Work vehicle

Abstract

To provide a work vehicle capable of reducing the shadow of a work device caused by illumination from a lighting device and ensuring visibility in front of a vehicle body.SOLUTION: In a wheel loader 1 comprising a vehicle body frame, a work device 2 attached to the front of the vehicle body frame so as to be movable in a vertical direction, a pair of right and left wheels 11 provided on the vehicle body frame, an axle 15 extending in a right-left direction of the vehicle body frame and connecting the pair of right and left wheels 11, a differential case 16 provided on the axle 15 and accommodating a differential gear for transmitting driving force to the wheels 11, and lower work lamps 33, 33A, 33B, 33C as lighting devices for illuminating toward the front of the work device 2, the lower work lamps 33, 33A, 33B, 33C are provided in front of the axle 15, below the vehicle body frame and above the lowest end 16B of the differential case 16.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a work vehicle equipped with a work implement at the front of the vehicle body. [Background technology]

[0002] In a work vehicle such as a wheel loader or a forklift, the work device attached to the front of the vehicle body may block the view ahead of the vehicle body. Therefore, especially when working at night or in a dark place, the operator in the cab may not notice the unevenness of the road surface ahead of the vehicle body or obstacles on the road surface. Therefore, a lighting device that brightly illuminates the front of the vehicle body during work has been provided in the past on work vehicles.

[0003] For example, Patent Document 1 discloses a wheel loader including a bucket connected to the vehicle body at the front of the vehicle body, a hydraulic cylinder arranged in the center in the vehicle width direction for moving the bucket, an axle ball accommodating a differential gear that transmits power to the tires, and a lighting device supported on part of the vehicle body in the center in the vehicle width direction below the hydraulic cylinder and above the axle ball, and for illuminating the area between the bucket and tires. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6259116 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the lighting device described in Patent Document 1 has an illumination range that overlaps with the bucket's movement range in many areas, and the light is blocked by the bucket, which tends to cast a shadow in front of the bucket, making it insufficient for use particularly when working at night or in dark places.

[0006] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide a work vehicle that is capable of reducing the shadow of the work implement caused by the illumination of the lighting device and ensuring visibility in front of the vehicle body. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the present invention provides a work vehicle comprising a body frame, a pair of left and right wheels mounted on the body frame, an axle extending in the left-right direction of the body frame and connecting the pair of left and right wheels, a differential case accommodating a differential gear mounted on the axle and transmitting driving force to the wheels, a working device attached to a front part of the body frame so as to be movable in the vertical direction, and a lighting device that illuminates toward the front of the working device, wherein the lighting device is mounted on the front side of the axle, below the body frame and above the lowest end of the differential case. Effect of the Invention

[0008] According to the present invention, the shadow of the working implement caused by the illumination of the lighting device can be reduced, and visibility in front of the vehicle body can be ensured. Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments. [Brief description of the drawings]

[0009] [Figure 1] 1 is an external side view showing one configuration example of a wheel loader according to an embodiment of the present invention. FIG. [Diagram 2] FIG. 2 is a perspective view showing the configuration of the lower front side of the wheel loader. [Diagram 3] 3 is an enlarged perspective view showing a lower work light and its surroundings in FIG. 2. [Figure 4] FIG. 2 is a front view showing the lower work light and its surroundings. [Diagram 5] FIG. 4 is a side view showing the mounting position of the lower work light. [Figure 6] FIG. 13 is a diagram illustrating the action and effect of the lower working light, showing the wheel loader as viewed from the side. [Figure 7] FIG. 13 is a diagram for explaining the action and effect of the lower working light, showing the wheel loader as viewed obliquely from above and in front. [Figure 8] FIG. 13 is a diagram for explaining the action and effect of the lower working light, showing the wheel loader as viewed obliquely from above and rearward. [Figure 9] FIG. 13 is a diagram for explaining the action and effect of the lower work light, showing the case viewed forward from the driver's cab side. [Figure 10] FIG. 13 is a diagram for explaining the action and effect of the lower working light, showing the wheel loader turning right as viewed from above on the rear side. [Figure 11] FIG. 13 is a diagram showing a configuration example of a lower work light according to a first modified example of the present invention, showing a front view of the lower work light with the cover closed. [Figure 12] FIG. 13 is a diagram showing a configuration example of a lower work light according to a first modified example, showing a side view of the lower work light with the cover closed. [Figure 13] FIG. 13 is a diagram showing a configuration example of a lower work light according to a first modified example, showing a perspective view of the lower work light with the cover closed. [Figure 14] FIG. 13 is a diagram showing a configuration example of a lower work light according to a first modified example, showing a perspective view of the lower work light with its cover slightly open. [Figure 15] FIG. 13 is a diagram showing a configuration example of a lower work light according to a first modified example, showing a perspective view of the lower work light with its cover open. [Figure 16] FIG. 13 is a diagram showing a configuration example of a lower work light according to a first modified example, showing a side view of the lower work light with the cover open. [Figure 17] FIG. 13 is a diagram showing a configuration example of a lower work light according to a second modified example of the present invention, showing the lower work light with the cover closed. [Figure 18] FIG. 13 is a diagram showing a configuration example of a lower work light according to a second modified example, showing the lower work light with the cover open. [Figure 19] FIG. 2 is a diagram showing a part of an example of the configuration inside a cab. [Figure 20]FIG. 13 is a functional block diagram showing functions of a controller according to a third modified example of the present invention. [Figure 21] 13 is a flowchart showing a flow of processes executed by a controller according to a third modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, a wheel loader that performs loading and unloading work will be described as an example of one aspect of a work vehicle according to an embodiment of the present invention.

