Working machinery

Abstract

The present invention provides a work machine that improves the accuracy of measuring the load of cargo in a bucket during loading. [Solution] The controller 120 calculates the center of gravity of the cargo (soil) inside the bucket 3 during loading from the angle of repose of the cargo (soil), the posture (toe angle) of the bucket 3, and the dimensional information of the bucket 3, and uses the calculated center of gravity to calculate the load of the cargo. Based on the load of the cargo inside the bucket 3 before loading, the controller 120 determines the shape (pattern) of the cargo before loading, and based on the determined shape (pattern) of the cargo, calculates the starting angle θ for the center of gravity. S To decide.

Description

[Technical Field]

[0001] This invention relates to a work machine equipped with a function for measuring the load of a load in a bucket. [Background technology]

[0002] When a dump truck is loaded with soil or other materials and driven on public roads, the maximum load that can be carried is regulated by law. Therefore, in recent years, machinery used to load soil and other materials into dump trucks has been equipped with a function to estimate the load of the soil or materials in the bucket. This function helps prevent overloading by notifying the operator of the load.

[0003] Generally, the load capacity of a work machine (hereinafter also referred to as the load) is measured based on the pressure sensor readings of the cylinder. However, depending on the posture of the work machine and the position and distribution of the load in the bucket, the pressure sensor readings may differ even for the same load capacity. In particular, during loading, when the load in the bucket is being released, the position and distribution of the load in the bucket fluctuate, and the pressure sensor readings fluctuate accordingly, thus reducing the accuracy of load measurement.

[0004] Patent Document 1 proposes a method for measuring the load of cargo in a bucket. Patent Document 1 describes a work machine equipped with a lift arm connected to the vehicle body via a hinge pin, a lift arm cylinder that rotates the lift arm vertically and is supported by the vehicle body, a bucket connected to the tip of the lift arm, a bucket cylinder that rotates the bucket vertically and is supported by the vehicle body, a lift arm angle sensor that detects the angle of the lift arm, and a pressure sensor that detects the pressure of the lift arm cylinder. The method calculates the distance between each link from the angle of the lift arm and the dimensional information of the vehicle body, solves the balance of moments around the fulcrum (hinge pin) of the lift arm from the distance between the links and the pressure applied to the lift cylinder, and calculates the load of cargo in the bucket. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent No. 6749878 [Summary of the Invention] [Problems to be Solved by the Invention]

[0006] However, in Patent Document 1, the load in the bucket is calculated with the center-of-gravity position of the load in the bucket being constant, and fluctuations in the center-of-gravity position of the load due to fluctuations in the position and distribution of the load in the bucket during loading are not taken into consideration.

[0007] <L Therefore, an object of the present invention is to provide a working machine that improves the accuracy of load measurement of the load in the bucket during loading. [Means for Solving the Problems]

[0008] In order to achieve the above object, a working machine of the present invention includes a vehicle body, a bucket, a lift arm that is supported by a hinge pin so as to be rotatable in the vertical direction with respect to the vehicle body and that supports the bucket so as to be tiltable, a lift cylinder that rotates the lift arm in the vertical direction, a bucket cylinder that tilts the bucket, a working device including these, a pressure sensor for acquiring the pressure acting on the lift cylinder, an angle sensor for acquiring the posture of the bucket, and a controller for calculating the load of the load in the bucket. In the working machine, the controller calculates the center-of-gravity position of the load in the bucket during loading when the load in the bucket is discharged based on the angle of repose of the load, the posture of the bucket, and the dimensional information of the bucket, and calculates the load of the load in the bucket during loading based on the calculated center-of-gravity position of the load. [Effects of the Invention]

[0009] According to the present invention, the center - of - gravity position of the load in the bucket during loading is calculated, and the load of the load is calculated using the calculated center - of - gravity position of the load. Therefore, the measurement accuracy of the load of the load during loading can be improved.

[0010] Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

Brief Description of the Drawings

[0011] [Figure 1A] External side view of the wheel loader in the embodiment. [Figure 1B] External perspective view of the wheel loader in the embodiment. [Figure 2] System configuration diagram of the wheel loader in the embodiment. [Figure 3] System configuration diagram of the load weight measurement of the controller in the embodiment. [Figure 4] Flowchart of the load weight measurement of the controller in the embodiment. [Figure 5] Explanation diagram of the load weight measurement method of the load during loading in the embodiment. [Figure 6] Explanation diagram of the center - of - gravity position of the load during loading in the embodiment. [Figure 7] Explanation diagram of the load shape in the bucket in the embodiment.

Modes for Carrying Out the Invention

[0012] Hereinafter, modes for carrying out the present invention will be described with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and the overlapping description thereof is omitted. In the following description, the up - down, left - right, front - rear directions and positions are based on the normal use state of the work machine (wheel loader), that is, the state where the wheels are in contact with the ground.

[0013] The embodiments for carrying out the present invention will be described using a wheel loader as an example of a working machine that has a bucket and is capable of measuring the load of the cargo in the bucket. A wheel loader is a machine that runs on wheels, has a four-wheel drive system, and is steered by an articulated mechanism, as well as derivative machines thereof.

