank 5.

[0191] The work vehicle 1 according to item A15 is a chemical sprayer vehicle equipped with a chemical tank 5 as a material storage section, a spraying device 6, and a body cover 90 that covers the chemical tank 5. With this work vehicle 1, the body cover 90 can protect the chemical tank 5 from the sun's radiant heat, ultraviolet rays, collisions with obstacles, etc. It can also prevent the chemical stored in the chemical tank 5 from being altered by the radiant heat and ultraviolet rays, and prevent the adverse effects that can occur when high-temperature chemicals are sprayed on crops or soil.

[0192] (Item A16) The work vehicle 1 according to Item A15, wherein the body cover 90 is formed of a material that is more weather resistant than the chemical solution tank 5.

[0193] By using a body cover 90 that is more weather resistant than the chemical tank 5, as in the work vehicle 1 related to item A16, it is possible to suppress ultraviolet deterioration of the body cover 90 itself and also to more effectively protect the chemical tank 5 and the chemical liquid inside it.

[0194] (Item A17) A work vehicle 1 as described in Item A15 or Item A16, which is provided with a bonnet 7 that covers the prime mover 3, and with the direction of straight-ahead travel of the vehicle body 2 being the front-to-rear direction, the bonnet 7 is positioned adjacent to the front of the body cover 90 and covers the front part of the chemical liquid tank 5 from the front.

[0195] According to the work vehicle 1 according to item A17, when traveling between trees in an orchard or the like, branches and leaves do not come into contact with the front part of the chemical tank 5. This effectively prevents deformation or damage to the chemical tank 5 due to physical loads.

[0196] (Item A18) The work vehicle 1 according to Item A17, wherein the bonnet 7 is formed of a material that is more weather resistant than the chemical liquid tank 5.

[0197] By using a bonnet 7 that is more weather resistant than the chemical tank 5, as in the work vehicle 1 related to item A18, it is possible to suppress ultraviolet deterioration of the bonnet 7 itself and also to more effectively protect the front of the chemical tank 5 from deformation and deterioration due to ultraviolet rays.

[0198] (Item A19) The work vehicle 1 according to item A17 or 18, wherein the prime mover 3 is disposed in front of the chemical solution tank 5 across an air vent chamber 20.

[0199] According to the work vehicle 1 relating to item A19, the air flowing through the ventilation chamber 20 can prevent the heat generated by the engine 3 from being transferred to the chemical tank 5, thereby effectively preventing deformation or deterioration of the chemical tank 5 due to heat, and alteration of the chemical liquid stored in the chemical tank 5.

[0200] (Item A20) The work vehicle 1 according to Item A19, wherein an air intake 91 communicating with the ventilation chamber 20 is provided between the butted ends 7E, 90E of the bonnet 7 and the body cover 90.

[0201] According to the work vehicle 1 relating to item A20, the air introduced into the ventilation chamber 20 from the air intake 91 acts as a wall, separating the location of the prime mover 3 from the location of the chemical tank 5, thereby more effectively preventing deformation or deterioration of the chemical tank 5 due to heat, and alteration of the chemical liquid stored in the chemical tank 5.

[0202] (Item A21) The work vehicle 1 described in any one of Items A15 to A20, wherein the spraying device 6 has a spray head 6A that sprays the chemical solution and a blower 6B that sends external air to the spray head 6A, the spray head 6A is arranged adjacent to the rear of the chemical solution tank 5 and the blower 6B is arranged adjacent to the rear of the spray head 6A, with the straight-ahead driving direction of the vehicle body 2 being the front-to-rear direction, and the body cover 90 has a rear end plate 92 that extends in a direction intersecting the front-to-rear direction at a position forward of the spray head 6A.

[0203] According to the work vehicle 1 according to item A21, the chemical solution sprayed from the spray head 6A is smoothly dispersed along the rear end plate 92 toward the sides of the vehicle body 2 together with the air blown by the blower 6B, so the chemical solution is less likely to adhere to the top or side surfaces of the body cover 90. This also improves maintainability.