[0011] <Wheel loader 1 configuration> First, the configuration of a wheel loader 1 according to an embodiment of the present invention will be described with reference to FIGS.

[0012] Fig. 1 is an external side view showing one configuration example of a wheel loader 1 according to an embodiment of the present invention. Fig. 2 is a perspective view showing the configuration of the lower front side of the wheel loader 1. Fig. 3 is an enlarged perspective view showing the lower work light 33 and its surrounding area in Fig. 2. Fig. 4 is a front view showing the lower work light 33 and its surrounding area. Fig. 5 is a side view showing the mounting position of the lower work light 33.

[0013] The wheel loader 1 is an articulated work vehicle that is steered by bending the vehicle body frame near the center. Specifically, a front frame 1A, which forms the front part of the vehicle body frame, and a rear frame 1B, which forms the rear part of the vehicle body frame, are connected by a center joint 10 so as to be rotatable in the left-right direction, and the front frame 1A bends in the left-right direction relative to the rear frame 1B. In the following explanation, of the left-right directions of the wheel loader 1, the left direction relative to the forward direction is referred to as the "left direction," and the right direction relative to the forward direction is referred to as the "right direction."

[0014] The vehicle body frame is provided with four wheels 11, a pair of wheels 11 being provided as front wheels 11A on both the left and right sides of the front frame 1A, and the remaining pair of wheels 11 being provided as rear wheels 11B on both the left and right sides of the rear frame 1B. Of the four wheels 11, only the front wheel 11A and rear wheel 11B provided on the left side are shown in FIG.

[0015] As shown in Fig. 2, the pair of left and right front wheels 11A are connected by an axle 15 extending in the left-right direction of the front frame 1A. Although not shown in Fig. 2, the pair of left and right rear wheels 11B are also connected by an axle 15 extending in the left-right direction of the rear frame 1B in the same manner as the pair of left and right front wheels 11A. In the following, the axle 15 connecting the pair of left and right front wheels 11A may be referred to as the "front axle 15," and the axle 15 connecting the pair of left and right rear wheels 11B may be referred to as the "rear axle 15."

[0016] 2 to 4, a differential case 16 that houses a differential gear (not shown) that transmits driving force to each front wheel 11A is provided in the center of the axial direction of the front axle 15 (left and right direction of the front frame 1A). The height direction of the differential case 16 corresponds to the up and down direction of the front frame 1A, and the width direction corresponds to the axial direction of the front axle 15.

[0017] The differential case 16 is formed so that the height dimension gradually increases from both ends in the width direction toward the center. That is, the center part in the width direction of the differential case 16 extends so as to bulge in the vertical direction of the front frame 1A, while both ends in the width direction are the same height as the front axle 15. Therefore, the uppermost end 16A and the lowermost end 16B of the differential case 16 are each located in the center part in the width direction.

[0018] Although not shown in Figures 2 to 4, the differential case 16 is also provided at the center of the axial direction of the rear axle 15 (the left-right direction of the rear frame 1B). This differential case 16 houses differential gears (not shown) that transmit driving force to each of the rear wheels 11B. That is, like the axle 15, the differential case 16 and the differential gears housed therein are each provided in pairs at the front and rear of the vehicle frame corresponding to the front wheels 11A and the rear wheels 11B.

