Work machine and load mass calculating method

Abstract

To provide a work machine capable of accurately calculating a load mass in a bucket during traveling of the work machine.SOLUTION: A work machine includes a body to which a traveling body is attached, a work machine including a boom attached to the body and a bucket attached to the boom, a boom cylinder for changing an angle of the boom with respect to the body, a sensor for detecting thrust of the boom cylinder, and a controller for correcting the value of the detected thrust on the basis of an attitude of the boom cylinder with respect to the body and calculating a load mass in the bucket with the usage of the corrected value of the thrust.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present disclosure relates to a work machine and a load mass calculation method for a work machine. [Background technology]

[0002] Conventionally, as disclosed in JP 2021-95710 A (Patent Document 1), a controller included in a work machine calculates the mass of a load in a bucket. In Patent Document 1, the controller calculates the mass of a load in a bucket using an arithmetic expression that includes, as a variable, the thrust of a boom cylinder that operates the boom. The arithmetic expression is derived from a balance equation for the moment around the boom foot pin. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-95710 Summary of the Invention [Problem to be solved by the invention]

[0004] When a certain amount of inertial force is applied to the boom cylinder due to the travel of the work machine, the magnitude of the component of inertial force applied in the extension direction of the boom cylinder varies depending on the angle of the boom or the angle of the boom cylinder relative to the main body of the work machine. For this reason, even if the detected value of the thrust of the boom cylinder is substituted into the above calculation formula, it may not be possible to accurately calculate the mass of the load in the bucket.

[0005] The present disclosure provides a work machine and a load mass calculation method that are capable of accurately calculating the load mass in a bucket while the work machine is traveling. [Means for solving the problem]

[0006] According to one aspect of the present disclosure, a work machine includes a work implement including a main body to which a traveling body is attached, a boom attached to the main body, and a bucket attached to the boom, a boom cylinder that changes the angle of the boom relative to the main body, a sensor that detects the thrust of the boom cylinder, and a controller that corrects the detected thrust value based on the attitude of the boom cylinder relative to the main body and calculates the load mass in the bucket using the corrected thrust value.

[0007] In accordance with another aspect of the present disclosure, a method for calculating a load mass of a self-propelled work machine includes the steps of detecting a thrust of a boom cylinder that changes an angle of a boom relative to a main body to which a work implement including a boom and a bucket is connected, correcting the detected thrust based on the attitude of the boom cylinder relative to the main body, and calculating the load mass in the bucket using the corrected thrust value. Effect of the Invention

[0008] According to the above disclosure, it is possible to accurately calculate the mass of the load in the bucket when the work machine is traveling. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a side view of the wheel loader. [Diagram 2] FIG. 2 is a diagram for explaining the dimensions of each part of the working machine and the balance of four moments. [Diagram 3] FIG. 4 is a diagram for explaining details of a moment due to the weight of a work machine. [Figure 4] FIG. [Diagram 5] FIG. 4 is a diagram for explaining the balance of forces when the wheel loader is traveling. [Figure 6] FIG. 2 is a functional block diagram showing a functional configuration of the wheel loader. [Figure 7] FIG. 4 is a flowchart illustrating a flow of a process executed by a controller. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the specification and the drawings, the same components or corresponding components are denoted by the same reference numerals, and duplicate explanations are not repeated. Also, in the drawings, for convenience of explanation, the configuration may be omitted or simplified. Further, at least a part of each embodiment and each modification may be arbitrarily combined with each other.

[0011] <A. Configuration of the working machine> As an example of the working machine according to the present embodiment, the configuration of a wheel loader will be described with reference to FIG. 1. Note that the working machine in the present embodiment is not limited to a wheel loader. The working machine of the present embodiment may be any working machine having wheels for excavation while traveling, such as a backhoe loader or a skid steer loader.

[0012] FIG. 1 is a side view of a wheel loader as an example of the working machine according to Embodiment 1. As shown in FIG. 1, the wheel loader 1 has a vehicle body frame 2, a working machine 3, a traveling device 4, and a cab 5. The wheel loader 1 further has a controller 50 (FIG. 6) for measuring the load mass in a bucket 14 described later.

[0013] The machine body 9 of the wheel loader 1 is composed of the vehicle body frame 2 and the cab 5. Inside the cab 5, a seat on which an operator sits, an operating device, a monitor, and the like are arranged. The operating device includes an operation lever for traveling (forward and backward) (hereinafter also referred to as a "travel lever"), an operation lever for the working machine 3, an input device, and the like. The working machine 3 and the traveling device 4 are attached to the machine body 9 of the wheel loader 1. The working machine 3 is arranged in front of the machine body 9, and a counterweight 6 is provided at the rearmost end of the machine body 9.

[0014] The vehicle body frame 2 includes a front frame 11 and a rear frame 12. A steering cylinder 13 is attached to the front frame 11 and the rear frame 12. The steering cylinder 13 is a hydraulic cylinder. The steering cylinder 13 expands and contracts with hydraulic oil from a steering pump (not shown). The expansion and contraction of the steering cylinder 13 allows the front frame 11 and the rear frame 12 to swing left and right relative to each other. This allows the traveling direction of the wheel loader 1 to be changed left and right.

[0015] In this specification, the direction in which the wheel loader 1 travels straight ahead is referred to as the fore-and-aft direction of the wheel loader 1. In the fore-and-aft direction of the wheel loader 1, the side where the work machine 3 is arranged relative to the vehicle body frame 2 is referred to as the front direction, and the side opposite the front direction is referred to as the rear direction. The left-right direction of the wheel loader 1 is the direction perpendicular to the fore-and-aft direction in a plan view. Looking forward, the right and left sides in the left-and-aft direction are the right direction and the left direction, respectively. The up-and-down direction of the wheel loader 1 is the direction perpendicular to the plane defined by the fore-and-aft direction and the left-and-aft direction. In the up-and-down direction, the side with the ground is the lower side, and the side with the sky is the upper side.

[0016] The traveling device 4 includes traveling wheels 4a, 4b. Each of the traveling wheels 4a, 4b is a wheel and has a tire made of rubber. The traveling wheel (front wheel) 4a is rotatably attached to the front frame 11. The traveling wheel (rear wheel) 4b is rotatably attached to the rear frame 12. The wheel loader 1 is self-propelled by the traveling wheels 4a, 4b being rotationally driven.

[0017] The work implement 3 is for performing work such as excavation. The work implement 3 is attached to a front frame 11. The work implement 3 includes a bucket 14, a boom 15, a bell crank 16, a tilt rod 17, a boom cylinder 18, and a bucket cylinder 19.

[0018] The base end of the boom 15 is rotatably attached to the front frame 11 by a boom foot pin 21. The boom 15 is thereby rotatably attached to the machine body 9. The bucket 14 is rotatably attached to the tip of the boom 15 by a bucket pin 22.

[0019] The boom cylinder 18 drives the boom 15. One end of the boom cylinder 18 is rotatably attached to the front frame 11 of the machine body 9 by a pin 23. In this way, the boom cylinder 18 is rotatably attached to the machine body 9. The other end of the boom cylinder 18 is rotatably attached to the boom 15 by a pin 24.

[0020] The boom cylinder 18 is, for example, a hydraulic cylinder. The boom cylinder 18 expands and contracts with hydraulic oil from a work equipment pump (not shown). This drives the boom 15, and the bucket 14 attached to the tip of the boom 15 moves up and down.

