Work vehicle

Abstract

To provide a work vehicle capable of accurately detecting obstacles that may come into contact with a work device while avoiding erroneous detection of the work device as an obstacle.SOLUTION: A work vehicle comprising a work device 2 comprises a cab-side obstacle sensor 31 provided on an upper portion of a front frame 1A to detect an obstacle located in front of and above a vehicle body, and an axle-side obstacle sensor 32 provided on a lower portion of the front frame 1A to detect an obstacle located in front of and below the vehicle body. A controller 5 that controls operation of the work device 2 enables detection of an obstacle by the cab-side obstacle sensor 31 when the work device 2 is in a horizontal or upward posture, enables detection of an obstacle by the axle-side obstacle sensor 32 when the work device 2 is in a downward posture, and performs operation stop control of the work device 2 when a distance L between the detected obstacle and the work device 2 is equal to or less than a predetermined distance threshold Lth.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a work vehicle equipped with a work implement. [Background technology]

[0002] Generally, in work machines such as hydraulic excavators and wheel loaders, the working implement has a wide rotation range, and is positioned between the loading target and the work machine. Therefore, depending on the position of the working implement, the forward view of the operator operating the work machine in the cab may be obstructed, making it difficult to see. Depending on the work performed in a situation where visibility is poor, there is a possibility that the machine body or working implement may come into contact with an obstacle around the work machine. Therefore, to avoid such a situation, the work machine is equipped with an obstacle detection sensor, and when the obstacle detection sensor detects an obstacle, control is executed to avoid contact between the obstacle and the work machine.

[0003] For example, the technology for avoiding contact with obstacles disclosed in Patent Document 1 discloses a control that stops the operation of the work device when a detected obstacle is located within a predetermined contact prevention area around the aircraft and the work device is operated in a direction approaching the obstacle. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-23486 Summary of the Invention [Problem to be solved by the invention]

[0005] However, since the contact avoidance technology described in Patent Document 1 constantly detects obstacles over a relatively wide range around the vehicle while the working equipment is being operated, if this device is applied to a wheel loader, there is a risk that the working equipment attached to the front of the vehicle will be erroneously detected as an obstacle and the working equipment will stop if it is operated while traveling. For example, if there is a shutter above and in front of the vehicle and you want to raise the working equipment to a height close to the shutter, or if there are rocks or road structures below and in front of the vehicle and you want to lower the working equipment to a height close to the shutter, the working equipment will not be able to operate.

[0006] Therefore, an object of the present invention is to provide a work vehicle that can accurately detect obstacles that may come into contact with the work equipment while avoiding erroneous detection of the work equipment as an obstacle. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention provides a work vehicle including a vehicle body, a working implement attached to a front portion of the vehicle body, a posture detection device that detects the posture of the working implement, and a controller that controls the operation of the working implement. The work vehicle further includes a first obstacle detection device that is provided on an upper portion of the front portion of the vehicle body and that detects obstacles that are located above and in front of the vehicle body, and a second obstacle detection device that is provided on a lower portion of the front portion of the vehicle body and that detects obstacles that are located below and in front of the vehicle body, and the controller detects whether the posture of the working implement detected by the posture detection device is a horizontal posture that is horizontal with respect to the ground surface of the vehicle body or an upward posture that is higher than the horizontal posture. and when the attitude of the working device detected by the attitude detection device is a downward attitude that is lower than the horizontal attitude, the detection of obstacles by the second obstacle detection device is enabled, and the distance between the detected obstacle and the working device is calculated based on the position of the obstacle included in the detection data of either the first obstacle detection device or the second obstacle detection device that is enabled and the attitude of the working device detected by the attitude detection device, and when the calculated distance is equal to or less than a predetermined distance threshold, operation stop control is executed to stop the operation of the working device. [Effects of the Invention]

[0008] According to the present invention, it is possible to accurately detect obstacles that may come into contact with the working device while avoiding erroneous detection of the working device as an obstacle. Problems, configurations, and effects other than those described above will become clear from the description of the following embodiments. [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. 2 is an enlarged perspective view of a front axle and its surrounding area. [Figure 3] 10A and 10B are diagrams illustrating the operating posture of the working device. [Figure 4] FIG. 2 is a system configuration diagram showing an example of a configuration of a drive system for a work device. [Figure 5] FIG. 2 is a functional block diagram showing functions of a controller. [Figure 6] 10 is a flowchart showing the flow of processing executed by a controller. DETAILED DESCRIPTION OF THE INVENTION

[0010] In the following, 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] <Overall configuration of wheel loader 1> First, the overall 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 exterior side view showing an example of the configuration of a wheel loader 1 according to an embodiment of the present invention. Fig. 2 is an enlarged perspective view showing a front axle 110 and its surrounding area. Fig. 3 is a diagram illustrating the operating posture of the working device 2.