[0019] A drive shaft 17 connecting a pair of differential gears is provided extending in the front-rear direction of the vehicle body frame between the pair of differential cases 16. The wheel loader 1 travels by transmitting the driving force of the engine, after being changed in speed by the transmission, to each wheel 11 via the drive shaft 17, differential gears, and axles 15.

[0020] A work device 2 for carrying out loading and unloading operations such as digging up work objects such as soil, sand, and minerals and loading them into a destination such as a dump truck or a hopper is attached to the front of the front frame 1A so as to be movable in the vertical direction relative to the front frame 1A.

[0021] The working device 2 has a lift arm 21 attached to the front frame 1A so as to be rotatable in the vertical direction, two lift arm cylinders (not shown) as hydraulic cylinders that drive the lift arm 21, a bucket 22 attached to the tip of the lift arm 21 so as to be rotatable in the vertical direction, a bucket cylinder 22A as a hydraulic cylinder that drives the bucket 22, and a bell crank 23 rotatably connected to the lift arm 21 to form a link mechanism between the bucket 22 and the bucket cylinder 22A.

[0022] Although not shown in Figs. 1 and 2, the two lift arm cylinders are arranged next to each other with a predetermined gap therebetween in the left-right direction of the body frame.

[0023] The lift arm 21 rotates upward (raises) relative to the front frame 1A when the rods of the two lift arm cylinders extend, and rotates downward (lowers) relative to the front frame 1A when the rods of the two lift arm cylinders contract.

[0024] The bucket 22 rotates upward relative to the lift arm 21 as the rod 220 of the bucket cylinder 22A extends (tilt operation), and rotates downward relative to the lift arm 21 as the rod 220 of the bucket cylinder 22A contracts (dump operation). This allows the bucket 22 to scoop up and discharge (dig and dump) work objects such as soil and minerals.

[0025] The bucket 22 can be replaced with various attachments, such as a blade or a plow, and the wheel loader 1 can perform various tasks such as snow removal and earth pushing in addition to loading and unloading operations using the bucket 22.

[0026] Furthermore, as shown in Fig. 1, a pair of headlights 31 are provided on the front frame 1A, sandwiching the base end of the lift arm 21 in the left-right direction. This pair of left and right headlights 31 play a role similar to that of so-called headlights of a passenger vehicle, and illuminate the area in front of the wheel loader 1 when the wheel loader 1 is traveling on a road at night or when work is performed in a dark place. Note that only the left headlight 31 of the pair of left and right headlights 31 is shown in Fig. 1.

[0027] The rear frame 1B is provided with a cab 12 in which an operator sits, a machine room 13 that houses various devices required for driving the wheel loader 1, and a counterweight 14 for maintaining balance with the working implement 2 so that the body frame does not tilt. In the rear frame 1B, the cab 12 is located at the front, the counterweight 14 at the rear, and the machine room 13 between the cab 12 and the counterweight 14.

[0028] In the cab 12, upper work lights 32 that illuminate the upper front side of the wheel loader 1 are provided at both left and right ends above the front window 121. When the wheel loader 1 operates the working implement 2 to perform work at night or in a dark place, the light from the pair of headlights 30 alone is insufficient, so by additionally turning on the pair of left and right upper work lights 32, the operating range of the working implement 2 can be brightly illuminated.

[0029] Unlike the pair of headlights 31, the pair of upper work lights 32 are not turned on while traveling on the road, and are used only when the wheel loader 1 is performing work. Note that of the pair of left and right upper work lights 32, only the left upper work light 32 is shown in Fig. 1.

[0030] 2 to 5, the wheel loader 1 is further equipped with a lower work light 33 as a lighting device that illuminates toward the front of the working implement 2. The lower work light 33 is provided in front of the front axle 15, below the front frame 1A (the front side of the vehicle body frame) and above the bottom end 16B of the differential case 16.

[0031] The position where this lower work light 33 is provided is above the minimum ground clearance of the wheel loader 1. Here, "minimum ground clearance" refers to the height of the part of the wheel loader 1 that is the lowest part above the ground, which is the contact surface with the four wheels 11, and in this embodiment, it is the lowest end of the rear frame 1B. Note that this minimum ground clearance differs depending on the specifications (model) of the wheel loader 1, and although in this embodiment it is the lowest end position of the rear frame 1B, it may also be the position of, for example, the axle 15 or a reduction gear (not shown), which is a reduction device.