[0021] The boom cylinder 18 is attached to the machine body 9 through a tube 18a (cylinder tube) and the boom 15. The boom cylinder 18 is attached to the tube 18a through a thrust F of the boom cylinder 18. cyl The boom cylinder 18 has a rod 18b (piston rod) that is moved by hydraulic pressure. The rod 18b has a piston 18c. The piston 18c moves within the tube 18a by hydraulic pressure, thereby changing the stroke length of the boom cylinder 18.

[0022] Bell crank 16 is rotatably supported on boom 15 by a support pin 29. Bell crank 16 has a first end located on one side of support pin 29 and a second end located on the opposite side of support pin 29 to the first end. The first end of bell crank 16 is connected to bucket 14 via tilt rod 17. The second end of bell crank 16 is connected to front frame 11 of machine body 9 via bucket cylinder 19.

[0023] One end of the tilt rod 17 is rotatably attached to a first end of the bell crank 16 by a pin 27. The other end of the tilt rod 17 is rotatably attached to the bucket 14 by a pin 28.

[0024] The bucket cylinder 19 drives the bucket 14 relative to the boom 15. The bucket cylinder 19 has one end and the other end opposite the one end. One end of the bucket cylinder 19 is rotatably attached to the front frame 11 of the machine body 9 by a pin 25. The other end of the bucket cylinder 19 is rotatably attached to the second end of the bell crank 16 by a pin 26.

[0025] The bucket cylinder 19 is, for example, a hydraulic cylinder. The bucket cylinder 19 expands and contracts by hydraulic oil from a work equipment pump (not shown). This drives the bucket 14, and the bucket 14 rotates up and down relative to the boom 15.

[0026] The wheel loader 1 is driven by the thrust F of the boom cylinder 18. cyl The bucket cylinder 19 further includes a sensor (a second sensor) that detects information regarding the thrust of the bucket cylinder 19.

[0027] The sensors that detect information related to the thrust of the boom cylinder 18 are, for example, pressure sensors 31b and 31h. Each of the pressure sensors 31b and 31h detects the cylinder pressure of the boom cylinder 18. The pressure sensor 31b detects the bottom pressure of the boom cylinder 18. The pressure sensor 31h detects the head pressure of the boom cylinder 18.

[0028] The head pressure means the pressure on the cylinder rod side of the piston of a hydraulic cylinder, and the bottom pressure means the pressure on the tube side of the piston.

[0029] The sensors that detect information related to the thrust of the bucket cylinder 19 are, for example, pressure sensors 32b and 32h. Each of the pressure sensors 32b and 32h detects the cylinder pressure of the bucket cylinder 19. The pressure sensor 32b detects the bottom pressure of the bucket cylinder 19. The pressure sensor 32h detects the head pressure of the bucket cylinder 19.

[0030] The wheel loader 1 further has sensors that detect information relating to the attitude of the work implement 3. The sensors that detect information relating to the attitude of the work implement 3 include, for example, a sensor (first sensor) that detects information relating to the boom angle, and a sensor that detects information relating to the bucket angle relative to the boom. Details of the information relating to the attitude of the work implement 3 will be described later (FIG. 2).

[0031] The boom angle is the angle of the boom 15 relative to the front frame 11 of the machine body 9. The bucket angle is the angle of the bucket 14 relative to the boom 15. More specifically, the boom angle is the angle between the boom 15 and an imaginary axis extending in the fore-and-aft direction of the vehicle body in a side view of the wheel loader 1 (FIG. 1) (more specifically, an axis that is horizontal when the wheel loader 1 is in a horizontal state). This point also applies to the angle of the boom cylinder 18, which will be described later.

[0032] The sensor that detects information related to the boom angle is, for example, a potentiometer 33. The potentiometer 33 is attached so as to be concentric with the boom foot pin 21. Instead of the potentiometer 33, a stroke sensor 35 of the boom cylinder 18 may be used as the sensor that detects information related to the boom angle.

[0033] As a sensor for detecting information related to the boom angle, an IMU (Inertial Measurement Unit) 37 or an imaging device (e.g., a camera) 39 may be used. The IMU 37 is attached to, for example, the boom 15. The imaging device 39 is attached to the machine body 9 (e.g., the cab 5).

[0034] The sensor for detecting information regarding the bucket angle is, for example, the potentiometer 34. The potentiometer 34 is attached so as to be concentric with the support pin 29. As the sensor for detecting information regarding the bucket angle, instead of the potentiometer 34, the stroke sensor 36 of the bucket cylinder 19 may be used.

[0035] As the sensor for detecting information regarding the bucket angle, the IMU 38 or the imaging device 39 may be used. The IMU 38 is attached to, for example, the tilt rod 17.

[0036] The above potentiometers 33, 34, stroke sensors 35, 36, IMUs 37, 38, and imaging device 39 may be used as sensors for detecting information regarding the position of the center of gravity GC1 of the working machine 3. The above potentiometers 33, 34, stroke sensors 35, 36, IMUs 37, 38, and imaging device 39 may be used as sensors for detecting information regarding the position of the center of gravity GC2 of the load in the bucket 14.

[0037] The wheel loader 1 may further include an angle sensor 40. The angle sensor 40 detects the tilt angle (pitch angle) of the machine body 9 with respect to the direction (horizontal plane) perpendicular to the reference gravity direction. As this angle sensor 40, for example, an IMU attached to the machine body 9 may be used. If the angle sensor 40 is attached to the machine body 9, it may be attached to any of the front frame 11, the rear frame 12, and the cab 5.

[0038] <B. Calculation of Instantaneous Payload Value> FIG. 2 is a diagram for explaining the dimensions of each part of the working machine 3 and the balance of the four moments. FIG. 3 is a diagram for explaining the details of the moment due to the weight of the working machine 3 among the four moments.

[0039] (b1. Dimensions) The above-mentioned "information regarding the posture of the work machine 3" is the dimension Rl2 and the dimension Rb5, as shown in Fig. 2. The dimension Rl2 is the dimension between the boom foot pin 21 and the pin 23, and is the dimension in the direction perpendicular to the extension direction of the boom cylinder 18. The dimension Rb5 is the dimension between the boom foot pin 21 and the pin 26, and is the dimension in the direction perpendicular to the extension direction of the bucket cylinder 19.

[0040] The above-mentioned "information relating to the position of the center of gravity GC1 of the work machine 3" is the dimension Rl3. The dimension Rl3 is the dimension between the center of gravity GC1 and the boom foot pin 21, and is the dimension along the front-to-rear direction of the wheel loader 1. When the wheel loader 1 is placed on a level ground, the dimension Rl3 is the dimension along the horizontal direction between the center of gravity GC1 and the boom foot pin 21.

[0041] The above-mentioned "information relating to the position of the center of gravity GC2 of the load in the bucket 14" is the dimension Rl1. The dimension Rl1 is the dimension between the center of gravity GC2 and the boom foot pin 21, and is the dimension along the front-to-rear direction of the wheel loader 1. When the wheel loader 1 is placed on level ground, the dimension Rl1 is the dimension along the horizontal direction between the center of gravity GC2 and the boom foot pin 21.