[0013] The wheel loader 1 is an articulated work vehicle that is steered by bending the vehicle body near the center, with 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 connected by a center joint 10 so that the front frame 1A can rotate freely in the left-right direction relative to the rear frame 1B. In the following explanation, within the left-right direction of the vehicle body, the direction to the left relative to the forward direction is referred to as the "left direction," and the direction to the right relative to the forward direction is referred to as the "right direction."

[0014] The vehicle body is provided with four wheels 11, two of which are front wheels 11A and are provided on both the left and right sides of the front frame 1A, and the remaining two are rear wheels 11B and are provided 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 Figures 1 and 3, and only the left and right front wheels 11A are shown in Figure 2.

[0015] A hydraulically driven working device 2 is attached to the front of the front frame 1A to perform loading and unloading operations, such as digging up work objects such as soil and minerals and loading the excavated work objects into a loading destination such as a dump truck or hopper.

[0016] 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 22L, 22R (see FIGS. 3 and 4) as hydraulic cylinders that drive the lift arm 21, a bucket 23 attached to the tip of the lift arm 21 so as to be rotatable in the vertical direction, a bucket cylinder 24 that serves as a hydraulic cylinder that drives the bucket 23, and a bell crank 25 rotatably connected to the lift arm 21 and that forms a link mechanism between the bucket 23 and the bucket cylinder 24.

[0017] The two lift arm cylinders 22L, 22R are arranged side by side at a predetermined distance in the left-right direction of the vehicle body, but are not shown in Figure 1 because they are located in a position hidden by the lift arm 21 and front wheel 11A.

[0018] The lift arm 21 rotates vertically relative to the front frame 1A as two lift arm cylinders 22L, 22R extend and retract. In this embodiment, the lift arm 21 is operated using a lift arm operating lever 121 (see FIG. 4) provided in the cab 12.

[0019] 1, a lift arm angle sensor 30 is attached to the base end of the lift arm 21 (the attachment portion to the front frame 1A) to detect the angle α of the lift arm 21 (hereinafter referred to as "lift arm angle α"). This lift arm angle sensor 30 is one form of a posture detection device that detects the posture of the working device 2 (the height of the lift arm 21).

[0020] For example, as shown in FIG. 3, if the lift arm angle α is 0° (α=0) when the lift arm 21 is in a horizontal position (the position at which the reach of the lift arm 21 rotating relative to the vehicle body is maximum) that is horizontal to the ground contact surface of the vehicle body (the ground surface with which the four wheels 11 are in contact), then when the lift arm 21 is in an upward position that is higher than the horizontal position, the lift arm angle α will be a positive value (α>0), and when the lift arm 21 is in a downward position that is lower than the horizontal position, the lift arm angle α will be a negative value (α<0).

[0021] In addition, the horizontal position in which the lift arm 21 is horizontal to the ground is synonymous with the part at the tip of the lift arm 21 where the bucket 23 is connected by a pin being at approximately the same height as the base end of the lift arm 21, when considered in terms of height based on the contact surface on which the vehicle body is in contact with the ground, and is also synonymous with the height of the bucket 23 being approximately the same as the height of the base end of the lift arm 21.

[0022] Therefore, when the lift arm angle α detected by the lift arm angle sensor 30 is a positive value (α>0), the height position of the lift arm 21 is in the range from the horizontal position βm to the uppermost position (highest position) βu, and the posture of the lift arm 21 is in the upward posture. On the other hand, when the lift arm angle α detected by the lift arm angle sensor 30 is a negative value (α<0), the height position of the lift arm 21 is in the range from the horizontal position βm to the lowermost position (lowest position on the ground) βd, and the posture of the lift arm 21 is in the downward posture.

[0023] In the example of how to determine the lift arm angle α shown in FIG. 3, the lift arm angle α when the height position of the lift arm 21 is at the horizontal position βm (horizontal posture) is used as the reference, but this is not limited to this, and for example, the lift arm angle α when the height position of the lift arm 21 is at the lowest position βd may also be used as the reference.

[0024] Bucket 23 rotates vertically relative to lift arm 21 as bucket cylinder 24 expands and contracts. This allows bucket 23 to scoop up and discharge (dig and release) work objects such as earth and sand or minerals. In this embodiment, bucket 23 is operated using bucket operating lever 122 (see FIG. 4) provided inside cab 12.