[0204] (Item A22) The work vehicle 1 according to Item A21, wherein the body cover 90 has a first slope portion 90A extending obliquely forward and outward from a side edge portion of the rear end plate 92.

[0205] According to the work vehicle 1 relating to item A22, the chemical solution sprayed from the spray head 6A is diffused along the first inclined portion 90A and the second inclined portion 90B together with the wind blown out from the blower 6B, diagonally forward and outward from the vehicle body 2, thereby enabling the chemical solution to be sprayed more efficiently over a wider area.

[0206] (Item A23) The work vehicle 1 according to Item A22, wherein the body cover 90 has a second sloped portion 90B extending obliquely forward and upward from the upper edge of the rear end plate 92.

[0207] According to the work vehicle 1 relating to item A23, the chemical solution sprayed from the spray head 6A is diffused along the second inclined portion 90B together with the wind blown out from the blower 6B, diagonally forward and upward from the vehicle body 2, thereby enabling the chemical solution to be sprayed more efficiently over a wider area.

[0208] (Item A24) The work vehicle 1 described in any one of Items A21 to A23, wherein the body cover 90 has a side cover 93 that covers the side of the chemical liquid tank 5, and the side cover 93 protrudes outward in the width direction of the vehicle body 2 and has a first convex portion 95 that extends upward from the front to the rear along the side portion of the side cover 93.

[0209] With the work vehicle 1 according to item A24, even if branches or leaves come into contact with the side cover 93 from the front when traveling between trees in an orchard or the like, the branches or leaves can be smoothly deflected upward and rearward along the first convex portion 95 of the vehicle body 2. This effectively prevents deformation or damage to the body cover 90 due to physical loads.

[0210] (Item A25) The body cover 90 has an upper cover 94 that covers the top of the chemical liquid tank 5, and the upper cover 94 has a second convex portion 96 that protrudes above the vehicle body 2 and expands outward in the width direction of the vehicle body 2 as it moves from the front to the rear along the upper surface of the upper cover 94. This is a work vehicle 1 described in any one of Items A21 to A24.

[0211] With the work vehicle 1 according to item A25, even if branches or leaves come into contact with the upper cover 94 from the front when traveling between trees in an orchard or the like, the branches or leaves can be smoothly deflected along the second convex portions 96 to the rear on the left and right outside of the vehicle body 2. This effectively prevents deformation or damage to the body cover 90 due to physical loads.

[0212] (Item A26) The body cover 90 has an upper cover 94 that covers the top of the chemical liquid tank 5 and a side cover 93 that covers the side of the chemical liquid tank 5, and the side cover 93 is removably attached to the vehicle body 2 or the upper cover 94. This is a work vehicle 1 described in any one of Items A15 to A25.

[0213] According to the work vehicle 1 relating to item A26, by removing the side cover 93, it is possible to inspect and clean the area around the side of the chemical tank 5, which is covered by the body cover 90, thereby further improving maintainability.

[0214] (Item B1) A work vehicle 1 comprising a vehicle body 2, a working device 6 mounted on the rear of the vehicle body 2, front wheels 4F and rear wheels 4R that support the vehicle body 2 so that it can travel, and a steering device 18 that adjusts the steering angle of the front wheels 4F and the steering angle of the rear wheels 4R, wherein the steering device 18 makes the steering angle of the front wheels 4F larger than the steering angle of the rear wheels 4R when the steering angles of the front wheels 4F and the rear wheels 4R are set to be in opposite phases.

[0215] According to the work vehicle 1 according to item B1, when turning by steering the front wheels 4F and the rear wheels 4R in opposite phases, the turning center Q1 can be set rearward as viewed from the side of the vehicle body 2, which provides high turning performance and allows smooth turning even in narrow spaces. This improves maneuverability.

[0216] (Item B2) The work vehicle 1 according to Item B1, wherein the steering device 18 sets the steering angle of the front wheels 4F to approximately twice the steering angle of the rear wheels 4R when the front wheels 4F and the rear wheels 4R are steered at angles in opposite phases.