[0042] Dimension Rb1 is the dimension between the load center GC2 and the pin 22, and is the dimension along the front-to-rear direction of the wheel loader 1. Dimension Rb1 is the dimension along the horizontal direction between the load center GC2 and the pin 22 when the wheel loader 1 is placed on level ground.

[0043] Dimension Rb2 is the dimension between pin 22 and pin 27, and is the dimension in the direction perpendicular to the extension direction of tilt rod 17. Dimension Rb3 is the dimension between pin 27 and support pin 29, and is the dimension in the direction perpendicular to the extension direction of tilt rod 17. Dimension Rb4 is the dimension between pin 26 and support pin 29, and is the dimension in the direction perpendicular to the extension direction of bucket cylinder 19.

[0044] The dimension Rb6 is the dimension between the center of gravity GC3 of the bucket 14 and the pin 22, and is the dimension along the front-to-rear direction of the wheel loader 1. The dimension Rb6 is the dimension along the horizontal direction between the center of gravity GC3 of the bucket 14 and the pin 22 when the wheel loader 1 is placed on level ground.

[0045] The values ​​of Rl1, Rl2, and Rbi (i = 1 to 6) are calculated by the controller 50 based on the design dimensions, boom angle, and bucket angle of each member constituting the work machine 3. Note that, since the controller 50 performs calculations using the center of gravity position of each component part of the work machine 3 as will be described with reference to Fig. 3, calculation of Rl3 is not essential.

[0046] (b2. Moment balance) In the following, the balance of the four moments determines the instantaneous payload value W load Calculate the moment a due to the weight F1 of the load with reference to Figure 2. Wload is expressed by the following equation (1).

[0047]

number

[0048] In addition, in formula (1), g is the gravitational acceleration. The same applies to formula (4) described later.

[0049] Moment b due to weight F2 of work machine 3 Wload is calculated by multiplying the weight F2 of the work machine 3 by Rl3 (Figure 2). Wload With reference to FIG. 3, is expressed by the following formula (2).

[0050]

number

[0051] In addition, in formula (2), Wg bucketis the mass of the bucket 14. The same applies to the equation (4) described later. tiltrod is the mass of the tilt rod 17. Wg bellcrank is the mass of the bell crank 16. Wg boom is the mass of the boom 15. In the following, these masses are referred to as "Wg j " (where j = bucket, tiltrod, bellcrank, boom).

[0052] Rg bucket is the horizontal distance from the boom foot pin 21 to the center of gravity of the bucket 14. Rg tiltrod is the horizontal distance from the boom foot pin 21 to the center of gravity of the tilt rod 17. Rg bellcrank is the horizontal distance from the boom foot pin 21 to the center of gravity of the bell crank 16. Rg boom is the horizontal distance from the boom foot pin 21 to the center of gravity of the boom 15. In the following, these horizontal distances are expressed as "Rg j " can also be written.

[0053] β is an unladen correction coefficient. β is a coefficient for correcting the unladen state when buckets 14 of different weights are attached to the boom 15. The same applies to the equation (4) described later.

[0054] MassCorrectionFactor is a coefficient that changes when the specifications of the work machine differ, such as a high-lift boom. In the case of standard specifications, the value of MassCorrectionFactor is "1".

[0055] Referring to FIG. 2, the thrust F of the boom cylinder 18 cyl Moment c by Wload is expressed by the following equation (3).

[0056]

number

[0057] In addition, in equation (3), η is the hydraulic transmission efficiency of the boom 15.

[0058] Moment d due to reaction force F4 of bucket 14 Wload is expressed by the following equation (4).

[0059]

number

[0060] Moment a due to the weight of the load F1 Wload and moment b due to the weight F2 of the work machine 3. Wload and the thrust F of the boom cylinder 18 cyl Moment c by Wload and moment d due to reaction force F4 of bucket 14 Wload There is a balance relationship between them as shown in the following equation (5).

[0061]

number

[0062] (b3. Instantaneous payload value correction) From equation (5), the instantaneous payload value W load The instantaneous payload value W is calculated as follows: load is included in equations (1) and (4).

[0063]

number

[0064] The instantaneous payload value W obtained from equation (6) load The load correction coefficient γ is multiplied by the thrust F of the boom cylinder 18. cyl With respect to the correction coefficient δ a This results in the corrected instantaneous payload value W as shown in the following equation (7). load_CR get.

[0065] [Number]

[0066] The controller 50 (Fig. 6) of the wheel loader 1 calculates the payload mass based on the instantaneous payload value W obtained from the mathematical formula shown in Equation (7). load_CR Specifically, the controller 50 calculates the payload mass periodically. The controller 50 outputs the calculated payload mass to the monitor in the cab 5. For example, the controller 50 displays the average value of a plurality of instantaneous payload values W obtained by consecutive calculation cycles on the monitor as the payload mass. Typically, when the controller 50 determines that the excavation operation by the working machine 3 has ended, it displays the calculated payload mass on the monitor. The end of the excavation operation is determined by the controller 50 based on the reverse state, raising of the boom 15, decrease in the boom bottom pressure, etc. load_CR

[0067] <C. Correction coefficient δ a > Next, the correction coefficient δ in Equation (7) will be described. As shown in Equation (8) below, when the wheel loader 1 is in the payload transportation process (the state of the wheel loader 1 is the payload transportation state), the controller 50 uses the mathematical formula (fraction formula) in the upper row in Equation (8) to correct the thrust F of the boom cylinder 18. a In this example, the controller 50 determines that the wheel loader 1 is in the payload transportation process when the posture of the boom cylinder 18 is in the horizontal state and / or when the wheel loader 1 is in the reverse state. cyl

[0068] In other cases (when the wheel loader 1 is not in the payload transportation process), as shown in the lower row in Equation (8), the controller 50 sets the value of the correction coefficient δ to "1". That is, the controller 50 does not correct the thrust F of the boom cylinder 18. a cyl

[0069] [Number]

[0070] In addition, in equation (8), A is a constant. lowBoom is a constant related to the boom angle. boom is the boom angle (variable). vehicle represents the horizontal acceleration (variable) of the machine body 9.

[0071] The value of constant A is the acceleration a per boom angle. vehicle and the thrust of the boom cylinder F cyl The value of constant A may be a decimal number less than 1. Specifically, the value of constant A is calculated in advance by the following method. Note that the calculation of the value of constant A is not limited to the controller 50, and may be performed by another information processing device.

[0072] Using the results of a simple test at the bucket full weight level, the acceleration a in the load update section with the boom 15 stopped vehicle and the thrust F of the boom cylinder of 18 cyl The acceleration a detected during the load reversing and boom 15 stop section is vehicle Thrust force F cyl The slope of the approximation line is found by plotting how many times the interval average is.

[0073] The slope is the acceleration a vehicle This indicates the degree of influence of inertia. The inclination and boom angle at that time are found for each excavation operation, and the inclination is plotted on the vertical axis and the boom angle on the horizontal axis. This point cloud roughly follows a cosine function (cos function) in which the inclination is minimum when the boom angle during reverse movement with a load is -30° (lower limit value), and the inclination is 0 when the boom angle is 0° (horizontal). For this reason, the relationship between the boom angle and the magnitude of the influence of inertia is determined by this cosine function. The amplitude of the cosine function at this time is defined as A. Note that since the moment that the load receives differs depending on the model of wheel loader 1, it is preferable to set the constant A for each model of wheel loader.

