Calculation device and calculation method

Abstract

To provide a computing device capable of accurately calculating the weight of a load carried by a working machine.SOLUTION: A hydraulic excavator 100 includes a vehicle body, a boom bottom pin 5a supported by the vehicle body, a boom 3a rotatably connected to the vehicle body by the boom bottom pin 5a, a boom top pin 5b attached to a tip of the boom 3a, an arm 3b rotatably connected to the boom 3a by the boom top pin 5b, an arm top pin 5c attached to a tip of the arm 3b, and a bucket 3c rotatably connected to the arm 3b by the arm top pin 5c. A computing device calculates the weight of a load carried by a working machine 3 from any two balance equations of a moment balance equation about the boom bottom pin 5a, a moment balance equation about the boom top pin 5b, and a moment balance equation about the arm top pin 5c.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a calculation device and a calculation method for calculating the weight of a load carried by a work machine. [Background technology]

[0002] Japanese Patent Laid-Open Publication No. 10-245874 (Patent Document 1) discloses a calculation device that calculates the weight of a load in a bucket from the balance condition of forces around the bucket support shaft in a hydraulic excavator equipped with a bucket. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-245874 Summary of the Invention [Problem to be solved by the invention]

[0004] The above-mentioned document describes a method of experimentally determining the center of gravity of a bucket load. However, the center of gravity of a bucket load is not always constant. Therefore, it is difficult to improve the accuracy of the load weight by using the experimentally determined center of gravity.

[0005] The present disclosure proposes a calculation device that can accurately calculate the weight of a load carried by a work machine. [Means for solving the problem]

[0006] According to one aspect of the present disclosure, there is proposed a calculation device for calculating the weight of a load carried by a work implement in a work machine equipped with a work implement. The work machine includes a vehicle body, a boom bottom pin supported on the vehicle body, a boom rotatably connected to the vehicle body by the boom bottom pin, a boom top pin attached to a tip of the boom, an arm rotatably connected to the boom by the boom top pin, an arm top pin attached to a tip of the arm, and an attachment rotatably connected to the arm by the arm top pin. The calculation device calculates the weight of the load from any two of the balance equations of the moment around the boom bottom pin, the balance equation of the moment around the boom top pin, and the balance equation of the moment around the arm top pin.

[0007] According to one aspect of the present disclosure, there is proposed a calculation device for calculating the weight of a load carried by a working implement in a work machine equipped with a working implement. The work machine includes a vehicle body, a boom bottom pin supported on the vehicle body, a boom rotatably connected to the vehicle body by the boom bottom pin, a boom top pin attached to a tip of the boom, an attachment rotatably connected to the boom by the boom top pin, and a rotating member supported on the boom and rotatable relative to the boom together with the attachment. The calculation device calculates the weight of the load from two balance equations, a balance equation for the moment about the boom bottom pin and a balance equation for the moment about the center of rotation of the rotating member.

[0008] According to one aspect of the present disclosure, there is proposed a calculation device for calculating the weight of a load carried by a working machine equipped with a working implement. The working machine includes a vehicle body, a boom bottom pin supported on the vehicle body, a boom having one end rotatably connected to the vehicle body by the boom bottom pin, a boom top pin attached to the other end of the boom, an arm having one end rotatably connected to the other end of the boom by the boom top pin, an arm top pin attached to the other end of the arm, an attachment having one end rotatably connected to the other end of the arm by the arm top pin, a boom hydraulic cylinder that drives the boom to rotate, an arm hydraulic cylinder that drives the arm to rotate, an attachment hydraulic cylinder that drives the attachment to rotate, a pressure sensor, and a position sensor. The pressure sensor includes at least two sensors among a boom pressure sensor attached to the boom hydraulic cylinder and outputting hydraulic oil pressure information of the boom hydraulic cylinder, an arm pressure sensor attached to the arm hydraulic cylinder and outputting hydraulic oil pressure information of the arm hydraulic cylinder, and an attachment pressure sensor attached to the attachment hydraulic cylinder and outputting hydraulic oil pressure information of the attachment hydraulic cylinder. The position sensor includes a boom position sensor outputting boom information for obtaining a position of the boom relative to the vehicle body, an arm position sensor outputting arm information for obtaining a position of the arm relative to the boom, and an attachment position sensor outputting attachment information for obtaining a position of the attachment relative to the arm. The calculation device calculates the weight of the load from any two of the following relational expressions in transporting the load: a first relational expression generated from the hydraulic oil pressure information of the boom hydraulic cylinder and the boom information, a second relational expression generated from the hydraulic oil pressure information of the arm hydraulic cylinder and the arm information, and a third relational expression generated from the hydraulic oil pressure information of the attachment hydraulic cylinder and the attachment information. The pressure sensor includes at least two sensors corresponding to the above two relational expressions.

[0009] According to an aspect of the present disclosure, an arithmetic method for calculating the weight of a load carried by a working implement of a construction machine equipped with the working implement is proposed. The working implement has, as members, a boom that rotates about a first rotation center, an arm that rotates about a second rotation center, and an attachment that rotates about a third rotation center. The arithmetic method includes the following processes. The first process is to Equation erect the movement around any two of the first rotation center, the second rotation center, and the third rotation center for the above members. The second process is to obtain the weight and the center-of-gravity position of each of the members. The third process is to obtain the position of the members during the transportation of the load. The fourth process is to obtain the thrust corresponding to the movement of the relational expression. The fifth process is to calculate the horizontal distance between each center-of-gravity position of the members during the transportation of the load and each of the corresponding first rotation center, second rotation center, and third rotation center from the center-of-gravity position of the members and the position of the members. The sixth process is to calculate the weight of the load carried by the working implement based on the relational expression, the obtained information, and the calculated information.

Advantages of the Invention

[0010] According to the arithmetic device and the arithmetic method according to the present disclosure, the weight of the load carried by the working implement can be accurately calculated.

Brief Description of the Drawings

[0011] [Figure 1] It is a diagram schematically showing the configuration of a construction machine based on a first embodiment of the present disclosure. [Diagram 2] It is a block diagram showing a schematic configuration of a system of the construction machine shown in FIG. 1. [Diagram 3] It is a diagram showing functional blocks in the controller shown in FIG. 2. [Figure 4] It is a schematic diagram showing the balance of the moment around the boom bottom pin. [Diagram 5] It is a schematic diagram showing the balance of the moment around the arm top pin. [Figure 6]FIG. 4 is a schematic diagram showing balance of moments around a boom top pin. [Figure 7] FIG. 13 is a diagram illustrating a schematic configuration of a work machine based on a third embodiment. [Figure 8] FIG. 13 is a diagram illustrating roughly the configuration of a work machine based on a fourth embodiment. [Figure 9] FIG. 13 is a diagram illustrating functional blocks in a controller according to a fourth embodiment. [Figure 10] FIG. 13 is a schematic diagram showing balance of moments around a support pin. [Figure 11] FIG. 2 is a flowchart of the computational method of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment will be described with reference to the drawings. In the following description, the same components are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

[0013] [First embodiment] <Work machine configuration> Fig. 1 is a side view showing a schematic configuration of a hydraulic excavator 100 as an example of a work machine based on a first embodiment of the present disclosure. As shown in Fig. 1, the hydraulic excavator 100 of this embodiment mainly has a traveling body 1, a rotating body 2, and a work implement 3. The traveling body 1 and the rotating body 2 form the body of the hydraulic excavator 100.