[0217] With the work vehicle 1 according to item B2, when turning with the front wheels 4F and rear wheels 4R steered at opposite phases, the turning center Q1 can be set at a fixed point towards the rear as viewed from the side of the vehicle body 2, enabling smooth and stable turning even in tight spaces. This further improves maneuverability.

[0218] (Item B3) The work vehicle 1 according to item B1 or B2, which includes a prime mover 3 mounted on the vehicle body 2, and the steering device 18 includes a steering pump 44 driven by power from the prime mover 3 to discharge hydraulic oil, a front wheel steering valve device 43F that adjusts the pressure of the hydraulic oil supplied from the steering pump 44 to adjust the steering angle of the front wheels 4F, a rear wheel steering valve device 43R that adjusts the pressure of the hydraulic oil supplied from the steering pump 44 to adjust the steering angle of the rear wheels 4R, and an adjustment device 45 that adjusts the hydraulic outputs from the front wheel steering valve device 43F and the rear wheel steering valve device 43R, and when the front wheels 4F and the rear wheels 4R are steered at angles that are in opposite phases, the adjustment device 45 makes the hydraulic output from the front wheel steering valve device 43F higher than the hydraulic output from the rear wheel steering valve device 43R.

[0219] According to the work vehicle 1 according to item B3, the steering angle of the front wheels 4F and the rear wheels 4R can be adjusted hydraulically, so both wheels 4F, 4R can be steered stably regardless of the road surface condition, thereby further improving mobility.

[0220] (Item B4) The work vehicle 1 described in Item B3, wherein the adjustment device 45 includes a steering motor 45A that rotates and a gear device 45B that transmits the rotational drive of the steering motor 45A to each input shaft of the front wheel steering valve device 43F and the rear wheel steering valve device 43R at different rotation ratios, and the rotation ratio is set to a ratio such that when the front wheels 4F and the rear wheels 4R are steered at angles in opposite phases, the steering angle of the front wheels 4F is larger than the steering angle of the rear wheels 4R.

[0221] According to the work vehicle 1 according to item B4, the steering angle of the front wheels 4F and rear wheels 4R can be adjusted by controlling the drive of the steering motor 45A, so high mobility can be achieved with relatively simple travel control.

[0222] (Item B5) The work vehicle 1 according to any one of Items B1 to B4, wherein the steering device 18 sets the steering angle of the front wheels 4F to be the same as the steering angle of the rear wheels 4R when the front wheels 4F and the rear wheels 4R are steered in the same phase.

[0223] With the work vehicle 1 according to item B5, the steering angles of the front wheels 4F and rear wheels 4R can be adjusted to opposite or the same phase depending on the travel route, further improving maneuverability. Moreover, with this vehicle, turning ability is high when traveling in the opposite phase, and the direction of movement and orientation of the vehicle body 2 are stable when traveling in the same phase, further contributing to improved maneuverability.

[0224] (Item B6) The steering device 18 includes a prime mover 3 mounted on the vehicle body 2, and includes a steering pump 44 driven by power from the prime mover 3 to discharge hydraulic oil, a front wheel steering valve device 43F that adjusts the steering angle of the front wheels 4F by adjusting the pressure of the hydraulic oil supplied from the steering pump 44, a rear wheel steering valve device 43R that adjusts the steering angle of the rear wheels 4R by adjusting the pressure of the hydraulic oil supplied from the steering pump 44, and a combination of the front wheel steering valve device 43F and the rear wheel steering valve device and an adjusting device 45 that adjusts the hydraulic output from the front wheel steering valve device 43F relative to the hydraulic output from the rear wheel steering valve device 43R when the front wheels 4F and the rear wheels 4R are steered at angles in opposite phases, and adjusts the hydraulic output from the front wheel steering valve device 43F to be the same as the hydraulic output from the rear wheel steering valve device 43R when the front wheels 4F and the rear wheels 4R are steered at angles in the same phase.