[0074] Referring to Figs. 4 and 5, θ lowBoom A method for calculating θ will be described. FIG. 4 is a side view of the boom 15. lowBoom is an example of the "angle data" of the present invention.

[0075] As shown in Figure 4, in a side view of the boom 15, the center of the through hole into which the boom foot pin 21 is inserted is designated as position Pa. The center of the through hole into which the bucket pin 22 is inserted is designated as position Pb. The center of the through hole into which the pin 24 (Figure 1) that secures the boom cylinder 18 to the boom 15 is inserted is designated as position Pc. The center of the through hole into which the support pin 29 is inserted is designated as position Pd. Furthermore, the center of the through hole into which the pin 23 (Figure 1) that secures the boom cylinder 18 to the machine body 9 is inserted is designated as position Pe.

[0076] As shown in FIG. 4, the distance between position Pa and position Pb is defined as L1. In the following, the direction from position Pa toward position Pb is defined as P direction. The direction perpendicular to the P direction is defined as Q direction. Similarly, the distance in the P direction between position Pa and position Pc is defined as L2. The distance in the Q direction between position Pa and position Pc is defined as L3. The distance in the P direction between position Pa and position Pd is defined as L4. The distance in the Q direction between position Pb and position Pd is defined as L5. Each of the distances L1 to L5 is a constant value and does not change.

[0077] θ lowBoom When calculating, of the distances L1 to L5, the distances L2 and L3 are used. In the following, the distance between the position Pa and the position Pc is defined as L. Note that, according to Pythagoras' theorem, the distance L is the square root of the sum of the square of the distance L2 and the square of the distance L3 (i.e., L = (L2 2 +L3 2 ) 1 / 2 )

[0078] The following description will be given using an XY coordinate system with its origin at position Pa. The XY coordinate system is a two-dimensional coordinate system with the Y axis pointing vertically upward and the X axis pointing in the horizontal direction along the travel direction of the wheel loader 1.

[0079] Boom angle θboom Using this, the X coordinate of position Pc is C x and Y coordinate C y are respectively expressed by the following formulas (9) and (10). Note that λ in formulas (9) and (10) is a constant shown in the following formula (11).

[0080]

number

[0081]

number

[0082]

number

[0083] The x and y coordinates of the mounting position of the boom cylinder 18 on the machine body 9 (i.e., position Pe) are respectively x cmt ,y cmt Then, the angle α (variable) of the boom cylinder 18 with respect to the machine body 9 is obtained by the following equation (12).

[0084]

number

[0085] Therefore, the angle α of the boom cylinder 18 is the boom angle θ boom It can be seen that it is a function of .

[0086] The x and y coordinates of the mounting position of the boom 15 on the machine body 9 (i.e., position Pa) are respectively x bmt ,y bmt Then, the above-mentioned dimension Rl2 (FIG. 2) can be calculated by the following formula (13). Note that in this example, since the position Pa is the origin as described above, x bmt ,y bmt are zero, respectively.

[0087]

number

[0088] Therefore, for dimension Rl2, the boom angle θ boom It can be seen that it is a function of .

[0089] In this way, the angle α of the boom cylinder 18 and the dimension Rl2 are related to the boom angle θ boom is given, it is uniquely determined based on the geometric relationship between the boom 15 and the boom cylinder 18. Therefore, even for a wheel loader of a different size from the wheel loader 1, the angle α of the boom cylinder 18 and the dimension Rl2 can be determined by the boom angle θ boom Regardless of the size of the wheel loader, the angle α and the dimension Rl2 of the boom cylinder 18 can be generalized.

[0090] The controller 50 calculates the angle of the boom cylinder 18 based on the geometric relationship between the boom 15 and the boom cylinder 18. In detail, the controller 50 calculates the angle of the boom cylinder 18 based on the dimensions of the boom 15, the attachment position of the base end of the boom cylinder 18 relative to the machine body 9, the attachment position of the tip end of the boom cylinder 18 relative to the bucket 14, and the boom angle θ boom The base end is the end of the boom cylinder 18 that is attached to the machine body 9 (the one end mentioned above). The tip end is the end of the boom cylinder 18 that is attached to the boom 15 (the other end mentioned above).

[0091] The method of calculating the angle of the boom cylinder 18 is not limited to the above. The wheel loader 1 may be equipped with a sensor (first sensor) that detects the angle of the boom cylinder 18, and the controller 50 may acquire (calculate) the angle of the boom cylinder 18 based on the output from the sensor.

[0092] A stroke sensor 35 of the boom cylinder 18 may be used as a sensor for detecting information relating to the angle of the boom cylinder 18. An imaging device 39 may be used as a sensor for detecting information relating to the angle of the boom cylinder 18. Also, a potentiometer (not shown) may be attached concentrically with the pin 23 and used as a sensor for detecting information relating to the angle of the boom cylinder 18.

[0093] 5 is a diagram for explaining the balance of forces when the wheel loader 1 is traveling. As shown in FIG. 5, a horizontal force F ma (i.e., inertia force) is the reaction force F generated in the boom cylinder 18 c To be balanced.

[0094] Reaction force F c The force in the extension direction of the boom cylinder 18 (reaction force F c The moment M around the boom foot pin 21 due to the component of the boom cylinder 18 is expressed by the following formula (14). The angle α of the boom cylinder 18 and the dimension Rl2 are related to the boom angle θ boom Since this is a function of the boom angle θ, the moment M is also a function of the boom angle θ boom It is a function of .

[0095]

number

[0096] As shown in the following equation (15), the boom angle θ when the moment M is maximum is boom The value of θ lowBoom Let us assume that.

[0097]

number

[0098] θ lowBoomThe value of θ is 30° in this example. When the wheel loader 1 is traveling, the boom angle at which the force in the telescoping direction of the boom cylinder 18 received by the boom cylinder 18 due to the inertial force generated is maximized is approximately -30°. Therefore, θ lowBoom is 30°. Specifically, since the boom angle when the posture of the boom cylinder 18 becomes horizontal is approximately -30°, θ lowBoom is 30°. Note that the value of θ lowBoom is appropriately set for each model of the wheel loader.

[0099] In addition, if a sensor for detecting the angle of the boom cylinder 18 is mounted on the wheel loader 1, θ lowBoom can be calculated more easily than by using the boom angle as described above. lowBoom

[0100] <D. Parentheses> [1] As shown in the above formula (7), the controller 50 corrects the value of the thrust F a of the boom cylinder 18 by multiplying it by the correction coefficient δ cyl . During the load carrying process, the correction coefficient δ a includes the boom angle θ boom as a variable as shown in the formula above the formula (8). The value of the correction coefficient δ a becomes "1" when the acceleration a vehicle is zero. Specifically, when the machine body 9 is moving at a constant speed and the value of the acceleration a vehicle is 0, the correction coefficient δ a is the same as the value "1" of δ a used when not in the load carrying process. Thus, the correction coefficient δ a in the formula (8) is a coefficient that acts when the machine body 9 is accelerating or decelerating. Therefore, when the acceleration a vehicle is zero, as a result, the value of the thrust F cyl of the boom cylinder 18 is not corrected.