[0032] The lower work light 33 has a light source unit 331 having a rectangular irradiation surface 331A facing forward of the front frame 1A, and a storage case 332 that stores the light source unit 331. The storage case 332 is formed so as to cover the parts of the light source unit 331 other than the irradiation surface 331A, i.e., the side and back parts.

[0033] In this embodiment, the lower work lights 33 are fixed by welding the upper end of the storage case 332 to the back surface of the bottom of the front frame 1A. A pair of lower work lights 33 are provided on either side of the differential case 16 in the left-right direction. In other words, the pair of lower work lights 33 are provided below the front frame 1A without contacting the differential case 16. This makes the illumination of the wheel loader 1 uniform in the left-right direction, reducing illumination unevenness.

[0034] In this embodiment, the lighting device that illuminates the front of the working device 2 is composed of two lower work lights 33, and these two lower work lights 33 are provided one on each side of the differential case 16, but this is not limited thereto, and the lighting device may be composed of a plurality of lower work lights 33, and these plurality of lower work lights 33 may be provided in pairs on either side of the differential case 16 in the left-right direction. Therefore, for example, the lighting device may be composed of four lower work lights 33, and two lower work lights 33 may be provided on each side of the differential case 16.

[0035] Since the lower work lights 33 are provided near the front wheels 11A, it is preferable that they do not protrude forward beyond the front surface of the differential case 16 in order to avoid splashes of mud and stones as much as possible. Similarly to the upper work lights 32, the lower work lights 33 are used only when the wheel loader 1 is performing work.

[0036] <Actions and Effects of the Lower Work Light 33> Next, the action and effect of the lower work light 33 will be described with reference to FIGS.

[0037] Fig. 6 is a diagram for explaining the action and effect of the lower work light 33, showing the wheel loader 1 as viewed from the side. Fig. 7 is a diagram for explaining the action and effect of the lower work light 33, showing the wheel loader 1 as viewed diagonally from above and to the front. Fig. 8 is a diagram for explaining the action and effect of the lower work light 33, showing the wheel loader 1 as viewed diagonally from above and to the rear. Fig. 9 is a diagram for explaining the action and effect of the lower work light 33, showing the wheel loader 1 as viewed from the front from the cab 12 side. Fig. 10 is a diagram for explaining the action and effect of the lower work light 33, showing the wheel loader 1 as viewed from above and to the rear in a state in which it has turned right.

[0038] The illumination range α of the pair of headlights 31 is mainly the front central area of ​​the wheel loader 1, as shown by the dashed line in Fig. 6. Moreover, the illumination range β of the pair of upper work lights 32 is mainly the front upper area of ​​the wheel loader 1, as shown by the dashed line in Fig. 6.

[0039] In this case, when the working implement 2 is moved upward from the ground contact position (the position shown in FIG. 1) in which the toe of the bucket 22 is on the ground, as shown in FIGS. 6 to 10, the illumination range α and the illumination range β overlap with the position of the bucket 22, and a shadow X (shown by sand in FIG. 6 and by black paint in FIGS. 7 to 10) is formed in front of the bucket 22.

[0040] 6, the illumination range γ of the pair of lower work lights 33 is mainly the area below and in front of the wheel loader 1, and also includes the area of ​​shadow X formed in front of the bucket 22. In this way, the pair of lower work lights 33 can light up the shadow X and make it thinner, so that visibility in front of the wheel loader 1 can be secured and the visibility of the operator in the cab 12 is improved.

[0041] In particular, when a large load is loaded into the bucket 22 or when a multi-plow is being held in place of the bucket 22 (tilting to its limit), if the position of the working implement 2 is relatively high, the range of the shadow X formed by blocking the light from the pair of headlights 31 becomes large (see FIG. 9), and therefore the action and effect of the pair of lower work lights 33 is significant.

[0042] Furthermore, when working in the early morning or at night when it is still dark, such as during snow removal or livestock work, the wheel loader 1 may scoop a load into the bucket 22 close to a wall or use the plow to remove snow close to curbs and guardrails on public roads. In such situations, as shown in Fig. 10, the wheel loader 1 often turns the steering wheel to approach surrounding objects, so the illumination range needs to follow the working implement 2 when the steering wheel is operated. The pair of lower work lights 33 are provided below the front frame 1A, so they can follow the direction of movement of the working implement 2 even when the steering wheel is turned in this way.