[0225] According to the work vehicle 1 of item B6, the steering angles of the front wheels 4F and the rear wheels 4R can be adjusted hydraulically, so both wheels 4F, 4R can be steered stably regardless of the road surface condition. This further improves maneuverability. Moreover, this vehicle can adjust the steering angles of the front wheels 4F and the rear wheels 4R to opposite or the same phase depending on the travel route, further improving maneuverability. Furthermore, when traveling in the opposite phase, the vehicle has high turning ability, and when traveling in the same phase, the direction of movement and orientation of the vehicle body 2 are stable, further contributing to improved maneuverability.

[0226] (Item B7) The work vehicle 1 described in Item B6, wherein the steering device 18 includes a rear wheel steering cylinder 41R that steers the rear wheels 4R using hydraulic output from the rear wheel steering valve device 43R, and a steering switch valve 42 that controls hydraulic oil supplied from the rear wheel steering valve device 43R to the rear wheel steering cylinder 41R and changes the steering direction of the rear wheels 4R to one of a first position that puts the steering direction of the rear wheels 4R in the opposite phase to that of the front wheels 4F, a second position that puts the steering direction of the rear wheels 4R in the same phase as the front wheels 4F, and a third position that restricts steering of the rear wheels 4R.

[0227] According to the work vehicle 1 relating to item B7, the steering angles of the front wheels 4F and rear wheels 4R can be set to opposite phases or the same phase depending on the travel route, or steering of the rear wheels 4R can be prohibited, thereby further improving maneuverability.

[0228] (Item B8) The adjustment device 45 has a front wheel steering motor 101F that rotationally drives the input shaft of the front wheel steering valve device 43F, and a rear wheel steering motor 45R that rotationally drives the input shaft of the rear wheel steering valve device 43R, and when the front wheels 4F and the rear wheels 4R are to be steered at angles of opposite phases, the front wheel steering motor 45F and the rear wheel steering motor 45R change their rotation speeds to make the hydraulic pressure output from the front wheel steering valve device 43F higher than the hydraulic pressure output from the rear wheel steering valve device 43R, and when the front wheels 4F and the rear wheels 4R are to be steered at angles of the same phase, the front wheel steering motor 45F and the rear wheel steering motor 45R change their rotation speeds to make the hydraulic pressure output from the front wheel steering valve device 43F and the hydraulic pressure output from the rear wheel steering valve device 43R the same. (Item B8) The work vehicle 1 described in any one of Items B1 to B7.

[0229] According to the work vehicle 1 of item B8, the steering angles of the front wheels 4F and the rear wheels 4R can be adjusted by controlling the drive of the front wheel steering motor 101F and the rear wheel steering motor 101R, so high maneuverability can be achieved with relatively simple driving control. Moreover, with this vehicle, the steering angles of the front wheels 4F and the rear wheels 4R can be set to opposite phases or in phase to suit the driving route, further improving maneuverability. Furthermore, with this vehicle, turning ability is high when traveling in the opposite phases, and the direction of movement and orientation of the vehicle body 2 are stable when traveling in the same phase, further contributing to improved maneuverability.

[0230] (Item B9) A work vehicle 1 described in any one of Items B1 to B8, in which the rear of the working device 6 is positioned rearward of the rear wheel 4R, with the direction of straight-ahead travel of the vehicle body 2 being the front-to-rear direction, and the length from the rear wheel 4R to the rear end of the working device 6 in the work vehicle 1 is greater than the length from the front wheel 4F to the front end of the vehicle body 2.

[0231] In the work vehicle 1 according to item B9, when turning with the front wheels 4F and rear wheels 4R steered at opposite phase angles, the front of the vehicle body 2 turns to face the direction of travel (turning direction) earlier than the rear, and accordingly the position of the work implement 6 can be changed quickly.

[0232] (Item B10) The work vehicle 1 according to item B9, comprising a chemical tank 5 that stores a chemical solution, and a spraying device 6 as the work device that sprays the chemical solution around the vehicle body 2.

[0233] The work vehicle 1 according to item B10 is a chemical spray vehicle equipped with a chemical tank 5 and a spraying device 6 as a work device. This work vehicle 1 can travel smoothly even in narrow spaces, allowing for efficient spraying of chemicals.