[0025] The bucket 23 can be replaced with various attachments, such as a blade, and the wheel loader 1 can perform various tasks such as snow removal and earth-raising in addition to loading and unloading operations using the bucket 23.

[0026] As shown in Fig. 1, 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 that maintains balance with the work implement 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.

[0027] The wheel loader 1, in particular, operates the working implement 2 while traveling to perform work, so there is a possibility that it may come into contact with obstacles such as objects or people around the vehicle body. Therefore, the wheel loader 1 is equipped with a device for detecting obstacles to avoid contact with the obstacles.

[0028] Specifically, the wheel loader 1 is provided with a cab-side obstacle sensor 31 on the front end side of the ceiling 120 of the cab 12 as shown in Figs. 1 and 3, and an axle-side obstacle sensor 32 on the front side of the axial center of the front axle 110 connecting the pair of front wheels 11A as shown in Fig. 2.

[0029] The cab-side obstacle sensor 31 is one aspect of a first obstacle detection device that detects obstacles in front of and above the front of the vehicle body (above the front). In this embodiment, the first obstacle detection device is disposed on the front end side of the ceiling 120 of the cab 12, but this is not limitative and there are no particular restrictions on the installation position as long as it is possible to detect obstacles in the above-forward direction of the vehicle body. However, by disposing the first obstacle detection device on the ceiling 120 of the cab 12 as in this embodiment, it is possible to prevent a situation in which soil, sand, minerals, etc. that have spilled from the bucket 23 collide with the first obstacle detection device.

[0030] The axle-side obstacle sensor 32 is one aspect of a second obstacle detection device that detects obstacles in front of and below the front of the vehicle body (below the front). In this embodiment, the second obstacle detection device is disposed on the front side of the axial center of the front axle 110, but this is not limitative and there are no particular restrictions on the installation position as long as it is possible to detect obstacles in the front below of the vehicle body. However, by disposing the second obstacle detection device in the axial center of the front axle 110 as in this embodiment, the second obstacle detection device can be protected from mud splashes and the like while driving.

[0031] The cab-side obstacle sensor 31 and the axle-side obstacle sensor 32 each use, for example, an imaging device such as a millimeter-wave radar, a LIDAR (Light Detection and Ranging), or a stereo camera.

[0032] <Work device 2 drive system> Next, the drive system of the working device 2 will be described with reference to FIG.

[0033] FIG. 4 is a system configuration diagram showing an example of the configuration of a drive system for the working device 2. As shown in FIG.

[0034] The drive system of the working implement 2 is of a hydraulic drive type and includes a hydraulic pump 40, a lift arm directional control valve 41 provided between the hydraulic pump 40 and the two lift arm cylinders 22L, 22R, a bucket directional control valve 42 provided between the hydraulic pump 40 and the bucket cylinder 24, a first lift arm electromagnetic control valve 41L and a second lift arm electromagnetic control valve 41R that control the lift arm directional control valve 41, and a first bucket electromagnetic control valve 42L and a second bucket electromagnetic control valve 42R that control the bucket directional control valve 42.

[0035] The hydraulic pump 40 is driven by the engine 40A, and pumps up hydraulic oil stored in a hydraulic oil tank 400 and supplies it to each of the two lift arm cylinders 22L, 22R and the bucket cylinder 24. Note that although the hydraulic pump 40 is shown as a variable displacement hydraulic pump in FIG. 4, it does not necessarily have to be a variable displacement type and may be a fixed displacement type.

[0036] The lift arm direction control valve 41 controls the flow (direction and flow rate) of hydraulic oil discharged from the hydraulic pump 40 and guided to each of the two lift arm cylinders 22L, 22R.

[0037] The first lift arm electromagnetic control valve 41L and the second lift arm electromagnetic control valve 41R each control the lift arm directional control valve 41 based on a command signal output from the controller 5.

[0038] When the controller 5 receives an operation command signal related to the lift arm 21 raising operation from the lift arm operation lever 121, it outputs an operation command signal to each of the first lift arm electromagnetic control valve 41L and the second lift arm electromagnetic control valve 41R to raise the lift arm 21. Then, based on the operation command signal output from the controller 5, the first lift arm electromagnetic control valve 41L and the second lift arm electromagnetic control valve 41R each control the operation of the spool of the lift arm directional control valve 41 so as to connect the hydraulic pump 40 to each bottom chamber of the two lift arm cylinders 22L, 22R.