[0101] In this way, the controller 50 determines the boom angle θ boom ​Based on this, the thrust F of the boom cylinder 18 detected by the sensor cyl Furthermore, the controller 50 corrects the value of the corrected thrust (F cyl ×δ a ) is used to calculate the mass of the cargo in the bucket 14.

[0102] In the wheel loader 1, the boom angle θ boom The attitude of the boom cylinder 18 and the boom angle θ boom There is such a correlation between the boom angle θ boom Once K is known, the geometric relationships can be used to determine the attitude of the boom cylinder 18 (in this example, the angle of the boom cylinder 18), as described above.

[0103] In this way, the boom angle θ boom It is the attitude of the boom cylinder 18 that determines the thrust F of the boom cylinder 18 detected by the sensor based on the attitude of the boom cylinder 18 relative to the machine body 9. cyl It can be said that the value of is corrected.

[0104] For details, see the attitude of the boom cylinder 18 and the boom angle θ boom From the relationship between the correction coefficient δ in Eq. (8), a Boom angle θ boom (second variable) can be replaced with a mathematical expression including the angle (second variable) of the boom cylinder 18. As is clear from this, the controller 50 controls the thrust F of the boom cylinder 18 based on the attitude of the boom cylinder 18. cyl It can be said that the value of is corrected.

[0105] When the load transport process is not in progress, the controller 50 controls the thrust F of the boom cylinder 18. cyl Without correcting the value of cyl The cargo mass is calculated using

[0106] Incidentally, when a certain amount of inertial force is applied to the boom cylinder 18 due to the travel of the wheel loader 1, the magnitude of the component of the inertial force applied in the extension direction of the boom cylinder 18 varies depending on the attitude of the boom cylinder 18 relative to the machine body 9 of the wheel loader 1. For this reason, particularly during the load transport process, the detected thrust force F cyl If the value of is used without correction, the mass of the cargo in the bucket cannot be calculated with high accuracy.

[0107] As described above, the controller 50 calculates the thrust F of the boom cylinder 18 based on the attitude of the boom cylinder 18. cyl The value of is corrected, and the corrected thrust (F cyl ×δ a ) is used to calculate the mass of the load in the bucket 14. In this way, the controller 50 calculates the mass of the load in the bucket 14 while the wheel loader 1 is traveling, taking into account the attitude of the boom cylinder 18.

[0108] Therefore, according to the wheel loader 1, it is possible to accurately calculate the mass of the load in the bucket while the wheel loader 1 is traveling. load_CR Since is calculated with high accuracy, as a result, the mass of the cargo in the bucket can be calculated with high accuracy.

[0109] [2] In detail, the controller 50 determines that the attitude of the boom cylinder 18 is horizontal and then adjusts the corrected thrust (F cyl ×δ a ) is used to calculate the mass of the load in the bucket 14. As described above, the angle of the boom cylinder 18 is determined by the boom angle θ boom When the angle of the boom cylinder 18 is in the range of -10° or more and 10° or less, the controller 50 determines that the attitude of the boom cylinder 18 is horizontal.

[0110] [3] Similarly, the controller 50 determines that the wheel loader 1 is in a reverse drive state and then adjusts the corrected thrust (F cyl ×δ a) to calculate the mass of the load in the bucket 14. In this example, the controller 50 judges whether the traveling direction of the wheel loader 1 is the reverse direction based on the operation information (operation state) of the travel lever 53 (FIG. 6). In particular, if the position of the travel lever 53 is in the reverse position, the controller 50 judges that the traveling direction of the wheel loader 1 is the reverse direction. The controller 50 may also judge whether the traveling direction of the wheel loader 1 is the reverse direction based on the rotation direction of the running wheels 4a.

[0111] [4] More specifically, after the excavation object (earth and sand, etc.) is scooped into the bucket 14 by the excavation process (scooping), the wheel loader 1 executes a load reverse process in which the wheel loader 1 is moved backward. In the load reverse process, the wheel loader 1 usually moves backward while keeping the angle of the boom 15 constant (specifically, an angle between -40° and -20°). Thereafter, the wheel loader 1 executes a load forward process in which the wheel loader 1 is moved forward and approached a dump truck (not shown) while raising the bucket 14 or while maintaining a state in which the bucket 14 was raised partway through. Next, the wheel loader 1 executes an earth discharge process in which the bucket 14 is dumped at a predetermined position and the excavation object is loaded onto the dump truck bed.

[0112] When the angle of the boom 15 is between -40° and -20°, the angle of the boom cylinder 18 is between -10° and 10°. In this way, in the load reverse process, the wheel loader 1 moves backward with the boom cylinder 18 in a horizontal position.

[0113] Therefore, when the wheel loader 1 is in a loaded reverse state, the controller 50 calculates the load mass in the bucket 14, taking into account the attitude of the boom cylinder 18. Specifically, the controller 50 calculates the corrected thrust (F cyl ×δ a) is used to calculate the mass of the load in the bucket 14. Therefore, with the wheel loader 1, it is possible to accurately calculate the mass of the load in the bucket 14 during the load reversing process. With the wheel loader 1, it is possible to accurately calculate the mass of the load in the bucket 14 during the load reversing process, which is an earlier stage than the load forwarding process. Therefore, the operator of the wheel loader 1 can know the mass of the load with high accuracy at an early stage.

[0114] [5] The controller 50 determines the boom angle θ when the force acting on the boom cylinder 18 in the extension / retraction direction of the boom cylinder 18 due to the inertial force generated when the wheel loader 1 is traveling is maximized. boom θ lowBoom The controller 50 stores the value (angle data) of the boom angle θ as shown in the formulas (7) and (8). boom In addition, θ lowBoom The thrust F of the boom cylinder 18 is further calculated using the value of cyl By correcting the value of θ lowBoom Without using the value of cyl This allows the cargo mass to be calculated with higher accuracy than when the value of is corrected.

[0115] [6] θ lowBoom The value of (angle data) is the reaction force F generated by the boom cylinder 18. c The boom angle θ when the moment around the boom foot pin 22 with respect to the force in the extension / retraction direction of the boom cylinder 18 is maximized. boom Such a boom angle θ boom In this case, the force in the extension / contraction direction of the boom cylinder 18 that is received by the boom cylinder 18 due to the inertial force generated during traveling becomes maximum.

[0116] [7] The controller 50 controls the thrust F of the boom cylinder 18. cylIt stores a second arithmetic expression obtained by multiplying a correction coefficient δa for correcting the value of the variable (first variable) with respect to a first arithmetic expression including the variable. The second arithmetic expression is the above-described formula (7). The first arithmetic expression is a formula obtained by multiplying the above-described formula (6) by a load correction coefficient γ.

[0117] The correction coefficient δa includes, as a variable (second variable), the boom angle θ boom As shown in the above-described formula (5), the first arithmetic expression is the moment a Wload due to the load in the bucket 14 and the moment b Wload due to the weight of the working machine 3, and the sum of the moment c cyl due to the thrust F Wload of the boom cylinder 18 and the moment d Wload due to the reaction force of the bucket 14. The controller 50 calculates the load mass in the bucket 14 based on the second arithmetic expression (formula (7)).

