Wheel loader

Abstract

To provide a wheel loader that enables an operator to easily grasp a posture of a work tool.SOLUTION: A wheel loader 1 of the present invention is composed of a carrier 232 in which a work implement 23 provided on a tip side of a lift arm 21 is rotatably attached to the tip of the lift arm 21, a bucket 231 rotatably supported on the carrier 232, and a high dump cylinder 25 provided between the carrier 232 and the bucket 231, and comprises an electromagnetic control valve 430 that controls a drive of the bucket cylinder to rotate the bucket relative to the carrier in accordance with a command signal output from a controller 5. The carrier 232 or the high dump cylinder 25 is provided with a first sensor 30 that can detect the seating state of the bucket on the carrier, and a second sensor 31 that can detect the dump state of the bucket relative to the carrier.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] Some wheel loaders are equipped with a high dump function that allows the bucket to be dumped from a position higher than the normal dump position, making it possible to dump the load into a dump truck, hopper, etc.

[0003] For example, Patent Document 1 discloses a wheel loader that includes a lift arm that is mounted on the front of the vehicle body so that it can rotate up and down, a support member that is rotatably mounted on the tip of the lift arm, a bucket that is rotatably supported on the support member, and a high dump cylinder that is mounted between the support member and the bucket, and is configured so that the bucket tilts or dumps relative to the lift arm in conjunction with the extension and contraction of the high dump cylinder. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-118197 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the wheel loader described in Patent Document 1, the work implement (high dump bucket) is made up of a support member, a bucket, and a high dump cylinder, and since this work implement is attached to the tip of the lift arm, there was a problem in that it was difficult for the operator to grasp the position of the work implement.

[0006] The present invention has been made in view of the above circumstances, and its object is to provide a wheel loader that allows the operator to easily grasp the posture of the work implement. [Means for solving the problem]

[0007] In order to achieve the above object, a representative aspect of the present invention is a wheel loader comprising a vehicle body, a lift arm whose base end is attached to the vehicle body and rotates up and down, and a work implement attached to the tip of the lift arm, the work implement being composed of a carrier rotatably attached to the tip of the lift arm, a bucket rotatably supported on the carrier, and a high dump cylinder provided between the carrier and the bucket, wherein the carrier or the high dump cylinder is provided with a sensor capable of detecting at least one of a seated state in which the bucket is seated on the carrier and a dumped state in which the bucket is dumped against the carrier. [Effects of the Invention]

[0008] According to the wheel loader of the present invention, the operator can easily grasp the attitude of the high dump bucket. Note that problems, configurations, and effects other than those described above will become apparent from the following description of the embodiment. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is an external side view showing an example of the configuration of a wheel loader according to an embodiment of the present invention. [Figure 2] FIG. 1 is a side view showing the wheel loader during a high dump operation. [Figure 3] FIG. [Figure 4] FIG. [Figure 5] FIG. 10 is an explanatory diagram illustrating a case where the entire working tool rotates. [Figure 6] FIG. 10 is an explanatory diagram illustrating a case where the bucket rotates independently. [Figure 7] FIG. 2 is a diagram illustrating the configuration of a drive system of the loading and unloading apparatus. [Figure 8] 10A and 10B are explanatory diagrams showing the relationship between the bucket position and whether or not the detent can be operated based on the detection pattern. [Figure 9] FIG. [Figure 10] FIG. 2 is a side view showing the working implement in a dump state. [Figure 11] FIG. 10 is a side view showing a seated state of the work tool according to the first modified example. [Figure 12] FIG. 10 is a perspective view showing a main part of the attachment portion of the third sensor. [Figure 13] FIG. 10 is a side view showing the working tool according to the first modification in a state immediately before being seated. [Figure 14] FIG. 10 is a side view showing an intermediate state of the work tool according to the first modified example. [Figure 15] FIG. 10 is a side view showing the working implement according to the first modification in a state immediately before dumping. [Figure 16] FIG. 10 is a side view showing a dump state of the implement according to the first modified example. [Figure 17] FIG. 10 is a functional block diagram showing functions of a controller according to a first modified example. [Figure 18] 10 is an explanatory diagram showing the relationship between the bucket position, the possibility of detent operation, and the bucket rotation speed based on the detection pattern according to Modification 1. FIG. [Figure 19] 10 is a time chart showing bucket movement according to a detection pattern according to Modification 1 when the dump truck side detent is operated from a seated state. [Figure 20] FIG. 10 is a functional block diagram showing functions of a controller according to Modification 2. [Figure 21] 10 is a flowchart showing the flow of processing executed by a controller according to Modification 2. [Figure 22] FIG. 11 is a side view showing a seated state of the work tool according to the third modification. [Figure 23] FIG. 11 is a side view showing an intermediate state of a work tool according to a third modified example. [Figure 24] FIG. 11 is a side view showing a state immediately before dumping of the implement according to the third modification. [Figure 25]FIG. 11 is a side view showing a dump state of the implement according to the third modification. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, a wheel loader according to an embodiment of the present invention will be described.