[0234] (Item C1) A work vehicle 1 comprising a vehicle body 2, a traveling device 4 that supports the vehicle body 2 so that it can travel, and a bumper device 8 provided on the vehicle body 2, with the direction of straight-ahead travel of the vehicle body 2 being the front-to-rear direction, the bumper device 8 having: a bumper 71; a link mechanism 72 that connects the bumper 71 to the vehicle body 2 so that it can move in the front-to-rear direction; a first buffer member 73 that, when an external force acts on the bumper 71 from the front-to-rear direction, applies an elastic force to the bumper 71 against the external force; and a second buffer member 75 that elastically contacts the bumper 71 when the external force acts on the bumper 71.

[0235] According to the work vehicle 1 of item C1, the external force when an obstacle or the like collides with the bumper 71 can be absorbed in two stages by the first buffer member 73 and the second buffer member 75, thereby improving safety.

[0236] (Item C2) The work vehicle 1 described in Item C1, wherein the link mechanism 72 has link frames 83, 84 whose first end 73A is pivotally supported on the vehicle body 2 and whose second end 73B is pivotally supported on the bumper 71, and the first buffer member 73 is a spring member that applies elastic force to the link frames 83, 84 in a direction in which the link frames 83, 84 swing around the first end 73A as a fulcrum.

[0237] According to the work vehicle 1 relating to item C2, the elastic force of the first buffer member 73 acts against the external force, further improving safety.

[0238] (Item C3) The work vehicle 1 according to Item C1 or C2, wherein the bumper device 8 has a tension adjustment mechanism 74 that adjusts the tension of the first buffer member 73.

[0239] According to the work vehicle 1 of item C3, the elastic force of the first buffer member 73 can be adjusted to suit the usage environment, making it possible to exhibit more appropriate buffering performance, thereby further improving safety.

[0240] (Item C4) The work vehicle 1 according to any one of Items C1 to C3, wherein the link mechanism 72 has a parallel link mechanism that moves the bumper 71 in parallel in the front-rear direction.

[0241] According to the work vehicle 1 according to item C4, when an obstacle or the like collides with the bumper 71 from the front or rear, the bumper 71 moves in the same direction to accommodate the collision, thereby providing more effective shock absorbing performance, thereby further improving safety.

[0242] (Item C5) The work vehicle 1 described in Item C4 is equipped with a contact sensor 76 that detects the external force acting on the bumper 71, and a control device 15 that controls the travel of the vehicle body 2 in accordance with the detection result of the contact sensor 76, and the contact sensor 76 is provided in a position where it can detect the external force before the bumper 71 contacts the second buffer member 75.

[0243] According to the work vehicle 1 relating to item C5, when an obstacle or the like collides with the bumper 71, the contact of the obstacle or the like with the bumper 71 can be detected before the bumper 71 comes into contact with the second buffer member 75, and the travel of the vehicle body 2 can be restricted, thereby further improving safety.

[0244] (Item C6) The work vehicle 1 described in Item C5, wherein the contact sensor 76 detects the external force when the bumper 71 moves from a reference position to a first position, and the second buffer member 75 is provided in a position where it comes into contact with the bumper 71 when the bumper 71 moves further from the first position to a second position.

[0245] According to the work vehicle 1 relating to item C6, when an obstacle or the like collides with the bumper 71, the external force is first absorbed by the first buffer member 73, and then the travel of the vehicle body 2 can be restricted, thereby further improving safety.

[0246] (Item C7) The work vehicle 1 according to any one of Items C1 to C6, wherein the bumper 71 includes a bumper main body 81 connected to the vehicle body 2 so as to be movable forward and backward, and a bumper bar 82 provided laterally on the bumper main body 81.

[0247] According to the work vehicle 1 of item C7, the bumper bar 82 attached laterally to the bumper body 81 can more reliably avoid collisions with obstacles and the like with the vehicle body 2, further improving safety. Moreover, when an obstacle or the like collides with the bumper bar 82 from the front or rear, the bumper body 81 also moves in the same direction, thereby providing more effective shock absorbing performance. Therefore, safety is further improved.