[0014] External views of the wheel loader are shown in Figures 1A and 1B.

[0015] The wheel loader 20 has a work device 2 at the front of the vehicle section 1, and a bucket 3 for scooping up soil and sand is attached to its tip.

[0016] The wheel loader 20 is a machine in which an operator seated in the driver's cab 4B installed in the vehicle controls the height and angle of the bucket 3, as well as the direction and speed of the vehicle on which the wheels are mounted. It performs excavation work by scooping up soil and sand from the ground surface with the bucket 3, transport work by moving the scooped soil and sand, and loading work by releasing the scooped soil and sand onto the bed of a dump truck.

[0017] The vehicle section 1 has a structure in which a front frame 6 having a work device 2 and front wheels 5 and a rear frame 8 having rear wheels 7, an engine compartment 4A and a driver's seat 4B are connected by a center pin 9 so as to be bendable, and the bending angle can be varied by left and right hydraulic cylinders (also called steering cylinders) 10. An engine 4 is mounted in the engine compartment 4A.

[0018] The wheel loader 20 steers by extending and retracting the left and right hydraulic cylinders 10 while in motion, thereby changing the angle (bending angle) of the front frame 6 relative to the rear frame 8.

[0019] The work device 2 comprises a bucket 3, a lift arm 11 for supporting the bucket 3, a bucket cylinder 16 for rotating the bucket 3 vertically, and a lift cylinder 12 for rotating the lift arm 11 vertically.

[0020] The lift arms 11 consist of a pair, left and right, and are connected to the front frame 6 via hinge pins (see reference numeral I in Figure 5) so that they can rotate (tilt) vertically. A lift cylinder 12 is connected (interposed) to the front frame 6 and the lift arms 11 so that the load of the lift arms 11 is supported by the front frame 6 and the angle (height) of the lift arms 11 relative to the front frame 6 can be varied. The lift cylinder 12 is fitted with a pressure sensor 12b for measuring the pressure on the bottom side of the lift cylinder 12 and a pressure sensor 12r for measuring the pressure on the rod side of the lift cylinder 12. These pressure sensors 12b and 12r may be installed at any location in the piping where the pressure is the same.

[0021] Bucket 3 is connected to the lift arm 11 so that it can rotate (tilt) vertically at a pivot point 13. The bucket cylinder 16 is connected to the front frame 6 via a push rod 14 and a bell crank 15 so that the angle (tilt) of bucket 3 relative to the lift arm 11 can be varied. The bucket cylinder 16 is connected to the front frame 6 at a pivot point 17 (a different position from the pivot point of the lift cylinder 12 on the front frame 6 side). The bucket cylinder 16 is fitted with a pressure sensor 16b for measuring the pressure on the bottom side of the bucket cylinder 16 and a pressure sensor 16r for measuring the pressure on the rod side of the bucket cylinder 16. These pressure sensors 16b and 16r may be installed at any location in the piping where the pressure is the same.

[0022] The height of the bucket 3 can be varied by extending and retracting the lift cylinder 12, and the angle (tilt) of the bucket 3 can be varied by extending and retracting the bucket cylinder 16. In other words, the extension and retraction of the lift cylinder 12 causes the lift arm 11 to rotate vertically, raising and lowering the bucket 3. Also, the extension and retraction of the bucket cylinder 16 causes the bucket 3 to rotate vertically via the bell crank 15 and push rod 14, causing the bucket 3 to tilt (tilt, cloud, or dump). The bell crank 15 and push rod 14 are rotatably connected to the lift arm 11 and interposed between the bucket cylinder 16 and the bucket 3, transmitting the thrust of the bucket cylinder 16 to the bucket 3. A lift arm angle sensor 18 is installed to acquire the angle that the lift arm 11 makes with respect to the front frame 6 (in other words, the relative posture of the lift arm 11 with respect to the front frame 6), and a bell crank angle sensor 19 is installed to acquire the angle that the bell crank 15 makes with respect to the lift arm 11 (in other words, the relative posture of the bell crank 15 with respect to the lift arm 11). From the angles acquired by these sensors, the results of the extension and retraction of the lift cylinder 12 and the bucket cylinder 16 can be calculated. Therefore, from the angles acquired by these sensors, the angle (relative posture) that the bucket 3 (its toe) makes with respect to the front frame 6 can be obtained. In other words, the lift arm angle sensor 18 and the bell crank angle sensor 19 constitute angle sensors for acquiring the toe angle (posture information) of the bucket 3.

[0023] The system configuration of the wheel loader 20 will be explained using Figure 2.

[0024] The output shaft 100 of engine 4 is directly connected to the torque converter 101, hydraulic pump 102, and brake pump 103, and the rotational speed of engine 4 is controlled by an electrical signal 105 from engine controller 104. Engine controller 104 instructs the rotational speed of engine 4 based on the amount the accelerator pedal 106 is pressed.