[0011] Fig. 1 is an exterior side view showing an example of the configuration of a wheel loader according to an embodiment of the present invention. Fig. 2 is a side view showing the wheel loader during high dump operation. Fig. 3 is a perspective view of the implement. Fig. 4 is a side view of the implement. Fig. 5 is an explanatory diagram illustrating a case where the implement as a whole rotates. Fig. 6 is an explanatory diagram illustrating a case where the bucket rotates independently.

[0012] A wheel loader 1 according to an embodiment of the present invention is an articulated work vehicle that is steered by bending the vehicle body near the center. Specifically, a front frame 1A, which forms the front part of the vehicle body, and a rear frame 1B, which forms 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] The front frame 1A is provided with a pair of left and right front wheels 11A, and the rear frame 1B is provided with a pair of left and right rear wheels 11B. 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. In addition, 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 machinery room 13 that houses various devices required for driving the wheel loader 1, and a counterweight 14 that maintains balance with the loading and unloading device 2 to prevent the vehicle body from tipping over. On the rear frame 1B, the cab 12 is located at the front, the counterweight 14 at the rear, and the machinery room 13 between the cab 12 and the counterweight 14.

[0015] The loading and unloading device 2 comprises a lift arm 21 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 Figure 2) that drive the lift arm 21, a working implement 23 having a bucket 231 that dumps a load at a dumping destination and a carrier 232 that is rotatably attached to the tip of the lift arm 21 and rotatably supports the bucket 231, a bucket cylinder 24 that drives the carrier 232 to operate the entire working implement 23, two high dump cylinders 25 (see Figures 3 to 6) 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 implement 23 (carrier 232) and the bucket cylinder 24.

[0016] As shown in Figure 2, this cargo handling apparatus 2 is capable of performing a high dump operation to dump a load into a dump destination such as a dump truck or hopper from a position higher than the standard dump position. In Figure 2, the bucket 231 is shown by a two-dot chain line in a state where it is tilted most forward after performing the high dump operation, and the lift arm 21 is shown in a state where it is raised to its highest position.

[0017] 3 and 4, the work implement 23 is configured to include a bucket 231, a carrier 232, and two high dump cylinders 25. The bucket 231 is provided with two pairs of partition walls 231D at a predetermined interval in the width direction (left-right direction), and a high dump cylinder 25 is housed inside each of these partition walls 231D.

[0018] The carrier 232 is a member extending in the width direction of the bucket 231 along the back surface 231C and bottom surface 231B of the bucket 231, and is rotatably connected to the tip of the lift arm 21 by a connecting pin 232A. The carrier 232 has a pair of claws 232D that are inserted into the interior of the partition wall 231D, and the bottom surface 231B side of the bucket 231 is rotatably supported by these claws 232D via support pins 231A.

[0019] The two high dump cylinders 25 are attached at the bottom side by a pin 251 at a position between the attachment position of the connecting pin 232A on the carrier 232 and the attachment position of the support pin 231A, and the rod 25A side is attached to the lower end of the side of the bucket 231 by another pin 252.

[0020] The carrier 232 is provided so as to be able to tilt or dump (rotate up and down) together with the bucket 231 relative to the lift arm 21 around a connecting pin 232A, which is a connecting portion with the lift arm 21, in response to the extension and retraction of the bucket cylinder 24 shown in FIG. 1. In FIG. 5, 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. Furthermore, solid lines indicate the posture of the bucket 231 when the two high dump cylinders 25 are fully retracted and the carrier 232 and bucket 231 are integrated. FIG. 6 shows a posture in which the implement 23 is dumped (high dumped) from a position higher than the normal dumping position (standard dump position). In the following description, a posture (state) in which the bucket 231 is fully tilted and seated on the carrier 232 is referred to as a seated state, and a posture (state) in which the bucket 231 is dumped on the carrier 232 is referred to as a dumped state.