[0248] (Item C8) The work vehicle 1 described in Item C7, wherein the width direction of the vehicle body 2 is the left-right direction, and the bumper bar 82 has a bumper front portion 82A extending in the left-right direction at the front of the vehicle body 2, and a pair of bumper end portions 82B extending diagonally outward and rearward from the left and right ends of the bumper front portion 82A, respectively.

[0249] According to the work vehicle 1 of item C8, obstacles that collide with the bumper bar 82 from the front can be deflected along the bumper end 82B to the rear outside the left and right sides of the vehicle body 2, thereby providing more effective shock-absorbing performance. This further improves safety. Furthermore, because the bumper end 82B extends diagonally outward and rearward from the vehicle body 2, it is possible to prevent the bumper end 82B from accidentally coming into contact with obstacles that are in a position where they are unlikely to come into contact with the vehicle body 2 or the front wheels 4F during cornering. This further improves safety.

[0250] (Item C9) The work vehicle 1 according to any one of Items C5 to C8, further comprising an object sensor 9 that detects objects around the vehicle body 2, the control device 15 controlling the travel of the vehicle body 2 in accordance with the detection results of the object sensor 9 in addition to the detection results of the contact sensor 76, and the object sensor 9 being provided on the bumper 71.

[0251] According to the work vehicle 1 according to item C9, an obstacle or the like can be detected before it collides with the bumper 71, and the travel of the vehicle body 2 can be restricted, thereby further improving safety.

[0252] Furthermore, if an obstacle or the like collides with the object sensor 9, there is a risk that the accuracy of object detection will decrease due to improper installation or deformation. However, with the work vehicle 1 according to item C9 above, if an obstacle or the like cannot be detected for some reason and the obstacle or the like collides with the bumper 71, the object sensor 9 will move forward and backward together with the bumper 71, so it is possible to reliably prevent the obstacle or the like from colliding with the object sensor 9. Therefore, sufficient safety is guaranteed even when used over a long period of time.

[0253] (Item C10) The work vehicle 1 according to Item C9, wherein the object sensor 9 is provided below the bumper 71 on the vehicle body 2 side.

[0254] The vehicle 1 according to item C10 can more reliably avoid collision of obstacles with the object sensor 9, so sufficient safety is guaranteed even when used over a long period of time.

[0255] (Item C11) The work vehicle 1 described in Item C9 or Item C10, wherein the bumper 71 has a sensor bracket 78 that supports the object sensor 9, and the sensor bracket 78 has protective frame portions 78U, 78L that extend to the left and right sides beyond the object sensor 9.

[0256] The work vehicle 1 according to item C11 can reliably prevent obstacles from colliding with the object sensor 9 by the protective frame portions 78U, 78L of the sensor bracket 78, so sufficient safety is guaranteed even when used over a long period of time.

[0257] (Item C12) The work vehicle 1 according to any one of Items C5 to C11, wherein the control device 15 stops the vehicle body 2 from traveling when the contact sensor 76 enters a contact detection state in which it detects the external force.

[0258] According to the work vehicle 1 according to item C12, the vehicle body 2 can be stopped from traveling early, further improving safety.

[0259] (Item C13) The work vehicle 1 according to any one of Items C5 to C12, wherein when the contact sensor enters the contact detection state, the control device allows the vehicle body to travel only in a predetermined forward and backward direction until the contact sensor enters a non-contact detection state in which it does not detect the external force.

[0260] According to the work vehicle 1 relating to item C13, if an obstacle or the like collides with the bumper 71, the movement of the vehicle body 2 is restricted to only the specified forward and backward directions until the collision state is resolved, thereby further improving safety.

