Work vehicles

Abstract

The present invention provides a work vehicle that minimizes the height of the front of the hood while resolving the issue of insufficient strength around the opening for taking in outside air at the front of the hood. [Solution] The hood is shaped so that the height of the front part is lower than the rear part so that the driver's seated worker can see forward. In addition, a wide opening is provided in the center of the front of the hood, and this opening is covered with a grille equipped with air intakes. Furthermore, the left and right ends of the opening with the grille are shaped to be narrow in the left and right direction for mounting headlights and work lights, and reinforcing protrusions are formed at the boundary between the left and right light mounting parts and the central opening.

Description

Technical Field

[0001] The present invention relates to a work vehicle mainly for agricultural use such as a tractor. More specifically, the present invention relates to a work vehicle in which a power unit is provided in front of a control unit having a driver's seat, and an engine and accessories of the engine provided in the power unit are covered by a resin hood.

Background Art

[0002] For example, a crawler tractor, which is an agricultural work vehicle, has a control unit provided near the rear of a chassis frame framed in a substantially rectangular shape by left and right side members and a cross member. The control unit is provided with a driver's seat, a steering wheel, etc. covered by a cab. Also, a power unit is provided in front of the control unit, and the power unit is provided with an engine, engine accessories, or accessories such as a battery and a condenser of an air conditioner provided in the cab, covered by a hood. Further, a crawler-type traveling device is provided below the chassis frame.

[0003] And a tractor configured in this way has high traction performance for freely operating large work machines. Therefore, a work machine or a transport vehicle is connected to a three-point link or a drawbar equipped at the rear of the machine body, and various operations such as tilling work in a field, spreading fertilizers, pesticides, and seeds, mowing grass, and transporting harvested products can be performed. Also, if a dozer or the like is attached to the front of the machine body, earthwork such as moving soil and snow removal work can also be performed.

[0004] By the way, in recent years, the development of unmanned tractors has been promoted in order to improve work efficiency by utilizing information and communication technologies and robot technologies. However, even though such an unmanned tractor can perform predetermined work using a specific work machine in a specific field without a person, when efficiently performing work in a wide range of fields using various work machines in a multi-faceted manner, it still has to rely on the steering and driving skills of a skilled operator. In that case, it goes without saying that it is important to ensure the visibility in front of the machine body of the operator sitting in the driver's seat.

[0005] Therefore, when an operator sitting in the cockpit of the control unit looks ahead to perform road driving or work driving maneuvers, the bonnet of the power unit located in front of the control unit is the first thing that comes into their field of vision, and the presence of this bonnet often worsens forward visibility. To solve this problem, the height of the bonnet should be lowered, but unfortunately, it is difficult to lower its height, especially the rear part of the bonnet, due to constraints that it must cover the engine and the exhaust gas aftertreatment device attached to the engine.

[0006] Therefore, the height of the front part of the hood, which covers the engine's auxiliary equipment, is made as low as possible to increase the angle at which the ground can be seen over the front of the hood (vertical field of view). By adopting this method, the blind spots of the operator sitting in the driver's seat are reduced, enabling high-speed operation by avoiding collisions with obstacles ahead, improving the accuracy of straight-line operation, and obtaining appropriate turning timing of the machine at headlands, thereby improving efficiency by shortening work time.

[0007] However, as mentioned above, the engine and exhaust gas aftertreatment devices attached to it are mounted towards the rear of the power unit covered by the hood. Furthermore, the radiator that cools the engine's coolant is cooled by exchanging heat with outside air drawn in by a cooling fan located in front of the engine. Therefore, when a high-output engine is used, the radiator must also be large and have a large capacity, and the cooling fan must also be able to take in a large amount of outside air.

[0008] On the other hand, engine accessories such as an air cleaner that removes foreign matter from the air intake of the engine, or cooling accessories such as a battery or air conditioner condenser located in the cabin, are installed in front of the engine, including the radiator, which is covered by the hood. For this reason, the front of the hood, in particular, covers the front of these accessories to prevent damage to them from collisions with flying stones, for example. A grille is also provided on the front of the hood to similarly protect the accessories from stones, etc., and to draw in outside air through its own intake vents and supply it to the cooling fan.

[0009] Furthermore, the front of the hood is equipped with several headlights, including not only the usual headlights used to illuminate the area in front of the vehicle during twilight and nighttime, but also work lights that provide bright illumination over long distances during work. These headlights, in conjunction with the aforementioned grille (front grille), possess a design importance as the tractor's front mask that goes beyond mere functionality, thanks to the originality of their light arrangement and the ingenious decoration of the light mounting frames.

[0010] Furthermore, given the technical background of the work vehicles described above, an example of a conventional bonnet configuration for a crawler tractor is described in Patent Document 1, which describes a resin bonnet for a tractor that is molded so that the height of the front side is lower than the rear side in order to ensure the forward view of the worker sitting in the driver's seat, and also describes that a wide upper and lower opening is provided from the front to the side of the bonnet, and this opening is covered with a grille equipped with an air intake, and a similar wide opening is provided below the grille, into which headlights and the like are mounted.

[0011] Furthermore, the tractor shown in Patent Document 2 has an exhaust gas aftertreatment device equipped with an oxidation catalyst (DOC) and a urea SCR system mounted on top of the engine in a front-to-back direction towards the rear of the drive unit. As a result, the overall height of the drive unit is increased, and even with its resin bonnet, the height of the front side is not kept as low as the rear side. In addition, in order to increase the output of the engine, this tractor has a front grille made of perforated screen that extends from the front to the side of the bonnet in a continuous line with a wide vertical width, and furthermore, two headlights are provided on each side of the top of this front grille along with a visor. [Prior art documents] [Patent Documents]

[0012] [Patent Document 1] Japanese Patent Publication No. 2007-76537 [Patent Document 2] Japanese Patent Publication No. 2018-95186 [Overview of the project] [Problems that the invention aims to solve]

[0013] As mentioned above, in work vehicles where the drive unit is located in front of the control section with the driver's seat, and the engine and its auxiliary components are covered by a resin bonnet, it is important to make the height of the front part of the bonnet covering the engine's auxiliary components as low as possible so that the ground can be seen over the front of the bonnet. By increasing the vertical field of view of the operator in this way, the blind spots of the operator sitting in the driver's seat are reduced, making it easier to avoid collisions with obstacles ahead and enabling high-speed work driving.

