Working machine and control method for working machine

Abstract

To provide a work machine capable of maintaining an angle of an attachment even in an inclined state.SOLUTION: A wheel loader 1 includes a vehicle body 2, a work machine 3, a ground bucket angle detection unit 20, and a control unit 9. The work machine 3 operates with respect to the vehicle body 2, and includes a bucket 15 or a fork 19. The ground bucket angle detection unit 20 detects information regarding an inclination angle with respect to the gravity direction of an attachment. The control unit 9 controls the inclination angle with respect to a gravity direction G of the bucket 15 or the fork 19 based on the detection value of the ground bucket angle detection unit 20.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a working machine and a control method for a working machine.

Background Art

[0002] A wheel loader is responsible for the dumping operation, raises the bucket by lifting the boom, and loads earth and sand by rotating the bucket.

[0003] In the loaded state, it is desirable to maintain the angle of the bucket with respect to the ground when the boom is raised in order to prevent the load from falling. However, since the boom is a rotating link, the angle of the bucket changes structurally when the boom is raised. Therefore, parallel link control is performed to operate the bucket angle corresponding to the boom operation so as to maintain the bucket angle.

[0004] In addition, some wheel loaders can be equipped with forks instead of a bucket in order to perform forklift work. Even in that case, parallel link control is performed to maintain the angle of the forks (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the working machine of Patent Document 1, since parallel link control is performed based on the vehicle body reference, the angle of the bucket may not be maintained when the boom is raised in a state where the vehicle body is placed on an inclined ground.

[0007] An object of the present disclosure is to provide a working machine and a control method for the working machine capable of maintaining the angle of an attachment even in an inclined state.

Means for Solving the Problems

[0008] The working machine according to the first aspect includes a main body, a working implement, an attachment inclination angle detection unit, and a control unit. The working implement operates with respect to the main body and has an attachment. The attachment inclination angle detection unit detects the inclination angle of the attachment with respect to the direction of gravity. The control unit controls the inclination angle of the attachment with respect to the direction of gravity based on the detection value of the attachment inclination angle detection unit.

[0009] The control method for a working machine according to the second aspect is a control method for a working machine including a main body and a working implement that operates with respect to the main body and has an attachment, and includes an attachment inclination angle detection step and a control step. The attachment inclination angle detection step detects the inclination angle of the attachment with respect to the direction of gravity. The control step controls the inclination angle of the attachment with respect to the direction of gravity based on the detection value in the attachment inclination angle detection step.

Effects of the Invention

[0010] According to the present disclosure, it is possible to provide a working machine and a control method for the working machine capable of maintaining the angle of an attachment even in an inclined state.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0012] A wheel loader as an example of a working machine according to the present disclosure will be described below with reference to the drawings.

[0013] (Embodiment 1) The wheel loader according to Embodiment 1 below will be described. <Configuration> (Outline of Wheel Loader) FIG. 1 is a schematic diagram showing the configuration of a wheel loader 1 according to the present embodiment.

[0014] The wheel loader 1 (an example of a working machine) according to the present embodiment includes a vehicle body 2 (an example of a main body) and a working machine 3. The vehicle body 2 includes a vehicle body frame 10, a pair of front tires 4, a cab 5, an engine room 6, a pair of rear tires 7, a pair of steering cylinders 8, a control unit 9 (see FIG. 6), a ground bucket angle detection unit 20 (an example of an attachment inclination angle detection unit) (see FIG. 6), and an operation unit 50 (see FIG. 6).

[0015] The wheel loader 1 performs operations such as earthmoving work using the work implement 3.

[0016] The vehicle body frame 10 is of a so-called articulated type and has a front frame 11, a rear frame 12, and a connecting shaft portion 13. The front frame 11 is disposed in front of the rear frame 12. The connecting shaft portion 13 is provided at the center in the vehicle width direction and connects the front frame 11 and the rear frame 12 so as to be swingable relative to each other.

[0017] The pair of steering cylinders 8 are driven by hydraulic pressure. The pair of steering cylinders 8 are arranged side by side on the left and right sides in the vehicle width direction with the connecting shaft portion 13 interposed therebetween. One end of each steering cylinder 8 is attached to the front frame 11, and the other end of each is attached to the rear frame 12.

[0018] The cab 5 is provided on the rear frame 12 and the driver's seat is arranged therein. The engine room 6 is disposed behind the cab 5 and houses the engine and the like.

[0019] The pair of front tires 4 are attached to the left and right of the front frame 11. Also, the pair of rear tires 7 are attached to the left and right of the rear frame 12.

[0020] The work implement 3 is driven by hydraulic oil from a work implement pump. The ground bucket angle detection unit 20 detects information regarding the inclination angle of the bucket 15 of the work implement 3 with respect to the gravitational direction G and sends the detected value to the control unit 9. The control unit 9 performs ground control (described later) of the bucket 15 based on the detected value and the information. The operation unit 50 is set by the operator to execute the ground control.

[0021] (Work implement 3) FIG. 2 is an enlarged side view of the work implement 3.