[0118] In this way, the controller 50 calculates the load mass in the bucket 14 using the second arithmetic expression obtained by correcting the thrust F cyl of the boom cylinder 18 included in the first arithmetic expression derived from the balance of the above four moments by the correction coefficient δa. Therefore, according to such a configuration, the load mass can be calculated with higher accuracy compared to the case of directly using the first arithmetic expression. Note that the correction coefficient δa may include, as a variable (second variable), the angle of the boom cylinder 18 instead of the boom angle θ boom .

[0119] <E. Functional Configuration> Next, the functional configuration of the wheel loader 1 will be described. In particular, the functional blocks of the controller 50 for measuring the load mass in the bucket 14 of the wheel loader 1 shown in FIG. 1 will be described with reference to FIG. 6.

[0120] Figure 6 is a functional block diagram showing the functional configuration of the wheel loader 1. As shown in Figure 6, the wheel loader 1 is equipped with a controller 50, an input unit 51, and a display unit 52. The input unit 51 corresponds to an input device such as an operation panel. The operation panel can be configured to include hard keys and / or software keys. The display unit 52 corresponds to a monitor. The input unit 51 and the display unit 52 are installed inside the cab 5.

[0121] The controller 50 includes a memory unit 500, a boom cylinder thrust calculation unit 501, a hydraulic transmission efficiency calculation unit 502, a dimension value calculation unit 503, a horizontal distance calculation unit 504, a cargo transport process determination unit 505, a horizontal acceleration acquisition unit 507, a correction coefficient determination unit 508, an instantaneous payload value calculation unit 509, a cargo mass calculation unit 510, and a display control unit 511.

[0122] The storage unit 500 stores in advance various data inputted via the input unit 51. The storage unit 500 stores the mass Wg bucket and the mass Wg of the tilt rod 17 tiltrod and the mass Wg of the bell crank 16 bellcrank and the mass Wg of the boom 15 boom , MassCorrectionFactor, an unladen correction coefficient β, a loaded correction coefficient γ, a work implement design dimension value, and a work implement design center of gravity position are stored.

[0123] The work machine design dimension values ​​are the design dimension values ​​of each part constituting the work machine 3, such as the bucket 14, boom 15, bell crank 16, tilt rod 17, etc. For the boom 15, the design dimension values ​​are, for example, the distance between the through hole into which the boom foot pin 21 is inserted and the through hole into which the bucket pin 22 is inserted, the distance between the through hole into which the boom foot pin 21 is inserted and the through hole into which the pin 24 is inserted, etc.

[0124] The work machine design center of gravity position is the center of gravity position (theoretical value) of each component constituting the work machine 3, such as the bucket 14, boom 15, bell crank 16, tilt rod 17, etc. The work machine design center of gravity position is the center of gravity position in a coordinate system specific to each component. The work machine design center of gravity position is indicated as a coordinate value for each component when a specific position of the component is set as the origin. The position of the origin can be set so that the work machine design center of gravity position can be expressed in a two-dimensional coordinate system. In this case, for example, for the boom 15, the center of the through hole into which the boom foot pin 21 is inserted in a side view of the boom 15 can be set as the specific position (origin).

[0125] The work machine design dimension values ​​are used in a dimension value calculation unit 503. The work machine design center of gravity position is used in a horizontal distance calculation unit 504. The mass Wg of the bucket 14 bucket and the mass Wg of the tilt rod 17 tiltrod and the mass Wg of the bell crank 16 bellcrank and the mass Wg of the boom 15 boom The MassCorrectionFactor, the unladen correction coefficient β, and the loaded correction coefficient γ are used in the instantaneous payload value calculation unit 509.

[0126] The boom cylinder thrust calculation unit 501 calculates the thrust F of the boom cylinder 18 described above based on the cylinder pressure detected by the pressure sensors 31b and 31h. cyl Specifically, the boom cylinder thrust calculation unit 501 calculates the thrust F based on the bottom pressure of the boom cylinder 18 acquired from the pressure sensor 31b and the head pressure acquired from the pressure sensor 31h. cyl The boom cylinder thrust calculation unit 501 periodically calculates the thrust F from only the bottom pressure of the boom cylinder 18. cyl The calculated thrust F cyl The value of is sent to the instantaneous payload value calculation unit 509.

[0127] The hydraulic transmission efficiency calculation unit 502 calculates the hydraulic transmission efficiency based on the boom angle θ boomIn detail, the hydraulic transmission efficiency calculation unit 502 calculates the hydraulic transmission efficiency η of the boom 15 based on the value of the boom angle θ boom The hydraulic transmission efficiency calculation unit 502 calculates the amount of change per unit time of the value of and determines the hydraulic transmission efficiency η based on the amount of change. The hydraulic transmission efficiency calculation unit 502 sends the calculated hydraulic transmission efficiency η to the instantaneous payload value calculation unit 509. The calculated hydraulic transmission efficiency η is substituted into the above-mentioned equation (7).

[0128] In addition, the boom angle θ boom Since the hydraulic transmission efficiency η cannot be calculated when the amount of change per unit time in the value of is zero, the hydraulic transmission efficiency calculation unit 502 sends, for example, the hydraulic transmission efficiency η calculated immediately before to the instantaneous payload value calculation unit 509.

[0129] As described above, instead of calculating the hydraulic transmission efficiency η each time, a fixed value determined in advance may be used as the hydraulic transmission efficiency η.

[0130] The dimension value calculation unit 503 calculates the above-mentioned work machine design dimension values ​​stored in the storage unit 500, the bucket angle, and the boom angle θ boom The dimension value calculator 503 periodically calculates the values ​​of the dimensions Rl1, Rl2, Rbi (i = 1 to 6) using the above. The dimension value calculator 503 sends the calculation results to the instantaneous payload value calculator 509.

[0131] The horizontal distance calculation unit 504 calculates the horizontal distance based on the work machine design center of gravity position, the bucket angle, and the boom angle θ boom Using the above horizontal distance Rg j Specifically, the horizontal distance calculation unit 504 calculates each horizontal distance Rg bucket ,Rg tiltrod ,Rg bellcrank ,Rg boom The horizontal distance calculation unit 504 sends the calculation result to the instantaneous payload value calculation unit 509.

[0132] The load transport process determination unit 505 determines whether or not the wheel loader 1 is in a load transport process. In particular, the load transport process determination unit 505 determines that the wheel loader 1 is in a load transport process when the attitude of the boom cylinder 18 is in at least one of the horizontal state and the wheel loader 1 is in a reverse drive state.

[0133] More specifically, the load transport process determination unit 505 determines whether the wheel loader 1 is in a reverse state based on the operation state of the travel lever 53. In this example, the load transport process determination unit 505 determines that the wheel loader 1 is in a reverse state if the travel lever 53 is in the reverse position. The load transport process determination unit 505 determines that the wheel loader 1 is not in a reverse state if the travel lever 53 is in a forward position or a neutral position.

[0134] More specifically, as described above, the load transport process determination unit 505 calculates the angle of the boom cylinder 18 based on the geometric relationship between the boom 15 and the boom cylinder 18. The load transport process determination unit 505 determines whether the attitude of the boom cylinder 18 is horizontal or not based on the angle of the boom cylinder 18. The load transport process determination unit 505 determines that the attitude of the boom cylinder 18 is horizontal when the angle of the boom cylinder 18 is in the range of -10° or more and 10° or less. Note that the determination is not limited to being based on the angle of the boom cylinder 18, and the controller 50 may also determine whether the attitude of the boom cylinder 18 is horizontal based on the boom angle θ boom is within a predetermined angle range (for example, a range of -40° or more and -20° or less), it may be determined that the load is being transported.