[0021] As shown in Fig. 4, the carrier 232 is equipped with a first sensor 30 capable of detecting the seating state of the bucket 231 and a second sensor 31 capable of detecting the dump state of the bucket 231. Proximity switches that detect the presence or absence of the bucket 231 in a non-contact manner are used as the first sensor 30 and the second sensor 31. Note that other devices such as limit switches can also be used for the first sensor 30 and the second sensor 31 as long as they can detect the presence or absence of the bucket 231.

[0022] The first sensor 30 is provided on the carrier 232 at a position facing the back surface 231C of the bucket 231. The first sensor 30 is turned on and outputs a detection signal when the back surface 231C of the bucket 231 is seated close to the carrier 232, and is turned off and no longer outputs a detection signal when the back surface 231C of the bucket 231 moves away from the carrier 232.

[0023] The second sensor 31 is provided near the support pin 231A on the claw portion 232D of the carrier 232. When the second sensor 31 is located opposite the inner wall surface of the partition wall 231D provided on the bucket 231, the second sensor 31 detects the presence of the bucket 231, turns on, and outputs a detection signal. When the bucket 231 rotates to an angle at which the bucket 231 is in the dump state, the bottom surface 231B of the bucket 231 moves out of the detection range of the second sensor 31, and the second sensor 31 turns off and no longer outputs a detection signal. The first sensor 30 and the second sensor 31 are fixed to elongated holes formed in the carrier 232 using fasteners, so that the attachment positions can be adjusted along the longitudinal direction of the elongated holes.

[0024] FIG. 7 is a diagram illustrating the configuration of the drive system of the cargo handling apparatus 2. As shown in FIG.

[0025] As shown in FIG. 7, the drive system of the loading and unloading device 2 includes two lift arm cylinders 22, a bucket cylinder 24, two high dump cylinders 25, a hydraulic pump 40 that supplies hydraulic oil to each of the cylinders 22, 24, and 25, first to third directional control valves 41 to 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, and 25, a hydraulic oil tank 44 that stores the hydraulic oil, first to third electromagnetic proportional control valves 410, 420, and 430 that control the first to third directional control valves 41 to 43, and a controller 5 that outputs command signals to the first to third electromagnetic proportional control valves 410, 420, and 430 to control the drive of the lift arm 21, carrier 232, and bucket 231, respectively.

[0026] A lift arm operation lever 121, a bucket operation lever 122, a high dump operation lever 123, a dump side detent operation signal 123A, and a seat side detent operation signal 123B are connected to the input side of the controller 5. The high dump operation lever 123 is one form of an operation device for performing a high dump operation, and the lift arm operation lever 121, the bucket operation lever 122, and the high dump operation lever 123 are provided inside the operator's cab 12.

[0027] The first directional control valve 41 has a first switching position 41L, a neutral position 41N, and a second switching position 41R. In this embodiment, when the first directional control valve 41 is in the first switching position 41L, it allows hydraulic oil discharged from the hydraulic pump 40 to flow into the bottom chamber 22B of the lift arm cylinder 22 and guides hydraulic oil discharged from the rod chamber 22C to the hydraulic oil tank 44. Therefore, when the first directional control valve 41 is in the first switching position 41L, the lift arm 21 rises. Similarly, when the first directional control valve 41 is in the neutral position 41N, the lift arm 21 stops, and when the first directional control valve 41 is in the second switching position 41R, the lift arm 21 descends.

[0028] The second direction control valve 42 has a first switching position 42L, a neutral position 42N, and a second switching position 42R. In this embodiment, when the second direction control valve 42 is in the first switching position 42L, it causes the hydraulic oil discharged from the hydraulic pump 40 to flow into the bottom chamber 24B of the bucket cylinder 24, and guides the hydraulic oil discharged from the rod chamber 24C to the hydraulic oil tank 44. Therefore, when the second direction control valve 42 is in the first switching position 42L, the carrier 232 performs a tilt operation together with the bucket 231. Similarly, when the second direction control valve 42 is in the neutral position 42N, the carrier 232 stops, and when the second direction control valve 42 is in the second switching position 42R, the carrier 232 performs a dump operation.

[0029] 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 carrier 232 in accordance with a command signal output from the controller 5. The third directional control valve 43 has a first switching position 43L, a neutral position 43N, and a second switching position 43R.