[0022] The work machine 3 includes a boom 14, a bucket 15 (an example of an attachment), a boom cylinder 16, a bucket cylinder 17, and a bell crank 18.

[0023] One attachment portion 14a of the boom 14 is rotatably attached to the front portion of the front frame 11. The other attachment portion 14b of the boom 14 is rotatably attached to the rear portion of the bucket 15. The tip of the cylinder rod 16a of the boom cylinder 16 is rotatably attached to an attachment portion 14c provided between the attachment portion 14a and the attachment portion 14b of the boom 14. The cylinder body of the boom cylinder 16 is rotatably attached to the front frame 11 at the attachment portion 16b.

[0024] The bell crank 18 includes a bell crank main body 18e and a rod 18f. An attachment portion 18a provided at one end of the bell crank main body 18e is rotatably attached to the tip of the cylinder rod 17a of the bucket cylinder 17. One end of the rod 18f is rotatably attached to an attachment portion 18b provided at the other end of the bell crank main body 18e. The other end of the rod 18f is rotatably attached to the rear portion of the bucket 15 at the attachment portion 18g. The bell crank main body 18e is rotatably supported by a bell crank support 14d near the center of the boom 14 at an attachment portion 18c provided between the attachment portion 18a and the attachment portion 18b. The cylinder body of the bucket cylinder 17 is rotatably attached to the front frame 11 at the attachment portion 17b. The expansion and contraction force of the bucket cylinder 17 is converted into rotational motion by the bell crank 18 and transmitted to the bucket 15.

[0025] By the expansion and contraction of the bucket cylinder 17, the bucket 15 rotates with respect to the boom 14 to perform a tilt operation (see arrow J) and a dump operation (see arrow K). The bucket 15 has a bottom surface 15a. The bottom surface 15a extends forward from below the attachment portion 14b. Further, a claw 15c is disposed at the tip of the bottom surface 15a. Here, the tilt operation of the bucket 15 means an operation in which the opening 15b and the claw 15c of the bucket 15 rotate toward the cab 5 to tilt. The dump operation of the bucket 15 is opposite to the tilt operation, and means an operation in which the opening 15b and the claw 15c of the bucket 15 rotate away from the cab 5 to tilt.

[0026] In the wheel loader 1 of the present embodiment, as shown in FIG. 3, when the boom 14 is moved up and down by operating the operation lever in the cab 5, control (ground control) can be performed so that the bucket 15 maintains a predetermined tilt angle θe with respect to the gravitational direction G. In FIG. 3, the buckets 15 in the upper position and the lower position are indicated by two-dot chain lines. The tilt angle (ground angle) of the bucket 15 with respect to the gravitational direction G is, for example, the angle formed by the claw 15c and the gravitational direction G, which is 90 degrees in FIG. 3, and the claw 15c faces the horizontal direction.

[0027] In FIG. 3, the wheel loader 1 is arranged on a horizontal road surface R. However, as shown in FIG. 4, even when the wheel loader 1 of the present embodiment is arranged on an inclined road surface R, when the boom 14 is moved up and down, ground control can be performed so that the bucket 15 maintains a predetermined tilt angle with respect to the gravitational direction G.

[0028] Also, as shown in FIG. 5, a fork 19 can be attached to the wheel loader 1 instead of the bucket 15. The fork 19 is attached to the attachment portion 14b and the attachment portion 18g shown in FIG. 2. As shown in FIG. 5, even when the boom 14 is moved up and down in an inclined state, the fork 19 can be maintained horizontal (in a state inclined 90 degrees with respect to the gravitational direction G (tilt angle θe = 90°)).

[0029] (Ground Bucket Angle Detection Unit 20) FIG. 6 is a block diagram showing the control configuration of the wheel loader 1 of the present embodiment. The ground bucket angle detection unit 20 includes a relative position detection unit 25, a vehicle body tilt angle sensor 23 (an example of a main body tilt angle detection unit), and an articulation angle sensor 24 (an example of a rotation angle detection unit).

[0030] The relative position detection unit 25 detects information regarding the relative position of the bucket 15 with respect to the vehicle body 2 and transmits the detected value to the control unit 9.

[0031] The relative position detection unit 25 includes a boom angle sensor 21 (an example of a boom angle detection unit) and a bell crank angle sensor 22 (an example of an attachment angle detection unit).

[0032] The boom angle sensor 21 is provided at the attachment portion 14a of the boom 14. As the boom angle sensor 21, for example, a potentiometer can be used. The boom angle sensor 21 detects the boom angle (indicated by θa in the figure) between the center line L1 of the boom 14 and the horizontal line H as a voltage value and outputs the detected detection voltage. The center line L1 of the boom 14 is a line connecting the attachment portion 14a and the attachment portion 14b of the boom 14. The boom angle becomes a negative value when the center line L1 is inclined toward the road surface R (see FIG. 1) side with respect to the horizontal line H. Note that the detection voltage corresponds to an example of information regarding the inclination angle, information regarding the relative position, and information regarding the rotation angle of the boom. Further, the boom angle sensor 21 may detect the cylinder length of the boom cylinder 16, and the rotation angle of the boom 14 can be calculated from the cylinder length.