[0014] However, when exhaust gas aftertreatment devices and other components are mounted on top of the engine towards the rear of the drive unit, oriented in the front-to-back or left-to-right directions, or when the engine output is increased, the height of the rear of the drive unit tends to increase. Furthermore, this necessitates a large amount of outside air to air-cool the engine's cooling accessories such as the radiator and intercooler. To address this, it becomes necessary to enlarge the opening in the hood and enlarge the intake area of ​​the grille attached to this opening to increase the amount of outside air taken in. This makes it difficult to reduce the volume of the front of the hood, and ultimately results in the problem of not being able to keep the height of the front of the hood low enough.

[0015] Furthermore, if the opening at the front of the hood where the grille is mounted is made larger, the strength of the periphery of the hood where this opening is located becomes somewhat insufficient. For example, if the hood is opened or closed forcefully, there is a risk that the periphery of the opening may be damaged, requiring the addition of reinforcing metal fittings inside the hood, which increases the manufacturing cost of the hood. Therefore, in view of the above-mentioned problems, the present invention aims to provide a work vehicle that solves the problem of insufficient strength of the periphery of the opening at the front of the hood for taking in outside air, while keeping the height of the front side of the hood as low as possible. [Means for solving the problem]

[0016] Firstly, in order to solve the above problems, the present invention provides a work vehicle in which a drive unit is provided in front of a control unit equipped with a driver's seat, and the engine and engine accessories provided in this drive unit are covered by a resin bonnet, wherein the bonnet is molded so that the height of the front part is lower than the rear part so that the forward view of the worker seated in the driver's seat is secured, and a wide opening in the left-right direction is provided in the center of the front of the bonnet, and this opening is covered by a grille equipped with an air intake, and furthermore, the left and right ends of the opening equipped with the grille are molded to be narrow in the left-right direction for mounting headlights and work lights, and reinforcing protrusions are molded at the boundary between the left and right light mounting parts and the central opening, thereby preventing accidental damage to the periphery of the opening of the bonnet.

[0017] Furthermore, in order to solve the above problems, the present invention is characterized in that the opening provided in the center of the front surface of the bonnet is made substantially trapezoidal in a front view, and the reinforcing protrusions formed at the boundary between the left and right light mounting parts and the central opening are formed so that the opening periphery corresponding to the left and right legs of the trapezoid protrudes forward in a V-shape in a front view, thereby preventing accidental damage to the opening periphery corresponding to the upper and lower bottom of the trapezoid.

[0018] Furthermore, in order to solve the above problems, the present invention is characterized by providing an upper opening above the opening provided in the center of the front of the bonnet, left and right openings at the light mounting areas provided at both left and right ends of the front of the bonnet, and left and right side openings on the sides near the front of the bonnet, and covering each of these openings with a grille equipped with an air intake hole, thereby increasing the amount of outside air taken into the bonnet.

[0019] Furthermore, in order to solve the above problems, the present invention is characterized by providing an opening in the front panel of the chassis frame, which has an upper end that receives and supports the lower end of the hood when the hood is closed downwards, or in the base plate of the bumper attached to the front panel of the chassis frame, covering one of these openings with a grille equipped with an air intake, and supplying outside air into the hood through the openings provided in the chassis frame or bumper, thereby increasing the amount of outside air taken into the hood. [Effects of the Invention]

[0020] In the work vehicle of the present invention, a drive unit is provided in front of the control unit which has a driver's seat, and the engine and engine accessories provided in this drive unit are covered by a resin bonnet. The bonnet is molded so that the height of the front side is lower than the rear side so that the forward view of the worker seated in the driver's seat is secured. Furthermore, a wide opening is provided in the center of the front of the bonnet in the left-right direction, and this opening is covered by a grille equipped with an air intake. In addition, the left and right ends of the opening with the grille are molded to be narrow in the left-right direction for mounting headlights and work lights, and reinforcing protrusions are molded at the boundary between the left and right light mounting parts and the central opening to prevent accidental damage to the periphery of the opening of the bonnet. Therefore, even if an exhaust gas aftertreatment device is provided on top of the engine or the engine is made to be more powerful, the bonnet is molded so that the height of the front side is lower than the rear side so that the forward view of the worker can be secured.

[0021] In other words, the mounting areas for headlights and work lights, which were conventionally provided in a wide, horizontal direction at the top and bottom of the front of the hood, are now formed in a narrow, horizontal direction at both ends of an opening in the center of the front of the hood. By eliminating the upper and lower space previously occupied by the light mounting areas, the height of the front of the hood (front side) can be reduced. However, because a wide, horizontal opening is provided in the center of the front of the hood, the left and right ends of the light mounting areas will protrude forward from the curved, narrower sides of the hood towards the front. However, this does not affect the horizontal field of view of the operator.

[0022] Furthermore, a wide opening is provided in the center of the front of the hood, and this opening is covered by a grille equipped with air intakes. This allows outside air to be supplied directly and efficiently to the engine's cooling components, such as the radiator and intercooler, located inside the hood, via the shortest possible route. In addition, reinforcing protrusions are formed at the boundary between the left and right light mounting areas and the central opening, preventing accidental damage to the periphery of the opening on the hood.

[0023] Furthermore, an opening provided at the center of the front of the bonnet is substantially trapezoidal in a front view, and reinforcing protrusions formed at the boundaries between the left and right light mounting portions and the central opening are formed by protruding the peripheral edge of the opening corresponding to the left and right legs of the trapezoid forward in a V-shaped manner in a front view. In this case, the V-shaped reinforcing protrusions serve as struts (diagonal members), particularly preventing deformation of the peripheral edge of the opening corresponding to the upper and lower bases of the trapezoid and preventing unexpected damage. As a result, it is possible to manufacture the bonnet at a low cost without adding additional reinforcing metal fittings. In addition, the reinforcing protrusions that protrude forward and are formed in a V-shaped manner also serve as a decoration that gives viewers a sense of spaciousness and stability in combination with the originality of the layout of the light mounting portion and the decoration of the light mounting frame portion.

