Work vehicles

Abstract

To provide a work vehicle allowing smooth switching from a normal main operation to an optional operation, without requiring labor of an operator.SOLUTION: A wheel loader 1 capable of performing a high-dump operation has a lift arm angle sensor 61 and a work tool angle sensor 62. A main operation signal output from a main operation lever 121 is inputted to a controller 5. On the basis of a lift arm angle θ1 detected by the lift arm angle sensor 61 and a work tool angle θ2 detected by the work tool angle sensor 62, whether a high-dump initiation condition is satisfied or not is determined, where a tip of a lift arm 21 is positioned higher than a dump tip and a bottom face 231B of a bucket 231 is positioned on an extension of the lift arm 21. When the high-dump initiation condition is satisfied, a command signal related to the high dump operation is output to a third solenoid proportional control valve 430, to automatically switch to the high dump operation being an optional operation.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a work vehicle having a bucket and used for loading. [Background technology]

[0002] Some work vehicles that use tools such as buckets to perform loading and unloading work are equipped with a high dump function that allows the tools to be dumped from a position higher than the normal dump position, allowing the load to be conveniently dumped into a dump truck, hopper, etc. When using this high dump function, an optional operation lever is required in addition to the normal operation lever, which increases the number of parts. Therefore, for example, Patent Document 1 discloses a hydraulic excavator that is equipped with a selection switch that allows one-touch switching between normal main operation and optional operation with a single operation lever. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-60947 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the hydraulic excavator described in Patent Document 1, the operator must release his / her hand from the control lever to operate the selection switch, which interrupts the operation and makes it difficult to move smoothly. In addition, the operator must look at his / her hand every time he / she releases his / her hand, which makes it difficult for him / her to check the front.

[0005] SUMMARY OF THE PRESENTLY PREFERRED EMBODIMENTS An object of the present invention is to provide a work vehicle that allows smooth switching from normal main operation to optional operation without requiring the operator to take the time and effort. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides a working tool having a vehicle body, an arm member having a base end attached to the vehicle body and pivoting vertically relative to the vehicle body, a bucket for dumping a load to a dump destination, and a support member pivotally attached to the tip end of the arm member and rotatably supporting the bucket, a main operation device for operating the arm member and the support member as a main operation, a controller for controlling the drive of the arm member, the bucket, and the support member, respectively, and an optional electromagnetic control valve for controlling the drive of the bucket to rotate the bucket relative to the support member in accordance with a command signal output from the controller, and wherein the bucket is dumped from a position higher than a position where the entire working tool is dumped. In a work vehicle capable of high dump operation, the controller has an attitude sensor that detects the attitude of the arm member relative to the vehicle body, and an angle sensor that detects the angle of the work tool relative to the arm member, and the controller receives a main operation signal output from the main operation device, and determines whether a high dump start condition is met in which the tip of the arm member is positioned higher than the dump destination and the bottom surface of the bucket is positioned on an extension of the arm member, based on the attitude of the arm member detected by the attitude sensor and the angle of the work tool detected by the angle sensor, and if the high dump start condition is met, outputs a command signal related to the high dump operation to the electromagnetic control valve, and automatically switches to the high dump operation, which is an optional operation. Effect of the Invention

[0007] According to the present invention, it is possible to smoothly switch from a normal main operation to an optional operation without requiring an operator to do anything. Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments. [Brief description of the drawings]

[0008] [Figure 1]1 is an external side view showing one configuration example of a wheel loader according to each embodiment of the present invention. FIG. [Diagram 2] FIG. 2 is a side view showing the wheel loader during a high dump operation. [Diagram 3] FIG. 11 is an explanatory diagram illustrating a case where the entire working tool rotates. [Figure 4] FIG. 11 is an explanatory diagram illustrating a case where the bucket rotates independently. [Diagram 5] FIG. 2 is a configuration diagram illustrating the configuration of a drive system of the loading and unloading apparatus. [Figure 6] FIG. 2 is a functional block diagram showing functions of a controller according to the first embodiment. [Figure 7] 5 is a flowchart showing a flow of processing executed by a controller according to the first embodiment. [Figure 8] FIG. 11 is a functional block diagram showing functions of a controller according to a second embodiment. [Figure 9] 10 is a flowchart showing a flow of processing executed by a controller according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, as one aspect of a work vehicle according to each embodiment of the present invention, a wheel loader that performs loading and unloading work objects such as earth and sand or minerals and loading them onto a dump truck or the like will be described.