[0033] The crank angle sensor 22 is provided at the mounting portion 18c of the crank 18. As the crank angle sensor 22, for example, a potentiometer can be used. The crank angle sensor 22 detects the crank angle (indicated as θb in the figure) between the line L2 connecting the mounting portions 18a and 18c of the crank 18 and the center line L1 of the boom 14 as a voltage value, and outputs the detected detection voltage. Note that the detection voltage corresponds to an example of information regarding the inclination angle, information regarding the relative position, and information regarding the rotation angle of the attachment. Further, the crank angle sensor 22 may detect the cylinder length of the bucket cylinder 17, and the rotation angle of the crank 18 can be calculated from the cylinder length.

[0034] The vehicle body inclination angle sensor 23 can use, for example, an IMU (inertial measurement unit). The vehicle body inclination angle sensor 23 detects the inclination angle of the vehicle body 2 with respect to the gravitational direction G, and outputs the detected inclination angle (an example of information regarding the inclination angle). The vehicle body inclination angle sensor 23 may be disposed on either the rear frame 12 or the front frame 11, but it is preferably provided on the front frame 11 because it is not necessary to correct the inclination angle error (described later) during the articulation operation in the inclined state.

[0035] The articulation angle sensor 24 detects the rotation angle of the front frame 11 with respect to the rear frame 12, and outputs the rotation angle (an example of information regarding the inclination angle). As the articulation angle sensor 24, a potentiometer can be used, but the cylinder lengths of the pair of steering cylinders 8 may be detected. The articulation angle can be detected from the cylinder lengths of the steering cylinders 8.

[0036] (Operation unit 50) The operation unit 50 is provided inside the cab 5. As shown in FIG. 6, the operation unit 50 includes a ground control setting unit 51 and a target value setting unit 52. The ground control setting unit 51 performs setting and cancellation of ground control. For example, it is a button or the like displayed on a liquid crystal panel. When the operator selects the execution button, the ground control is executed, and when the cancellation button is selected, the ground control is cancelled. The target value setting unit 52 sets the inclination angle of the bucket 15 with respect to the gravitational direction G during ground control. The target value setting unit 52 may be, for example, a numeric keypad or the like displayed on the liquid crystal panel.

[0037] (Control unit 9) The control unit 9 includes a processor and a storage device. The processor is, for example, a CPU (Central Processing Unit). Alternatively, the processor may be a processor different from the CPU. The processor executes processing for controlling the wheel loader 1 according to a program. The storage device includes a non-volatile memory such as a ROM (Read Only Memory) and a volatile memory such as a RAM (Random Access Memory). The storage device may include an auxiliary storage device such as a hard disk or an SSD (Solid State Drive). The storage device is an example of a non-transitory computer-readable recording medium. The storage device stores a program and data for controlling the wheel loader 1.

[0038] The detection value of the boom angle sensor 21, the detection value of the bell crank angle sensor 22, the detection value of the vehicle body inclination angle sensor 23, and the detection value of the articulation angle sensor 24 are input to the control unit 9. The control unit 9 has the functions of the following units by executing a program while using the input detection values and the data stored in the storage device.

[0039] The control unit 9 includes a vehicle body-to-bucket angle calculation unit 31, a ground-to-bucket angle calculation unit 32, a vehicle body / ground control determination unit 33, and a bucket control amount determination unit 34.

[0040] (Vehicle body bucket angle calculation unit 31) The vehicle body bucket angle calculation unit 31 calculates the vehicle body bucket angle, which is the angle of the bucket 15 with respect to the vehicle body 2, based on the detected value of the boom angle sensor 21 and the detected value of the bell crank angle sensor 22. The vehicle body bucket angle is the angle of the bucket 15 when the vehicle body 2 is used as a reference.

[0041] Since the posture of the working machine 3 is determined by the detected value of the boom angle sensor 21 and the detected value of the bell crank angle sensor 22, the relative position of the bucket 15 with respect to the vehicle body 2 can be detected. Therefore, the vehicle body bucket angle of the bucket 15 can be obtained by using the detected value of the boom angle sensor 21 and the detected value of the bell crank angle sensor 22.

[0042] The vehicle body bucket angle can be set by setting the angle of the bucket 15 with respect to the vehicle body 2. For example, it can be set as the angle θc formed by a line parallel to the line connecting two points of the vehicle body frame (preferably the front frame 11) and the claw 15c of the bucket 15. Note that as the two points, a part with high vehicle body rigidity is desirable, and for example, the boom mounting part can be cited as one point.

[0043] (Ground bucket angle calculation unit 32) The ground bucket angle calculation unit 32 calculates the ground bucket angle, which is the angle of the bucket 15 with respect to the gravitational direction G, based on the vehicle body bucket angle calculated by the vehicle body bucket angle calculation unit 31, the detected value of the vehicle body tilt angle sensor 23, and the detected value of the articulation angle sensor 24.