[0014] The traveling body 1 has a pair of left and right track belt devices 1a. Each of the pair of left and right track belt devices 1a has a track. The pair of left and right tracks are rotationally driven to cause the hydraulic excavator 100 to self-propel.

[0015] The rotating body 2 is installed so as to be freely rotatable with respect to the traveling body 1. The rotating body 2 mainly has an operator's room (cab) 2a, an operator's seat 2b, an engine room 2c, and a counterweight 2d. The operator's room 2a is disposed, for example, on the front left side (vehicle front side) of the rotating body 2. The operator's seat 2b for an operator to sit on is disposed in the internal space of the operator's room 2a.

[0016] The engine room 2c and the counterweight 2d are each disposed on the rear side of the revolving body 2 (the rear side of the vehicle) with respect to the driver's cab 2a. The engine room 2c houses an engine unit (engine, exhaust treatment structure, etc.). The upper part of the engine room 2c is covered by an engine hood. The counterweight 2d is disposed behind the engine room 2c.

[0017] The work machine 3 is journaled on the front side of the revolving structure 2, for example on the right side of the operator's cab 2a. The work machine 3 has, for example, a boom 3a, an arm 3b, a bucket 3c, a boom cylinder 4a, an arm cylinder 4b, a bucket cylinder 4c, etc. A base end (one end) of the boom 3a is rotatably connected to the revolving structure 2 by a boom bottom pin 5a. A base end (one end) of the arm 3b is rotatably connected to a tip end (other end) of the boom 3a by a boom top pin 5b. (One end) of the bucket 3c is rotatably connected to a tip end (other end) of the arm 3b by an arm top pin 5c.

[0018] In this embodiment, the positional relationship of each part of the hydraulic excavator 100 will be described with reference to the work machine 3.

[0019] The boom 3a of the working machine 3 rotates around the boom bottom pin 5a relative to the revolving body 2. A specific part of the boom 3a that rotates relative to the revolving body 2, for example, the tip of the boom 3a, moves along a circular arc, and a plane including the circular arc is specified. When the hydraulic excavator 100 is viewed from above, the plane is expressed as a straight line. The direction in which this straight line extends is the front-rear direction of the vehicle body of the hydraulic excavator 100 or the front-rear direction of the revolving body 2, and will be simply referred to as the front-rear direction hereinafter. The left-right direction (vehicle width direction) of the vehicle body of the hydraulic excavator 100 or the left-right direction of the revolving body 2 is a direction perpendicular to the front-rear direction in a plan view, and will be simply referred to as the left-right direction hereinafter. The up-down direction of the vehicle body of the hydraulic excavator 100 or the up-down direction of the revolving body 2 is a direction perpendicular to a plane defined by the front-rear direction and the left-right direction, and will be simply referred to as the up-down direction hereinafter.

[0020] In the front-to-rear direction, the side where the work implement 3 protrudes from the vehicle body is the front direction, and the opposite direction to the front direction is the rear direction. Looking forward, the right side and the left side in the left-right direction are the right direction and the left direction, respectively. In the up-down direction, the side with the ground is the lower side, and the side with the sky is the upper side.

[0021] The front-to-rear direction is the front-to-rear direction of the operator seated in the driver's seat 2b in the driver's cab 2a. The left-to-right direction is the left-to-right direction of the operator seated in the driver's seat 2b. The up-to-down direction is the up-to-down direction of the operator seated in the driver's seat 2b. The direction facing the operator seated in the driver's seat 2b is the forward direction, and the direction behind the operator seated in the driver's seat 2b is the rearward direction. The right and left sides of the operator seated in the driver's seat 2b when facing directly ahead are the right direction and the left direction, respectively. The side near the feet of the operator seated in the driver's seat 2b is the lower side, and the side above the head is the upper side.

[0022] The boom 3a can be driven by a boom cylinder (boom hydraulic cylinder) 4a. This drive allows the boom 3a to rotate vertically relative to the rotating body 2 around the boom bottom pin 5a. The arm 3b can be driven by an arm cylinder (arm hydraulic cylinder) 4b. This drive allows the arm 3b to rotate vertically relative to the boom 3a around the boom top pin 5b. The bucket (attachment) 3c can be driven by a bucket cylinder (attachment hydraulic cylinder) 4c. This drive allows the bucket 3c to rotate vertically relative to the arm 3b around the arm top pin 5c. In this manner, the work machine 3 can be driven.

[0023] The boom bottom pin 5a is supported by the vehicle body of the hydraulic excavator 100. The boom bottom pin 5a is supported by a pair of vertical plates (not shown) of the frame of the rotating body 2. The boom top pin 5b is attached to the tip of the boom 3a. The arm top pin 5c is attached to the tip of the arm 3b. The boom bottom pin 5a, the boom top pin 5b and the arm top pin 5c all extend in the left-right direction. The boom bottom pin 5a is also called a boom foot pin.

[0024] The work machine 3 has a bucket link 3d. The bucket link 3d has a first link member 3da and a second link member 3db. An end of the first link member 3da and an end of the second link member 3db are connected to each other via a bucket cylinder top pin 3dc so as to be capable of relative rotation. The bucket cylinder top pin 3dc is connected to an end of a bucket cylinder 4c. Therefore, the first link member 3da and the second link member 3db are connected to the bucket cylinder 4c by a pin.

[0025] A base end of the first link member 3da is rotatably connected to the arm 3b by a first link pin 3dd. A base end of the second link member 3db is rotatably connected to a bracket at the base of the bucket 3c by a second link pin 3de.

[0026] A pressure sensor 6a is attached to the head side of the boom cylinder 4a. The pressure sensor 6a can detect the pressure (head pressure) of hydraulic oil in the cylinder head side oil chamber 40A of the boom cylinder 4a. A pressure sensor 6b is attached to the bottom side of the boom cylinder 4a. The pressure sensor 6b can detect the pressure (bottom pressure) of hydraulic oil in the cylinder bottom side oil chamber 40B of the boom cylinder 4a. The pressure sensors 6a and 6b output hydraulic oil pressure information consisting of the head pressure and bottom pressure to a controller 10 described below.

[0027] A pressure sensor 6c is attached to the head side of the arm cylinder 4b. The pressure sensor 6c can detect the pressure (head pressure) of the hydraulic oil in the cylinder head side oil chamber of the arm cylinder 4b. A pressure sensor 6d is attached to the bottom side of the arm cylinder 4b. The pressure sensor 6d can detect the pressure (bottom pressure) of the hydraulic oil in the cylinder bottom side oil chamber of the arm cylinder 4b. The pressure sensors 6c and 6d output hydraulic oil pressure information consisting of the head pressure and bottom pressure to a controller 10 described later.

[0028] A pressure sensor 6e is attached to the head side of the bucket cylinder 4c. The pressure sensor 6e can detect the pressure (head pressure) of the hydraulic oil in the cylinder head side oil chamber of the bucket cylinder 4c. A pressure sensor 6f is attached to the bottom side of the bucket cylinder 4c. The pressure sensor 6f can detect the pressure (bottom pressure) of the hydraulic oil in the cylinder bottom side oil chamber of the bucket cylinder 4c. The pressure sensors 6e and 6f output hydraulic oil pressure information consisting of the head pressure and bottom pressure to a controller 10 described later.