[0010] <Wheel loader 1 configuration> First, the configuration of a wheel loader 1 according to each embodiment of the present invention will be described with reference to FIGS.

[0011] Fig. 1 is an external side view showing one configuration example of a wheel loader 1 according to each embodiment of the present invention. Fig. 2 is a side view showing the wheel loader 1 during high dump operation. Fig. 3 is an explanatory diagram explaining a case where the entire working implement 23 rotates. Fig. 4 is an explanatory diagram explaining a case where the bucket 231 rotates independently. Fig. 5 is a configuration diagram explaining the configuration of the drive system of the loading and unloading apparatus 2.

[0012] The wheel loader 1 is an articulated work vehicle that is steered by bending the vehicle body near the center. Specifically, a front frame 1A forming the front part of the vehicle body and a rear frame 1B forming the rear part of the vehicle body are connected by a center joint 10 so as to be freely rotatable in the left-right direction, and the front frame 1A bends in the left-right direction relative to the rear frame 1B.

[0013] A pair of left and right front wheels 11A are provided on the front frame 1A, and a pair of left and right rear wheels 11B are provided on the rear frame 1B. Of the pair of left and right front wheels 11A and rear wheels 11B, only the left front wheel 11A and rear wheel 11B are shown in Figures 1 and 2. A loading and unloading device 2 used for loading and unloading work is attached to the front of the front frame 1A.

[0014] 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 loading and unloading device 2 so that the vehicle body does not tilt. On 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.

[0015] The loading and unloading work device 2 comprises a lift arm 21 as an arm member whose base end is attached to the front frame 1A and which rotates vertically relative to the vehicle body, two lift arm cylinders 22 (see Figures 2 and 5) that drive the lift arm 21, a working tool 23 having a bucket 231 for dumping a load at a dump destination and a support member 232 that is rotatably attached to the tip of the lift arm 21 and rotatably supports the bucket 231, a first working tool cylinder 24 that drives the support member 232 to operate the entire working tool 23, two second working tool cylinders 25 (see Figures 4 and 5) that drive the bucket 231, and a bell crank 26 that is rotatably connected to the lift arm 21 and forms a link mechanism between the working tool 23 (support member 232) and the first working tool cylinder 24.

[0016] As shown in Fig. 2, this loading and unloading apparatus 2 is capable of performing a high dump operation in which a load is suitably dumped into a dump destination such as a dump truck or a hopper from a position higher than the standard dump position. In Fig. 2, the bucket 231 in the most forward tilted state after performing the high dump operation is shown by a two-dot chain line, and the lift arm 21 is shown in the most raised state.

[0017] 3, the support member 232 is L-shaped in a side view and extends in the width direction of the bucket 231 along the back surface 231C and the bottom surface 231B of the bucket 231. The support member 232 is provided so as to be capable of tilting or dumping (rotating up and down) integrally with the bucket 231 relative to the lift arm 21, centered on a connecting pin 232A which is a connecting portion with the lift arm 21, in conjunction with the extension and contraction of the first work tool cylinder 24 shown in FIG.

[0018] 3, the dashed lines indicate a state in which the implement 23 is tilted to the most rearward tilt position Y1 and a state in which the implement 23 is dumped to the most forward tilt position Y2. In addition, the dashed lines indicate a state in which the implement 23 is tilted to the most rearward tilt position Y2 and the implement 23 is tilted to the most forward tilt position Y2. In addition, the dashed lines indicate a state in which the implement 23 is tilted to the most rearward tilt position Y1 ...

[0019] 4, the bucket 231 is rotatably supported on the support member 221 via a support pin 231A on the bottom surface 231B side, and is provided so as to be capable of tilting or dumping with respect to the support member 232 centered on the support pin 231A in conjunction with the extension and contraction of the two second work tool cylinders 25. Here, the two second work tool cylinders 25 are attached at their bottom sides by pins 251 at positions between the attachment positions of the connecting pins 232A and the support pins 231A on the support member 232, and the rod 25A side is attached to the lower end of the side surface of the bucket 231 by another pin 252.