[0039] As a result, the hydraulic oil discharged from the hydraulic pump 40 flows into the bottom chambers of the two lift arm cylinders 22L, 22R, causing the rods 220 to extend and the lift arms 21 to rotate upward relative to the front frame 1A.

[0040] Furthermore, when the controller 5 receives an operation command signal related to the lowering operation of the lift arm 21 from the lift arm operation lever 121, it outputs an operation command signal to each of the first lift arm electromagnetic control valve 41L and the second lift arm electromagnetic control valve 41R to lower the lift arm 21. Then, based on the operation command signal output from the controller 5, the first lift arm electromagnetic control valve 41L and the second lift arm electromagnetic control valve 41R each control the operation of the spool of the lift arm directional control valve 41 so as to connect the hydraulic pump 40 with each rod chamber of the two lift arm cylinders 22L, 22R.

[0041] As a result, the hydraulic oil discharged from the hydraulic pump 40 flows into the rod chambers of the two lift arm cylinders 22L, 22R, causing the rods 220 to contract and the lift arms 21 to rotate downward relative to the front frame 1A.

[0042] The bucket directional control valve 42 controls the flow (direction and flow rate) of hydraulic oil discharged from the hydraulic pump 40 and guided to the bucket cylinder 24 .

[0043] The first bucket electromagnetic control valve 42L and the second bucket electromagnetic control valve 42R each control the bucket directional control valve 42 based on a command signal output from the controller 5.

[0044] When the controller 5 acquires an operation command signal related to the tilt operation (rearward tilt operation) of the bucket 23 from the bucket operation lever 122, it outputs an operation command signal to each of the first bucket electromagnetic control valve 42L and the second bucket electromagnetic control valve 42R to tilt rearward the bucket 23. Then, based on the operation command signal output from the controller 5, the first bucket electromagnetic control valve 42L and the second bucket electromagnetic control valve 42R each control the operation of the spool of the bucket directional control valve 42 so as to connect the hydraulic pump 40 and the bottom chamber of the bucket cylinder 24.

[0045] As a result, the hydraulic oil discharged from the hydraulic pump 40 flows into the bottom chamber of the bucket cylinder 24, the rod 240 extends, and the bucket 23 rotates upward relative to the lift arm 21 and tilts backward (towards the vehicle body).

[0046] Furthermore, when the controller 5 acquires an operation command signal related to the dump operation (forward tilting operation) of the bucket 23 from the bucket operating lever 122, it outputs an operation command signal to each of the first bucket electromagnetic control valve 42L and the second bucket electromagnetic control valve 42R to tilt forward the bucket 23. Then, based on the operation command signal output from the controller 5, the first bucket electromagnetic control valve 42L and the second bucket electromagnetic control valve 42R each control the operation of the spool of the bucket directional control valve 42 so as to connect the hydraulic pump 40 and the rod chamber of the bucket cylinder 24.

[0047] As a result, the hydraulic oil discharged from the hydraulic pump 40 flows into the rod chamber of the bucket cylinder 24, the rod 240 contracts, and the bucket 23 rotates downward relative to the lift arm 21 and tilts forward (towards the front of the vehicle body).

[0048] The lift arm operation lever 121 and the bucket operation lever 122 are one aspect of an operation device for operating the work implement 2, and are provided inside the cab 12. In this embodiment, the lift arm operation lever 121 and the bucket operation lever 122 are provided separately, but this is not limiting and they may also be provided integrally.

[0049] 4, in addition to the lift arm operation lever 121 and the bucket operation lever 122, the controller 5 is also connected to a lift arm angle sensor 30, a cab-side obstacle sensor 31, and an axle-side obstacle sensor 32. The controller 5 executes operation stop control to stop the operation of the working implement 2 based on the obstacle detection data output from each of these sensors.

[0050] In this embodiment, a changeover switch 123 is provided in the cab 12 as a switching device that switches whether or not the controller 5 executes control to stop the operation of the working implement 2. The changeover switch 123 is connected to the controller 5. Note that the switching device does not necessarily have to be a switch type, and there are no particular restrictions on the switching method.

[0051] When the operator switches the selector switch 123 ON, the controller 5 executes control to stop the operation of the working implement 2. On the other hand, when the operator switches the selector switch 123 OFF, the controller 5 does not execute control to stop the operation of the working implement 2, and controls the operation of the working implement 2 based on the operation command signals output from the lift arm operation lever 121 and the bucket operation lever 122, respectively.