[0043] <First Modification> Next, the configuration of a lower work light 33A according to a first modified example of the present invention will be described with reference to FIGS.

[0044] FIG. 11 is a diagram showing a configuration example of the lower work light 33A according to the first modified example of the present invention, showing a front view of the lower work light 33A in a state where the cover 333 is closed. FIG. 12 is a diagram showing a configuration example of the lower work light 33A according to the first modified example, showing a side view of the lower work light 33A in a state where the cover 333 is closed. FIG. 13 is a diagram showing a configuration example of the lower work light 33A according to the first modified example, showing a perspective view of the lower work light 33A in a state where the cover 333 is closed. FIG. 14 is a diagram showing a configuration example of the lower work light 33A according to the first modified example, showing a perspective view of the lower work light 33A in a state where the cover 333 is slightly open. FIG. 15 is a diagram showing a configuration example of the lower work light 33A according to the first modified example, showing a perspective view of the lower work light 33A in a state where the cover 333 is open. FIG. 16 is a diagram showing a configuration example of a lower work light 33A according to a first modified example, showing a side view of the lower work light 33A with a cover 333 open.

[0045] 11 to 16, components common to those described in the above embodiment are denoted by the same reference numerals and description thereof will be omitted, which also applies to the second and third modified examples.

[0046] The lower work light 33A according to this modification further includes a cover 333 as a protective member that covers the light source unit 331 from the front side to protect the light source unit 331. The cover 333 is a rectangular plate member that is slightly larger than the irradiation surface 331A of the light source unit 331, and is made of the same material as the housing case 332 (for example, iron material or SUS).

[0047] 11 to 14, the upper end of cover 333 is connected to the front surface of front frame 1A via hinge 334, and opens and closes by rotating vertically around the pin of hinge 334. Specifically, the lower end of hinge 334, which is one side of the pin, is fixed to the upper end of cover 333, and the upper end, which is the other side of the pin, is fixed to the front surface of front frame 1A.

[0048] That is, the cover 333 changes between a closed state in which the light source unit 331 is covered from the front to protect the light source unit 331, and an open state in which the light source unit 331 is exposed so that light can be irradiated toward the front of the working device 2.

[0049] 15 and 16, when the cover 333 rotates upward to the open state (a state in which the entire light source unit 331 is exposed), it is fixed by a catch clip 41 attached to the front frame 1A. This makes it possible to prevent the cover 333 from rotating downward and blocking the light source unit 331.

[0050] Furthermore, when the cover 333 rotates downward to the closed state (a state in which the light source unit 331 is entirely covered and hidden by the cover 333), it is fixed in place by a magnet 42 attached to the lower portion of the light source unit 331 in the storage case 332. This prevents the cover 333 from opening or closing due to vibrations, for example, even when the wheel loader 1 is traveling.

[0051] In this way, by having an openable / closable cover 333, the lower work light 33A can expose the light source unit 331 only when it needs to be turned on, and protect the light source unit 331 from splashes of mud, stones, etc. when it does not need to be turned on.

[0052] In this modification, the cover 333 is opened and closed by rotating in the vertical direction around the upper side of the light source unit 331, but the present invention is not limited to this, and for example, the cover 333 may be opened and closed by rotating in the vertical direction around the lower side of the light source unit 331. Also, the fixing member for fixing the cover 333 does not necessarily have to be the catch clip 41 or the magnet 42, but a fixing member that can be fixed and released without using a tool, such as the catch clip 41 and the magnet 42, is preferable.

[0053] <Second Modification> Next, the configuration of a lower work light 33B according to a second modified example of the present invention will be described with reference to FIGS.

[0054] Fig. 17 is a diagram showing an example of the configuration of the lower work light 33B according to the second modified example of the present invention, showing the lower work light 33B in a state where the cover 333B is closed. Fig. 18 is a diagram showing an example of the configuration of the lower work light 33B according to the second modified example, showing the lower work light 33B in a state where the cover 333B is open.

[0055] The lower work light 33B according to this modification differs from the lower work light 33A according to the first modification in that the cover 333B slides vertically relative to the light source unit 331 to switch between a closed state and an open state. A screw 43 is attached to each of both ends in the width direction (left and right direction of the front frame 1A) at the lower end of the cover 333B.