[0020] In this way, the bucket 231 is provided so as to be dumpable around the support pin 231A disposed on the tip side of the connecting pin 232A, and therefore can be dumped (high dumped) from a position higher than the position (standard dump position) at which the work tool 23 is normally dumped. Note that, in Fig. 4, only one of the two second work tool cylinders 25 is shown.

[0021] When the operator manually operates the high dump operation, first, the operator operates the main operation lever 121 (see FIG. 5) to rotate the lift arm 21 and the support member 232 to the high dump operation switching position Y3 shown in FIG. 3. At this high dump operation switching position Y3, the support member 232 is located on an extension of the lift arm 21. At this time, since the bucket 231 has not yet been operated, the bottom surface 231B is in contact with the support member 232. Therefore, at the high dump operation switching position Y3, the bottom surface 231B of the bucket 231 is located on an extension of the lift arm 21.

[0022] Then, when the lift arm 21 and the work implement 23 are positioned at the high dump operation switching position Y3, the operator releases his / her hand from the main operation lever 121 and switches his / her hand to the option operation lever 122 (see FIG. 5), and operates the option operation lever 122 to dump the bucket 231.

[0023] Here, in the operation of the loading and unloading equipment 2, the operation of the bucket 231 which is the operation for performing a high dump operation corresponds to an optional operation, and the operation of the lift arm 21 and the operation of the support member 232 (the entire operation of the work implement 23) corresponds to a main operation. Note that the main operation lever 121 is one aspect of a main operation device for performing the main operation, and the option operation lever 122 is one aspect of an option operation device for performing the option operation, and they are provided in the operator's cab 12 (see Figs. 1 and 2).

[0024] As shown in FIG. 5, the drive system of the loading / unloading device 2 includes two lift arm cylinders 22, a first work tool cylinder 24, two second work tool cylinders 25, a hydraulic pump 40 that supplies hydraulic oil to each of the cylinders 22, 24, 25, first to third directional control valves 41-43 that switch the flow (direction and flow rate) of the hydraulic oil discharged from the hydraulic pump 40 and supplied to each of the cylinders 22, 24, 25, a hydraulic oil tank 44 that stores the hydraulic oil, first to third electromagnetic proportional control valves 410, 420, 430 that control the first to third directional control valves 41-43, and a controller 5 that outputs command signals to the first to third electromagnetic proportional control valves 410, 420, 430 to control the drive of the lift arm 21, the support member 232, and the bucket 231, respectively.

[0025] The third electromagnetic proportional control valve 430 is one aspect of an optional electromagnetic control valve that controls the drive of the bucket 231 so as to rotate the bucket 231 relative to the support member 232 in accordance with a command signal output from the controller 5.

[0026] The first directional control valve 41 has a first switching position 41L, a neutral position 41N, a second switching position 41R, and a float position 41F.

[0027] The first switching position 41L allows the hydraulic oil discharged from the hydraulic pump 40 to flow into the bottom chambers 22B of the two lift arm cylinders 22, and guides the hydraulic oil discharged from the rod chambers 22C to the hydraulic oil tank 44.

[0028] The neutral position 41N guides the hydraulic oil discharged from the hydraulic pump 40 directly to the hydraulic oil tank 44.

[0029] The second switching position 41R causes the hydraulic oil discharged from the hydraulic pump 40 to flow into the rod chambers 22C of the two lift arm cylinders 22, and guides the hydraulic oil discharged from the bottom chamber 22B to the hydraulic oil tank 44.

[0030] The float position 41F is a position that connects both the rod chamber 22C and the bottom chamber 22B of each of the two lift arm cylinders 22 to the hydraulic oil tank 44, and allows the two lift arm cylinders 22 to move freely due to external forces acting on the two lift arm cylinders 22.