[0052] (Controller 5 configuration) Next, the configuration of the controller 5 will be described with reference to FIG.

[0053] FIG. 5 is a functional block diagram showing the functions of the controller 5.

[0054] The controller 5 is configured by interconnecting a CPU, RAM, ROM, HDD, input I / F, and output I / F via a bus. Various operating devices such as the lift arm operation lever 121, bucket operation lever 122, and selector switch 123, as well as various sensors such as the lift arm angle sensor 30, cab-side obstacle sensor 31, and axle-side obstacle sensor 32, are connected to the input I / F, and the first lift arm electromagnetic control valve 41L, second lift arm electromagnetic control valve 41R, first bucket electromagnetic control valve 42L, and second bucket electromagnetic control valve 42R are connected to the output I / F.

[0055] 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 RAM, and executes the expanded control program, whereby the control program and hardware work together to realize the functions of the controller 5.

[0056] In this embodiment, the configuration of the controller 5 is described as a combination of software and hardware, but this is not limiting, and the controller 5 may also be configured using an integrated circuit that realizes the functions of a control program executed on the wheel loader 1 side.

[0057] The controller 5 includes a data acquisition unit 51, an attitude determination unit 52, a detection validity determination unit 53, an approach determination unit 54, a distance calculation unit 55, an operation stop determination unit 56, a memory unit 57, and a command unit 58.

[0058] The data acquisition unit 51 acquires the operation command signals output from the lift arm operation lever 121 and the bucket operation lever 122, the switching signals (ON signal and OFF signal) output from the changeover switch 123, the lift arm angle α detected by the lift arm angle sensor 30, and the obstacle data detected by the cab side obstacle sensor 31 and the axle side obstacle sensor 32.

[0059] The attitude determination unit 52 determines whether the lift arm angle α acquired by the data acquisition unit 51 is equal to or greater than the angle threshold αth that indicates the horizontal attitude of the working device 2. Specifically, the angle threshold αth is the lift arm angle α when the lift arm 21 is located at the horizontal position βm shown in Fig. 3. In the example of how to determine the lift arm angle α shown in Fig. 3, the angle threshold αth is 0°.

[0060] When the posture determination unit 52 determines that the lift arm angle α is equal to or greater than the angle threshold value αth (α≧αth, α≧0 in the example shown in FIG. 3), that is, when the working implement 2 is in the upward posture, the detection validity determination unit 53 validates the detection of an obstacle by the cab-side obstacle sensor 31. More specifically, when the working implement 2 is in the upward posture, when issuing a command to stop the operation of the working implement 2, the controller 5 uses the detection data of the obstacle detected by the cab-side obstacle sensor 31 and does not use the detection data of the obstacle detected by the axle-side obstacle sensor 32.

[0061] Furthermore, when the posture determination unit 52 determines that the lift arm angle α is smaller than the angle threshold value αth (α<αth, α<0 in the example shown in FIG. 3), that is, when the working implement 2 is in a downward posture, the detection validity determination unit 53 validates the detection of an obstacle by the axle-side obstacle sensor 32. More specifically, when the working implement 2 is in a downward posture, when issuing a command to stop the operation of the working implement 2, the controller 5 uses the detection data of the obstacle detected by the axle-side obstacle sensor 32 and does not use the detection data of the obstacle detected by the cab-side obstacle sensor 31.

[0062] The approach determination unit 54 determines whether the working implement 2 is operating in a direction approaching the detected obstacle. Specifically, when the attitude determination unit 52 determines that the working implement 2 is in an upward attitude and the cab-side obstacle sensor 31 detects an obstacle, the approach determination unit 54 determines whether at least one of the lift arm 21 raising operation and the bucket 23 tilt operation (rearward tilt operation) is being performed.

[0063] In addition, when the attitude determination unit 52 determines that the working implement 2 is in a downward attitude and the axle side obstacle sensor 32 detects an obstacle, the approach determination unit 54 determines whether at least one of the operations of lowering the lift arm 21 and dumping (forward tilting) the bucket 23 is being performed.

[0064] The distance calculation unit 55 calculates the distance L between the obstacle and the working implement 2 based on the position of the obstacle detected by the cab-side obstacle sensor 31 or the axle-side obstacle sensor 32 and the lift arm angle α detected by the lift arm angle sensor 30.

[0065] In this embodiment, the distance calculation unit 55 calculates the distance L between the obstacle and the working device 2 when the approach determination unit 54 determines that the working device 2 is moving in a direction approaching the obstacle.