[0024] Then, an upper opening is provided above the opening provided at the center of the front of the bonnet, left and right openings are provided at the left and right light mounting portions provided at both ends of the front of the bonnet, and left and right side openings are provided on the side surfaces near the front of the bonnet, respectively. When each of these openings is covered with a grill having intake holes, in addition to taking in outside air from the wide opening provided at the center of the front of the bonnet, outside air can be taken in from these multiple openings to increase the amount of outside air taken into the bonnet. Therefore, it is possible to supply the outside air required by the cooling accessories without excess or deficiency, and to maintain a good heat balance of the engine.

[0025] Moreover, when the bonnet is closed downward, an opening is provided in the front panel of the chassis frame having an upper end that receives and supports the lower end of the bonnet, or in the substrate of the bumper attached to the front panel of the chassis frame. Any of these openings is covered with a grill having intake holes, and outside air is supplied into the bonnet through the openings provided in the chassis frame and the bumper. In this way, it is possible to smoothly supply outside air to the cooling accessories provided by dropping them into the chassis frame, and to increase the amount of outside air taken into the bonnet while reducing the load on the cooling fan provided in the engine.

Brief Description of the Drawings

[0026] [Figure 1] This is a side view of the tractor. [Figure 2] This is a perspective view of the chassis frame. [Figure 3] This is a plan view of the control panel. [Figure 4] This is a perspective view of the hood covering the power unit. [Figure 5] This is a perspective view with the hood open. [Figure 6] This is a side cross-sectional view of the engine, auxiliary equipment, and hood of the power unit. [Figure 7] This is an exploded view showing the mounting of the grille and headlights to the hood. [Figure 8] This is an exploded view of the same object, seen from the bottom side. [Figure 9] This is a plan cross-sectional view showing a reinforcing projection provided at the boundary between the light mounting area and the central opening. [Figure 10] This is a perspective view showing the installation status of the cooling accessories. [Figure 11] This is a perspective view of the same image with the dustproof net removed. [Figure 12] This is a perspective view showing the maintenance status of the cooling auxiliary equipment. [Figure 13] This is an exploded view from the front right, showing the installation of cooling accessories. [Figure 14] This is an exploded view of the same object, seen from the front left. [Figure 15] This is an explanatory diagram of the chassis frame and bumper's outside air intake. [Modes for carrying out the invention]

[0027] Embodiments for carrying out the present invention will be described with reference to the drawings. As shown in Figures 1 to 5, the crawler tractor 1, which is mainly used for agricultural purposes as a work vehicle, has a chassis frame 4 that is framed in a substantially rectangular shape by left and right side members 2 and cross members 3, and tank mounting platforms 7 for mounting hydraulic oil tanks 5 and fuel tanks 6 or urea aqueous solution tanks are provided extending outwards on the left and right sides near the rear, and a track frame 8 that is framed in a rectangular shape is provided at the bottom of the chassis frame 4 to constitute the machine body (vehicle body).

[0028] Furthermore, a four-cylinder direct-injection common-rail diesel engine (engine) 9, a radiator 10, an air cleaner 11, and other engine accessories are mounted on the front of the chassis frame 4 with vibration-damping support, and these components on the drive unit 12 are covered by a bonnet 13 that can be opened and closed at the front. In addition, a cabin 14 is mounted on the chassis frame 4 behind the bonnet 13 with vibration-damping support, and a control unit 15 is provided inside this cabin 14. Finally, a work implement coupling device consisting of an external three-point linkage device 16 with a top link and left and right lower links is provided at the rear of the chassis frame 4, and work implements such as a rotary tiller are connected to it so that they can be raised and lowered.

[0029] Furthermore, motor housings 17 are provided on the left and right front ends of the track frame 8, a travel motor 18 is attached to this motor housing 17, and a drive sprocket 19 is attached to the travel motor 18. In addition, carrier rollers 20 and track rollers 21 are rotatably provided on the left and right square pipe sections 8a of the track frame 8, and an adjuster frame 22 biased by an adjuster cylinder and spring is inserted into the square pipe section 8a so as to be slidable back and forth, and an idler wheel 23 is rotatably pivoted at the rear of the adjuster frame 22.

[0030] Then, rubber tracks 24 are wrapped around drive sprockets 19 located at the front left and right of the track frame 8, idler wheels 23 located at the rear, and carrier rollers 20 and track rollers 21 located between them, to form a full-crawler type running gear. The left and right travel motors 18 are hydraulic motors, each connected in a closed circuit to a servo-equipped hydraulic pump located on a transmission case (not shown). The trunnion shaft of this hydraulic pump is operated by a control link mechanism linked to a main gear lever 25 and steering handle 26 located on the control unit 15, enabling the tractor 1 to perform stepless speed changes and steering.

[0031] The aforementioned transmission case is located in the center of the chassis frame 4, towards the rear, and houses a gear-type transmission that transmits power from the output shaft of the engine 9 to the PTO shaft (external power take-off shaft) which protrudes from the rear of the vehicle. The left and right hydraulic pumps located on top of the transmission case are driven by power branched off from the engine power transmitted to the transmission case.

[0032] On the other hand, the cabin 14 described above has a cabin frame formed by connecting a lower frame to which the floor 27 and the bottom plate are fixed and an upper frame to which the roof 28 and the like are attached, with left and right front pillars 29, a center pillar 30 and a rear pillar 31. A windshield 32 and a lower windshield 33 are mounted between the left and right front pillars 29, and the left and right door windows 34 are mounted between the front pillars 29 and the center pillar 30 so that their front ends can be opened and closed via hinges provided on the center pillar 30.

[0033] Furthermore, between the center pillar 30 and the rear pillar 31, the left and right side windows 35 are provided so that their front ends can be opened and closed via hinges provided on the rear pillar 31. Also, between the left and right rear pillars 31, the rear window 36 is provided so that its lower end can be opened and closed via hinges provided on the rear of the upper frame, and a lower rear window is also provided below the rear window 36.