[0031] The second directional control valve 42 has a first switching position 42L, a neutral position 42N, and a second switching position 42R. The first switching position 42L allows the hydraulic oil discharged from the hydraulic pump 40 to flow into the bottom chamber 24B of the first implement cylinder 24, and guides the hydraulic oil discharged from the rod chamber 24C to the hydraulic oil tank 44. The neutral position 42N guides the hydraulic oil discharged from the hydraulic pump 40 directly to the hydraulic oil tank 44. The second switching position 42R allows the hydraulic oil discharged from the hydraulic pump 40 to flow into the rod chamber 24C of the first implement cylinder 24, and guides the hydraulic oil discharged from the bottom chamber 24B to the hydraulic oil tank 44.

[0032] Similarly, the third directional control valve 43 has a first switching position 43L, a neutral position 43N, and a second switching position 43R. The first switching position 43L allows the hydraulic oil discharged from the hydraulic pump 40 to flow into the bottom chambers 25B of the two second implement cylinders 25, respectively, and guides the hydraulic oil discharged from the rod chambers 25C to the hydraulic oil tank 44. The neutral position 43N guides the hydraulic oil discharged from the hydraulic pump 40 directly to the hydraulic oil tank 44. The second switching position 43R allows the hydraulic oil discharged from the hydraulic pump 40 to flow into the rod chambers 25C of the two second implement cylinders 25, respectively, and guides the hydraulic oil discharged from the bottom chambers 25B to the hydraulic oil tank 44.

[0033] For example, when the main operation lever 121 is operated in a direction to raise the lift arm 21, a main operation signal related to the lifting operation of the lift arm 21 is output from the main operation lever 121. Based on the main operation signal, the controller 5 outputs a command signal corresponding to the amount of lifting operation of the lift arm 21 to the first electromagnetic proportional control valve 410. As a result, the first directional control valve 41 switches to the first switching position 41L, and hydraulic oil is supplied to the bottom chambers 22B of the two lift arm cylinders 22 to extend the rods 22A, so that the lift arms 21 move upward.

[0034] Furthermore, for example, when the main operation lever 121 is operated in a direction to tilt the support member 232 forward (dumping direction of the working tool 23), a main operation signal related to the forward tilting operation of the support member 232 is output from the main operation lever 121. Based on the main operation signal, the controller 5 outputs a command signal corresponding to the forward tilting operation amount of the support member 232 to the second electromagnetic proportional control valve 420. As a result, the second directional control valve 42 is switched to the second switching position 42R, and hydraulic oil is supplied to the rod chamber 24C of the first working tool cylinder 24 to contract the rod 24A, so that the support member 232 moves in the forward tilting direction (the entire working tool 23 is dumped).

[0035] Also, for example, when the option operation lever 122 is operated in a direction to dump the bucket 231, an option operation signal related to the dump operation of the bucket 231 is output from the option operation lever 122. Based on the option operation signal, the controller 5 outputs a command signal corresponding to the dump operation amount of the bucket 231 to the third electromagnetic proportional control valve 430. As a result, the third directional control valve switches to the second switching position 43R, and hydraulic oil is supplied to the rod chambers 25C of the two second implement cylinders 25, respectively, and the rods 25A contract, so that the bucket 231 is dumped (high dump).

[0036] As described above, when operating the bucket 231, including the high dump operation, the operator must take his / her hand off the main operation lever 121 and switch to the option operation lever 122, which makes the operation complicated. Therefore, in the drive system of the loading and unloading work apparatus 2, the controller 5 can automatically switch to the operation of the bucket 231 without the operator having to operate the option operation lever 122. The configuration of the controller 5 will be described below for each embodiment.

[0037] First Embodiment First, the controller 5 according to the first embodiment of the present invention will be described with reference to FIGS.

[0038] (Controller 5 configuration) The configuration of the controller 5 will be described with reference to FIG.

[0039] FIG. 6 is a functional block diagram showing functions of the controller 5 according to the first embodiment.

[0040] The controller 5 is configured by connecting a CPU, RAM, ROM, HDD, input I / F, and output I / F to one another via a bus. Various operating devices such as a main operation lever 121, an option operation lever 122, and a selection switch 123, and various sensors such as a lift arm angle sensor 61 and a work tool angle sensor 62 are connected to the input I / F, and a first electromagnetic proportional control valve 410, a second electromagnetic proportional control valve 420, and a third electromagnetic proportional control valve 430 are connected to the output I / F. The selection switch 123 corresponds to a selection device that selects automatic switching to an option operation (high dump operation) by the controller 5.