[0044] Here, when the wheel loader 1 is arranged along an inclined surface and the front frame 11 is arranged linearly with respect to the rear frame 12, the inclination angle (ground-facing bucket angle) of the bucket 15 with respect to the gravitational direction G can be calculated from the detected values of the vehicle body bucket angle and the vehicle body inclination angle sensor 23. For example, taking the inclination angle θd (see FIG. 4) and the vehicle body bucket angle as θc (see FIG. 3), since the inclination angle of the claw 15c of the bucket 15 with respect to the horizontal direction can be calculated by θd + θc, the ground-facing bucket angle, which is the inclination angle with respect to the gravitational direction G, can be calculated by θd + θc + 90 degrees.

[0045] In addition, when the wheel loader 1 is arranged on an inclined surface and the front frame 11 is rotating with respect to the rear frame 12, if the vehicle body inclination angle sensor 23 is arranged on the rear frame 12, the inclination angles with respect to the gravitational direction G of the front frame 11 and the rear frame 12 are different. That is, when the rear frame 12 is along the inclination, the inclination angle of the rotating front frame 11 with respect to the gravitational direction G may be smaller than the inclination angle of the rear frame 12 with respect to the gravitational direction G. Therefore, by using the detected value by the articulation angle sensor 24 to correct the detected value of the vehicle body inclination angle sensor 23, the ground-facing bucket angle can be calculated more accurately.

[0046] (Vehicle Body / Ground Control Determination Unit 33) The vehicle body / ground control determination unit 33 determines whether to perform ground control or vehicle body control. The target value set by the operator in the target value setting unit 52 is input to the vehicle body / ground control determination unit 33.

[0047] FIGS. 7(a) to 7(c) are diagrams for explaining vehicle body control and ground control.

[0048] As shown in FIG. 7(a), in a state where the wheel loader 1 is arranged on a horizontal plane, the rotation angle of the bucket 15 is set to an angle such that the claw 15c is arranged horizontally.

[0049] The ground control is to perform control so that the bucket 15 maintains a desired angle with respect to the gravitational direction G, and the bucket 15 can be maintained at a desired angle with respect to the gravitational direction G regardless of the inclination of the ground where the wheel loader 1 is disposed. For this reason, as shown in FIG. 7(b), even when the wheel loader 1 is disposed on an inclined surface and the boom 14 rotates upward, the bottom surface 15a of the bucket 15 maintains a constant angle with respect to the gravitational direction G. In the example shown in FIG. 7(b), the constant angle is the angle at which the bottom surface 15a of the bucket 15 is parallel to the horizontal plane. Also, the angle of the bucket 15 with respect to the gravitational direction G does not necessarily have to be determined based on the bottom surface 15a, and may be based on any configuration that forms a line segment or vector in the bucket 15.

[0050] On the other hand, the vehicle body control is to perform control so that the bucket 15 maintains a desired angle with respect to the vehicle body 2, and the angle of the bucket 15 with respect to the vehicle body 2 can be maintained constant. However, as shown in FIG. 7(c), when the boom 14 is rotated due to the inclination of the ground where the wheel loader 1 is disposed, the angle with respect to the gravitational direction G changes. For this reason, in FIG. 7(c), the bucket 15 is disposed at an angle at which the claw 15c faces upward from the horizontal.

[0051] The vehicle body / ground control determination unit 33 executes ground control when the posture of the working machine 3 for setting the ground bucket angle of the bucket 15 to the target value is outside the movable limit or moves away from the movable limit. Further, the vehicle body / ground control determination unit 33 does not execute ground control and executes vehicle body control when the posture of the working machine 3 for setting the ground bucket angle of the bucket 15 to the target value is within the movable limit or approaches the movable limit.

[0052] Information regarding the movable limit of the posture of the working machine 3 is stored in the control unit 9. As information regarding the movable limit, the control unit 9 stores, for example, the rotatable range of the boom 14 and the rotatable range of the bell crank 18 at each rotation angle of the boom 14.

[0053] When the operating lever is operated and the rotation angle of the boom 14 changes, the vehicle body / ground control determination unit 33 calculates the rotation angle of the bell crank 18 for maintaining the ground bucket angle of the bucket 15 at the target value. Then, it is determined whether or not the calculated rotation angle of the bell crank 18 is within the movable range at the target rotation angle of the boom 14. If it is within the movable range, ground control is executed, and if it is outside the movable range, vehicle body control is executed. In this way, the vehicle body / ground control determination unit 33 switches between vehicle body control and ground control.

[0054] Note that even after switching to vehicle body control, if the posture of the working machine 3 is outside the movable limit or moves away from the movable limit, the vehicle body / ground control determination unit 33 can switch back to ground control again.

[0055] (Bucket control amount determination unit 34) When executing ground control, the bucket control amount determination unit 34 obtains the difference between the ground bucket angle calculated by the ground bucket angle calculation unit 32 and the target value, and determines the control amount of the bucket cylinder 17 so that the ground bucket angle becomes the target value. Thereby, when the boom 14 is moved up and down, the control amount can be determined so as to maintain the angle of the bucket 15 with respect to the gravity direction G at a desired angle.