[0066] The operation stop determination unit 56 determines whether the distance L calculated by the distance calculation unit 55 is equal to or less than a predetermined distance threshold Lth. This "predetermined distance threshold Lth" corresponds to an allowable stop range set in consideration of the delay time that occurs from when the command unit 58 of the controller 5 stops outputting operation command signals to the electromagnetic control valves 41L, 41R, 42L, and 42R until the extension and contraction of the rods 220 of the two lift arm cylinders 22L and 22R and the extension and contraction of the rod 240 of the bucket cylinder 24 each stops (the operation of the working device 2 stops), and is, for example, about 0.5 m.

[0067] The storage unit 57 stores an angle threshold αth that indicates the horizontal attitude of the working device 2 and a predetermined distance threshold Lth that corresponds to the allowable range within which the working device 2 can be stopped.

[0068] As described above, under normal circumstances (when no obstacle is detected and there is no need to automatically stop the operation of the work implement 2 through the operation stop control of the controller 5), the command unit 58 outputs operation command signals to each of the electromagnetic control valves 41L, 41R, 42L, and 42R based on the operation command signals output from each of the lift arm operation lever 121 and the bucket operation lever 122 acquired by the data acquisition unit 51.

[0069] As a result, the rods 220 of the two lift arm cylinders 22L and 22R are driven in accordance with the operation of the lift arm operation lever 121, and the rod 240 of the bucket cylinder 24 is driven in accordance with the operation of the bucket operation lever 122.

[0070] On the other hand, when the operation stop determination unit 56 determines that the distance L between the obstacle and the working device 2 is less than or equal to a predetermined distance threshold Lth (L≦Lth), the command unit 58 stops outputting operation command signals to each electromagnetic control valve 41L, 41R, 42L, 42R.

[0071] As a result, the operation of each of the rods 220 of the two lift arm cylinders 22L, 22R and the operation of the rod 240 of the bucket cylinder 24 are stopped, and the operation of the working device 2 is stopped.

[0072] In this embodiment, when the approach determination unit 54 determines that the working device 2 is operating in a direction approaching an obstacle and the operation stop determination unit 56 determines that the distance L between the obstacle and the working device 2 is less than or equal to a predetermined distance threshold Lth (L≦Lth), the command unit 58 stops outputting operation command signals to each of the electromagnetic control valves 41L, 41R, 42L, and 42R.

[0073] In addition, in this embodiment, the command unit 58 stops outputting operation command signals to each electromagnetic control valve 41L, 41R, 42L, 42R, and outputs an alarm signal to the alarm device 124 to alert the approach (possibility of contact) of an obstacle and the working device 2.

[0074] The alarm device 124 is provided inside the cab 12, and when it receives an alarm signal from the controller 5, it alerts the operator by, for example, voice or alarm sound that an obstacle is approaching the work implement 2. It should be noted that the wheel loader 1 does not necessarily have to be equipped with the alarm device 124.

[0075] (Processing executed by controller 5) Next, the flow of processing executed by the controller 5 will be described with reference to FIG.

[0076] FIG. 6 is a flowchart showing the flow of processing executed by the controller 5.

[0077] First, when the data acquisition unit 51 acquires an ON signal from the changeover switch 123 (step S501 / YES), the controller 5 proceeds to processing from step S502 onwards and executes operation stop control to stop the operation of the working device 2 (step S509).

[0078] On the other hand, if the data acquisition unit 51 does not acquire an ON signal from the changeover switch 123, i.e., if it acquires an OFF signal (step S501 / NO), the controller 5 ends the process without proceeding to step S502 and subsequent steps.

[0079] In step S501, when the data acquiring unit 51 acquires an ON signal from the changeover switch 123 (step S501 / YES), the data acquiring unit 51 subsequently acquires the lift arm angle α output from the lift arm angle sensor 30 (step S502).

[0080] Next, the attitude determination unit 52 determines whether or not the lift arm angle α acquired in step S502 is equal to or greater than the angle threshold value αth (step S503).

[0081] If it is determined in step S503 that the lift arm angle α is equal to or greater than the angle threshold value αth (α≧αth), that is, if the working implement 2 is in a horizontal or upward position (step S503 / YES), the detection validity determination unit 53 enables the detection of an obstacle by the cab-side obstacle sensor 31 (step S504).

[0082] Next, when the data acquisition unit 51 acquires obstacle detection data from the cab-side obstacle sensor 31 (step S505 / YES), the approach determination unit 54 determines whether the lift arm 21 is being raised or the bucket 23 is being tilted, based on the operation command signals from the lift arm operation lever 121 and the bucket operation lever 122 acquired by the data acquisition unit 51 (step S506).