[0025] The output shaft of the torque converter 101 is connected to the front and rear wheels via the transmission 107 and drive shaft 108. Here, the driving force transmitted from the torque converter 101 to the transmission 107 increases as the rotational speed of the engine 4's output shaft 100 is greater than the rotational speed of the torque converter 101. Therefore, the greater the amount the accelerator pedal 106 is pressed, the higher the rotational speed of the engine 4 becomes, and the greater the driving force output by the torque converter 101.

[0026] The transmission 107, in response to an electrical signal 110 from the transmission controller 109, disconnects the connection between the output shaft of the torque converter 101 and the drive shaft 108 to reduce the driving force on the front and rear wheels, or reverses the direction of rotation to change the direction of the driving force.

[0027] The electrical signal 110 of the transmission controller 109 is output to disconnect the connection when the amount of depression of the brake pedal 112 exceeds a certain level.

[0028] The hydraulic pump 102 outputs a constant flow rate of pressurized oil for each rotation of the output shaft 100 of the engine 4. The pressurized oil output from the hydraulic pump 102 is supplied to the lift cylinder 12 and bucket cylinder 16, which act as hydraulic actuators, via the bucket control hydraulic circuit 113, causing the lift cylinder 12 and bucket cylinder 16 to extend and retract.

[0029] The amount of pressurized oil output from the hydraulic pump 102 increases as the rotational speed of the output shaft 100 of the engine 4 increases. Therefore, increasing the rotational speed of the engine 4 by pressing the accelerator pedal 106 increases the extension and retraction speed of the lift cylinder 12 and bucket cylinder 16 (and consequently, the operating speed of the lift arm 11 or bucket 3).

[0030] The bucket control hydraulic circuit 113, in response to the operator's operation of the lift lever 114, can disconnect the connection between the hydraulic pump 102 and the lift cylinder 12 to stop the movement of the lift arm 11, or reverse the extension / retraction direction to switch the vertical movement of the lift arm 11.

[0031] The bucket control hydraulic circuit 113, in response to the operator's operation of the bucket lever 115, can stop the operation of the bucket 3 by disconnecting the output of the hydraulic pump 102 and the connection to the bucket cylinder 16, or reverse the direction of extension and retraction, switching the forward and backward movement of the bucket 3's angle (tilt).

[0032] The pressurized oil output from the hydraulic pump 102 is connected to the left and right steering cylinders 10, which act as hydraulic actuators, via the steering control hydraulic circuit 116, causing the left and right steering cylinders 10 to extend and retract.

[0033] When the operator rotates the steering wheel 117 to the right, the steering control hydraulic circuit 116 outputs a steering angle signal 116S and simultaneously connects the pressurized oil output from the hydraulic pump 102 in the direction that compresses the right steering cylinder 10R and in the direction that extends the left steering cylinder 10L, causing the vehicle to turn to the right. When the operator rotates the steering wheel 117 to the left, the steering control hydraulic circuit 116 outputs a steering angle signal 116S and simultaneously connects the pressurized oil output from the hydraulic pump 102 in the direction that extends the right steering cylinder 10R and in the direction that compresses the left steering cylinder 10L, causing the vehicle to turn to the left.

[0034] The pressurized oil output from the brake pump 103 is stored in the accumulator 118, and the pressurized oil stored in the accumulator 118 controls the braking force of the four wheels via the brake control hydraulic circuit 119.

[0035] The brake control hydraulic circuit 119 adjusts the control pressure (brake force) based on the amount the operator depresses the brake pedal 112.

[0036] The wheel loader 20 is equipped with a controller 120. The controller 120 includes, for example, a CPU (Central Processing Unit), ROM (Read Only Memory), and RAM (Random Access Memory). The CPU reads and executes program code stored in the ROM, thereby realizing each of the functional blocks described later. The RAM is used as a work area when the CPU executes the program. However, the specific configuration of the controller 120 is not limited to this, and it may be implemented by hardware such as an ASIC (Application Specific Integrated Circuit) or FPGA (Field-Programmable Gate Array).

[0037] The controller 120 is connected to the lift arm angle sensor 18, the bell crank angle sensor 19, the bucket control hydraulic circuit 113, the monitor 123, the input device 121, and the bucket lever 115. In addition, the values ​​of the lift cylinder rod side pressure sensor 12r and the lift cylinder bottom side pressure sensor 12b are input to the controller 120 via the bucket control hydraulic circuit 113.

[0038] The controller 120 outputs the result calculated based on a portion of the input signal to the monitor 123.

[0039] The input device 121 is connected to the controller 120 and is configured to transmit signals.

[0040] Figure 3 shows the system configuration diagram for measuring the load capacity of the bucket.

[0041] The load measurement system mainly consists of a lift arm angle sensor 18, a bell crank angle sensor 19, a lift cylinder rod side pressure sensor 12r, a lift cylinder bottom side pressure sensor 12b, a controller 120, and a monitor 123, which are connected by electrical wiring to transmit electrical signals. The controller 120 includes a bucket attitude information generation unit 31, a vehicle body parameter generation unit 32, a vehicle body information storage unit 33, and a bucket internal load calculation unit 34 as functional blocks for performing calculation processing. The vehicle body information storage unit 33 may be located outside the controller 120 as long as it can store physical information such as vehicle body dimensions and weight information.