[0056] On the other hand, when executing vehicle body control, the bucket control amount determination unit 34 determines the control amount of the bucket cylinder 17 so as to maintain the vehicle body bucket angle calculated by the vehicle body bucket angle calculation unit 31. Thereby, when the boom 14 is moved up and down, the control amount can be determined so as to maintain the angle of the bucket 15 with respect to the vehicle body 2 at a desired angle.

[0057] Based on the control amount determined by the bucket control amount determination unit 34, the bucket cylinder 17 is controlled.

[0058] <Operation> Next, the operation of the wheel loader 1 according to the embodiment of the present invention will be described, and the control method of the working machine will also be described simultaneously.

[0059] First, in step S10, the operator sets the ground control. The operator sets to perform the ground control by means of the operation unit in the cab 5.

[0060] Next, in step S20, the target value of the ground bucket angle set by the operator is input to the control unit 9.

[0061] Next, in step S30, the vehicle body bucket angle calculation unit 31 calculates the angle of the bucket 15 with respect to the vehicle body 2 (vehicle body bucket angle) based on the detection value of the boom angle sensor 21 and the detection value of the bell crank angle sensor 22.

[0062] Next, in step S40 (an example of the attachment tilt angle detection step), the ground bucket angle calculation unit 32 calculates the angle of the bucket 15 with respect to the gravity direction G (ground bucket angle) based on the vehicle body bucket angle, the detection value of the vehicle body tilt angle sensor 23, and the detection value of the articulation angle sensor 24.

[0063] Next, in step S50, the vehicle body / ground control determination unit 33 determines whether to perform either ground control or vehicle body control. When the posture of the working machine 3 for achieving the input target value is not included in the movable limit or moves away from the movable limit, the vehicle body / ground control determination unit 33 determines to execute the ground control, and the control proceeds to step S60. On the other hand, when the posture of the working machine 3 for achieving the input target value is within the movable limit or approaches the movable limit, the vehicle body / ground control determination unit 33 determines to execute the vehicle body control, and the flow proceeds to step S70.

[0064] In step S60, the bucket control amount determination unit 34 obtains the difference between the ground bucket angle calculated by the ground bucket angle calculation unit and the target value, determines the control amount of the bucket cylinder 17 so that the ground bucket angle becomes the target value, and the control proceeds to step S80.

[0065] On the other hand, in step S70, the bucket control amount determination unit 34 determines the control amount of the bucket cylinder 17 so as to maintain the vehicle body bucket angle calculated by the vehicle body bucket angle calculation unit 31, and the control proceeds to step S80.

[0066] In step S80 (an example of a control step), the bucket cylinder 17 is controlled based on the determined control amount.

[0067] Next, in step S90, the control unit 9 determines whether or not the operator has canceled the setting of the ground control. If the operator has not canceled the setting of the ground control, the control returns to step S30, and steps S30 to S80 are repeated. On the other hand, when the operator cancels the ground control setting, the ground control ends.

[0068] Thereby, when the ground control is set and the boom 14 is moved up and down by the operation lever, the bucket 15 can maintain a predetermined inclination angle with respect to the gravitational direction G. Further, when the working machine 3 approaches the movable limit or the movable limit while trying to maintain the bucket 15 at the target value, the control can be switched to the vehicle body control.

[0069] (Embodiment 2) The wheel loader according to Embodiment 2 will be described below. The wheel loader according to Embodiment 2 has a different control configuration from that of Embodiment 1. Therefore, in Embodiment 2, the differences will be mainly described.

[0070] <Configuration> FIG. 9 is a block diagram showing the control configuration of the wheel loader according to Embodiment 2.

[0071] The wheel loader according to Embodiment 2 is provided with no vehicle body inclination angle sensor 23 and is provided with a bucket IMU 41 (an example of a ground bucket angle detection unit) as compared with Embodiment 1. The bucket IMU 41 is an IMU provided on the bucket 15.

[0072] The control unit 9' of the wheel loader 1 according to the second embodiment includes a vehicle body bucket angle calculation unit 31', a ground bucket angle calculation unit 32', a vehicle body / ground control determination unit 33, and a bucket control amount determination unit 34.

[0073] The ground bucket angle calculation unit 32' calculates the inclination angle (ground bucket angle) of the bucket 15 with respect to the gravity direction G from the detected values of the bucket IMU 41.

[0074] The vehicle body bucket angle calculation unit 31' calculates the angle of the bucket 15 with respect to the vehicle body 2 (vehicle body bucket angle) based on the detected values of the boom angle sensor 21 and the bell crank angle sensor 22. Since the relative position of the bucket 15 with respect to the vehicle body 2 can be detected by the detected values of the boom angle sensor 21 and the bell crank angle sensor 22, the vehicle body bucket angle can be calculated from this relative position and the ground bucket angle. When a boom IMU is provided on the boom 14 instead of the boom angle sensor 21 and a bell crank IMU is provided on the bell crank 18 instead of the bell crank angle sensor 22, the vehicle body bucket angle calculation unit 31' calculates the vehicle body bucket angle based on the detected values of the boom IMU and the bell crank IMU in addition to the ground bucket angle calculated by the ground bucket angle calculation unit 32'.