[0034] Furthermore, as shown in Figure 3, a steering column 37 is provided at the front of the floor 27 of the cabin 14. This steering column 37 is equipped with a control link mechanism for the hydrostatic continuously variable transmission consisting of the aforementioned two pumps and two motors, and a steering wheel 26 is positioned above it. A panel body 38 is provided in front of the steering wheel 26, and a rear panel cover is provided below it. The panel body 38 is used to mount the meter assembly, starter switch, combination lever, switch assembly, etc.

[0035] The meter assembly incorporates an analog tachometer that displays engine speed in work mode and driving speed in driving mode, warning lights that display information from the engine control module such as the charge lamp, indicator lights for work equipment control such as the depth automatic lamp, and a relatively small liquid crystal display that constitutes the main monitor. The switch assembly on the lower right side is equipped with a group of selector switches that change the display content of the main monitor and allow for detailed settings of various automatic controls, while the combination lever operates switches for the turn signals, horn, headlights, etc.

[0036] Furthermore, a driver's seat 39 is provided behind the floor 27 of the cabin 14, which can be adjusted fore and aft and rotated 10 degrees clockwise and 20 degrees counterclockwise. A side console 40 is also provided to the right of the driver's seat 39, with a support column erected on the bottom plate of the cabin 14 and covered around and above with an operating cover. This side console 40 is equipped with the aforementioned main gear lever 25, as well as multiple operating levers, switches, and volume controls related to driving and work equipment control.

[0037] The overall configuration of the crawler tractor 1 has been described above. Next, the engine 9 installed in the aforementioned drive unit 12 and the bonnet 13 covering the auxiliary equipment of this engine 9 will be explained using Figures 1 and 4 to 9. The bonnet 13 used here is a one-piece molded resin product, and more specifically, its strength is enhanced by fiber-reinforced plastic (FRP).

[0038] Incidentally, as described in the problem that this invention aims to solve, it is important to make the height of the front part of the bonnet 13 as low as possible so that the worker sitting in the driver's seat 39 can see the ground over the front of the bonnet 13 when driving on the road or performing work. In other words, as shown in Figure 1, even if the height of the front part of the bonnet 13 is made to be the same as the height of the rear part, by lowering the height of the front part, especially the tip (front), the worker can see the ground by shortening it by several meters just by increasing the vertical field of view α of the worker by about 1 degree, so that the blind spot of the worker sitting in the driver's seat 39 is reduced, making it easier to avoid collisions with obstacles in front and enabling high-speed work driving.

[0039] However, if an exhaust gas aftertreatment device 41 such as a diesel particulate filter (DPF) or urea SCR is mounted towards the rear of the power unit 12, or if the engine 9 is mounted in the front-to-back direction on top of the engine 9, or if the engine 9 is made to have a high output, the height of the rear of the power unit 12 tends to increase. In addition, a large amount of outside air is required to air-cool the cooling auxiliary equipment such as the radiator 10 that cools the coolant of the engine 9, and the intercooler 42 that cools the pressurized air before it is sent to the engine 9.

[0040] Furthermore, in order to address this issue, it becomes necessary to enlarge the opening in the bonnet 13 and increase the intake area of ​​the grille attached to this opening to increase the amount of outside air taken in. This makes it difficult to reduce the volume (area) of the front side of the bonnet 13, and as a result, the problem arises that the height of the front side of the bonnet 13 cannot be kept low enough. Moreover, if the opening on the front of the bonnet to which the grille is attached is made larger, the strength of the peripheral edge where this opening is made tends to be insufficient.

[0041] Therefore, for example, if the hood 13 is opened or closed forcefully, there is a risk of damage such as cracks due to buckling occurring around the periphery of the opening. This necessitates the addition of reinforcing metal fittings inside the hood 13 behind the grille, which increases the manufacturing cost of the hood 13. Thus, the present invention aims to minimize the height of the front part of the hood 13 while making the opening for taking in outside air on the front of the hood 13 larger, and to eliminate the insufficient strength around the periphery of the opening.

[0042] In other words, in this embodiment, the bonnet 13 comprises a top plate 13a, left and right side plates 13b, and a front surface 13c, and is integrally molded with its lower and rear ends open. Furthermore, as shown in Figures 5 and 6, a metal frame 13d is attached to the inside of the rear-facing top plate 13a of the bonnet 13, and this frame 13d is attached to a hinge 44 provided on the upper part of a gate-type mounting frame 43 erected in the middle of the chassis frame 4, thereby allowing the front part of the bonnet 13 to be opened and closed around the hinge 44. The bonnet 13 is also equipped with a gas spring 45 for cushioning, a bonnet stay consisting of a rod and a hook, and a hook 48 on the lower inside of its front surface 13c that engages with a bonnet catcher 47 attached to the upper surface of the front plate 46 of the chassis frame 4.

[0043] Furthermore, as shown in Figure 4, the bonnet 13 has openings 49 for taking in outside air, including a central opening 50 that is roughly trapezoidal in a front view in the center of its front surface 13c, an upper opening 51 that is roughly heptagonal in a front view above the central opening 50, left and right openings 52 that are roughly rectangular in shape to the left and right of the upper part of the central opening 50, and left and right side openings 53 that are roughly rectangular in shape in the middle of the front part of the left and right sides 13b. In addition, the bonnet 13 has openings 54 for discharging the outside air taken in through the openings 49 from inside the bonnet 13 to the outside, including an upper opening 55 and a lower opening 56 that are roughly rectangular in shape to the upper and lower parts near the rear of the left and right sides 13b.

[0044] Furthermore, a heat exhaust opening 57 is provided at the rear of the top plate 13a of the bonnet 13. This opening is narrow vertically and wide horizontally, and faces forward, allowing hot air generated during DPF regeneration to escape upward, and also allowing hot air that accumulates inside the bonnet 13 when the engine 9 is stopped to escape upward. The opening is shaped to make it difficult for rainwater to enter the bonnet 13 through this opening 57. The aforementioned gate-type mounting frame 43 is provided with a strip-shaped cover 58 that covers its top and both sides in a continuous line. This closes the rear of the bonnet 13 with the cover 58, which is connected to a shielding plate provided on the front of the cabin 14.