[0042] The controller 120 generates the tip angle of the bucket 3 relative to the tire contact surface as attitude information from the values ​​of the lift arm angle sensor 18 and the bell crank angle sensor 19 using the bucket attitude information generation unit 31. The bucket attitude information generation unit 31 may also include a vehicle body tilt angle sensor to generate the tip angle of the bucket 3 relative to the horizontal plane.

[0043] The controller 120 uses a vehicle parameter generation unit 32 to geometrically calculate the distance between links for each orientation of the work machine from the orientation information and the dimensional information of the vehicle body stored in the vehicle information storage unit 33.

[0044] The controller 120 calculates the load in bucket 3 using the bucket load calculation unit 34, based on the link distance, the attitude information, and load information (support force information) obtained from the pressure sensors 12r and 12b of the lift cylinder 12, and displays it on the monitor 123 screen. The load value of the cargo in bucket 3 displayed on the monitor 123 screen is constantly updated. Therefore, for example, when loading excavated soil into a dump truck using a wheel loader, the operator is notified of the load in bucket 3 changing during loading, allowing the operator to stop the loading operation at the appropriate time, thus helping to prevent overloading. Furthermore, by controlling bucket 3 using the load in bucket 3, which is constantly updated within the controller 120, automatic loading control of a specified amount becomes possible.

[0045] Figure 4 shows a flowchart for measuring the load capacity of the bucket in this embodiment. This flowchart is basically executed by the bucket load calculation unit 34 of the controller 120. This flowchart includes the contents described in the explanations of Figures 5 to 7 below. Figure 5 shows the method for measuring the load capacity of the bucket during loading. The explanation of Figure 5 describes the method for measuring the load capacity of the bucket from the balance of the load and the moment of cylinder thrust in the work device 2. Figure 6 shows the shape of the load inside the bucket 3 as seen from the side of the vehicle during loading. The explanation of Figure 6 describes the method for obtaining the center of gravity of the load from the shape of the load during loading. Figure 7 shows the shape of the load inside the bucket 3 as seen from the side of the vehicle after excavation. The explanation of Figure 7 describes the definition of the load shape inside the bucket 3 after excavation and the timing for starting the correction of the center of gravity of the load.

[0046] First, let's explain the flowchart for measuring load capacity shown in Figure 4.

[0047] The operator performs the excavation by operating the lever, and the controller 120 controls the load W of the load in the bucket 3 of the work machine. int Once measured, control of this embodiment is started (S1 / Yes). Load W of the load in bucket 3 after excavation. int The method for measuring this may be the method described in Patent Document 1. For example, by using equation (6) described in Patent Document 1, the distance between each link can be calculated from the angle of the lift arm 11 and the dimensional information of the vehicle body, and the load of the cargo in the bucket 3 can be calculated by solving the balance of moments around the pivot point of the lift arm 11 from the distance between the links and the pressure applied to the lift cylinder 12. At this time, the distances a and Lw between the center of gravity of the cargo in the bucket 3 and each pivot point are variables that depend on the angle of the lift arm 11. Load of the cargo W int After measurement, the load W of the cargo int Based on this, the pattern of the cargo shape is determined by the method described in Figure 7 (S2), and the calculation start angle θ of the center of gravity position is determined according to the determined pattern of the cargo shape. SThe operator determines (S3). Then, the operator operates bucket 3 and loading begins (S4 / Yes). The load during loading is measured by the method described in Figure 5. The tip angle θ of bucket 3 is the starting angle θ for calculating the center of gravity. S Until the limit is reached (S5 / No), the load of the cargo being loaded is calculated using the distance a from the fulcrum A at the time of load measurement of the cargo after excavation to the center of gravity of the cargo. The decision to start loading may also be made when the tip angle θ of the bucket 3 decreases by a certain value or more. In addition, although not shown in the system configuration diagram of Figure 3, information on the amount of lever operation in the direction of tilting the bucket 3 forward (hereinafter referred to as the dump direction) may be acquired, and the decision to start loading may be made when the amount of lever operation increases by a certain value or more.

[0048] The tip angle θ of bucket 3 is the starting angle θ for calculating the center of gravity. S If the following occurs (S5 / Yes), the center of gravity of the load in the bucket 3 is estimated (acquired) (S6) based on the angle of repose φ of the load (e.g., soil), the tip angle θ of the bucket 3 (attitude information), and the dimensional information of the bucket 3, using the method described in Figure 6. The angle of repose φ of the load may be stored in the controller 120 by the operator via the input device 121. Alternatively, the angle of repose information stored in the controller 120 may be read out as appropriate and used. Or, a sensor for acquiring accumulation information of the excavation target may be attached to the vehicle body, the information acquired by the sensor may be input to the controller 120, and the angle of repose may be determined by comparing it with the information stored in the controller 120.