[0056] Further, long holes 44 extending in the up-down direction are formed in the housing case 332B on both sides of the light source unit 331. The diameter of each long hole 44 in the short side direction is set to a size that allows each screw 43 to fit in it. Each screw 43 fits in each long hole 44, and can move in the longitudinal direction of each long hole 44 when loosened.

[0057] Then, the cover 333B is fixed to the storage case 332B by tightening the screws 43. Therefore, the cover 333B is fixed to the storage case 332B by tightening the screws 43 in an open state (open state) and a closed state (closed state) with respect to the light source unit 331.

[0058] The fixing member for fixing the cover 333B to the storage case 332B does not necessarily have to be the screw 43, and there is no particular limitation as long as it can be fitted movably into the long hole .

[0059] This modification also provides the same functions and effects as the first modification.

[0060] <Third Modification> Next, the configuration of a lower work light 33C according to a third modified example of the present invention will be described with reference to FIGS.

[0061] Fig. 19 is a diagram showing a part of an example of the configuration inside the cab 12. Fig. 20 is a functional block diagram showing functions of a controller 5 according to a third modified example of the present invention. Fig. 21 is a flowchart showing the flow of processing executed by the controller 5 according to the third modified example.

[0062] In this modified example, the lower working light 33C is not only switched on and off by manual operation by the operator, but also automatically switched on and off depending on the attitude of the working implement 2.

[0063] 19, a front panel 123 is installed in front of the handlebars 122 inside the cab 12. The front panel 123 is equipped with a monitor 124 that displays operational information of the wheel loader 1 and an operation unit 125 made up of a number of switches for performing various operations.

[0064] The multiple switches in the operation unit 125 include an ON switch 61 for turning on the lower work light 33C, an OFF switch 62 for turning off the lower work light 33C, and an automatic mode switch 63 for controlling the controller 5 to switch between turning on and off the lower work light 33C.

[0065] The ON switch 61 and the OFF switch 62 correspond to manual operation devices for manually turning the lower work light 33C on and off, and the lower work light 33C can be turned on and off by the operator pressing them.

[0066] Furthermore, the automatic mode switch 63 corresponds to an automatic operation device for automatically turning on and off the lower work light 33C by the controller 5, and when the operator presses the switch, the controller 5 turns on and off the lower work light 33C based on the attitude of the working implement 2. The controller 5 is one aspect of an automatic switching device that switches between turning on and off the lower work light 33C depending on the attitude of the working implement 2.

[0067] The controller 5 is configured by connecting a CPU, RAM, ROM, HDD, input I / F, and output I / F to each other via a bus. An automatic mode switch 63 and a lift arm angle sensor 64 that detects the angle of the lift arm 21 are connected to the input I / F, and the lower work light 33C is connected to the output I / F. The lift arm angle sensor 64 is one aspect of a posture detection device that detects the posture of the working device 2.

[0068] In such a hardware configuration, the CPU reads out a control program (software) stored on a recording medium such as a ROM, HDD, or optical disk, expands it on the RAM, and executes the expanded control program, whereby the control program and the hardware work together to realize the functions of the controller 5.

[0069] In this modified example, the controller 5 is described as a computer configured by a combination of software and hardware, but this is not limited to the above. For example, as an example of another computer configuration, an integrated circuit that realizes the functions of a control program executed on the wheel loader 1 side may be used.

[0070] The controller 5 includes a data acquisition unit 51, a posture determination unit 52, a storage unit 52A, and a signal output unit 53, as shown in FIG.

[0071] As shown in FIG. 21, in the controller 5, first, the data acquisition unit 51 acquires the automatic mode signal from the automatic mode switch 63 (step S501), and then acquires the lift arm angle θ detected by the lift arm angle sensor 64 (step S502).

[0072] Next, the posture determination unit 52 determines whether the lift arm angle θ acquired in step S502 is equal to or smaller than a predetermined angle threshold θth (step S503). Here, the "predetermined angle threshold θth" is the angle of the lift arm 21 (relative angle with respect to the front frame 1A) when the working implement 2 is in a ground contact posture in which the tip of the bucket 22 (the tip of the working implement 2) is in contact with the ground, and is stored in the storage unit 52A.

[0073] In step S503, when it is determined that the lift arm angle θ is equal to or less than a predetermined angle threshold θth (θ≦θth), that is, when it is determined that the posture of the working implement 2 has reached the ground contact posture (step S503 / YES), the signal output unit 53 outputs a light-off signal to the lower work light 33C (step S504), and the processing in the controller 5 ends.