[0041] 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.

[0042] In this embodiment, the controller 5 is described as a computer configured by a combination of software and hardware, but this is not limiting. 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.

[0043] The lift arm angle sensor 61 is one type of posture sensor that detects the posture of the lift arm 21 relative to the vehicle body, and is attached to the base end of the lift arm 21 (the connecting portion with the front frame 1A). It is possible to detect the height of the lift arm 21 from the ground based on the lift arm angle detected by the lift arm angle sensor 61. Note that the posture sensor does not necessarily have to be a sensor that detects the lift arm angle, and may also be a sensor that detects, for example, the stroke length or bottom pressure of the lift arm cylinder 22.

[0044] The work implement angle sensor 62 is one form of angle sensor that detects the angle of the work implement 23 relative to the lift arm 21, and is attached to the bell crank 26. Note that the angle sensor does not necessarily have to be a sensor that detects the work implement angle, and may also be, for example, a sensor that detects the stroke length or bottom pressure of the first work implement cylinder 24.

[0045] As shown in FIG. 6, the controller 5 includes a data acquisition unit 51, a condition determination unit 52, a storage unit 53, and a signal output unit .

[0046] The data acquisition unit 51 acquires data relating to the main operation signal output from the main operation lever 121, the automatic switching selection signal output from the selection switch 123, the lift arm angle θ1 detected by the lift arm angle sensor 61, and the work tool angle θ2 detected by the work tool angle sensor 62.

[0047] When the data acquisition unit 51 acquires the main operation signal and the automatic switch selection signal, the condition determination unit 52 determines whether or not a high dump start condition is met based on the lift arm angle θ1 and the work tool angle θ2 acquired by the data acquisition unit 51. This "high dump start condition" is the minimum necessary condition for the wheel loader 1 to start a high dump operation, and is that the tip of the lift arm 21 is positioned higher than the dump destination and the bottom surface 231B of the bucket 231 is positioned on an extension of the lift arm 21.

[0048] In this embodiment, the condition determination unit 52 determines whether the lift arm angle θ1 acquired by the data acquisition unit 51 is equal to or greater than a predetermined first threshold value α1 (hereinafter simply referred to as the "first threshold value α1") and whether the work tool angle θ2 acquired by the data acquisition unit 51 is equal to or smaller than a predetermined second threshold value α2 (hereinafter simply referred to as the "second threshold value α2"). Here, the first threshold value α1 is a lift arm angle associated with the height of the dump destination, and the second threshold value α2 is a work tool angle when the bottom surface 231B of the bucket 231 is located on an extension of the lift arm 21, and these threshold values ​​are both stored in advance in the storage unit 53 which is a memory.

[0049] When the condition determination unit 52 determines that the high dump start condition is satisfied, the signal output unit 54 outputs a command signal related to the high dump operation to the third electromagnetic proportional control valve 430. This automatically switches to the high dump operation, which is an optional operation.

[0050] (Processing within controller 5) Next, the flow of processing executed within the controller 5 will be described with reference to FIG.

[0051] FIG. 7 is a flowchart showing the flow of processing executed by the controller 5 according to the first embodiment.

[0052] First, the controller 5 judges whether or not the data acquisition unit 51 has acquired an automatic switching selection signal from the selection switch 123, i.e., whether or not the selection switch 123 has been turned ON (step S501). If it is judged in step S501 that the selection switch 123 has been turned ON (step S501 / YES), the controller 5 then judges whether or not the data acquisition unit 51 has acquired a main operation signal from the main operation lever 121, i.e., whether or not the main operation lever 121 has been operated (step S502).

[0053] When it is determined in step S502 that the main operating lever 121 has been operated (step S502 / YES), the data acquisition unit 51 acquires the lift arm angle θ1 detected by the lift arm angle sensor 61 and the work tool angle θ2 detected by the work tool angle sensor 62 (step S503).

[0054] Next, the condition determination unit 52 determines whether or not the lift arm angle θ1 acquired in step S503 is equal to or greater than the first threshold value α1 and the implement angle θ2 acquired in step S502 is equal to or less than the second threshold value α2, i.e., whether or not the high dump start condition is satisfied (step S504).