[0030] In this embodiment, when the third direction control valve 43 is in the first switching position 43L, it causes the hydraulic oil discharged from the hydraulic pump 40 to flow into the bottom chambers 25B of the two high dump cylinders 25, and guides the hydraulic oil discharged from the rod chambers 25C to the hydraulic oil tank 44. Therefore, when the third direction control valve 43 is in the first switching position 43L, the bucket 231 performs a rotational movement (high dumping movement) in a direction away from the carrier 232. Similarly, when the third direction control valve 43 is in the neutral position 43N, the bucket 231 maintains its positional relationship with the carrier 232, and when the third direction control valve 43 is in the second switching position 43R, the bucket 231 performs a rotational movement (seating movement) in a direction to seat on the carrier 232.

[0031] Furthermore, in this embodiment, the third directional control valve 43 is configured to be able to control the displacement of a spool (not shown) so as to supply hydraulic oil to the high dump cylinder 25 at a flow rate that corresponds to the strength (current value, control pressure) of the command signal of the third electromagnetic proportional control valve 430. As a result, the third directional control valve 43 is configured to be able to adjust not only the operating direction but also the operating speed of the high dump cylinder 25 by displacing (holding) the spool to a position between the first switching position 43L and the neutral position 43N or between the neutral position 43N and the second switching position 43R (a position intermediate between the above three positions).

[0032] In this embodiment, the operating speed of the high dump cylinder 25 (bucket 231) when the third directional control valve 43 is in the first switching position 43L or the second switching position 43R is referred to as normal speed, and the operating speed of the high dump cylinder 25 (bucket 231) when the third directional control valve 43 is in a position between the first switching position 43L and the neutral position 43N or between the neutral position 43N and the second switching position 43R is referred to as low speed.

[0033] The above configuration is common to the relationship between the first to third electromagnetic proportional control valves 410, 420, 430 that control the first to third directional control valves 41 to 43, and the relationship between the command signals to the first to third electromagnetic proportional control valves 410, 420, 430 and the drive speeds of the lift arm 21, carrier 232, and bucket 231.

[0034] In the drive system of the cargo handling apparatus 2 configured in this manner, for example, when the high dump operation lever 123 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 high dump operation lever 123. Based on the operation signal, the controller 5 outputs a command signal corresponding to the amount of dump operation of the bucket 231 to the third electromagnetic proportional control valve 430. As a result, the third directional control valve 43 switches to the first switching position 43L, and hydraulic oil is supplied to the bottom chambers 25B of the two high dump cylinders 25, causing the rods 25A to extend, thereby performing a dump (high dump) operation on the bucket 231.

[0035] The wheel loader 1 according to this embodiment enables detent operation, in which the loading and unloading device 2 is automatically moved to any position, by the first sensor 30 and the second sensor 31 detecting the bucket 231.

[0036] Fig. 8 is an explanatory diagram showing the relationship between the bucket position and whether or not detent operation is possible based on the detection patterns of the first sensor 30 and the second sensor 31. Fig. 9 is a side view showing the seated state of the implement 23. Fig. 10 is a side view showing the dumped state of the implement 23. In Fig. 8, the detection pattern of the first sensor 30 is shown as "seated," and the detection pattern of the second sensor 31 is shown as "dump." Circular circles indicate cases where the detection patterns for "seated" and "dump" are in the detected state, and crosses indicate cases where the detection patterns for "seated" and "dump" are not in the detected state.

[0037] As shown in FIG. 9, when the bucket 231 is in the seated position, both the first sensor 30 and the second sensor 31 are in the detection state.

[0038] When the controller 5 detects the dump side detent operation signal 123A from this state, it outputs a command signal to the third electromagnetic proportional control valve 430. As a result, the third directional control valve 43 switches to the first switching position 43L, hydraulic oil is supplied to the bottom chambers 25B of the two high dump cylinders 25, and the rods 25A extend, causing the bucket 231 to begin a dumping operation. Furthermore, when the controller 5 detects the seating side detent operation signal 123B from this state, it determines that the bucket is already in the seated state, and does not output a command signal to the third electromagnetic proportional control valve 430.

[0039] When bucket 231 performs a dumping operation from the seated position and enters an intermediate state, back surface 231C of bucket 231 moves away from carrier 232, and first sensor 30 enters a non-detection state. In addition, second sensor 31 is located inside partition wall 231D of bucket 231, and seating sensor 301 enters a detection state.

[0040] When the dump side detent operation signal 123A and the seating side detent operation signal 123B are detected from this state, the controller 5 outputs a command signal to the third electromagnetic proportional control valve 430 according to each operation direction, thereby rotating the bucket 231 in each operation direction.