[0029] The boom 3a, the arm 3b and the bucket 3c are provided with position sensors for obtaining information on their respective positions and attitudes. The position sensors output boom information, arm information and attachment information for obtaining the respective positions of the boom 3a, the arm 3b and the bucket 3c to a controller 10, which will be described later.

[0030] A stroke sensor 7a is attached to the boom cylinder 4a as a position sensor. The stroke sensor 7a detects the amount of displacement of the cylinder rod 4ab relative to the cylinder aa in the boom cylinder 4a as boom information. A stroke sensor 7b is attached to the arm cylinder 4b as a position sensor. The stroke sensor 7b detects the amount of displacement of the cylinder rod in the arm cylinder 4b as arm information. A stroke sensor 7c is attached to the bucket cylinder 4c as a position sensor. The stroke sensor 7c detects the amount of displacement of the cylinder rod in the bucket cylinder 4c as attachment information.

[0031] The position sensor may be an angle sensor. An angle sensor 9a is attached around the boom bottom pin 5a. An angle sensor 9b is attached around the boom top pin 5b. An angle sensor 9c is attached around the arm top pin 5c. The angle sensors 9a, 9b, and 9c may be potentiometers or rotary encoders. The angle sensors 9a, 9b, and 9c output rotation angle information (boom information, arm information, and attachment information) of the boom 3a and the like to a controller 10 described later.

[0032] As shown in FIG. 1, in a side view, the angle between a straight line passing through the boom bottom pin 5a and the boom top pin 5b (shown by a two-dot chain line in FIG. 1) and a straight line extending in the vertical direction (shown by a dashed line in FIG. 1) is defined as the boom angle θb. The boom angle θb is usually an acute angle. The boom angle θb represents the angle of the boom 3a relative to the rotating body 2. The boom angle θb can be calculated from the detection result of the stroke sensor 7a, and can also be calculated from the measurement value of the angle sensor 9a.

[0033] In a side view, the angle between a straight line passing through the boom bottom pin 5a and the boom top pin 5b and a straight line passing through the boom top pin 5b and the arm top pin 5c (shown by a two-dot chain line in FIG. 1) is defined as the arm angle θa. The arm angle θa represents the angle of the arm 3b with respect to the boom 3a in the region in which the arm 3b rotates in a side view. The arm angle θa can be calculated from the detection result of the stroke sensor 7b, and can also be calculated from the measurement value of the angle sensor 9b.

[0034] In a side view, the angle between a line passing through the boom top pin 5b and the arm top pin 5c and a line passing through the arm top pin 5c and the cutting edge of the bucket 3c (shown by a two-dot chain line in FIG. 1) is defined as the bucket angle θk. The bucket angle θk represents the angle of the bucket 3c with respect to the arm 3b in the area where the bucket 3c rotates in a side view. The bucket angle θk can be calculated from the detection result of the stroke sensor 7c, and can also be calculated from the measurement value of the angle sensor 9c.

[0035] The position sensor may be an IMU (Inertial Measurement Unit). IMUs 8a, 8b, 8c, and 8d are attached to the rotating body 2, the boom 3a, the arm 3b, and the first link member 3da, respectively. The IMU 8a measures the acceleration of the rotating body 2 in the forward / backward, left / right, and up / down directions, and the angular velocity of the rotating body 2 around the forward / backward, left / right, and up / down directions. The IMUs 8b, 8c, and 8d measure the acceleration of the boom 3a, the arm 3b, and the first link member 3da in the forward / backward, left / right, and up / down directions, and the angular velocity of the boom 3a, the arm 3b, and the first link member 3da around the forward / backward, left / right, and up / down directions, respectively.

[0036] The acceleration of the extension and retraction of the boom cylinder 4a (the amount of change in the extension and retraction speed of the boom cylinder 4a) can be obtained based on the difference between the acceleration measured by the IMU 8a attached to the rotating structure 2 and the acceleration measured by the IMU 8b attached to the boom 3a. The boom angle θb, the arm angle θa, and the bucket angle θk may be calculated from the detection results of the IMUs 8b, 8c, and 8d, respectively.

[0037] Although the stroke sensor of each hydraulic cylinder, the angle sensor of each link such as the boom 3a, and the IMU have been given as position sensors, the position sensor may be a six-axis acceleration sensor. The position sensor may be a combination of several of the above sensors. The position sensor may be a combination of the above sensors and a Global Navigation Satellite System (GNSS).

[0038] <Overview of the work machine system> Next, the schematic configuration of the system of the work machine will be described with reference to Fig. 2. Fig. 2 is a block diagram showing the schematic configuration of the system of the work machine shown in Fig. 1.

[0039] As shown in Fig. 2, the system in this embodiment is a system for determining a load weight, which is the weight of a load L (Fig. 1) carried by a work machine 3. The system in this embodiment includes a hydraulic excavator 100 as an example of a work machine shown in Fig. 1, and a controller 10 shown in Fig. 2. The controller 10 may be mounted on the hydraulic excavator 100. The controller 10 may be installed outside the hydraulic excavator 100. The controller 10 may be arranged at the work site of the hydraulic excavator 100, or may be arranged in a remote location away from the work site of the hydraulic excavator 100.

[0040] The engine 31 is, for example, a diesel engine. The amount of fuel injected into the engine 31 is controlled by the controller 10, whereby the output of the engine 31 is controlled.

[0041] The hydraulic pump 33 is connected to the engine 31. The rotational driving force of the engine 31 is transmitted to the hydraulic pump 33, thereby driving the hydraulic pump 33. The hydraulic pump 33 is, for example, a variable displacement hydraulic pump that has a swash plate and changes the discharge capacity by changing the tilt angle of the swash plate. A part of the oil discharged from the hydraulic pump 33 is supplied to the directional control valve 34 as hydraulic oil. A part of the oil discharged from the hydraulic pump 33 is reduced to a constant pressure by a pressure reducing valve and used as pilot oil.

[0042] The directional control valve 34 is, for example, a spool-type valve that switches the direction of hydraulic oil flow by moving a rod-shaped spool. The amount of hydraulic oil supplied to the actuator 40 is adjusted by the axial movement of the spool. The directional control valve 34 is provided with a spool stroke sensor that detects the movement distance of the spool (spool stroke).

[0043] The supply and discharge of hydraulic pressure to the actuator 40 is controlled to control the operation of the work implement 3, the rotation of the rotating body 2, and the traveling operation of the traveling body 1. The actuator 40 includes a boom cylinder 4a, an arm cylinder 4b, a bucket cylinder 4c, a traveling motor, a swing motor (not shown), and the like, all of which are shown in FIG.

[0044] In this embodiment, the oil supplied to the actuator 40 to operate the actuator 40 is called hydraulic oil. Also, the oil supplied to the directional control valve 34 to operate the directional control valve 34 is called pilot oil. Also, the pressure of the pilot oil is called pilot oil pressure.

[0045] The hydraulic pump 33 may be one that delivers both the hydraulic oil and the pilot oil as described above. The hydraulic pump 33 may have a hydraulic pump that delivers the hydraulic oil (main hydraulic pump) and a hydraulic pump that delivers the pilot oil (pilot hydraulic pump) separately.

[0046] The operation device 25 is disposed in the operator's cab 2a. The operation device 25 is operated by an operator. The operation device 25 accepts an operator operation to drive the work machine 3. The operation device 25 also accepts an operator operation to rotate the rotating body 2. The operation device 25 outputs an operation signal in response to the operator operation.