[0261] Although the present invention has been described above, the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0262] REFERENCE SIGNS LIST 1 Work vehicle 2 Vehicle body 3 Motor 4 Traveling device 4F Front wheels 4R Rear wheels 5 Chemical liquid tank (material storage section) 6 Spraying device (working device) 6A Spray head 6B Blower 6C Spraying pump 7 Bonnet 7E Rear end (butt end) 8 Bumper device 9 Object sensor 10 Radiator device 11 Cooling fan 12 Oil cooler 13 Exhaust device 14 Air purifier 15 Control device 16 Pump device 16A Travel pump 16B Spraying pump 17 Travel motor 18 Steering device 19 Spraying motor 20 Ventilation chamber 31 First ventilation surface 32 Second ventilation surface 41F Front wheel steering cylinder 41R Rear wheel steering cylinder 42 Steering switching valve 43F Front wheel steering valve device 43R Rear wheel steering valve device 44 Steering pump 45 Adjusting device 45A Steering motor 45B Gear device 71 Bumper 72 Link mechanism 73 First buffer member 74 Tension adjustment mechanism 75 Second buffer member 83 First link frame (link frame) 84 Second link frame (link frame) 90 Body cover 90A First inclined portion 90B Second inclined portion 90E Front end portion (butt end portion) 91 Gap (air intake port) 92 Rear end plate 93 Side cover 94 Upper cover 95 First convex portion 96 Second convex portion

Claims

1. A work vehicle comprising: a vehicle body; a prime mover mounted on the vehicle body; traveling gear supporting the vehicle body so that it can travel; a material storage section for storing work materials; and a radiator unit for cooling liquid circulated through the prime mover by heat exchange with external air, wherein the direction of straight-ahead travel of the vehicle body is the front-to-rear direction, the prime mover is disposed in front of the material storage section across an air vent through which the external air flows, and the radiator unit is disposed in the air vent.

2. A work vehicle as described in claim 1, further comprising a cooling fan for blowing the outside air from the material storage section side to the prime mover side.

3. A work vehicle as described in claim 1, further comprising a cooling fan which sends the outside air to the prime mover, the radiator device having a first ventilation surface portion which is arranged opposite the material storage section and a second ventilation surface portion which is arranged opposite the prime mover, and the cooling fan being arranged adjacent to the second ventilation surface portion.

4. A work vehicle as described in claim 1, further comprising an oil cooler that cools hydraulic oil of each hydraulic device mounted on the vehicle body by heat exchange with the outside air, the oil cooler being disposed in the ventilation chamber.

5. A work vehicle as described in claim 4, wherein the radiator device has a first ventilation surface portion arranged opposite the material storage section and a second ventilation surface portion arranged opposite the prime mover, and the oil cooler is arranged adjacent to the first ventilation surface portion.

6. A work vehicle as claimed in claim 5, further comprising a cooling fan for sending the outside air to the prime mover, the cooling fan being disposed adjacent to the second ventilation surface portion.

7. A work vehicle as described in claim 1, comprising: a travel pump driven by the prime mover and discharging hydraulic oil; and a travel motor that drives the traveling device with the hydraulic oil discharged from the travel pump, wherein the travel pump is disposed adjacent to and in front of the prime mover.

8. A work vehicle as claimed in claim 1, further comprising an exhaust device for guiding air discharged from said prime mover to the outside of the vehicle, said exhaust device being disposed adjacent to the front of said prime mover.

9. A work vehicle as claimed in claim 1, further comprising an air purifying device for purifying air supplied to said prime mover, said air purifying device being disposed in said ventilation chamber.

10. A work vehicle as claimed in any one of claims 1 to 9, comprising a spraying device for spraying a chemical solution around the vehicle body, and the material storage section is a chemical solution tank for storing the chemical solution.

11. A work vehicle as described in claim 10, comprising a spray pump for spraying the chemical solution from the spray device, and a spray motor for providing rotational power to the spray device, wherein the spray pump and the spray motor are positioned below the radiator device in the air ventilation chamber.

12. A work vehicle as described in claim 1, comprising: a bonnet which covers the prime mover; and a body cover which covers the material storage section, and an air intake opening which leads to the ventilation chamber is provided between the butt ends of the bonnet and the body cover.

13. A work vehicle according to claim 12, wherein at least a portion of the air intake is provided rearward of the ventilation chamber.

14. The work vehicle according to claim 13, wherein the butt end of the body cover extends toward the inside of the bonnet.

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