[0075] The vehicle body / ground control determination unit 33 and the bucket control amount determination unit 34 are the same as those in the first embodiment, so the description thereof is omitted.

[0076] <Operation> Next, the operation of the wheel loader 1 according to the second embodiment will be described, and an example of a control method for a working machine will also be described simultaneously. FIG. 10 is a flowchart showing the operation of the wheel loader 1 according to the second embodiment.

[0077] In the second embodiment, steps S30 and S40 are different from those in the first embodiment.

[0078] That is, after steps S10 and S20, in step S30' (an example of the attachment tilt angle detection step), the ground bucket angle calculation unit 32' calculates the tilt angle (ground bucket angle) of the bucket 15 with respect to the gravity direction G from the detection value of the bucket IMU 41.

[0079] Next, in step S40', the vehicle body bucket angle calculation unit 31' calculates the angle of the bucket 15 with respect to the vehicle body 2 (vehicle body bucket angle) based on the detection value of the boom angle sensor 21, the detection value of the bell crank angle sensor 22, and the ground bucket angle calculated by the ground bucket angle calculation unit 32'.

[0080] Subsequent steps S50 to S90 are omitted because they are the same as those in the first embodiment.

[0081] <Feature> (1) The wheel loader 1 according to the first and second embodiments includes a vehicle body 2, a working machine 3, a ground bucket angle detection unit 20 or a bucket IMU 41, and control units 9 and 9'. The working machine 3 operates with respect to the vehicle body 2 and has a bucket 15 or a fork 19. The ground bucket angle detection unit 20 or the bucket IMU 41 detects information regarding the tilt angle of the attachment with respect to the gravity direction. The control units 9 and 9' control the tilt angle of the bucket 15 or the fork 19 with respect to the gravity direction G based on the detection value of the ground bucket angle detection unit 20 or the bucket IMU 41.

[0082] In this way, by detecting information regarding the tilt angle of the bucket 15 or the fork 19 with respect to the gravity direction G and performing control based on the tilt angle, the tilt angle of the bucket 15 or the fork 19 with respect to the gravity direction G can be maintained constant even when the wheel loader 1 is in a tilted state.

[0083] (2) In the wheel loader 1 according to the first embodiment, the ground bucket angle detection unit 20 includes a vehicle body tilt angle sensor 23 and a relative position detection unit 25. The vehicle body tilt angle sensor 23 detects the tilt angle of the vehicle body 2 with respect to the gravity direction G. The relative position detection unit 25 detects information regarding the relative position of the bucket 15 or the fork 19 with respect to the vehicle body 2. The control unit 9 calculates the tilt angle (the angle of the bucket with respect to the vehicle body) of the bucket 15 or the fork 19 with respect to the vehicle body 2 from the detection value of the relative position detection unit 25, and calculates the tilt angle of the bucket 15 or the fork 19 with respect to the gravity direction G from the calculated angle of the bucket with respect to the vehicle body and the detection value of the vehicle body tilt angle sensor 23.

[0084] In this way, the tilt angle of the bucket 15 or the fork 19 with respect to the gravity direction G can be calculated from the relative position of the bucket 15 or the fork 19 with respect to the vehicle body 2 and the tilt angle of the vehicle body 2 with respect to the gravity direction G.

[0085] (3) In the wheel loader 1 according to the first embodiment, the working machine 3 further includes a boom 14 that is rotatably connected to the vehicle body 2. The bucket 15 or the fork 19 is rotatably connected to the boom 14. The relative position detection unit 25 includes a boom angle sensor 21 and a bell crank angle sensor 22. The boom angle sensor 21 detects information regarding the rotation angle of the boom 14. The bell crank angle sensor 22 detects information regarding the rotation angle of the bucket 15 or the fork 19. The control unit 9 calculates the tilt angle of the bucket 15 or the fork 19 with respect to the vehicle body 2 using the detection value of the boom angle sensor 21 and the detection value of the bell crank angle sensor 22.

[0086] In this way, the relative position of the bucket 15 or the fork 19 with respect to the vehicle body 2 can be specified by the information regarding the rotation angle of the boom 14 and the information regarding the rotation angle of the bucket 15 or the fork 19.

[0087] (4) In the wheel loader 1 according to the first embodiment, the control unit 9 performs control based on the inclination angle of the bucket 15 or the fork 19 with respect to the vehicle body 2, or control based on the inclination angle of the bucket 15 or the fork 19 with respect to the gravitational direction G, based on the detection value of the ground bucket angle detection unit 20.

[0088] Thereby, it is possible to perform either control based on the relative inclination angle of the bucket 15 or the fork 19 with respect to the vehicle body 2 or control based on the inclination angle of the bucket 15 or the fork 19 with respect to the gravitational direction G.