[0135] The load transfer process determination unit 505 determines that the load transfer process is in progress if it determines that the load is in the reverse state. The load transfer process determination unit 505 also determines that the load transfer process is in progress if it determines that the attitude of the boom cylinder 18 is horizontal. The load transfer process determination unit 505 determines that the load is not in progress if the load is not in the reverse state and the attitude of the boom cylinder 18 is not horizontal.

[0136] The cargo transport process determination unit 505 periodically sends a determination result indicating "load transport process in progress" or "load transport process not in progress" to the correction coefficient determination unit 508.

[0137] The horizontal acceleration acquisition unit 507 acquires the horizontal acceleration a vehicle The horizontal acceleration acquisition unit 507 periodically acquires the acceleration a vehicle The value of is periodically sent to the correction coefficient determination unit 508.

[0138] acceleration a vehicle For example, the horizontal acceleration acquisition unit 507 may acquire the horizontal acceleration a detected by an acceleration sensor (not shown). vehicle Alternatively, the horizontal acceleration acquisition unit 507 acquires the acceleration a from the data detected by the IMU. vehicle Alternatively, the horizontal acceleration acquisition unit 507 may calculate the acceleration a by differentiating the velocity of the machine body 9 with respect to time. vehicle The acceleration a may be calculated from the speed of the machine body 9. vehicle When calculating the acceleration a vehicle It is preferable to calculate

[0139] The correction coefficient determination unit 508 determines the correction coefficient δ based on the posture of the boom cylinder 18. a In detail, the correction coefficient determination unit 508 determines the boom angle θ boom Using the correction coefficient δ a Specifically, the correction coefficient determination unit 508 determines the boom angle θ boom The result of the judgment by the cargo transport process judgment unit 505 and the acceleration a acquired by the horizontal acceleration acquisition unit 507 vehicle Based on this, the correction coefficient δ a Specifically, the correction coefficient determination unit 508 determines the correction coefficient δ using the above-mentioned equation (8). a Determine.

[0140] When the judgment result of the cargo transport process judgment unit 505 is “in the cargo transport process”, the correction coefficient determination unit 508 calculates the correction coefficient δ using the formula in the upper row of the formula (8). a In this case, the correction coefficient determination unit 508 periodically determines the acceleration a vehicle Using the correction coefficient δ a Determine.

[0141] When the judgment result of the cargo transport process judgment unit 505 is “not in the cargo transport process”, the correction coefficient determination unit 508 calculates a correction coefficient δ as shown in the lower row of the formula (8). a Specifically, when the boom cylinder 18 is moving and the travel lever 53 is in the forward position or the neutral position, the correction coefficient determination unit 508 sets the correction coefficient δ a The value is set to “1”.

[0142] The correction coefficient determination unit 508 calculates the correction coefficient δ a The instantaneous payload value calculator 509 periodically sends the value of

[0143] The instantaneous payload value calculation unit 509 calculates the mass Wg bucket ,Wg tiltrod ,Wg bellcrank ,Wg boom , MassCorrectionFactor, each correction coefficient β, γ, and thrust F cyl , hydraulic transmission efficiency η, each dimension Rl1, Rl2, Rbi (i = 1 to 6), and each horizontal distance Rg bucket ,Rg tiltrod ,Rg bellcrank ,Rg boom and the correction coefficient δ a Based on this, the instantaneous payload value W load_CR is calculated periodically.

[0144] In detail, the instantaneous payload value calculation unit 509 calculates the instantaneous payload value W load_CR Calculate the mass of each bucket ,Wg tiltrod ,Wg bellcrank ,Wg boomand, as shown in the above-described formula (2), the MassCorrectionFactor is used for calculating "b" included in the numerator of formula (7). The instantaneous payload value calculation unit 509 periodically sends the instantaneous payload value W Wload to the payload mass calculation unit 510. load_CR

[0145] The payload mass calculation unit 510 calculates the average value of a plurality of continuously sent instantaneous payload values W load_CR and determines the average value as the payload mass. For example, the payload mass calculation unit 510 uses the average value of five continuously sent instantaneous payload values W load_CR as the payload mass. The payload mass calculation unit 510 sends the determined payload mass to the display control unit 511.

[0146] The display control unit 511 causes the payload mass to be displayed on the display unit 52. The display control unit 511 updates the value of the payload mass displayed on the display unit 52 each time it acquires the payload mass from the payload mass calculation unit 510.

[0147] <F. Control Structure> FIG. 7 is a flowchart for explaining the flow of processing executed by the controller 50. Note that FIG. 7 shows the processing up to the calculation of the instantaneous payload value W load_CR . Also, the series of processes shown in FIG. 7 is periodically and repeatedly executed.

[0148] In step S1, the controller 50 calculates the values of each dimension Rl1, Rl2, Rbi (i = 1 to 6). In step S2, the controller 50 calculates each horizontal distance Rg bucket , Rg tiltrod , Rg bellcrank , Rg boom . In step S3, the controller 50 calculates the value of the moment b Wload due to the working machine weight. Note that the calculated value of b Wload is substituted into formula (7).

[0149] In step S4, the controller 50 calculates the thrust F of the boom cylinder 18​cyl is calculated. In step S5, the controller 50 calculates the hydraulic transmission efficiency η based on the change amount of the boom angle θ boom per unit time. As described above, when the change amount per unit time of the value of the boom angle θ boom is zero, the controller 50 uses, for example, the hydraulic transmission efficiency η calculated immediately before.

[0150] In step S6, the controller 50 determines whether it is during the load transfer process. If it is determined that it is not during the load transfer process (NO in step S6), the controller 50 sets the value of the correction coefficient δ a to "1" in step S7. Specifically, the controller 50 refers to the above-described formula (8) and sets the value of the correction coefficient δ a to "1".

[0151] If it is determined that it is during the load transfer process (YES in step S6), the controller 50 obtains the value of the acceleration a vehicle in step S9. Further, in step S10, the controller 50 calculates the value of the correction δ vehicle using the value of the acceleration a a . Specifically, the controller 50 calculates the value of the correction coefficient δ a using the formula in the upper row of formula (8).

[0152] After step S7 or step S10, in step S8, the controller 50 substitutes the value of the correction coefficient δ a into the above-described formula (7) to calculate the instantaneous payload value W load_CR .

[0153] <G. Modification Example> (1) In the above, as shown in step S6 of FIG. 7, when it is during the load transfer process, the controller 50 corrects the thrust F cyl of the boom cylinder 18 by multiplying the formula in the upper row of formula (8) (correction coefficient δ a , variable), and the value of the corrected thrust (Fcyl ×δ a ) was used to calculate the mass of the load in the bucket 14. However, the present invention is not limited to this. The controller 50 controls the thrust F of the boom cylinder 18 regardless of whether the load is being transported or not. cyl The formula above (8) (correction coefficient δ a ) and correct the thrust value (F cyl ×δ a ) may be used to calculate the mass of the load in the bucket 14.

[0154] (2) The controller 50 calculates the instantaneous payload value W load_CR The controller 50 may output the instantaneous payload value W load_CR Without calculating the average of load_CR may be displayed on the display unit 52.