[0055] If it is determined in step S504 that the lift arm angle θ1 is equal to or greater than the first threshold value α1 (θ1≧α1) and the implement angle θ2 is equal to or less than the second threshold value α2 (θ2≦α2) (step S504 / YES), the signal output unit 54 outputs a command signal related to the high dump operation to the third electromagnetic proportional control valve 430 (step S505), whereby the controller 5 automatically switches from the main operation based on the operation of the main operating lever 121 to the high dump operation.

[0056] If the selection switch 123 is not turned ON (remains OFF) in step S501 (step S501 / NO), if the main operating lever 121 is not operated in step S502 (step S502 / NO), and if it is determined in step S504 that the lift arm angle θ1 is less than the first threshold value α1 (θ1<α1) or the implement angle θ2 is greater than the second threshold value α2 (θ2>α2) (step S504 / NO), the processing in the controller 5 is terminated.

[0057] In this way, by executing a process in the controller 5 to automatically switch to the high dump operation when the high dump start condition is satisfied, the operator does not need to operate the option operation lever 122, so that switching from the normal main operation to the high dump operation, which is an optional operation, can be performed smoothly without requiring the operator to do anything. Also, since the operator does not need to check what is in his / her hand when switching from the main operation lever 121 to the option operation lever 122, he / she can adequately check what is ahead.

[0058] Furthermore, in this embodiment, the controller 5 determines the high dump start conditions based on a table in which the height of the dump destination and the posture of the lift arm 21 are associated, making it possible to automatically switch to a flexible high dump operation for dump destinations with various specifications.

[0059] Furthermore, in this embodiment, the operator can arbitrarily select automatic switching to high dump operation by the controller 5 using the selection switch 123, and even if the high dump start conditions are met, operation can be performed using the optional operating lever 122 as long as the selection switch 123 is in the OFF state.

[0060] <Second embodiment> Next, a wheel loader 1 according to a second embodiment of the present invention will be described with reference to Figures 8 and 9. In Figures 8 and 9, components common to those described for the wheel loader 1 according to the first embodiment are given the same reference numerals and descriptions thereof will be omitted.

[0061] Fig. 8 is a functional block diagram showing functions of a controller 5A according to the second embodiment. Fig. 9 is a flowchart showing the flow of processing executed by the controller 5A according to the second embodiment.

[0062] In this embodiment, unlike the first embodiment, the wheel loader 1 further comprises a learning mode changeover switch 124 as a learning mode changeover device for switching to a learning mode in which the high dump start conditions are learned based on the operation of the main operation lever 121 and the operation of the option operation lever 122. Then, as shown in FIG. 8, the controller 5A includes a learning unit 55 in addition to the data acquisition unit 51A, condition determination unit 52A, memory unit 53A, and signal output unit 54.

[0063] As shown in FIG. 9, first, the controller 5A determines whether or not the data acquisition unit 51A has acquired the mode switching signal output from the learning mode switching switch 124, that is, whether or not the learning mode switching switch 124 has been turned ON (step S506).

[0064] If it is determined in step S506 that the learning mode changeover switch 124 is turned ON (step S506 / YES), the learning unit 55 learns the lift arm angle β1 and the implement angle β2 at the start of the high dump operation acquired by the data acquisition unit 51A, and the learned lift arm angle β1 and the learned implement angle β2 are stored in the memory unit 55A as a first learned value β1 and a second learned value β2, respectively (step S507).

[0065] When the first learned value β1 and the second learned value β2 are stored in step S507, the controller 5A turns off the learning mode (step S508). After that, when the data acquisition unit 51A acquires the main operation signal output from the main operation lever 121 (step S502 / YES), the condition determination unit 52A determines whether or not the lift arm angle θ1 acquired in step S503 is equal to or greater than the first learned value β1 and the implement angle θ2 acquired in step S503 is equal to or less than the second learned value β2 (step S504A).

[0066] In step S504A, if it is determined that the lift arm angle θ1 is equal to or greater than the first learned value β1 (θ1≧β1) and the work tool angle θ2 is equal to or less than the second learned value β2 (θ2≦β2) (step S504 / YES), the process proceeds to step S505. If it is determined that the lift arm angle θ1 is less than the first learned value β1 (θ1<β1) and the work tool angle θ2 is greater than the second learned value β2 (θ2>β2) (step S504 / NO), the processing in controller 5A ends.