[0049] Subsequently, based on the acquired center of gravity position of the cargo, the load W of the cargo in bucket 3 is measured using the cargo load measurement method described in Figure 5. LOADEstimate (update) it (S7). If the loading continues (S8 / No), the processes of S6 and S7 are repeated. When the operator's dumping operation ends (S8 / Yes), the correction control of the load weight ends. The determination of the end of loading by the dumping operation may be made when the claw tip angle θ of the bucket 3 is held for a certain period of time or more. Also, by additionally connecting a lever operation amount acquisition unit or a switch in the dumping direction to the controller 120, when the operator's dumping lever operation amount decreases from a certain value, or when the operator notifies the controller 120 with a switch or the like that the loading has ended, it may be determined that the loading operation has ended.

[0050] The calculation method of the load weight in the bucket 3 during loading in FIG. 5 will be described.

[0051] First, consider the balance of forces acting on the bucket 3. Let the gravity of the entire bucket 3 be F W , the force received by the bucket 3 from the push rod 14 be F B , and the force received by the bucket 3 from the lift arm 11 be F A . Then, the balance of forces in the vertical and horizontal directions is expressed by equations (1) and (2). [Equation 1] JPEG2026085185000002.jpg12125

[0052] The balance of moments around the fulcrum A is expressed by equation (3). [Equation 2] JPEG2026085185000003.jpg7125

[0053] Next, consider the balance of forces of the push rod 14. Since the force F B between the push rod 14 and the bucket 3 and the force F C between the push rod 14 and the bell crank 15 are in balance, equation (4) holds. [Equation 3] JPEG2026085185000004.jpg7125

[0054] Next, let's focus on the bell crank 15. When the pivot point is D, the thrust F from the bucket cylinder 16 E Then, the force F that the push rod 14 exerts on the bell crank 15. C Since these are in equilibrium as moments around the pivot point D, equation (5) holds true. [Math 4] JPEG2026085185000005.jpg6125

[0055] Furthermore, equations (6) and (7) hold true from the vertical and horizontal equilibrium of forces acting on the bell crank 15. Here, F D1 This represents the force that the bell crank 15 receives from the lift arm 11. [Number 5] JPEG2026085185000006.jpg12125

[0056] From equations (5) to (7), F D1 By organizing the information, we obtain equation (8). [Number 6] JPEG2026085185000007.jpg15125

[0057] Next, we solve for the balance of moments around the fulcrum I (hinge pin) from the force acting on the lift arm 11, and determine the load W of the bucket 3. Load We will find the force F that the lift arm 11 receives from the bucket 3 around the fulcrum I. A And the force F received from bell crank 15. D The gravity F acting on the lift arm 11 G , the thrust F of the lift cylinder 12 H Since the moments are balanced, equation (9) holds. Here, θ D This is expressed by equation (10). [Number 7] JPEG2026085185000008.jpg13134

[0058] By rearranging equation (9) for Fw using equations (1) to (5) and (8), we obtain equation (11). [Number 8] TIFF2026085185000009.tif17163

[0059] Here, F W Since this is the total weight of bucket 3, by dividing it by the acceleration due to gravity g, we can find the total mass of bucket 3, and from there we can find the mass W of bucket 3. Bkt By pulling, the load W inside bucket 3 Load Therefore, the load W in bucket 3 can be determined. Load This is expressed by equation (12). [Number 9] JPEG2026085185000010.jpg9129

[0060] The definitions of the symbols used in equations (1) to (12) above are as follows. JPEG2026085185000011.jpg123142

[0061] At this time, the distances between each pivot point b, c, and d and the force can be determined by the method described in Patent Document 1. Furthermore, the angle between the horizontal and the direction of the force acting on each point can be geometrically determined using the law of cosines, based on the dimensional information of the work device 2 stored in the vehicle body information storage unit 33, the lift arm angle obtained by the lift arm angle sensor 18, and the bell crank angle obtained by the bell crank angle sensor 19.

[0062] The method for determining 'a', that is, the position of the center of gravity of the load in bucket 3, is described in the explanation of Figure 6.

[0063] Figure 6 will be used to explain how to determine the center of gravity of the load inside bucket 3.

[0064] During loading, as bucket 3 tilts in the dumping direction, soil exceeding the angle of repose begins to collapse from the top of bucket 3. At this time, the shape of the load immediately after loading begins will differ depending on the amount of soil excavated, but from a certain angle after loading begins, it can be assumed that the shape of the load when bucket 3 is viewed from the side of the vehicle is a sector. When the shape becomes a sector as shown in Figure 6 during loading, the central angle of the sector is expressed as the sum of the toe angle θ and the angle of repose φ. Distance H from the vertex of the sector to the center of gravity of the load. g It can be expressed using the following equation (13) from the central angle (θ+φ) and radius R. [Number 10] JPEG2026085185000012.jpg15136

[0065] Furthermore, the distance a from the pin support point connecting the lift arm 11 and the bucket 3 to the center of gravity of the load is given by the distance H in equation (13). g Using this, it can be calculated using equation (14). [Number 11] JPEG2026085185000013.jpg11136

[0066] At this time, by substituting a, which is obtained from equation (14), into equation (11), the load W of the cargo in bucket 3 during loading can be found. Load It is possible to find this.