[0083] In step S506, if it is determined that at least one of the lifting operation of the lift arm 21 and the tilting operation of the bucket 23 is being performed (step S506 / YES), the distance calculation unit 55 calculates the distance L between the obstacle and the bucket 23 (working device 2) based on the position of the obstacle acquired by the data acquisition unit 51 (included in the obstacle detection data output from the cab-side obstacle sensor 31) and the lift arm angle α (corresponding to the position of the bucket 23) acquired by the data acquisition unit 51 (step S507).

[0084] Next, the operation stop determination unit 56 determines whether the distance L calculated in step S507 is equal to or less than a predetermined distance threshold Lth (step S508).

[0085] If it is determined in step S508 that the distance L is less than or equal to the predetermined distance threshold Lth (L≦Lth) (step S508 / YES), the command unit 58 stops outputting operation command signals to each electromagnetic control valve 41L, 41R, 42L, 42R (step S509), and the operation stop control in the controller 5 ends.

[0086] In this embodiment, in step S509, the command unit 58 stops outputting operation command signals to the electromagnetic control valves 41L, 41R, 42L, and 42R, and outputs an alarm signal to the alarm device 124 to notify the approach of an obstacle to the working device 2. This allows the operator to know in advance that the operation of the working device 2 will automatically stop under the control of the controller 5.

[0087] Furthermore, if it is determined in step S503 that the lift arm angle α is smaller than the angle threshold value αth (α<αth), that is, if the working implement 2 is in a downward posture (step S503 / NO), the detection validity determination unit 53 enables the detection of an obstacle by the axle-side obstacle sensor 32 (step S510).

[0088] Next, when the data acquisition unit 51 acquires obstacle detection data from the axle-side obstacle sensor 32 (step S511 / YES), the approach determination unit 54 determines whether or not a lowering operation of the lift arm 21 or a dumping operation of the bucket 23 is being performed, based on the operation command signals from the lift arm operation lever 121 and the bucket operation lever 122 acquired by the data acquisition unit 51 (step S512).

[0089] In step S512, if it is determined that at least one of the operations of lowering the lift arm 21 and dumping the bucket 23 is being performed (step S512 / YES), the process proceeds to step S507 and subsequent steps, as in the case of step S506 / YES.

[0090] In step S505, if the data acquisition unit 51 does not acquire obstacle detection data from the cab-side obstacle sensor 31 (step S505 / NO), if it is determined in step S506 that neither the lift arm 21 raising operation nor the bucket 23 tilt operation has been performed (step S506 / NO), if it is determined in step S508 that the distance L is greater than a predetermined distance threshold Lth (L>Lth) (step S508 / NO), if the data acquisition unit 51 does not acquire obstacle detection data from the axle-side obstacle sensor 32 in step S511 (step S511 / NO), or if it is determined in step S512 that neither the lift arm 21 lowering operation nor the bucket 23 dump operation has been performed (step S512 / NO), the operation stop control in the controller 5 is terminated in all of the following cases.

[0091] Here, when the working implement 2 is in a horizontal or upward position, the position of the cab-side obstacle sensor 31 is closer to the working implement 2 than the position of the axle-side obstacle sensor 32, so the cab-side obstacle sensor 31 is less likely to erroneously detect the working implement 2 as an obstacle. Conversely, when the working implement 2 is in a downward position, the position of the axle-side obstacle sensor 32 is closer to the working implement 2 than the position of the cab-side obstacle sensor 31, so the axle-side obstacle sensor 32 is less likely to erroneously detect the working implement 2 as an obstacle.

[0092] Therefore, the controller 5 uses detection data of an obstacle detected by the cab-side obstacle sensor 31 located on the side closer to the working implement 2 when the working implement 2 is in a horizontal or upward position, and when the working implement 2 is in a downward position, uses detection data of an obstacle detected by the axle-side obstacle sensor 32 located on the side closer to the working implement 2 in a downward position. This makes it possible to avoid using detection data that erroneously detects the working implement 2 as an obstacle, while executing operation stop control of the working implement 2 using detection data of an obstacle that is accurately detected, and to prevent contact between the working implement 2 and an obstacle.