[0047] The operating device 25 has a first operating lever 25R and a second operating lever 25L. The first operating lever 25R is disposed, for example, on the right side of the driver's seat 2b. The second operating lever 25L is disposed, for example, on the left side of the driver's seat 2b. The forward / backward / leftward / rightward movements of the first operating lever 25R and the second operating lever 25L correspond to movements of two axes.

[0048] The first operating lever 25R, for example, operates the boom 3a and the bucket 3c. Forward and backward operation of the first operating lever 25R corresponds to, for example, operation of the boom 3a, and the boom 3a is lowered or raised in response to the forward and backward operation. Left and right operation of the first operating lever 25R corresponds to, for example, operation of the bucket 3c, and the bucket 3c is moved in the excavation direction (upward) and the dump direction (downward) in response to the left and right operation.

[0049] The second operating lever 25L, for example, operates the arm 3b and the rotating body 2. Operation of the second operating lever 25L in the forward / backward direction corresponds to, for example, the rotation of the rotating body 2, and the rightward and leftward rotation of the rotating body 2 is performed in response to the forward / backward operation. Operation of the second operating lever 25L in the left / right direction corresponds to, for example, the operation of the arm 3b, and the arm 3b is moved in the dumping direction (upward) and the excavation direction (downward) in response to the left / right operation.

[0050] Pilot oil delivered from the hydraulic pump 33 and reduced in pressure by the pressure reducing valve is supplied to the operating device 25. The pilot oil pressure is adjusted based on the amount of operation of the operating device 25.

[0051] The operating device 25 and the directional control valve 34 are connected via a pilot oil passage 450. Pilot oil is supplied to the directional control valve 34 via the pilot oil passage 450. This causes the spool of the directional control valve 34 to move in the axial direction, adjusting the flow direction and flow rate of the hydraulic oil supplied to the boom cylinder 4a, the arm cylinder 4b, and the bucket cylinder 4c, and causing the boom 3a, the arm 3b, and the bucket 3c to move in the up and down directions.

[0052] A pressure sensor 36 is disposed in the pilot oil passage 450. The pressure sensor 36 detects the pilot oil pressure. The detection result of the pressure sensor 36 is output to the controller 10. The amount of increase in the pilot oil pressure varies depending on the angle at which each of the operating levers 25L, 25R is tilted from the neutral position. The operation content of the operating device 25 can be determined based on the detection result of the pilot oil pressure by the pressure sensor 36.

[0053] The controller 10 also receives detection signals from the stroke sensors 7a to 7c, the IMUs 8a to 8d, the angle sensors 9a to 9c, and the pressure sensors 6a to 6f.

[0054] The controller 10 may be electrically connected by wire to each of the stroke sensors 7a-7c, the IMUs 8a-8d, the angle sensors 9a-9c, and the pressure sensors 6a-6f, 36, or may be capable of wireless communication with them. The controller 10 may be, for example, a computer, a server, a mobile terminal, or a CPU (Central Processing Unit).

[0055] Although the above description has been given of the case where the operating device 25 is of a pilot hydraulic type, the operating device 25 may also be of an electrical type. When the operating device 25 is of an electrical type, the amount of operation of each of the first operating lever 25R and the second operating lever 25L is detected, for example, by a potentiometer. A potentiometer is a displacement sensor that obtains an electrical (voltage) output proportional to a mechanical position. The detection result of the potentiometer is output to the controller 10. The operation content of the operating device 25 can be determined based on the detection result of the potentiometer.

[0056] <Function blocks in the controller 10> Next, functional blocks within the controller 10 will be described with reference to Fig. 3. Fig. 3 is a diagram showing functional blocks within the controller 10 shown in Fig. 2.

[0057] 3, boom cylinder thrust calculation unit 10a acquires the detection results of pressure sensors 6a, 6b. Specifically, boom cylinder thrust calculation unit 10a acquires the head pressure of boom cylinder 4a detected by pressure sensor 6a. Boom cylinder thrust calculation unit 10a acquires the bottom pressure of boom cylinder 4a detected by pressure sensor 6b. Boom cylinder thrust calculation unit 10a calculates boom cylinder thrust Fboom based on the head pressure and bottom pressure of boom cylinder 4a.

[0058] A thrust is defined as a force that pushes an object in the direction of movement, and the boom cylinder thrust Fboom is a thrust generated by the boom cylinder 4a that rotates the boom 3a relative to the vehicle body. The boom cylinder thrust Fboom is a force that acts in the extension direction of the boom cylinder 4a. The boom cylinder thrust calculation unit 10a outputs the calculated boom cylinder thrust Fboom to the load weight calculation unit 10i.

[0059] The arm cylinder thrust calculation unit 10b acquires the detection results of the pressure sensors 6c and 6d. Specifically, the arm cylinder thrust calculation unit 10b acquires the head pressure of the arm cylinder 4b detected by the pressure sensor 6c. The arm cylinder thrust calculation unit 10b acquires the bottom pressure of the arm cylinder 4b detected by the pressure sensor 6d. The arm cylinder thrust calculation unit 10b calculates the arm cylinder thrust Farm based on the head pressure and bottom pressure of the arm cylinder 4b.

[0060] The arm cylinder thrust Farm is a thrust generated by the arm cylinder 4b that rotates the arm 3b relative to the boom 3a. The arm cylinder thrust Farm is a force that acts in the extension direction of the arm cylinder 4b. The arm cylinder thrust calculation unit 10b outputs the calculated arm cylinder thrust Farm to the load weight calculation unit 10i.

[0061] The bucket cylinder thrust calculation unit 10c acquires the detection results of the pressure sensors 6e and 6f. Specifically, the bucket cylinder thrust calculation unit 10c acquires the head pressure of the bucket cylinder 4c detected by the pressure sensor 6e. The bucket cylinder thrust calculation unit 10c acquires the bottom pressure of the bucket cylinder 4c detected by the pressure sensor 6f. The bucket cylinder thrust calculation unit 10c calculates the bucket cylinder thrust Fbucket based on the head pressure and bottom pressure of the bucket cylinder 4c.

[0062] The bucket cylinder thrust Fbucket is a thrust generated by the bucket cylinder 4c that rotates the bucket 3c relative to the arm 3b. The bucket cylinder thrust Fbucket is a force that acts in the extension direction of the bucket cylinder 4c. The bucket cylinder thrust calculation unit 10c outputs the calculated bucket cylinder thrust Fbucket to the load weight calculation unit 10i.

[0063] The boom angle calculation unit 10d acquires information about the boom angle θb from at least one of the stroke sensor 7a, the IMU 8b, and the angle sensor 9a. The boom angle calculation unit 10d calculates the boom angle θb based on the acquired information. The boom angle calculation unit 10d outputs the calculated boom angle θb to the center of gravity position calculation unit 10g.

[0064] The arm angle calculation unit 10e acquires information about the arm angle θa from at least one of the stroke sensor 7b, the IMU 8c, and the angle sensor 9b. The arm angle calculation unit 10e calculates the arm angle θa based on the acquired information. The arm angle calculation unit 10e outputs the calculated arm angle θa to the center of gravity position calculation unit 10g.