[0074] On the other hand, when it is determined in step S503 that the lift arm angle θ is greater than the predetermined angle threshold θth (θ>θth), that is, that the posture of the working implement 2 has not reached the ground contact posture (step S503 / NO), the signal output unit 53 outputs a turn-on signal to the lower work light 33C (step S505), and the processing in the controller 5 ends.

[0075] If the working implement 2 takes a grounded posture while the lower work light 33C is on, the lower work light 33C cannot illuminate the area in front of the working implement 2, and instead illuminates the area toward the back of the bucket 22. Therefore, the controller 5 outputs a turn-off signal to the lower work light 33C to turn off the lower work light 33C, thereby reducing glare due to reflection and saving the power consumed by the lower work light 33C.

[0076] In addition, the operator can appropriately select whether to manually switch on and off the lower work light 33C or to have the controller 5 switch on and off. This allows the operator to flexibly use the lower work light 33C according to the operator's preference and the situation at the work site.

[0077] The embodiments of the present invention have been described above. Note that the present invention is not limited to the above-described embodiments, and various modified examples are included. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those having all of the configurations described. In addition, it is possible to replace a part of the configuration of this embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of this embodiment. Furthermore, it is possible to add, delete, or replace a part of the configuration of this embodiment with another configuration.

[0078] For example, in the above embodiment, the wheel loader 1 has been described as an example of one type of work vehicle, but the present invention is not limited to this, and may be other work vehicles such as a forklift.

[0079] In the above third modified example, the controller 5 is described as an example of an automatic switching device, but the present invention is not limited to this and may be, for example, an analog switch device. As the switch device, for example, a wire may be used to connect the lift arm 21 and the power supply unit of the lower work light 33C, and when the lift arm angle θ reaches a predetermined angle threshold θth, the wire is pulled to switch the power supply unit of the lower work light 33C to the OFF side and turn it off. [Explanation of symbols]

[0080] 1: Wheel loader (work vehicle) 1A: Front frame (body frame) 1B: Rear frame (body frame) 2: Working equipment 5: Controller (automatic switching device) 11,11A: Front wheel (wheel) 11,11B: Rear wheel (wheel) 15: Axle 16: Differential case 16B: Bottom end 33, 33A, 33B, 33C: Lower work light (lighting device) 64: Lift arm angle sensor (position detection device) 331: Light source section 333, 333B: Cover (protective material)

Claims

1. The vehicle frame, A pair of left and right wheels provided on the body frame; an axle extending in a left-right direction of the body frame and connecting the pair of left and right wheels; A differential case that houses a differential gear provided on the axle and transmits driving force to the wheels; a working device attached to a front portion of the vehicle body frame so as to be movable in a vertical direction; A lighting device that illuminates the front of the working device; In a work vehicle equipped with The lighting device includes: The differential case is provided on the front side of the axle, below the vehicle body frame, and above the bottom end of the differential case. A work vehicle characterized by:

2. The work vehicle according to claim 1, The lighting device comprises a plurality of task lights, The plurality of work lights are provided in pairs on either side of the differential case in the left-right direction. A work vehicle characterized by:

3. The work vehicle according to claim 1, a posture detection device for detecting a posture of the working device; an automatic switching device that automatically switches the lighting device on and off in response to the posture of the working device detected by the posture detection device; Further equipped A work vehicle characterized by:

4. The work vehicle according to claim 3, The automatic switching device is When the attitude of the working implement detected by the attitude detection device is higher than a ground contact attitude in which a tip portion of the working implement is in contact with a ground, the lighting device is turned on; When the attitude of the working device detected by the attitude detection device reaches the grounding attitude, the lighting device is turned off. A work vehicle characterized by:

5. The work vehicle according to claim 1, The lighting device includes: The light source unit is covered from the front side to protect the light source unit. The light source unit is exposed to the front side to allow light to be irradiated toward the front of the working device. The light source unit is exposed to the front side to allow light to be irradiated toward the front of the working device. A work vehicle characterized by:

6. The work vehicle according to claim 5, The protective member is The closed state and the open state are changed by vertically rotating the light source unit around the upper or lower side of the light source unit. A work vehicle characterized by:

7. The work vehicle according to claim 5, The protective member is The light source unit is slid vertically to change between the closed state and the open state. A work vehicle characterized by:

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