[0093] Furthermore, in this embodiment, the controller 5 performs control to stop the operation of the work device 2 only when it determines that the work device 2 is operating in a direction approaching an obstacle and that the distance L between the obstacle and the work device 2 is less than or equal to a predetermined distance threshold Lth (L≦Lth), that is, when there is a high possibility that the work device 2 will come into contact with the obstacle, so the operation of the work device 2 is not stopped unnecessarily. This allows the wheel loader 1 to avoid contact between the work device 2 and an obstacle without reducing workability.

[0094] In addition, when executing the operation stop control of the working device 2, the controller 5 does not necessarily need to determine whether the working device 2 is moving in a direction approaching an obstacle, i.e., it does not need to include an approach determination unit 54, and may uniformly execute the operation stop control of the working device 2 when it is determined that the distance L between the obstacle and the working device 2 is equal to or less than a predetermined distance threshold Lth (L≦Lth).

[0095] Furthermore, in this embodiment, a selector switch 123 is provided inside the cab 12, so the operator can freely select whether or not to execute operation stop control of the work implement 2 by the controller 5 by switching the selector switch 123. It should be noted that the wheel loader 1 does not necessarily have to be equipped with the selector switch 123.

[0096] The above describes an embodiment of the present invention. However, the present invention is not limited to the above embodiment and includes various other modifications. For example, the above embodiment has been described in detail to clearly explain the present invention, and is not necessarily limited to having all of the described configurations. Furthermore, it is possible to replace part of the configuration of the above embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of the above embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of the above embodiment with other configurations.

[0097] For example, in the above embodiment, a 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 applied to other work vehicles as long as they are equipped with a work implement 2. [Explanation of symbols]

[0098] 1: Wheel loader 1A: Front frame (body, front part) 1B: Rear frame (body) 2: Work equipment 5: Controller 11A: Front wheel 12: Cab 30: Lift arm angle sensor (posture detection device) 31: Cab-side obstacle sensor (first obstacle detection device) 32: Axle-side obstacle sensor (second obstacle detection device) 110: Axle 120: Ceiling 121: Lift arm operating lever (operating device) 122: Bucket operation lever (operation device) 123: Changeover switch (switching device) 124: Alarm device L: distance Lth: a predetermined distance threshold

Claims

1. The car body and a working device attached to the front of the vehicle body; an attitude detection device that detects the attitude of the working device; a controller for controlling the operation of the working device; In a work vehicle equipped with a first obstacle detection device provided on an upper portion of the front part of the vehicle body and configured to detect an obstacle present above and in front of the vehicle body; a second obstacle detection device provided in a lower portion of the front part of the vehicle body and configured to detect an obstacle present in front of and below the vehicle body; and The controller when the attitude of the working implement detected by the attitude detection device is a horizontal attitude that is horizontal with respect to the ground surface of the vehicle body or an upward attitude that is higher than the horizontal attitude, detecting an obstacle by the first obstacle detection device is enabled; when the attitude of the working implement detected by the attitude detection device is a downward attitude that is lower than the horizontal attitude, detecting an obstacle by the second obstacle detection device is enabled; calculating a distance between the detected obstacle and the working device based on the position of the obstacle included in the valid detection data of either the first obstacle detection device or the second obstacle detection device and the attitude of the working device detected by the attitude detection device; When the calculated distance is equal to or less than a predetermined distance threshold, an operation stop control is executed to stop the operation of the working device. A work vehicle characterized by:

2. The work vehicle according to claim 1, The first obstacle detection device is The vehicle body is provided with a cab ceiling portion on a front end side thereof. The second obstacle detection device is The axle is disposed in front of the center of the axial direction of the axle connecting the pair of front wheels provided at the front part of the vehicle body. A work vehicle characterized by:

3. The work vehicle according to claim 1, further comprising an operating device for operating the working device, The controller when the detection of an obstacle by the first obstacle detection device is enabled, an operation signal related to an upward operation of the working device is acquired from the operation device, and when the calculated distance is equal to or less than the predetermined distance threshold, the operation stop control is executed; When the detection of an obstacle by the second obstacle detection device is enabled, an operation signal related to a downward movement of the working device is acquired from the operation device, and when the calculated distance is equal to or less than the predetermined distance threshold, the operation stop control is executed. A work vehicle characterized by:

4. The work vehicle according to claim 1, The device further includes a switching device for switching whether or not the controller executes the operation stop control. A work vehicle characterized by:

5. The work vehicle according to claim 1, Further provided is an alarm device that notifies the approach of an obstacle to the working device, The controller When the calculated distance is equal to or less than the distance threshold, a notification signal for notifying the approach of the obstacle and the working device is output to the notification device, and the operation stop control is executed. A work vehicle characterized by:

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