[0065] The bucket angle calculation unit 10f acquires information about the bucket angle θk from at least one of the stroke sensor 7c, the IMU 8d, and the angle sensor 9c. The bucket angle calculation unit 10f calculates the bucket angle θk based on the acquired information. The bucket angle calculation unit 10f outputs the calculated bucket angle θk to the center of gravity position calculation unit 10g.

[0066] The memory unit 10j stores various information such as the dimensions, weight, and position of the center of gravity of each member constituting the work machine 3. These various information may be input to the memory unit 10j from an input unit 11 outside the controller 10. The memory unit 10j may not be included in the controller 10 and may be disposed outside the controller 10.

[0067] The center of gravity position calculation unit 10g calculates the relative position of the center of gravity of each member constituting the work machine 3, such as the boom 3a, the cylinder 4aa of the boom cylinder 4a, the first link member 3da, etc., with respect to the boom bottom pin 5a. The center of gravity position calculation unit 10g calculates the above-mentioned relative position of each member constituting the work machine 3 from the boom angle θb calculated by the boom angle calculation unit 10d, the arm angle θa calculated by the arm angle calculation unit 10e, the bucket angle θk calculated by the bucket angle calculation unit 10f, and the position of the center of gravity of each member constituting the work machine 3 stored in the memory unit 10j.

[0068] The center of gravity position calculation unit 10g calculates the posture of the boom 3a, arm 3b, and bucket 3c based on the boom bottom pin 5a from the boom angle θb, arm angle θa, and bucket angle θk. The center of gravity position calculation unit 10g calculates the state (posture, stroke) of the other components of the work machine 3 from the calculated postures. The center of gravity position calculation unit 10g calculates the relative position of each component of the work machine 3 based on the boom bottom pin 5a from the calculation result and the stored center of gravity position of each component.

[0069] The moment distance calculation unit 10h calculates the horizontal distance from the boom bottom pin 5a to the center of gravity of each member constituting the work machine. Specifically, the moment distance calculation unit 10h calculates the horizontal distance Xboom from the boom bottom pin 5a to the center of gravity of the boom 3a. The moment distance calculation unit 10h calculates the horizontal distance Xarm from the boom bottom pin 5a to the center of gravity of the arm 3b. The moment distance calculation unit 10h calculates the horizontal distance Xbucket from the boom bottom pin 5a to the center of gravity of the bucket 3c.

[0070] The moment distance calculation unit 10h calculates the horizontal distance XboomC from the boom bottom pin 5a to the center of gravity of the cylinder portion (cylinder 4aa) of the boom cylinder 4a. The moment distance calculation unit 10h calculates the horizontal distance XboomCR from the boom bottom pin 5a to the center of gravity of the cylinder rod portion (cylinder rod 4ab) of the boom cylinder 4a.

[0071] The moment distance calculation unit 10h calculates the horizontal distance XarmC from the boom bottom pin 5a to the center of gravity of the cylinder part of the arm cylinder 4b. The moment distance calculation unit 10h calculates the horizontal distance XarmCR from the boom bottom pin 5a to the center of gravity of the cylinder rod part of the arm cylinder 4b.

[0072] The moment distance calculation unit 10h also calculates the horizontal distance Xboomtop from the boom bottom pin 5a to the boom top pin 5b. The moment distance calculation unit 10h also calculates the horizontal distance Xarmtop from the boom bottom pin 5a to the arm top pin 5c.

[0073] In addition, the moment distance calculation unit 10h calculates the distance hboom from the boom bottom pin 5a to the boom cylinder 4a in a direction perpendicular to the extension direction of the boom cylinder 4a. The moment distance calculation unit 10h calculates the distance harm from the boom top pin 5b to the arm cylinder 4b in a direction perpendicular to the extension direction of the arm cylinder 4b. The moment distance calculation unit 10h calculates the distance hbucket from the arm top pin 5c to the bucket cylinder 4c in a direction perpendicular to the extension direction of the bucket cylinder 4c.

[0074] The moment distance calculation unit 10h outputs these calculated distances to the load weight calculation unit 10i.

[0075] The load weight calculation unit 10i calculates the weight Mpayload of the load L loaded in the bucket 3c. A method for calculating the weight Mpayload will be described later. The load weight calculation unit 10i outputs the calculated weight Mpayload to a display unit 12 outside the controller 10. The display unit 12 may be disposed, for example, in the cab 2a (FIG. 1) or in a remote location away from the hydraulic excavator 100. The display unit 12 displays the calculated weight Mpayload on a screen. An operator who operates the hydraulic excavator 100 in the cab 2a, an operator who operates the hydraulic excavator 100 in a remote location, or an observer who monitors the operation of the hydraulic excavator 100 can recognize the weight Mpayload of the load L loaded in the bucket 3c by looking at the display unit 12.

[0076] Each of the input unit 11 and the display unit 12 may be connected to the controller 10 by wire or wirelessly.

[0077] <Calculation of the weight of load L> The method of calculating the weight Mpayload of the load L loaded on the bucket 3c will be described in detail below. The weight Mpayload of the load L is calculated from any two of three relational expressions set up from information from position sensors and information from pressure sensors for each of the three links (boom 3a, arm 3b, bucket 3c) constituting the work machine 3 during transport of the load L. Below, the method of calculating the weight Mpayload of the load L will be described by setting up a moment balance equation as the relational expression, with the boom 3a and bucket 3c as the links.

[0078] The load weight calculation unit 10i shown in Fig. 3 reads out the balance equation of the moment around the boom bottom pin 5a from the memory unit 10j. Fig. 4 is a schematic diagram showing the balance of the moment around the boom bottom pin 5a. The balance equation of the moment around the boom bottom pin 5a is expressed by the following equation (1).

[0079]

number

[0080] The left side of equation (1) is the moment due to the boom cylinder thrust Fboom. In the first term on the right side of equation (1), Mpayload is the weight of the load L loaded in the bucket 3c. Xpayload is the horizontal distance from the boom bottom pin 5a to the center of gravity of the load L loaded in the bucket 3c. The first term on the right side of equation (1) is the moment due to the load L loaded in the bucket 3c.

[0081] The second term MXwe on the right side of the formula (1) is the moment due to the weight of the work machine 3. The moment MXwe is calculated by the following formula (2).

[0082]

number

[0083] In equation (2), Mboom is the weight of the boom 3a. MboomC is the weight of the cylinder portion of the boom cylinder 4a. MboomCR is the weight of the cylinder rod portion of the boom cylinder 4a. Marm is the weight of the arm 3b. MarmC is the weight of the cylinder portion of the arm cylinder 4b. MarmCR is the weight of the cylinder rod portion of the arm cylinder 4b. Mbucket is the weight of the bucket 3c.

[0084] Each of these weights Mboom, MboomC, MboomCR, Marm, MarmC, MarmCR and Mbucket is stored in storage unit 10j, for example, by performing an input operation to storage unit 10j using input unit 11 shown in FIG.

[0085] Next, the load weight calculation unit 10i reads out the equation for the balance of the moment around the arm top pin 5c from the storage unit 10j. Figure 5 is a schematic diagram showing the balance of the moment around the arm top pin 5c. The equation for the balance of the moment around the arm top pin 5c is expressed by the following equation (3).

[0086]

number

[0087] The left side of equation (3) is the moment due to the thrust Fbucket of the bucket cylinder 4c. The first term on the right side of equation (3) is the moment due to the load L loaded in the bucket 3c. The second term MXwe_bucket on the right side of equation (3) is the moment due to the weight of the bucket 3c.