[0041] As shown in FIG. 10, when the bucket 231 assumes the dump posture, the first sensor 30 enters a non-detection state, and the bottom surface 231B of the bucket 231 moves out of the detection range of the second sensor 31, so the second sensor 31 also enters a non-detection state.

[0042] When the controller 5 detects the seating side detent operation signal 123B from this state, it outputs a command signal to the third electromagnetic proportional control valve 430. As a result, the third directional control valve 43 switches to the second switching position 43R, and hydraulic oil is supplied to the rod chambers 25C of the two high dump cylinders 25, causing the rods 25A to contract, and the bucket 231 begins to rotate toward the seating side. Furthermore, when the controller 5 detects the dump side detent operation signal 123A from this state, it determines that the vehicle is already in the dump state, and does not output a command signal to the third electromagnetic proportional control valve 430.

[0043] In this way, in the wheel loader 1 according to the embodiment, the carrier 232 is provided with the first sensor 30 and the second sensor 31, and these two sensors 30, 31 are used to detect the seating state and dump state of the bucket 231, so the detent function can be effectively used to perform high dump work efficiently.

[0044] In the above embodiment, the first sensor 30 and the second sensor 31 are provided on the carrier 232, but the second sensor 31 may be omitted and only the first sensor 30 may be provided on the carrier 232, or the first sensor 30 may be omitted and only the second sensor 31 may be provided on the carrier 232.

[0045] Next, modified examples of the work implement 23 will be described.

[0046] <Variation 1> Fig. 11 is a side view showing a seated state of the implement 23 according to Modification 1. Fig. 12 is a perspective view showing a main part of the attachment portion of the third sensor 32. Fig. 13 is a side view showing a state close to seating of the implement 23 according to Modification 1. Fig. 14 is a side view showing an intermediate state of the implement 23 according to Modification 1. Fig. 15 is a side view showing a state close to dumping of the implement 23 according to Modification 1. Fig. 16 is a side view showing a dumping state of the implement 23 according to Modification 1.

[0047] As shown in Figures 11 to 16, the work implement 23 according to the first modification includes a third sensor 32 in addition to a first sensor 30 and a second sensor 31. The third sensor 32 is attached to the bottom side of the high dump cylinder 25 using a cable tie or the like (see Figure 12), and is a proximity switch like the first sensor 30 and the second sensor 31. The third sensor 32 rotates integrally with the high dump cylinder 25 around a pin 251 as the high dump cylinder 25 extends and retracts.

[0048] The claw portion 232D of the carrier 232 is provided with a first receiving portion 232E and a second receiving portion 232F that are detection targets of the third sensor 32, and these first receiving portion 232E and second receiving portion 232F are arranged at a predetermined interval on the rotation trajectory of the third sensor 32. The third sensor 32 is turned on and outputs a detection signal when it is located opposite the first receiving portion 232E or the second receiving portion 232F, and is turned off and no longer outputs a detection signal when it moves out of the detection range of the first receiving portion 232E or the second receiving portion 232F. In other words, the third sensor 32 is a device that can detect the extension / contraction state of the high dump cylinder 25 that rotates the bucket 231 relative to the carrier 232.

[0049] FIG. 17 is a functional block diagram showing functions of controller 5 according to Modification 1. FIG. 18 is an explanatory diagram showing the relationship between bucket position, detent operation availability, and bucket rotation speed according to the detection pattern according to Modification 1. FIG. 19 is a time chart showing the movement of bucket 231 according to the detection pattern according to Modification 1 when dump-side detent operation is performed from a seated state. In FIG. 18, the detection pattern of first sensor 30 is shown as "seated," the detection pattern of second sensor 31 as "dump," and the detection pattern of third sensor 32 as "deceleration section." Circular circles indicate cases where the detection patterns of "seated," "dump," and "deceleration section" are in a detected state, and crosses indicate cases where the detection patterns of "seated," "dump," and "deceleration section" are in a non-detected state.

[0050] 17, the controller 5 includes a data acquisition unit 51, a condition determination unit 52, a memory unit 53, and a signal output unit 54. The input side of the controller 5 is connected to the detection signals of the first sensor 30, the second sensor 31, the third sensor 32, the dump side detent operation signal 123A, and the seating side detent operation signal 123B, and the output side of the controller 5 is connected to the third electromagnetic proportional control valve 430.