[0089] For example, in the posture of the work implement 3 obtained from the rotation angle of the bucket 15 or the fork 19 and the rotation angle of the boom 14, when it is determined that control based on the inclination angle of the bucket 15 or the fork 19 with respect to the gravitational direction cannot be performed, it is possible to switch to perform control based on the inclination angle of the bucket 15 or the fork 19 with respect to the vehicle body 2. (5) In the wheel loader 1 according to the first embodiment, the work implement 3 further has a boom 14 rotatably connected to the vehicle body 2. The bucket 15 or the fork 19 is rotatably connected to the boom 14. When raising the boom 14, the control unit 9 maintains the inclination angle of the bucket 15 or the fork 19 with respect to the gravitational direction G constant. Thereby, for example, when raising the boom 14 while ascending an inclined ground, the angle of the bucket 15 or the fork 19 with respect to the gravitational direction G can be made constant.

[0090] (6) In the wheel loader 1 of Embodiment 1, the vehicle body 2 includes a front frame 11, a rear frame 12, front tires 4, and rear tires 7. An operating machine 3 is connected to the front frame 11. The rear frame 12 is disposed on the rear side of the front frame 11. The front tires 4 are provided on the front frame 11. The rear tires 7 are provided on the rear frame 12. The wheel loader 1 further includes an articulation angle sensor 24 that detects the rotation angle of the front frame 11 with respect to the rear frame 12. The control unit 9 controls the inclination angle of the bucket 15 or the fork 19 with respect to the gravity direction G based on the detection value of the ground bucket angle detection unit 20 and the detection value of the articulation angle sensor 24.

[0091] When the wheel loader 1 is disposed on an inclined surface, when the front frame 11 rotates with respect to the rear frame 12, the inclination angle of the bucket 15 or the fork 19 with respect to the gravity direction G may deviate from the inclined surface. Therefore, by correcting the detection value of the ground bucket angle detection unit 20 with the articulation angle, the inclination angle of the bucket 15 or the fork 19 with respect to the gravity direction G can be calculated more accurately.

[0092] (7) The wheel loader 1 of Embodiment 2 further includes a relative position detection unit 25. The relative position detection unit 25 detects the relative position of the bucket 15 or the fork 19 with respect to the vehicle body 2. The control unit 9' controls the inclination angle of the bucket 15 or the fork 19 with respect to the gravity direction G based on the detection value of the IMU 41 and the detection value of the relative position detection unit 25.

[0093] Thereby, the inclination angle of the bucket 15 or the fork 19 with respect to the gravity direction G can be controlled based on the detection value of the ground bucket angle detection unit 20 and the detection value of the relative position detection unit 25.

[0094] (8) In the wheel loaders 1 of Embodiments 1 and 2, the control units 9 and 9' control the bucket 15 or the fork 19 so that the inclination angle with respect to the gravitational direction G becomes a predetermined angle.

[0095] Accordingly, it is possible to control so as to keep the angle of the bucket 15 or the fork 19 with respect to the gravitational direction G constant.

[0096] (9) The control method of the wheel loader 1 according to Embodiments 1 and 2 is a control method of a wheel loader 1 including a vehicle body 2 and a working machine 3 that operates with respect to the vehicle body 2 and has a bucket 15 or a fork 19, and includes step S40 or step S30' (an example of an attachment inclination angle detection step) and step S80 (an example of a control step). Step S40 or step S30' obtains the inclination angle of the bucket 15 or the fork 19 with respect to the gravitational direction G. Step S80 controls the inclination angle of the bucket 15 or the fork 19 with respect to the gravitational direction based on the detection value in step S40 or step S30'.

[0097] <Other Embodiments> As described above, one embodiment of the present invention has been described. However, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the gist of the invention.

[0098] (A) In the above Embodiments 1 and 2, the vehicle body / ground control determination unit 33 is provided and the control is automatically switched. However, when it is determined not to perform ground control, the operator may be given the option of whether to perform vehicle body control.

[0099] (B) In the above Embodiments 1 and 2, the ground control setting unit 51 is provided in the operation unit 50, but a vehicle body control setting unit for setting the execution of vehicle body control may be further provided.

[0100] (C) In the above-described Embodiments 1 and 2, the vehicle body / ground control determination unit 33 is provided, and when the posture of the working machine 3 for setting the ground angle of the bucket 15 to a set target value is within the movable limit or approaches the movable limit, the switching to the vehicle body control is performed, but the control may be stopped without switching.

[0101] That is, the control units 9 and 9' stop the control of the inclination angle of the attachment with respect to the gravity direction G based on the detected values of the boom angle sensor 21 and the bell crank angle sensor 22.

[0102] Thereby, in the posture of the working machine 3 obtained from the rotation angle of the bucket 15 or the fork 19 and the rotation angle of the boom 14, when it is determined that the control based on the inclination angle of the bucket 15 or the fork 19 with respect to the gravity direction G cannot be performed, the control can be stopped.

[0103] Also, a warning display may be provided to the operator. The warning display can be provided in the cab 5.

[0104] (D) In the above-described Embodiment 1, since the vehicle body inclination angle sensor 23 is provided on the rear frame 12, the vehicle body inclination angle sensor 23 is corrected by the articulation angle sensor 24. However, when the vehicle body inclination angle sensor 23 is arranged on the front frame 11, the articulation angle sensor 24 may not be provided. In this case, it is more preferable that the vehicle body inclination angle sensor 23 is arranged in the vicinity of the working machine 3 on the front frame 11.