[0045] Then, as shown in Figures 7 and 8, the front grilles 59, 60, 61 and left and right side grilles 62, which are made of perforated metal with numerous holes that serve as intake vents for outside air into the bonnet 13, are attached to the periphery of the openings 50 to 53 on the inside of the bonnet 13 using bolts (an emblem, not shown, is attached to the front of the front grille 60). Similarly, the upper and lower openings 55 and 56, which serve as openings 54 for expelling the taken-in outside air from inside the bonnet 13 to the outside, are attached to the periphery of the openings 63 and 64 using bolts, which are made of perforated metal with numerous holes that serve as exhaust vents.

[0046] To describe the shape of the front of the bonnet 13c (front mask) in more detail, as mentioned above, the central part of the front of the bonnet 13c has a wide opening 50 in the left-right direction that is roughly trapezoidal in a front view, and this opening 50 is covered by a front grille 59 equipped with air intakes. At both ends of the opening 50 equipped with the front grille 59, the light mounting sections 67 for the headlights 65 located below and the work lights 66 located above are formed to be narrow in the left-right direction. The headlights 65 are used to illuminate the area in front of the vehicle in twilight and at night, and are high / low beam switchable projector headlights, while the work lights 66, which brightly illuminate the area at a distance during work, are LED lamps.

[0047] Furthermore, the left and right light mounting sections 67, to which the headlights 65 and work lights 66 are mounted vertically, are provided with cylinders 67a and 67b aligned vertically, to which the headlights 65 and work lights 66 are attached with bolts from the inside of the bonnet 13, and to which the light is projected forward. Also, as shown in Figures 4, 7, and 9, the periphery of the two upper and lower cylinders 67a and 67b is formed with an enclosure 67c that protrudes forward to protect the light emitted by the headlights 65 and work lights 66, and a partition 67d that separates the light emitted by the headlights 65 and work lights 66 vertically.

[0048] Furthermore, the outer surfaces of the enclosures 67c of the left and right light mounting sections 67 are either an extension of the left and right front ends of the bonnet 13 sides 13b, or slightly pulled inward. As a result, the left and right light mounting sections 67 are positioned as close to the left and right ends of the bonnet front 13c as possible from a design perspective, making it possible to create a wide trapezoidal opening 50 in the center of the bonnet front 13c. In addition, the front grille 59 that covers the enclosures 67c of the left and right light mounting sections 67 and the central opening 50 is shaped with a slight forward tilt towards the top, as is evident in the side view, creating a unique design that allows accumulated dust to easily fall downwards.

[0049] Furthermore, the opening 50 provided in the center of the front surface 13c of the bonnet is, as mentioned above, roughly trapezoidal in a front view, and as shown in Figure 9, a reinforcing projection 68 in the shape of "<" is provided at the boundary (periphery of the opening) between the left and right light mounting parts 67 (especially the enclosure 67c closer to the center) and the central opening 50, and is directed forward. This projection 68 is formed by making the peripheral edges s of the opening, which correspond to the left and right legs of the trapezoid, protrude forward in a V-shape in a front view, as shown in Figure 4. As a result, this V-shaped reinforcing projection 68 acts as a brace (diagonal member), preventing deformation of the peripheral edges u and d of the opening 50, which correspond to the upper and lower bases of the trapezoid, and preventing unexpected damage, thus eliminating the need to add reinforcing fittings and allowing the bonnet 13 to be manufactured at low cost.

[0050] Furthermore, the reinforcing protrusions 68, which are projected forward and shaped into a V-shape, contribute to the originality of the layout of the left and right light mounting sections 67 and the decoration of the light mounting frame (enclosure 67c and partition 67d), giving the viewer a sense of spaciousness and stability. The upper end of the protrusions 68, which are continuous from the V-shape, flows outward towards the upper part of the enclosure 67c of the left and right light mounting sections 67. When viewed as a whole from the front, the left and right ">" and "<" shaped protrusions 68 evoke a crossover "X" where different elements intersect across boundaries.

[0051] Therefore, in conventional tractors, the light mounting sections 67 for headlights 65 and work lights 66, which were previously widely provided in the left-right direction at the upper and lower parts of the front bonnet 13c, are now formed to be narrower in the left-right direction at both ends of an opening 50 provided in the center of the front bonnet 13c. This eliminates the upper and lower space previously occupied by the light mounting sections 67, allowing the height of the front bonnet 13c to be lowered and ensuring good forward visibility for the operator.

[0052] However, since a wide opening 50 is provided in the center of the front bonnet 13c, the left and right ends of the light mounting section 67 will protrude forward from the front side 13b of the bonnet 13, which normally curves and narrows. However, this does not affect the horizontal field of view of the worker.

[0053] Furthermore, a wide opening 50 is provided in the center of the front surface 13c of the bonnet, and this opening 50 is covered by a front grille 59 equipped with an air intake. This allows outside air to be supplied directly and via the shortest possible route from the center of the front surface 13c of the bonnet to the cooling accessories such as the radiator 10 and intercooler 42 of the engine 9 located inside the bonnet 13, thereby efficiently cooling them.

[0054] Furthermore, by providing an upper opening 51 above the opening 50 in the center of the front bonnet 13c, left and right openings 52 at the light mounting areas 67 on both the left and right ends of the front bonnet 13c, and left and right side openings 53 on the side 13b near the front of the bonnet, and covering each of these openings with a front grille 59, 60, 61 and left and right side grilles 62 equipped with air intakes, the amount of outside air taken into the bonnet 13 can be increased by taking in outside air from these numerous openings in addition to the wide opening 50 in the center of the front bonnet 13c. This ensures that the cooling accessories are supplied with just the right amount of outside air, and the engine 9's heat balance can be maintained in good condition.

[0055] The above describes the bonnet 13 that covers the engine 9 and its auxiliary components. Next, we will describe the auxiliary components of the engine 9 that will be covered by the bonnet 13, focusing particularly on their arrangement, based on Figures 5, 6, 10 to 14. First, regarding the radiator 10 that cools the coolant of the engine 9, the rectangular radiator 10, which has a radiator core 10c between the upper tank 10a and the lower tank 10b, is attached via a cushion to an opening formed in the center of the rear plate 69a of the radiator bracket 69, which is also framed in a rectangular shape, and the upper inlet pipe 10d and the lower outlet pipe 10e are routed toward the engine 9.