[0067] Figure 7 shows the contents of bucket 3 as viewed from the side of the vehicle. Based on the amount of excavation, the shape of the contents inside bucket 3 after excavation is defined in four patterns. The four patterns of contents will be explained using the case where soil and sand are excavated as the contents.

[0068] Pattern 1 represents the shape of the load when the bucket 3 is filled to capacity during excavation. When the load is viewed from the side of the vehicle, the shape is such that the soil inside the bucket 3 forms a fan shape, with a triangular layer of soil on top of it whose base angle is the angle of repose. Therefore, it is defined as the sum of two shapes: a fan shape and a triangle.

[0069] If loading is started from this shape, once the soil in the triangular section accumulated at the top of the fan shape is completely discharged, the soil in bucket 3 can be assumed to be fan-shaped, and the center of gravity position a of the soil can be obtained from equation (14).

[0070] Next, let's consider Pattern 2, which represents a state where the loading volume has decreased from the fully loaded state of Pattern 1. In Pattern 2, similar to Pattern 1, a fan-shaped pile of soil and a triangular pile of soil are deposited inside Bucket 3, with a triangular pile of soil on top of it. If loading is started from this state, the soil inside Bucket 3 can be assumed to be fan-shaped only when the triangular pile on top of the fan-shaped soil has been completely released. At this time, when the triangular pile is deposited on top of the fan-shaped soil, it may be deposited at a slope equal to the angle of repose, or it may be deposited at a slope less than the angle of repose. Comparing the two, if it is deposited at the angle of repose, the dumping angle required to completely release the triangular pile on top of the fan-shaped soil will be larger. Therefore, assuming that the triangular pile on top of the fan-shaped soil is deposited at a slope equal to the angle of repose, if we calculate the dumping angle required to completely release the triangular pile, the shape of the soil inside Bucket 3 will be fan-shaped after dumping by the angle calculated above, regardless of the slope of the triangle at the start of loading.

[0071] In Pattern 1 and Pattern 2, triangular soil is discharged, and the tip angle of Bucket 3 that causes the soil shape inside Bucket 3 to become fan-shaped is used as the starting angle θ for calculating the center of gravity. S The following procedure is used to determine this.

[0072] Let θ2 be the angle between sides C and D of the sector in Figure 7, and let θ be the vertex angle of bucket 3. T Let's assume that the lateral surface area S of the soil inside bucket 3, when viewed from the side of the vehicle body, is the sum of the sector and the triangle (S1 + S2), and is expressed by equation (15). [Number 12] JPEG2026085185000014.jpg11136

[0073] If E is the width of bucket 3 and ρ is the density of the soil, then the load W obtained after excavation is... int The relationship is expressed by equation (16). [Number 13] JPEG2026085185000015.jpg12136

[0074] Solving equation (16) will give us θ².

[0075] In this case, the central angle of the sector is θ T The angle is -θ2, and the soil at side C of the sector begins to fall at the toe angle θ. T The sum of the angle of repose φ is the central angle (θ) of the sector. T This occurs when it is equal to -θ². The starting angle θ for calculating the centroid position is the toe tip angle θ. S This can be expressed by the following equation (17). [Number 14] JPEG2026085185000016.jpg6136

[0076] Next, we consider patterns 3 and 4, which are cases where the amount of excavated soil is further reduced from pattern 2. The distinction between patterns 1 and 2 and patterns 3 and 4 is W int It is done by W. int When equation (18) is satisfied, consider the cargo shapes for pattern 3 and pattern 4. [Number 15] JPEG2026085185000017.jpg12122

[0077] In both Pattern 3 and Pattern 4, the shape of the soil inside Bucket 3 can be assumed to be a sector, and the central angle is θ. T It is represented by -φ. The radius r of the sector in this case is expressed as r=kR, using the radius R of bucket 3 and a constant k. Load W int Since it can be expressed by the following equation (19), the load W that can be determined by measurement is int From this, we can determine the constant k. [Number 16] JPEG2026085185000018.jpg12122

[0078] Furthermore, since r = kR, if we can find the constant k, we can find the radius r.

[0079] When loading begins with a sector of radius r, the load in bucket 3 eventually becomes a sector of radius R. If the central angle of this sector is θ3, the area viewed from the side remains unchanged until the soil in bucket 3 falls out. Therefore, the relationship between the area of ​​the sector of radius r and the area of ​​the sector of radius R is expressed by equation (20). [Number 17] JPEG2026085185000019.jpg12122

[0080] Since r=kR, θ3 is expressed by equation (21). [Number 18] JPEG2026085185000020.jpg7122

[0081] If the dumping continues until θ3 = θ + φ, the sector-shaped soil with radius R inside bucket 3 will begin to collapse. The toe angle θ at this point is the starting angle θ for calculating the center of gravity. S Then, θ S This is expressed by equation (22). [Number 19] JPEG2026085185000021.jpg7122

[0082] Therefore, the load W of the cargo in bucket 3 after excavation and before loading int By taking measurements and estimating (determining) the pattern of the cargo shape inside bucket 3 before loading, the starting angle θ for calculating the center of gravity position is determined. S Determine the starting angle θ for calculating the center of gravity. S The result can be determined by equation (17) if the cargo shape is pattern 1 or 2 as shown in Figure 7, and by equation (22) if it is pattern 3 or 4.