[0088] From the simultaneous equations of equations (1) and (3), the following equation (4), which does not depend on the distance Xpayload, can be formulated as an equation for calculating the payload weight Mpayload.

[0089]

number

[0090] Equation (1) includes the distance Xpayload, and equation (3) also includes the distance Xpayload. By solving these two balance equations as simultaneous equations, equation (4) that does not include the distance Xpayload is derived. It becomes possible to calculate the payload weight Mpayload based on equation (4). This makes it possible to eliminate the influence of the shift in the center of gravity position of the load L loaded in the bucket 3c and to calculate the payload weight Mpayload with greater accuracy.

[0091] The distance Xpayload can be calculated by substituting the payload Mpayload calculated according to formula (4) into formula (1) or formula (3). In addition, the following formula (5), which does not depend on the payload Mpayload, can be formulated as a formula for calculating the distance Xpayload from the simultaneous equations of formula (1) and formula (3).

[0092]

number

[0093] The position of the center of gravity of the load L loaded in the bucket 3c can be corrected according to the calculated distance Xpayload.

[0094] In summary, the calculation method for calculating the weight Mpayload of the load L carried by the bucket 3c includes the following processes: Fig. 11 is a diagram showing a flowchart of the calculation method of the present disclosure.

[0095] The process executed in step S1 shown in FIG. 11 is to formulate a relational equation for the motion of the members of the work machine 3 about any two of the rotation centers of the boom bottom pin 5a (first rotation center), the boom top pin 5b (second rotation center), and the arm top pin 5c (third rotation center). In this embodiment, a relational equation for the motion about the first rotation center and the third rotation center is formulated. The relational equation for the motion may be a balance equation for the moment about the rotation center of the motion. The formulation may be to acquire relational equation information stored in the storage unit 10j. The relational equation information acquired from the storage unit 10j may be one relational equation arranged for the payload weight Mpayload from the relational equation for the motion about the above two rotation centers.

[0096] The process executed in step S2 is to obtain the weight and center of gravity position of each member of the boom 3a, the arm 3b, and the bucket 3c (attachment). Information on the center of gravity and the center of gravity position of each member may be obtained from the storage unit 10j.

[0097] The process executed in step S3 is to obtain the position of each member during transportation of the load L. The position of each member may be obtained by obtaining a rotation angle of each member indicating the posture of each member and performing a calculation based on the rotation angle.

[0098] The process executed in step S4 is to obtain the thrust corresponding to the motion of each member in the relational expression of the motion of each member. In this embodiment, the thrust is obtained by measuring the hydraulic pressure of the hydraulic cylinder that operates the boom 3a and the bucket 3c. The thrust may be obtained from the head pressure and the bottom pressure of the hydraulic cylinder that rotates each member of the boom 3a, the arm 3b, and the bucket 3c (attachment).

[0099] The processing performed in step S5 is to calculate the horizontal distance (moment distance) between the center of gravity of each component when load L is being transported and each of the first, second and third rotation centers, which are the rotation centers of each component, from the center of gravity of each component and the position of each component when load L is being transported.

[0100] The process executed in step S6 is to input the acquired information and calculated information into the relational equation for the motion of each member to calculate the weight (payload weight Mpayload) of the load L carried by the work machine 3. The acquired information refers to the weight and center of gravity position of each member of the work machine 3, and the thrust of the hydraulic cylinder that rotates each member when carrying the load L. The calculated information refers to the horizontal distance between the center of gravity position of each member and the center of rotation of each member when carrying the load L.

[0101] [Second embodiment] In the first embodiment, an example is described in which the weight Mpayload of the load L loaded on the bucket 3c is calculated from two balance equations, the balance equation of the moment around the boom bottom pin 5a and the balance equation of the moment around the arm top pin 5c. This example is not limited to this example, and the controller 10 can calculate the weight Mpayload of the load L loaded on the bucket 3c from any two balance equations among the balance equation of the moment around the boom bottom pin 5a, the balance equation of the moment around the boom top pin 5b, and the balance equation of the moment around the arm top pin 5c. In the second embodiment, an example is described in which the weight Mpayload is calculated from two balance equations, the balance equation of the moment around the boom bottom pin 5a and the balance equation of the moment around the boom top pin 5b.

[0102] The configuration of the hydraulic excavator 100, the system configuration, and the functional blocks within the controller 10 in the second embodiment are as described in the first embodiment with reference to Figs. 1 to 3.

[0103] In the second embodiment, the load weight calculation unit 10i reads out the balance equation of the moment around the boom top pin 5b from the memory unit 10j. Figure 6 is a schematic diagram showing the balance of the moment around the boom top pin 5b. The balance equation of the moment around the boom top pin 5b is expressed by the following equation (6).

[0104]

number

[0105] The left side of equation (6) is the moment due to the arm cylinder thrust Farm. The first term on the right side of equation (6) is the moment due to the load L loaded on the bucket 3c. The second term MXwe_arm on the right side of equation (6) is the moment due to the weight of the work machine 3 on the tip side of the work machine 3 relative to the boom top pin 5b. The moment MXwe_arm is calculated using a balance equation similar to equation (2).

[0106] From the simultaneous equations of equations (1) and (6), the following equation (7), which does not depend on the distance Xpayload, can be formulated as an equation for calculating the payload weight Mpayload.

[0107]

number

[0108] Equation (1) includes the distance Xpayload, and equation (6) also includes the distance Xpayload. By solving these two balance equations as simultaneous equations, equation (7) that does not include the distance Xpayload is derived. It becomes possible to calculate the payload weight Mpayload based on equation (7). This makes it possible to eliminate the influence of the shift in the center of gravity position of the load L loaded in the bucket 3c and to calculate the payload weight Mpayload with greater accuracy.

[0109] The distance Xpayload can be calculated by substituting the load weight Mpayload calculated according to the formula (7) into the formula (1) or the formula (6). In addition, an equation that does not depend on the load weight Mpayload can be formulated as an equation for calculating the distance Xpayload from the simultaneous equations of the formulas (1) and (6). The position of the center of gravity of the load L loaded in the bucket 3c can be corrected according to the calculated distance Xpayload.

[0110] In the first and second embodiments, an example has been described in which the payload Mpayload, which is the weight of the load L loaded in the bucket 3c, is calculated. However, the present invention is not limited to this example, and it is possible to accurately calculate the weight of the suspended load by applying the concept of the embodiment to, for example, an arm crane hydraulic excavator 100 in which a hoisting hook is attached to the second link pin 3de and which is capable of hoisting and lowering the load L.

[0111] In the hydraulic excavator 100 shown in the first and second embodiments, the three links (boom 3a, arm 3b, bucket 3c) of the work machine 3 are each provided with a position sensor 9a, 9b, 9c and a corresponding pressure sensor 6a, 6b, 6c, but the present invention is not limited to this configuration. Only the links that are the targets of the two relational expressions used to calculate the payload Mpayload may be provided with pressure sensors.

[0112] [Third embodiment] In the first and second embodiments, a hydraulic excavator 100 is described that includes a bucket 3c as an attachment at the tip of the work implement 3. The attachment is not limited to the bucket 3c, and the attachment may be replaced with a grapple, a lifting magnet, or the like depending on the type of work. In the third embodiment, a hydraulic excavator 100 is described that includes a lifting magnet 103 as an attachment.