[0105] (E) In the above-described Embodiments 1 and 2, the boom angle sensor 21 and the bell crank angle sensor 22 are provided as the relative position detection unit 25, but it is not limited thereto. For example, instead of the bell crank angle sensor 22, the rotation angle of the bucket 15 with respect to the boom 14 may be detected by a sensor, and the vehicle body bucket angle may be calculated using the detected value and the detected value of the boom angle sensor 21.

[0106] (F) In the above Embodiment 2, the boom angle sensor 21 and the bell crank angle sensor 22 are provided as the relative position detection unit 25, but this is not the only case. As long as any two of the boom angle sensor 21, the bell crank angle sensor 22, and the vehicle body tilt angle sensor 23 are provided, the relative position of the bucket 15 with respect to the vehicle body 2 can be known. Therefore, the angle of the bucket with respect to the vehicle body can be calculated, and it is also possible to determine whether to perform vehicle body control or ground control. Further, for the vehicle body tilt angle sensor 23, an articulation angle sensor 24 may be combined.

Industrial Applicability

[0107] According to the working machine and the control method of the working machine of the present invention, it has the effect of being able to maintain the angle of the attachment even in an inclined state, and is useful as a hydraulic excavator, a wheel loader, etc.

Explanation of Signs

[0108] 1: Wheel Loader 2: Vehicle Body 3: Working Machine 9: Control Unit 15: Bucket 19: Fork 20: Ground Bucket Angle Detection Unit

Claims

1. A main body, A working machine that operates with respect to the main body and has an attachment, An attachment inclination angle detection unit that detects information regarding an inclination angle of the attachment with respect to the gravitational direction, A control unit that controls an inclination angle of the attachment with respect to the gravitational direction based on a detection value of the attachment inclination angle detection unit, The working machine further has a boom rotatably connected to the main body, The attachment is rotatably connected to the boom, The control unit, When raising the boom by an operator's operation, maintains a constant inclination angle of the attachment with respect to the gravitational direction, The working machine is a wheel loader, The main body, A front frame to which the working machine is connected, A rear frame disposed on the rear side of the front frame, Front tires provided on the front frame, Rear tires provided on the rear frame, Further includes a rotation angle detection unit that detects a rotation angle of the front frame with respect to the rear frame, The control unit controls to maintain a constant inclination angle of the attachment with respect to the gravitational direction based on a detection value of the attachment inclination angle detection unit and a detection value of the rotation angle detection unit, Working machine.

2. The attachment inclination angle detection unit, A main body inclination angle detection unit that detects an inclination angle of the main body with respect to the gravitational direction, And a relative position detection unit that detects information regarding a relative position of the attachment with respect to the main body, The control unit calculates the inclination angle of the attachment with respect to the main body from the detection value of the relative position detection unit, and calculates the inclination angle of the attachment with respect to the gravitational direction from the calculated inclination angle and the detection value of the main body inclination angle detection unit. The working machine according to claim 1.

3. The working machine further includes a boom rotatably connected to the main body. The attachment is rotatably connected to the boom. The relative position detection unit includes a boom angle detection unit that detects information regarding the rotation angle of the boom, and an attachment angle detection unit that detects information regarding the rotation angle of the attachment. The control unit calculates the inclination angle of the attachment with respect to the main body using the detection value of the boom angle detection unit and the detection value of the attachment angle detection unit. The working machine according to claim 2.

4. The control unit stops controlling the inclination angle of the attachment with respect to the gravitational direction based on the detection value of the boom angle detection unit and the detection value of the attachment angle detection unit. The working machine according to claim 3.

5. The working machine further includes a relative position detection unit that detects the relative position of the attachment with respect to the main body. The control unit controls the inclination angle of the attachment with respect to the gravitational direction based on the detection value of the attachment inclination angle detection unit and the detection value of the relative position detection unit. The working machine according to claim 1.

6. A control method for a working machine including a main body and a working machine that operates with respect to the main body and has an attachment, the method including: an attachment inclination angle detection step of detecting the inclination angle of the attachment with respect to the gravitational direction; A control step of controlling the tilt angle of the attachment with respect to the direction of gravity based on the detection value in the attachment tilt angle detection step, The work machine further has a boom rotatably connected to the main body, The attachment is rotatably connected to the boom, The control step is, When the boom is raised by an operator's operation, the tilt angle of the attachment with respect to the direction of gravity is kept constant, The work machine is a wheel loader, The main body is, A front frame to which the work machine is connected and A rear frame disposed on the rear side of the front frame, and Front tires provided on the front frame, and Rear tires provided on the rear frame, The work machine further includes a rotation angle detection step of detecting the rotation angle of the front frame with respect to the rear frame, The control step controls to keep the tilt angle of the attachment with respect to the direction of gravity constant based on the detection value of the attachment tilt angle detection step and the detection value of the rotation angle detection step, A control method of a work machine.

Images