[0083] As described above, the work machine (wheel loader 20) of this embodiment includes a vehicle body, a bucket 3, a lift arm 11 that is supported by the vehicle body so as to be rotatable in the vertical direction via a hinge pin and supports the bucket 3 so as to be tiltable, a lift cylinder 12 that rotates the lift arm 11 in the vertical direction, a bucket cylinder 16 that tilts the bucket 3, a pressure sensor 12r, 12b for acquiring the pressure (load information) acting on the lift cylinder 12, and an angle sensor (lift arm angle for acquiring the posture of the lift arm 11) for acquiring the posture (toe angle) of the bucket 3. In a working machine (wheel loader 20) equipped with a degree sensor 18, a bell crank angle sensor 19 for acquiring the posture of the bell crank 15, and a controller 120 for calculating the load of the cargo in the bucket 3, the controller 120 calculates the position of the center of gravity of the cargo in the bucket 3 during loading when the cargo is released from the bucket 3, based on the angle of repose of the cargo (soil), the posture (toe angle) of the bucket 3, and the dimensional information of the bucket 3 (S6 in Figure 4: Figure 6), and calculates the load of the cargo in the bucket 3 during loading based on the calculated position of the center of gravity of the cargo (S7 in Figure 4: Figure 5).

[0084] The controller 120 calculates the center of gravity of the load in the bucket 3 during loading based on the load of the load in the bucket 3 before loading, and based on the calculated center of gravity of the load, it starts calculating the load of the load in the bucket 3 during loading by setting the orientation of the bucket 3 (center of gravity calculation start angle θ) S ) is determined (S3 in Figure 4).

[0085] The controller 120 determines the shape (pattern) of the load before loading based on the orientation of the bucket 3 and the load of the load inside the bucket 3 (S2 in Figure 4), calculates the center of gravity of the load inside the bucket 3 during loading (based on the calculated center of gravity of the load), and starts calculating the load of the load inside the bucket 3 during loading by determining the orientation of the bucket 3 (start angle θ of the center of gravity calculation). S ) is determined (S3 in Figure 4: Figure 7).

[0086] The controller 120 determines the shape (pattern) of the load before loading, specifically, the shape of the load when viewed from the side of the bucket 3, and distinguishes between patterns where a triangular load is piled on top of a fan-shaped load (patterns 1 and 2) and patterns where a fan-shaped load is piled up (patterns 3 and 4). Based on the determined pattern, it calculates the center of gravity of the load in the bucket 3 during loading, and based on the calculated center of gravity of the load, it starts calculating the load of the load in the bucket 3 during loading by setting the bucket 3's orientation (center of gravity calculation start angle θ) S ) is determined (S3 in Figure 4: Figure 7).

[0087] Furthermore, the work machine (wheel loader 20) of this embodiment includes a vehicle body, a bucket 3, a lift arm 11 that is supported on the vehicle body so as to be rotatable in the vertical direction via a hinge pin and tiltable in supporting the bucket 3, a lift cylinder 12 that rotates the lift arm 11 in the vertical direction, a bucket cylinder 16 that tilts the bucket 3, a work device 2 including a bell crank 15 and a push rod 14 that are rotatably connected to the lift arm 11 and interposed between the bucket cylinder 16 and the bucket 3 to transmit the thrust of the bucket cylinder 16 to the bucket 3, pressure sensors 12r and 12b for acquiring the pressure (load information) acting on the lift cylinder 12, and an angle sensor (lift) for acquiring the posture of the lift arm 11 and the bell crank 15. In a working machine (wheel loader 20) equipped with an arm angle sensor 18, a bell crank angle sensor 19, and a controller 120 that calculates the load of the cargo in the bucket 3, the controller 120 calculates the position of the center of gravity of the cargo in the bucket 3 during loading when the cargo is released from the bucket 3, based on the angle of repose of the cargo (soil), the posture of the bucket 3 (toe angle) obtained from the posture of the lift arm 11 and the bell crank 15, and the dimensional information of the bucket 3 (S6 in Figure 4: Figure 6). Based on the calculated position of the center of gravity of the cargo, the pressure of the lift cylinder 12, the posture of the lift arm 11, and the moment around the hinge pin obtained from the dimensional information of the working device 2, the controller 120 calculates the load of the cargo in the bucket 3 during loading (S7 in Figure 4: Figure 5).

[0088] According to this embodiment, the center of gravity of the cargo (soil and sand) inside the bucket 3 during loading is calculated from the angle of repose of the cargo (soil and sand), the posture (tip angle) of the bucket 3, and the dimensional information of the bucket 3. The load of the cargo is then calculated using the calculated center of gravity, thereby improving the accuracy of measuring the load of the cargo during loading.