[0113] Fig. 7 is a side view showing a schematic configuration of a hydraulic excavator 100 as an example of a work machine according to the third embodiment. The hydraulic excavator 100 according to the third embodiment has almost the same configuration as the hydraulic excavator 100 according to the first embodiment shown in Fig. 1, and differs in that a lifting magnet 103 is provided at the tip of the work implement 3 instead of the bucket 3c.

[0114] The lifting magnet 103 has a main body 105 and a support 104. The main body 105 is a magnet that generates a magnetic force. The main body 105 is, for example, an electromagnet. The main body 105 can hold and transport a magnetic body by the magnetic force. The support 104 supports the main body 105. The support 104 is rotatably connected to the tip of the arm 3b by the arm top pin 5c. The base end of the second link member 3db is rotatably connected to a bracket at the base of the support 104 by the second link pin 3de.

[0115] In the hydraulic excavator 100 equipped with the lifting magnet 103, it is difficult to keep constant the relative position of the load L carried by the work machine 3, i.e., the magnetic body attracted and held by the main body 105, relative to the main body 105 and the attitude of the magnetic body. Therefore, the center of gravity of the magnetic body is easily shifted. As shown in FIG. 7, by formulating an equation for calculating the weight of the load L that is not dependent on the shift in the center of gravity of the load L from two balance equations, the balance equation for the moment around the boom bottom pin 5a and the balance equation for the moment around the arm top pin 5c, it is possible to eliminate the influence of the shift in the center of gravity of the load L held by the lifting magnet 103 and calculate the weight of the load L with higher accuracy.

[0116] In the hydraulic excavator 100 shown in the first to third embodiments, by calculating the weight of the load L while the rotating body 2 is rotating relative to the traveling body 1, the weight of the load L can be calculated with higher accuracy.

[0117] [Fourth embodiment] In the first to third embodiments, an example has been described in which the work machine is the hydraulic excavator 100. By applying the ideas of the embodiments to a work machine other than the hydraulic excavator 100 that is equipped with a work implement 3 having a multi-link mechanism and that transports a load L, it is possible to accurately calculate the weight of the load L transported by the work implement 3. For example, the work machine may be a wheel loader, a backhoe loader, a skid steer loader, or the like.

[0118] Fig. 8 is a side view showing a schematic configuration of a wheel loader 200 as an example of a work machine based on the fourth embodiment. As shown in Fig. 8, the wheel loader 200 has a body frame 202, a work implement 203, a traveling device 204, and a cab 205.

[0119] The body of the wheel loader 200 is made up of the body frame 202 and the cab 205. A seat for an operator, operating devices, and the like are arranged inside the cab 205. A work implement 203 and a traveling device 204 are attached to the body of the wheel loader 200. The work implement 203 is arranged at the front of the body, and a counterweight 206 is provided at the rearmost end of the body.

[0120] The vehicle body frame 202 includes a front frame 211 and a rear frame 212. A steering cylinder 213 is attached to the front frame 211 and the rear frame 212. The steering cylinder 213 is a hydraulic cylinder. The steering cylinder 213 expands and contracts with hydraulic oil from a steering pump (not shown). The expansion and contraction of the steering cylinder 213 allows the front frame 211 and the rear frame 212 to swing left and right relative to each other. This allows the traveling direction of the wheel loader 200 to be changed left and right.

[0121] In the fourth embodiment, the direction in which the wheel loader 200 travels straight ahead is referred to as the fore-aft direction of the wheel loader 200. In the fore-aft direction of the wheel loader 200, the side where the work machine 203 is arranged with respect to the vehicle body frame 202 is the front direction, and the side opposite the front direction is the rear direction. The left-right direction of the wheel loader 200 is the direction perpendicular to the fore-aft direction in a plan view. Looking forward, the right side and the left side in the left-right direction are the right direction and the left direction, respectively. The up-down direction of the wheel loader 200 is the direction perpendicular to the plane defined by the fore-aft direction and the left-right direction. In the up-down direction, the side where the ground is located is the lower side, and the side where the sky is located is the upper side.

[0122] The traveling device 204 includes traveling wheels 204a and 204b. Each of the traveling wheels 204a and 204b is a wheel and has a tire made of rubber. The traveling wheel (front wheel) 204a is rotatably attached to the front frame 211. The traveling wheel (rear wheel) 204b is rotatably attached to the rear frame 212. The wheel loader 200 can travel by rotationally driving the traveling wheels 204a and 204b.

[0123] The working machine 203 is for performing operations such as excavation. The working machine 203 is attached to the front frame 211. The working machine 203 includes a bucket 214, a boom 215, a bell crank 216, a tilt rod 217, a boom cylinder 218, and a bucket cylinder 219.

[0124] The base end portion of the boom 215 is rotatably attached to the front frame 211 by a boom bottom pin 221. Thereby, the boom 215 is rotatably attached to the vehicle body. The bucket 214 is rotatably attached to the tip of the boom 215 by a boom top pin 222. The boom bottom pin 221 is supported by the vehicle body of the wheel loader 200. The boom top pin 222 is attached to the tip of the boom 215. The boom bottom pin 221 and the boom top pin 222 extend in the left - right direction.

[0125] The boom cylinder 218 drives the boom 215. One end of the boom cylinder 218 is rotatably attached to the front frame 211 of the vehicle body by a pin 223. Thereby, the boom cylinder 218 is rotatably attached to the vehicle body. The other end of the boom cylinder 218 is rotatably attached to the boom 215 by a pin 224.

[0126] The boom cylinder 218 is, for example, a hydraulic cylinder. The boom cylinder 218 expands and contracts by hydraulic oil from a working machine pump (not shown). Thereby, the boom 215 is driven, and the bucket 214 attached to the tip of the boom 215 moves up and down.

[0127] Bell crank 216 is rotatably supported on boom 215 by support pin 229. Bell crank 216 has a first end located on one side of support pin 229 and a second end located on the opposite side of support pin 229 to the first end. The first end of bell crank 216 is connected to bucket 214 via tilt rod 217. The second end of bell crank 216 is connected to front frame 211 of the vehicle body via bucket cylinder 219.

[0128] One end of tilt rod 217 is rotatably attached to a first end of bell crank 216 by pin 227. The other end of tilt rod 217 is rotatably attached to bucket 214 by pin 228.

[0129] The bucket cylinder 219 drives the bucket 214 relative to the boom 215. One end of the bucket cylinder 219 is rotatably attached to the front frame 211 of the vehicle body by a pin 225. The other end of the bucket cylinder 219 is rotatably attached to the second end of the bell crank 216 by a pin 226.

[0130] Bucket cylinder 219 is, for example, a hydraulic cylinder. Bucket cylinder 219 expands and contracts with hydraulic oil from a work machine pump (not shown). The expansion and contraction of bucket cylinder 219 drives bell crank 216, which rotates relative to boom 215. The rotation of bell crank 216 is transmitted to bucket 214 via tilt rod 217, which drives bucket 214, causing bucket 214 to rotate up and down relative to boom 215. Bell crank 216 corresponds to a rotating member in the embodiment, which is rotatable together with bucket 214 relative to boom 215.

[0131] The wheel loader 200 further has a sensor that detects information relating to the thrust Fboom of the boom cylinder 218 and a sensor that detects information relating to the thrust Fbucket of the bucket cylinder 219.