[0051] As shown in Figure 11, when the bucket 231 is in a seated position, the third sensor 32 is located opposite one end side (the right end in the figure) of the first receiving portion 232E, and the first sensor 30, the second sensor 31, and the third sensor 32 are all in a detection state.

[0052] When the controller 5 detects a dump-side detent operation signal 123A from this state, it outputs a command signal to the third electromagnetic proportional control valve 430 with an intensity (current value) such that the high dump cylinder 25 operates at a low speed (hereinafter referred to as a low-speed output). As a result, the third directional control valve 43 is displaced to a position between the first switching position 43L and the neutral position 43N, and hydraulic oil is supplied to the bottom chambers 25B of the two high dump cylinders 25, respectively, and the rods 25A extend, so that the bucket 231 begins dumping at a low speed. Furthermore, when the controller 5 detects a seating-side detent operation signal 123B from this state, it determines that the bucket is already in the seated state, and does not output a command signal to the third electromagnetic proportional control valve 430.

[0053] 13, when the bucket 231 is in a pre-seating state in which it is positioned just before the seating posture, the third sensor 32 is in a position facing the other end side (the left end in the figure) of the first receiving portion 232E, and the third sensor 32 is in a detecting state. The second sensor 31 is also in a detecting state, and the first sensor 30 is in a non-detecting state as the back surface 231C of the bucket 231 moves away from the carrier 232.

[0054] When the dump side detent operation signal 123A and the seating side detent operation signal 123B are detected from this state, the controller 5 outputs a command signal at a low speed to the third electromagnetic proportional control valve 430 according to each operation direction. As a result, the bucket 231 rotates in each operation direction at a low speed slower than the normal speed (the speed when the third directional control valve 43 is in the first switching position 43L or the second switching position 43R).

[0055] 14, when the bucket 231 is in an intermediate state between the seated posture (seated state) and the dump posture (dump state), the third sensor 32 is out of the detection range of both the first receiving portion 232E and the second receiving portion 232F, and therefore the third sensor 32 is in a non-detecting state. The first sensor 30 is also in a non-detecting state, and only the second sensor 31 is in a detecting state.

[0056] From this state, when the dump side detent operation signal 123A and the seating side detent operation signal 123B are detected, the controller 5 normally outputs a command signal to the third electromagnetic proportional control valve 430 according to each operation direction, thereby rotating the bucket 231 at a normal speed in each operation direction.

[0057] 15, when the bucket 231 is in a pre-dump state where it is positioned just before the dump posture, the third sensor 32 is in a detecting state because it is in a position facing one end side (the right end in the figure) of the second receiving portion 232F. Also, the second sensor 31 is in a detecting state, and the first sensor 30 is in a non-detecting state.

[0058] When the dump side detent operation signal 123A and the seating side detent operation signal 123B are detected from this state, the controller 5 outputs a command signal at a low speed to the third electromagnetic proportional control valve 430 according to each operation direction, thereby rotating the bucket 231 at a low speed in each operation direction.

[0059] 16, when bucket 231 is in the dump state, third sensor 32 is in a detecting state because it is in a position facing the other end side (left end in the figure) of second receiving portion 232F. Also, first sensor 30 is in a non-detecting state, and second sensor 31 is in a non-detecting state because bottom surface 231B of bucket 231 is out of the detection range of second sensor 31.

[0060] When the controller 5 detects the seating side detent operation signal 123B from this state, it outputs a command signal to the third electromagnetic proportional control valve 430. As a result, the third directional control valve 43 switches to the second switching position 43R, and hydraulic oil is supplied to the rod chambers 25C of the two high dump cylinders 25, causing the rods 25A to retract, and the bucket 231 begins to rotate at a low speed toward the seating side. Furthermore, when the controller 5 detects the dump side detent operation signal 123A from this state, it determines that the vehicle is already in the dump state, and does not output a command signal to the third electromagnetic proportional control valve 430.

[0061] In this way, in Modification 1, in addition to first sensor 30 and second sensor 31, third sensor 32 is attached to high dump cylinder 25, and therefore a low-speed section in which the operating speed of bucket 231 is slower than normal can be set based on the detection patterns of these three sensors 30, 31, and 32. This allows bucket 231 to operate at a low speed just before it assumes the dump position or seated position, reducing the impact and noise caused by the bucket 231 suddenly starting to move or stopping.

[0062] <Variation 2> Fig. 20 is a functional block diagram showing functions of the controller 5 according to the modified example 2. Fig. 21 is a flowchart showing the flow of processing executed by the controller 5 according to the modified example 2.