[0056] Furthermore, the rear plate 69a of the radiator bracket 69 has a fan shroud at its rear, so the cooling fan 70 of the engine 9 is positioned to face this fan shroud. The bottom plate 69b of the radiator bracket 69 is lowered by h1 below the lower front end of the chassis frame 4 and is bolted upright onto a mounting plate 71 provided on the chassis frame 4. Therefore, in order to have sufficient cooling capacity, the upper height of the large radiator 10 is lowered as much as possible, so that the height of the front part of the bonnet 13 can be kept as low as possible.

[0057] Furthermore, a reserve tank 72 is attached to the rear surface of the upper frame plate 69c, which is located on top of the radiator bracket 69. In addition, a horizontally elongated intercooler 42, which cools the air pressurized by the supercharger in the engine 9, is mounted near the top of the left and right side frame plates 69d of the radiator bracket 69, so as to overlap the upper half of the front side of the radiator 10. The inlet hose and outlet hose 42a of the intercooler 42 are routed towards the engine 9 at the rear through round holes provided in the left and right side frame plates 69d and round holes provided in the rear plate 69a.

[0058] Furthermore, the air cleaner 11, which removes foreign matter such as dust from the air drawn in by the engine 9, is equipped with an elliptical mess-box-shaped primary filter 11a, a safety filter 11b, and a dust discharge valve 11c, etc., and these are combined by a cover 11d to form a roughly rectangular parallelepiped air cleaner (main body). This air cleaner 11 is mounted on a base 69e provided on the upper frame plate 69c of the radiator bracket 69, located slightly in front of the upper part of the radiator 10 that cools the engine 9's coolant, with the longitudinal direction of the air cleaner 11 being in the front-to-back direction.

[0059] In this case, as shown in Figure 6, the air cleaner 11 is installed with its front end slightly lower than its rear end (tilted about 15 degrees from horizontal) so as to follow the downward slope of the inner surface of the top plate 13a when the bonnet 13 is closed downward. Also, when the bonnet 13 is closed downward, the left and right side grilles 62 installed on the front side 13b of the bonnet 13 are installed lower than the lower end surface of the air cleaner 11.

[0060] Therefore, cooling accessories such as the radiator 10 and intercooler 42, which are located in front of the engine 9, can receive outside air smoothly and adequately from the intake holes of the front grille 59, 60, 61 and left and right side grille 62 of the bonnet 13 without being obstructed by the air cleaner 11 which is located slightly downward sloping towards the front of them. As a result, the cooling efficiency of each cooling accessory can be properly maintained, eliminating the need to enlarge them in order to increase the amount of cooling.

[0061] Furthermore, the air cleaner 11 is angled so that its front is slightly lower than its rear, following the slope of the inner surface of the top plate 13a of the bonnet 13. This helps to keep the height of the front of the bonnet 13 as low as possible, ensuring a good forward view for the operator. The air hose 11e connected to the air cleaner 11 is routed towards the engine 9 at the rear through a round hole provided in the upper frame plate 69c of the radiator bracket 69. In addition, the hot air heated by heat exchange with cooling accessories such as the radiator 10 and intercooler 42 is blocked by the upper frame plate 69c of the radiator bracket 69, so the air cleaner 11 does not draw in this hot air.

[0062] On the other hand, in addition to the aforementioned cooling accessories such as the radiator 10 and intercooler 42, the tractor 1 is equipped with cooling accessories such as an oil cooler (hydraulic oil cooler) 73 for cooling the hydraulic fluid used in the hydrostatic continuously variable transmission of the crawler-type running gear, a condenser 74 for cooling the refrigerant of the air conditioner installed in the cabin 14 in order to liquefy it, an oil cooler (transmission oil cooler) 75 for cooling the oil stored in the transmission case, and a fuel cooler 76 for cooling the diesel fuel supplied to the engine 9. These are also air-cooled by outside air drawn in by the cooling fan 70 of the engine 9.

[0063] Therefore, among these cooling accessories, the condenser 74 is first attached together with the air conditioner's receiver dryer 78 to a condenser bracket 77 that is rotatable around two pivot pins 69f located on the upper front part of the left frame plate 69d of the radiator bracket 69. The condenser bracket 77 has its boss 77a attached to the pivot pins 69f, and the right side can be opened forward around the pivot pins 69f. However, it is normally closed, and to open it, the bolts 79 that fasten it to the right frame plate 69d of the radiator bracket 69 are loosened.

[0064] Furthermore, the capacitor bracket 77 has a width greater than the width required to mount the main capacitor 74, and a rectangular upper dustproof net 80 with a mesh attached is detachably mounted on its front. Specifically, the dustproof net 80, which is supported so as to be able to slide left and right by receiving plates 77b provided on the upper and lower front surfaces of the capacitor bracket 77, can be removed from the capacitor bracket 77 by disengaging the engagement between the capacitor bracket 77 and the catch 81, which consists of resin protrusions and indentations provided on the right end of the dustproof net 80, and pulling the dustproof net 80 to the right. By performing the reverse operation, the dustproof net 80 can be returned to its operational position, which completely covers the front surface of the capacitor bracket 77 without any gaps.

[0065] Furthermore, the remaining hydraulic oil cooler 73, transmission oil cooler 75, and fuel cooler 76 are mounted on an oil cooler bracket 82 that is rotatable around two pivot pins 69g located at the front lower part of the left and right side frame plates 69d of the radiator bracket 69. In this case, the lower part of the hydraulic oil cooler 73 is attached to a U-shaped lower piece 82b that is fixed at both ends to the lower part of the left and right side plates 82a of the oil cooler bracket 82, and the transmission oil cooler 75 and fuel cooler 76 are mounted side by side in the left-right direction on the front of the oil cooler bracket 82.

[0066] The oil cooler bracket 82 can be opened forward at the top, centered on the pivot pin 69g of the radiator bracket 69, but it is normally closed, and to open it, the bolts 83 that fasten it to the left and right side frame plates 69d of the radiator bracket 69 are removed. In addition, the lower dustproof net 84, which is provided in front of the oil cooler bracket 82, is supported so as to be able to slide up and down by receiving plates 69h and 69i provided on the lower side of the left and right side frame plates 69d of the radiator bracket 69.