[0155] <Additional Notes> [Item 1] A main body to which the running body is attached; A work machine including a boom attached to the main body and a bucket attached to the boom; a boom cylinder that changes an angle of the boom relative to the main body; A sensor for detecting a thrust of the boom cylinder; a controller that corrects the detected thrust value based on an attitude of the boom cylinder relative to the main body, and calculates the load mass in the bucket using the corrected thrust value.

[0156] [Item 2] 2. The work machine according to item 1, wherein the controller calculates the load mass in the bucket using the corrected thrust value on condition that it is determined that the work machine is in a load transport process.

[0157] [Item 3] The work machine according to item 2, wherein the controller determines that the work machine is in a load transport process when the attitude of the boom cylinder is horizontal and / or when the work machine is in a reverse drive state.

[0158] [Item 4] The controller: angle data indicating an angle of the boom when a force in a direction in which the boom cylinder extends and retracts due to an inertial force generated when the work machine is traveling is maximized; 4. The work machine according to any one of items 1 to 3, further using the angle data to correct the detected thrust to calculate the load mass in the bucket.

[0159] [Item 5] A boom foot pin is further provided to connect the boom to the main body, 5. The work machine according to item 4, wherein the angle data is an angle of the boom when a moment about the boom foot pin for a force in a direction in which the boom cylinder extends and retracts, out of a reaction force generated in the boom cylinder, is maximized.

[0160] [Item 6] the controller stores a second arithmetic expression obtained by multiplying a first arithmetic expression including a thrust of the boom cylinder as a first variable by a correction coefficient for correcting a value of the first variable; The correction factor includes, as a second variable, an angle of the boom cylinder or an angle of the boom, the first calculation formula is derived from a balance between a sum of a moment due to a load in the bucket and a moment due to a weight of the work machine, and a sum of a moment due to a thrust of the boom cylinder and a moment due to a reaction force of the bucket, 6. The work machine according to any one of items 1 to 5, wherein the controller calculates the load mass in the bucket based on the second arithmetic expression.

[0161] [Item 7] 7. The work machine according to any one of items 1 to 6, wherein the controller calculates the attitude of the boom cylinder based on an angle of the boom cylinder.

[0162] [Item 8] The boom cylinder has a base end attached to the main body and a tip end attached to the bucket, 7. The work machine according to any one of items 1 to 6, wherein the controller calculates the attitude of the boom cylinder based on a dimension of the boom, an attachment position of the base end relative to the main body, an attachment position of the tip end relative to the bucket, and an angle of the boom relative to the main body.

[0163] [Item 9] A first sensor that detects an angle of the boom cylinder; and a second sensor for detecting the thrust. 9. The work machine according to item 8, wherein the controller further acquires a result of the detection by the first sensor and a result of the detection by the second sensor.

[0164] [Item 10] A first sensor that detects an angle of the boom; and a second sensor for detecting the thrust. 9. The work machine according to item 8, wherein the controller further acquires a result of the detection by the first sensor and a result of the detection by the second sensor.

[0165] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0166] 1 wheel loader, 2 vehicle frame, 3 work machine, 4 traveling device, 4a traveling wheel, 5 cab, 6 counterweight, 9 machine body, 11 front frame, 12 rear frame, 13 steering cylinder, 14 bucket, 15 boom, 16 bell crank, 17 tilt rod, 18 boom cylinder, 18a tube, 18b rod, 18c piston, 19 bucket cylinder, 21 boom foot pin, 22 bucket pin, 29 support pin, 31b, 31h, 32b, 32h pressure sensor, 33, 34 potentiometer, 35, 36 stroke sensor, 39 imaging device, 40 angle sensor, 50 controller, 51 input unit, 52 display unit, 53 traveling lever, 500 memory unit, 501 boom cylinder thrust calculation unit, 502 hydraulic transmission efficiency calculation unit, 503 A dimension value calculation unit, 504 a horizontal distance calculation unit, 505 a cargo transport process determination unit, 507 a horizontal acceleration acquisition unit, 508 a correction coefficient determination unit, 509 an instantaneous payload value calculation unit, 510 a cargo mass calculation unit, and 511 a display control unit.

Claims

1. The main body to which the vehicle is attached, A work machine including a boom attached to the main body and a bucket attached to the boom, A boom cylinder that changes the angle of the boom relative to the main body, A sensor for detecting the thrust of the boom cylinder, A work machine comprising: a controller that corrects the detected thrust value based on the orientation of the boom cylinder relative to the main body, and calculates the load mass in the bucket using the corrected thrust value.

2. The work machine according to claim 1, wherein the controller determines that the work machine is in the process of transporting the load, and calculates the load mass in the bucket using the corrected thrust value.

3. The work machine according to claim 2, wherein the controller determines that the work machine is in the process of transporting a load when the boom cylinder is in a horizontal position and / or when the work machine is in a reverse position.

4. The aforementioned controller, The system pre-stores angle data indicating the boom angle at which the force acting on the boom cylinder in the extension / retraction direction is maximum due to the inertial force generated when the work machine is in motion. The work machine according to any one of claims 1 to 3, wherein the mass of the load in the bucket is calculated by further correcting the detected thrust using the angle data.

5. The boom is further provided with a boom foot pin for connecting the boom to the main body, The working machine according to claim 4, wherein the angle data is the angle of the boom at which the moment around the boom foot pin is maximized with respect to the force in the extension and retraction direction of the boom cylinder among the reaction forces generated by the boom cylinder.

6. The controller stores a second calculation formula obtained by multiplying a first calculation formula, which includes the thrust of the boom cylinder as a first variable, by a correction coefficient for correcting the value of the first variable. The correction coefficient includes, as a second variable, the angle of the boom cylinder or the angle of the boom. The first calculation formula is derived from the balance between the sum of the moment due to the load in the bucket and the moment due to the weight of the work machine, and the sum of the sum of the moment due to the thrust of the boom cylinder and the moment due to the reaction force of the bucket. The work machine according to claim 1, wherein the controller calculates the load mass in the bucket based on the second calculation formula.

7. The work machine according to claim 1, wherein the controller calculates the posture of the boom cylinder based on the angle of the boom cylinder.

8. The boom cylinder has a base end that is attached to the main body and a tip end that is attached to the bucket, The work machine according to claim 1, wherein the controller calculates the posture of the boom cylinder based on the dimensions of the boom, the mounting position of the base end to the main body, the mounting position of the tip to the bucket, and the angle of the boom to the main body.

9. A first sensor for detecting the angle of the boom cylinder, The system further comprises a second sensor for detecting the aforementioned thrust, The work machine according to claim 7, wherein the controller further acquires the result of the detection by the first sensor and the result of the detection by the second sensor.

10. A first sensor for detecting the angle of the boom, The system further comprises a second sensor for detecting the aforementioned thrust, The work machine according to claim 8, wherein the controller further acquires the result of the detection by the first sensor and the result of the detection by the second sensor.

11. A method for calculating the load mass of a self-propelled work machine, A step of detecting the thrust of a boom cylinder that changes the angle of the boom relative to the main body to which the work machine, including the boom and bucket, is connected, A step of correcting the detected thrust based on the orientation of the boom cylinder relative to the main body, A method for calculating cargo mass, comprising the step of calculating the cargo mass in the bucket using the corrected thrust value.

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