[0089] Embodiments of the present invention have been described above. It should be noted that the present invention is not limited to the embodiments described above, and various modifications are included. For example, the embodiments described above are explained in detail for the purpose of clearly illustrating the present invention, and are not necessarily limited to those having all the configurations described.

[0090] For example, in the above embodiment, a wheel loader was used as an example of a work machine, but the present invention is not limited to this, and can also be applied to work machines such as hydraulic excavators equipped with buckets, arms, and booms as work tools. Furthermore, the present invention can be applied to work machines operated by an operator riding in a driver's seat installed on a vehicle, and to work machines operated by an operator from an operator's room installed away from the vehicle (remote control).

[0091] Furthermore, each of the above configurations, functions, processing units, and processing means may be implemented in hardware, either partially or entirely, by designing them as integrated circuits, for example. Alternatively, each of the above configurations and functions may be implemented in software by having the processor interpret and execute programs that implement each function. Information such as programs, tables, and files that implement each function can be stored in memory, storage devices such as hard disks and SSDs (Solid State Drives), or recording media such as IC cards, SD cards, and DVDs.

[0092] Furthermore, the control lines and information lines shown are those deemed necessary for explanatory purposes, and not all control lines and information lines are necessarily shown in the actual product. In reality, it is safe to assume that almost all components are interconnected. [Explanation of symbols]

[0093] 1. Vehicle section (car body) 2. Working equipment 3 buckets 4 engines 4A Engine Room 4B Driver's seat 5 Front wheels 6 Front Frame 7 Rear wheel 8 Rear frame 9 Center pin 10. Hydraulic cylinder (steering cylinder or steering cylinder) 11 Lift Arm 12 Lift Cylinders 12b Lift cylinder bottom side pressure sensor 12r Lift Cylinder Rod Side Pressure Sensor 14 Pushrods 15 Bell Crank 16 Bucket Cylinder 16b Bucket cylinder bottom side pressure sensor 16r Bucket Cylinder Rod Side Pressure Sensor 18. Lift arm angle sensor 19. Bell crank angle sensor 20. Wheel loader (working machine) 31 Bucket attitude information generation unit 32 Vehicle body parameter generation unit 33. Vehicle Information Storage Unit 34 Bucket internal load calculation section 120 controllers 121 Input device 123 Monitors

Claims

1. The car body and, A working device including a bucket, a lift arm supported by the vehicle body via a hinge pin so as to be rotatable in the vertical direction and tiltable in the vertical direction, a lift cylinder for rotating the lift arm in the vertical direction, and a bucket cylinder for tilting the bucket, A pressure sensor for obtaining the pressure acting on the lift cylinder, An angle sensor for acquiring the attitude of the bucket, A work machine comprising a controller for calculating the load of the cargo in the bucket, The controller is characterized by calculating the position of the center of gravity of the load in the bucket during loading, based on the angle of repose of the load, the orientation of the bucket, and the dimensional information of the bucket, and calculating the load of the load in the bucket during loading, based on the calculated position of the center of gravity of the load.

2. In the work machine described in claim 1, The work machine is characterized in that the controller determines the position of the bucket and starts calculating the load of the cargo in the bucket during loading based on the load of the cargo in the bucket before loading.

3. In the work machine described in claim 1, The controller is characterized in that it determines the shape of the load before loading based on the orientation of the bucket before loading and the load of the load in the bucket, and determines the orientation of the bucket in which it will begin calculating the load of the load in the bucket during loading based on the determined shape of the load.

4. In the work machine described in claim 3, The controller is characterized in that, as the shape of the load before loading, when the load is viewed from the side of the bucket, it determines whether the shape is such that a triangular load is piled on top of a fan-shaped load, or a fan-shaped load is piled up, and determines the position of the bucket to start calculating the load of the load inside the bucket during loading based on the determined pattern.

5. The car body and, A working device including a bucket, a lift arm supported by the vehicle body via a hinge pin so as to be rotatable in the vertical direction and tiltable in the lift arm, a lift cylinder for rotating the lift arm in the vertical direction, a bucket cylinder for tilting the bucket, and a bell crank and push rod rotatably connected to the lift arm and interposed between the bucket cylinder and the bucket to transmit the thrust of the bucket cylinder to the bucket, A pressure sensor for obtaining the pressure acting on the lift cylinder, An angle sensor for acquiring the posture of the lift arm and the bell crank, A work machine comprising a controller for calculating the load of the cargo in the bucket, The controller is characterized in that it calculates the position of the center of gravity of the load in the bucket during loading, when the load is released from the bucket, based on the angle of repose of the load, the posture of the bucket obtained from the posture of the lift arm and the bell crank, and the dimensional information of the bucket, and calculates the load of the load in the bucket during loading, based on the calculated position of the center of gravity of the load, the pressure of the lift cylinder, the posture of the lift arm, and the moment around the hinge pin obtained from the dimensional information of the work device.

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