[0067] Therefore, when performing maintenance on the cooling accessories 73-76, dust nets 80 and 84, or the intercooler 42 and radiator 10 attached to the radiator bracket 69, as described above, the following procedure should be followed.

[0068] Specifically, first the hood 13 is opened, and then the upper dust net 80 attached to the condenser bracket 77 is pulled to the right while releasing the engagement of the catch 81, without being obstructed by the air cleaner 11 located above it. Also, since there is nothing obstructing it above, the lower dust net 84 is lifted upward to open the front side of the cooling accessories (see Figure 11). The removed dust nets 80 and 84 can then be cleaned by removing any attached straw or debris using a brush or air gun.

[0069] Furthermore, by loosening the bolt 79 that fastens the radiator bracket 69 to the right frame plate 69d and opening the condenser bracket 77, the condenser bracket 77 can be opened to a maximum of 90 degrees, facing forward, as shown in Figure 12. This allows dust adhering to the condenser 74 to be blown off from both sides using an air gun or the like. Also, the front of the intercooler 42 is exposed, so dust adhering to the intercooler 42 can similarly be blown off using an air gun or the like.

[0070] In this case, in order to completely expose and clean the upper half of the radiator core 10c, which is located behind the intercooler 42, it is necessary to remove the intercooler 42. However, since the intercooler 42 is located in front of the radiator core 10c, most of the dust and debris adheres to the intercooler 42 and does not reach the radiator core 10c at the back. Therefore, clogging of the radiator core 10c rarely occurs, and good cooling performance can be maintained without any special maintenance.

[0071] Furthermore, the condenser bracket 77 is limited to a 90-degree opening angle by a stopper (details omitted). This is to prevent the condenser bracket 77 from rotating beyond this point, as this could cause pinching of the air conditioning hose or the wiring harness connecting the battery to the engine 9, or deformation of the condenser bracket 77. When the condenser bracket 77 is opened to nearly 90 degrees, there is no obstruction in front of the upper part of the hydraulic oil cooler 73, allowing the oil cooler bracket 82 to rotate.

[0072] In this case, by removing the two bolts 83 that fasten the oil cooler bracket 82 to the left and right side frame plates 69d of the radiator bracket 69 and tilting the top of the oil cooler bracket 82 forward, the oil cooler bracket 82 can be tilted up to 6 degrees, allowing dust and debris adhering to the hydraulic oil cooler 73, transmission oil cooler 75, and fuel cooler 76 to be blown away using an air gun or the like. Note that the opening angle of the oil cooler bracket 82 is limited by a stopper (details omitted), and the maximum opening angle is only 6 degrees. However, since there are no obstructions above these auxiliary components, even a small opening makes cleaning easier, and the lower half of the radiator core 10c at the back is exposed, allowing dust and debris clogged in the radiator core 10c to be blown away.

[0073] The reason for limiting the opening angle of the oil cooler bracket 82 is to prevent damage caused by contact between the battery 85 located in front of it and the transmission oil cooler 75 or fuel cooler 76. Furthermore, when attempting to close the condenser bracket 77 while the oil cooler bracket 82 is open, the lower plate 77a of the condenser bracket 77 will come into contact with the upper part of the left side plate 82a of the oil cooler bracket 82, preventing it from being closed. This prevents the oil cooler bracket 82 from being left open and also prevents damage caused by contact between the condenser bracket 77 and the hydraulic oil cooler 73.

[0074] Furthermore, as mentioned above, the battery 85, which supplies power to the engine 9, as well as the electronic control devices, air conditioner, and lighting equipment mounted on the tractor 1, was mounted on a mounting plate that also holds the radiator 10 and the cooling accessories located in front of it. However, since the height of this mounting plate will be lowered, it is conceivable that the mounting height of the battery 85 will also be lowered. However, there is a problem with the battery 85: when outside air is taken in through the intake holes of the front grilles 59, 60, and 61 on the bonnet 13 and the left and right side grilles 62 and flows to the aforementioned cooling accessories 73, 75, and 76 to cool them, the top of the battery 85 blocks the lower front of the cooling accessories.

[0075] Therefore, as shown in Figure 6, the mounting plate 86 for the battery 85 is lowered by h2 further than the mounting plate 71 on which the radiator 10 and the cooling accessories located on its front side are mounted, and is positioned lower towards the front of the chassis frame 4. As a result, the outside air taken in through the intake holes of the front grilles 59, 60, 61 and the left and right side grilles 62 on the bonnet 13 is not obstructed much by the top of the battery 85 and flows smoothly to the cooling accessories 73, 75, 76 and the radiator 10, thus resolving the problem of poor cooling efficiency. Although this lowers the lower height of the front of the chassis frame 4, slightly worsening the approach angle when crossing over obstacles such as ridges, it does not make it lower than, for example, the ground clearance of the bottom of the engine 9, so off-road capability is maintained.

[0076] By the way, an upper opening 51 is provided above the opening 50 in the center of the front bonnet 13c, left and right openings 52 are provided at the left and right ends of the light mounting areas 67 on the front bonnet 13c, and left and right side openings 53 are provided on the side 13b near the front of the bonnet, and each of these openings is covered by a front grille 59, 60, 61 equipped with air intakes and left and right side grilles 62 to increase the amount of outside air taken into the bonnet 13. However, this amount of outside air taken in is not necessarily sufficient, and there is a need to provide further leeway in the amount of outside air taken in.

[0077] Therefore, as shown in Figure 15, etc., openings 88 and 89 are provided in the front plate 46 of the chassis frame 4, which has an upper end that receives and supports the lower end of the bonnet 13 when the bonnet 13 is closed downwards, and in the base plate 87a of the bumper 87 to which a balance weight can be attached, which is bolted to the front plate 46 of the chassis frame 4. In addition, one of these openings 88 and 89 is covered by a grille 90 which has an air intake, and outside air is supplied into the bonnet 13 through the openings 88 and 89 provided in the chassis frame 4 and the bumper 87.

[0078] With this configuration, as shown in Figure 6, outside air can be smoothly supplied through the front openings 88 and 89 to the cooling accessories 73, 75, 76, and 10 that are recessed into the chassis frame 4. This reduces the load on the cooling fan 70 of the engine 9 while increasing the amount of outside air taken into the bonnet 13, thus providing ample space for outside air intake.