[0063] 20, the controller 5 includes a data acquisition unit 51, a condition determination unit 52, a storage unit 53, and a signal output unit 54. The input side of the controller 5 is connected to an operation signal of the high dump operation lever 123, a detection signal of the first sensor 30, and a detection signal of the carrier angle sensor 62 that detects the angle of the carrier 232, and the output side of the controller 5 is connected to a determination result display device 501 that serves as an alarm notification means.

[0064] 21, after acquiring seating information of the bucket 231 from the first sensor 30 (step S1), the controller 5 acquires angle information of the carrier 232 from the carrier angle sensor 62 (step S2). Next, it is determined whether the bucket 231 is seated (step S3), and if it is determined that the bucket 231 is not seated (NO in step S3), an excavation posture warning such as "Do not perform excavation while the bucket is in a high dump position" is displayed on the determination result display device 501 (step S4).

[0065] Furthermore, if it is determined in step S3 that bucket 231 is in a seated state (YES), the process proceeds to step S5, where it is determined whether or not the angle of carrier 232 is horizontal. If it is determined in step S5 that the angle of carrier 232 is not horizontal (NO), bucket 231 is in an angled state, and therefore an excavation posture warning such as "Please do not perform excavation work while dumped" is displayed on determination result display device 501 (step S6).

[0066] On the other hand, if it is determined in step S5 that the angle of the carrier 232 is horizontal (YES), it is determined that the attitude is suitable for excavation, and precautions for excavation are displayed on the determination result display device 501 (step S7).

[0067] In this way, in Modification 2, the operator can be notified of information necessary for work based on information from first sensor 30 that detects the seating position of bucket 231 and information from carrier angle sensor 62 that detects the angle of carrier 232. This prevents excavation from being performed in a high dump state, and prevents damage to work tool 23 that may result from excavation work in an awkward position.

[0068] In addition, in Figure 21, the judgment process of the controller 5 based on the first sensor 30 and the carrier angle sensor 62 has been explained, but the information necessary for the work may also be notified to the operator by judgment based on the seating sensor 301 and the high dump operation lever 123.

[0069] In this case, controller 5 acquires seating information of bucket 231 from first sensor 30 and acquires operation information of high dump operation lever 123. If seating sensor 301 enters a non-detection state even though there is no operation signal from high dump operation lever 123, it determines that bucket 231 is overloaded, and displays a warning such as, for example, "Do not perform work that places a load only on the cutting edge" on determination result display device 501. This makes it possible to prevent bucket 231 from opening due to an overload, enabling efficient work.

[0070] In the second modification, the content of the warning is notified by the screen display of the determination result display device 501, but an alarm device may be used instead of a display device as the warning notification means, and the content of the warning may be notified by voice, alarm sound, etc. Alternatively, a display device and an alarm device may be used together.

[0071] <Variation 3> Fig. 22 is a side view showing a seated state of the implement according to Modification 3. Fig. 23 is a side view showing an intermediate state of the implement according to Modification 3. Fig. 24 is a side view showing a state just before dumping of the implement according to Modification 3. Fig. 25 is a side view showing a dumping state of the implement according to Modification 3.

[0072] 22 to 25, the work implement 23 according to the third modification does not include a first sensor that detects the seating state of the bucket 231 or a second sensor that detects the dump state of the bucket 231, but only includes a third sensor 32 that can detect the extension / retraction state of the high dump cylinder 25. As in the first modification, the third sensor 32 is attached to the bottom side of the high dump cylinder 25, and rotates integrally with the high dump cylinder 25 around a pin 251 as the high dump cylinder 25 extends or retracts.

[0073] The claw portion 232D of the carrier 232 is provided with a first receiving portion 232E and a second receiving portion 232F that are the detection targets of the third sensor 32, and these first receiving portion 232E and second receiving portion 232F are arranged at a predetermined interval on the rotation trajectory of the third sensor 32. When the third sensor 32 is in a position facing the first receiving portion 232E and the second receiving portion 232F, it turns on and outputs a detection signal, and when it moves out of the detection range of the first receiving portion 232E and the second receiving portion 232F, it turns off and no longer outputs a detection signal.

[0074] In the work tool 23 according to the third modification, only the "deceleration section" corresponding to the third sensor 32 is used as the detection pattern in FIG. 18, and detent operation is performed based on whether the detection pattern of the "deceleration section" is in a detection state (○) or a non-detection state (×).