[0067] In this way, in the controller 5A of this embodiment, automatic switching to high dump operation is not performed using high dump start conditions based on preset threshold values, but rather automatic switching to high dump operation is performed using high dump start conditions based on learning values ​​learned from the operator's initial operation of the main operation lever 121 and the operation of the optional operation lever 122.Therefore, the high dump start conditions can be changed at any time to suit dump destinations with various specifications and on-site environments, making it possible to perform automatic switching to high dump operation with high precision.

[0068] 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.

[0069] For example, in the above embodiment, a wheel loader 1 has been described as a work vehicle capable of high dump operation, but the present invention is not limited to this and can also be applied to other work vehicles, such as a lift truck having an extendable arm member. [Explanation of symbols]

[0070] 1: Wheel loader (work vehicle) 5,5A: Controller 21: Lift arm (arm component) 23: Work tools 43: 3rd solenoid proportional control valve (solenoid control valve) 61: Lift arm angle sensor (position sensor) 62: Tool angle sensor (angle sensor) 121: Main operation lever (main operation device) 122: Optional operation lever (optional operation device) 123: Selection switch (selection device) 124: Learning mode changeover switch (learning mode changeover device) 231: Bucket 231B: Bottom 232: Support member α1: First threshold α2: Second threshold β1: First learning value β2: Second learning value

Claims

1. a vehicle body, an arm member having a base end attached to the vehicle body and pivoting vertically relative to the vehicle body, a working tool having a bucket for dumping a load to a dump destination, and a support member pivotally attached to the tip of the arm member and rotatably supporting the bucket, a main operation device for operating the arm member and the support member as a main operation, a controller for controlling the drive of the arm member, the bucket, and the support member, respectively, and an optional electromagnetic control valve for controlling the drive of the bucket so as to rotate the bucket relative to the support member in accordance with a command signal output from the controller, and which is capable of a high dump operation in which the bucket is dumped from a position higher than a position at which the entire working tool is dumped, a posture sensor for detecting a posture of the arm member relative to the vehicle body; an angle sensor for detecting an angle of the working tool relative to the arm member, The controller: A main operation signal output from the main operation device is input, determining whether or not a high dump start condition is satisfied, where the tip of the arm member is positioned higher than the dump destination and the bottom surface of the bucket is positioned on an extension of the arm member, based on the posture of the arm member detected by the posture sensor and the angle of the work tool detected by the angle sensor; When the high dump start condition is satisfied, a command signal related to the high dump operation is output to the electromagnetic control valve, and the operation is automatically switched to the high dump operation, which is an optional operation. A work vehicle characterized by:

2. The work vehicle according to claim 1, The controller: The posture of the arm member associated with the height of the dump destination is stored as a predetermined first threshold value, and the angle of the work tool when the bottom surface of the bucket is located on an extension of the arm member is stored as a predetermined second threshold value, When the posture of the arm member detected by the posture sensor is equal to or greater than the first threshold value and the angle of the work tool detected by the angle sensor is equal to or less than the second threshold value, it is determined that the high dump start condition is satisfied. A work vehicle characterized by:

3. The work vehicle according to claim 1, An option operation device for performing the option operation; a learning mode switching device for switching to a learning mode in which the high dump start condition is learned based on an operation of the main operation device and an operation of the option operation device, The controller: when a mode switching signal output from the learning mode switching device is input, the posture of the arm member and the angle of the work tool at the start of the high dump operation are learned, storing the learned posture of the arm member as a first learned value and the learned angle of the work tool as a second learned value, When the posture of the arm member detected by the posture sensor is equal to or greater than the first learned value and the angle of the work tool detected by the angle sensor is equal to or less than the second learned value, it is determined that the high dump start condition is satisfied. A work vehicle characterized by:

4. The work vehicle according to claim 1, A selection device for selecting automatic switching to the optional operation by the controller is further provided, The controller: When an automatic switching selection signal is input from the selection device and the high dump start condition is satisfied, a command signal relating to the high dump operation is output to the electromagnetic control valve. A work vehicle characterized by:

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