[0079] Next, to explain the detailed structure for increasing the amount of outside air intake as described above, the bumper 87, which will be installed at the very front of the machine, will be bolted to the front plate 46 of the chassis frame 4 and will serve to mitigate the impact when the tractor 1 collides with something, and will also serve as a mounting point on the machine side for attaching numerous balance weights 92 to eliminate the head-up phenomenon when a heavy implement is attached to the rear of the machine, thereby balancing the front and rear of the tractor 1. For this reason, the bumper 87 is constructed by fixing a relatively thin front plate 87b, which can be attached by engaging the balance weights 92, to the front of a base plate 87a made of a long, thick plate in the left-right direction, via left and right retaining plates 87c and two intermediate partition plates 87d.

[0080] Furthermore, the three rectangular openings 88 and 89 provided in the front panel 46 and bumper 87 of the chassis frame 4 are arranged so that they overlap each other in the front-to-back direction. In addition, the openings 88 and 89 are set higher than the upper surface of the battery 85 which is placed on a mounting plate 86 located at the lower front part of the chassis frame 4. This allows outside air taken in through the intake holes of the grille 90 covering the openings 88 and 89 to be supplied to the cooling accessories 73, 75, 76, and 10 located behind the battery without being obstructed by the battery 85.

[0081] With this configuration, outside air can be smoothly supplied to the cooling accessories 73, 75, 76, and 10 located behind the battery 85, thereby improving their cooling efficiency. In addition, by setting the lower limit position of the openings 88 and 89 in the chassis frame 4 and bumper 87 to a position that is not too low, approximately the same as the top surface of the battery 85, the intake holes of the grille 90 covering the openings 88 and 89 can be prevented from being clogged by mud and dust from near the ground.

[0082] Furthermore, the bumper 87 is provided with a protective body (protective plate) 91 made of steel plate, which is tilted forward and downward towards the front of the opening 89, to prevent contact between the grille 90, which covers the opening 89 in its base plate 87a, and stones, mud, etc. Specifically, both ends of this protective plate 91 are fixed to the left and right retaining plates 87c. By providing the protective plate 91 in this way, damage to the grille 90 and clogging of the air intake holes of the grille 90 can be prevented. In addition, the forward-tilting protective plate 91 can protect the opening 89 by causing stones and mud flying from the ground to fall downwards, and can also guide more clean air from a higher position away from the ground to the opening 89.

[0083] Furthermore, when a dozer is attached to the front of the tractor 1 for earthwork or snow removal, the balance weights 90 and bumper 87 themselves become unnecessary and are removed from the chassis frame 4. In such cases, the grille 90 is attached with bolts to three rectangular openings 88 provided in the front panel 46 of the chassis frame 4 to prevent straw and other debris from entering the bonnet 13.

[0084] Furthermore, when attaching the grille 90 to the three rectangular openings 88 and 89 provided in the front panel 46 and bumper 87 of the chassis frame 4 using bolts, if the grille 90 is attached to the front side of the openings 88 and 89, it is preferable to provide a gap, for example, between the protective body 91 and the front of the grille 90, so that when the engine 9 is stopped and the cooling fan 70 stops operating, dust such as fallen leaves and straw that have been attached to the grille 90 will fall to the ground along the front of the grille 90 and not accumulate on the chassis frame 4 or bumper 87.

[0085] Although embodiments of the present invention have been described above, for example, only the cooling accessories such as the intercooler 42, hydraulic oil cooler 73, condenser 74, transmission oil cooler 75, and fuel cooler 76 installed in front of the radiator 10 that are required by the tractor 1 should be installed in front of the radiator 10. It is common to change the type of accessories or the arrangement of accessories attached to each bracket 77, 78, so the present invention should not necessarily be interpreted as being limited to the above embodiments. [Explanation of Symbols]

[0086] 1. Tractor (work vehicle) 9 Engines 12. Driving Unit 13 Hood 14. Cabin (control room) 39 Driver's seat 50 Center opening 51 Upper opening 52 Left and right opening 53 Side opening 65 Headlights 66 Work Lights 67 Light mounting section 68 Reinforcing protrusions

Claims

1. A work vehicle characterized in that a drive unit is provided in front of the control unit equipped with a driver's seat, and the engine and engine accessories provided in the drive unit are covered by a resin bonnet, wherein the bonnet is molded so that the height of the front side is lower than the rear side so that the forward view of the worker seated in the driver's seat is secured, and a wide opening is provided in the center of the front of the bonnet in the left-right direction, and this opening is covered by a grille equipped with an air intake, and furthermore, the left and right ends of the opening equipped with the grille are molded to be narrow in the left-right direction for mounting headlights and work lights, and reinforcing protrusions are molded at the boundary between the left and right light mounting areas and the central opening to prevent accidental damage to the periphery of the opening of the bonnet.

2. The work vehicle according to claim 1, characterized in that the opening provided in the center of the front of the bonnet is substantially trapezoidal in a front view, and the reinforcing protrusions formed at the boundary between the left and right light mounting parts and the central opening are formed so that the opening periphery corresponding to the left and right legs of the trapezoid protrudes forward in a V-shape in a front view, thereby preventing accidental damage to the opening periphery corresponding to the upper and lower bottom of the trapezoid.

3. A work vehicle according to claim 1 or 2, characterized in that an upper opening is provided above an opening provided in the center of the front of the hood, left and right openings are provided at the left and right ends of the front of the hood where lights are mounted, and left and right side openings are provided on the sides near the front of the hood, and each of these openings is covered by a grille equipped with an air intake to increase the amount of outside air taken into the hood.

4. A work vehicle according to any one of claims 1 to 3, characterized in that an opening is provided in the front panel of the chassis frame, which has an upper end that receives and supports the lower end of the hood when the hood is closed downward, or in the base plate of the bumper attached to the front panel of the chassis frame, and either of these openings is covered with a grille equipped with an air intake, and outside air is supplied into the hood through the openings provided in the chassis frame or bumper, thereby increasing the amount of outside air taken into the hood.

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