[0075] That is, as shown in Fig. 22, when bucket 231 is in the seated position, third sensor 32 faces one end side (right end in the figure) of first receiving portion 232E and is in a detecting state. From this state, when dump-side detent operation signal 123A is detected, bucket 231 starts a dumping operation at a low speed, and when third sensor 32 rotates to an angle that puts it out of the detection range of first receiving portion 232E, third sensor 32 goes into a non-detecting state, and bucket 231 moves to a normal speed in the intermediate state shown in Fig. 23. Then, when the bucket reaches the state just before dumping shown in Fig. 24, third sensor 32 faces one end side (right end in the figure) of second receiving portion 232F and is in a detecting state, and bucket 231 again rotates at a low speed to an angle that puts it in the dumping state shown in Fig. 25.

[0076] It should be noted that the above-described embodiment and each modification are merely examples for explaining the present invention, and are not intended to limit the scope of the present invention to only those embodiments. Those skilled in the art can implement the present invention in various other forms without departing from the gist of the present invention. [Explanation of symbols]

[0077] 1. Wheel loader 1A Front frame (front of vehicle) 1B Rear frame (rear of the vehicle) 2. Loading and unloading equipment 5 Controller 12 Driver's cab 21 Lift arm 22 Lift arm cylinder 23 Work tools 24 Bucket cylinder 25 High dump cylinder 25A Rod 25B Bottom Chamber 26 Bell crank 30 First Sensor 31 Second Sensor 32 Third Sensor 121 Lift arm operating lever 122 Bucket operation lever 123 High dump operation lever (high dump operation device) 123A Dump side detent operation signal 123B Seat side detent operation signal 231 Bucket 231A Support Pin 231B Bucket bottom 231C Bucket back 231D Bulkhead 232 Career 232A Connecting Pin 232D Claw part 232E 1st receiving part 232F 2nd receiving part 251 pins 430 Third electromagnetic proportional control valve (electromagnetic control valve) 501 Determination result display device (alarm notification means)

Claims

1. The car body and a lift arm whose base end is attached to the vehicle body and which rotates in the vertical direction; a work tool provided on the tip side of the lift arm; Equipped with In a wheel loader, the working implement is composed of a carrier rotatably attached to the tip of the lift arm, a bucket rotatably supported by the carrier, and a high dump cylinder provided between the carrier and the bucket, a sensor that can detect at least one of a seated state in which the bucket is seated on the carrier and a dumped state in which the bucket is dumped onto the carrier is provided on the carrier or the high dump cylinder; A wheel loader characterized by:

2. The wheel loader according to claim 1, The sensor a first sensor that detects the presence or absence of the back surface of the bucket, or a second sensor that detects the presence or absence of the bottom surface of the bucket; A wheel loader characterized by:

3. The wheel loader according to claim 1, The sensor a first sensor for detecting the presence or absence of the back surface of the bucket, and a second sensor for detecting the presence or absence of the bottom surface of the bucket; A wheel loader characterized by:

4. The wheel loader according to claim 1, The sensor a first sensor that detects the presence or absence of the back surface of the bucket, a second sensor that detects the presence or absence of the bottom surface of the bucket, and a third sensor that detects the extension / contraction state of the high dump cylinder; A wheel loader comprising:

5. The wheel loader according to claim 3, A detent device is provided to hold the high dump cylinder in an extended or retracted position. The rotation of the bucket is maintained / released according to the detection states of the first sensor and the second sensor. A wheel loader characterized by:

6. The wheel loader according to claim 3, and an alarm notification means for notifying an operator of information necessary for work in accordance with the detection results of at least one of the first sensor and the second sensor. A wheel loader characterized by:

7. The wheel loader according to claim 6, A high dump operation device is provided for operating the bucket, When the first sensor detects the bucket being unseated without a signal input from the high dump operation device, The warning notification means notifies information that the bucket is in an overload state. A wheel loader characterized by:

8. The wheel loader according to claim 4, a controller that controls the lift arm and the work implement; the controller switches the rotation speed of the bucket between normal operation and low-speed operation in accordance with the detection state of the third sensor. A wheel loader characterized by:

9. The wheel loader according to claim 1, a controller that controls the lift arm and the work implement; The sensor is capable of detecting an extension / contraction state of the high dump cylinder, the controller controls the driving of the high dump cylinder to rotate the bucket relative to the carrier based on the detection signal of the sensor. A wheel loader characterized by:

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