[0132] The sensors that detect information related to the thrust Fboom of the boom cylinder 218 are, for example, pressure sensors 231b and 231h. Each of the pressure sensors 231b and 231h detects the cylinder pressure of the boom cylinder 218. The pressure sensor 231b detects the bottom pressure of the boom cylinder 218. The pressure sensor 231h detects the head pressure of the boom cylinder 218.

[0133] 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.

[0134] The sensors that detect information related to the thrust force Fbucket of the bucket cylinder 219 are, for example, pressure sensors 232b and 232h. Each of the pressure sensors 232b and 232h detects the cylinder pressure of the bucket cylinder 219. The pressure sensor 232b detects the bottom pressure of the bucket cylinder 219. The pressure sensor 232h detects the head pressure of the bucket cylinder 219.

[0135] The wheel loader 200 further has sensors that detect information relating to the attitude of the work implement 203. The sensors that detect information relating to the attitude of the work implement 203 include, for example, a first sensor that detects information relating to the boom angle and a second sensor that detects information relating to the bucket angle relative to the boom.

[0136] The information about the attitude of the work implement 203 includes a distance hboom and a distance hbucket ( FIG. 10 ). The distance hboom is the distance between the boom bottom pin 221 and the pin 223, and is the distance in a direction perpendicular to the extension direction of the boom cylinder 218. The distance hbucket is the distance between the support pin 229 and the pin 226, and is the distance in a direction perpendicular to the extension direction of the bucket cylinder 219.

[0137] The boom angle is the angle of the boom 215 relative to the front frame 211 of the vehicle body. The bucket angle is the angle of the bucket 214 relative to the boom 215.

[0138] The first sensor that detects information related to the boom angle is, for example, a potentiometer 233. The potentiometer 233 is attached so as to be concentric with the boom bottom pin 221. Instead of the potentiometer 233, a stroke sensor 235 of the boom cylinder 218 may be used as the first sensor that detects information related to the boom angle.

[0139] In addition, an IMU (Inertial Measurement Unit) 237 may be used as a first sensor that detects information related to the boom angle. The IMU 237 is attached to the boom 215, for example.

[0140] The second sensor that detects information related to the bucket angle is, for example, a potentiometer 234. The potentiometer 234 is attached so as to be concentric with the support pin 229. As the second sensor that detects information related to the bucket angle, a stroke sensor 236 of the bucket cylinder 219 may be used instead of the potentiometer 234.

[0141] In addition, the IMU 238 may be used as a second sensor that detects information related to the bucket angle. The IMU 238 is attached to the tilt rod 217, for example.

[0142] The above-mentioned potentiometers 233, 234, stroke sensors 235, 236, and IMUs 237, 238 may be used as sensors that detect information relating to the position of the center of gravity GC1 of the work machine 203. The information relating to the position of the center of gravity GC1 of the work machine 203 is the distance Xwe.

[0143] The distance Xwe is the distance between the center of gravity GC1 and the boom bottom pin 221, and is the distance along the front-to-rear direction of the wheel loader 200. The distance Xwe is the distance along the horizontal direction between the center of gravity GC1 and the boom bottom pin 221 when the wheel loader 200 is placed on a horizontal ground surface.

[0144] The potentiometers 233, 234, stroke sensors 235, 236, and IMUs 237, 238 may also be used as sensors that detect information about the position of the center of gravity GC2 of the load in the bucket 214. The information about the position of the center of gravity GC2 of the load in the bucket 214 is the distance Xpayload.

[0145] The distance Xpayload is the distance between the center of gravity GC2 and the boom bottom pin 221, and is the distance along the front-to-rear direction of the wheel loader 200. Xpayload is the distance along the horizontal direction between the center of gravity GC2 and the boom bottom pin 221 when the wheel loader 200 is placed on a horizontal ground surface.

[0146] Fig. 9 is a diagram showing functional blocks within a controller 250 of the fourth embodiment. The system in this embodiment is a system for determining a load weight, which is the weight of a load carried by a work machine 203. The system in this embodiment includes a wheel loader 200 as an example of a work machine shown in Fig. 8, and a controller 250 shown in Fig. 9. The controller 250 may be mounted on the wheel loader 200. The controller 250 may be installed outside the wheel loader 200. The controller 250 may be arranged at the work site of the wheel loader 200, or may be arranged in a remote location away from the work site of the wheel loader 200.

[0147] 9, boom cylinder thrust calculation unit 250a acquires the detection results of pressure sensors 231b, 231h. Specifically, boom cylinder thrust calculation unit 250a acquires the head pressure of boom cylinder 218 detected by pressure sensor 231h. Boom cylinder thrust calculation unit 250a acquires the bottom pressure of boom cylinder 218 detected by pressure sensor 231b. Boom cylinder thrust calculation unit 250a calculates boom cylinder thrust Fboom based on the head pressure and bottom pressure of boom cylinder 218.

[0148] A thrust is defined as a force that pushes an object in the direction of movement, and the boom cylinder thrust Fboom is a thrust that is generated by the boom cylinder 218 and rotates the boom 215 relative to the vehicle body. The boom cylinder thrust calculation unit 250a outputs the calculated boom cylinder thrust Fboom to the load weight calculation unit 250i.

[0149] The bucket cylinder thrust calculation unit 250c acquires the detection results of the pressure sensors 232b, 232h. Specifically, the bucket cylinder thrust calculation unit 250c acquires the head pressure of the bucket cylinder 219 detected by the pressure sensor 232h. The bucket cylinder thrust calculation unit 250c acquires the bottom pressure of the bucket cylinder 219 detected by the pressure sensor 232b. The bucket cylinder thrust calculation unit 250c calculates the bucket cylinder thrust Fbucket based on the head pressure and bottom pressure of the bucket cylinder 219.

[0150] The bucket cylinder thrust Fbucket is a thrust generated by the bucket cylinder 219 that rotates the bucket 214 relatively to the boom 215. The bucket cylinder thrust calculation unit 250c outputs the calculated bucket cylinder thrust Fbucket to the load weight calculation unit 250i.

[0151] The boom angle calculation unit 250d acquires information about the boom angle from at least one of the stroke sensor 235, the IMU 237, and the potentiometer 233. The boom angle calculation unit 250d calculates the boom angle based on the acquired information. The boom angle calculation unit 250d outputs the calculated boom angle to the center of gravity position calculation unit 250g.

[0152] The bucket angle calculation unit 250f acquires information about the bucket angle from at least one of the stroke sensor 236, the IMU 238, and the potentiometer 234. The bucket angle calculation unit 250f calculates the bucket angle based on the acquired information. The bucket angle calculation unit 250f outputs the calculated bucket angle to the center of gravity position calculation unit 250g.

[0153] The storage unit 250j stores various information such as the dimensions and weight of each member constituting the work machine 203, and the position of the center of gravity GC1 of the work machine 203. These various information may be input to the storage unit 250j from an input unit 251 outside the controller 250. The storage unit 250j may not be included in the controller 250, and may be disposed outside the controller 250.

[0154] The center of gravity position calculation unit 250g calculates the relative position of the center of gravity GC1 of the work implement 203 with respect to the boom bottom pin 221. The center of gravity position calculation unit 250g calculates the above-mentioned relative position of the center of gravity GC1 of the work implement 203 from the boom angle calculated by the boom angle calculation unit 250d, the bucket angle calculated by the bucket angle calculation unit 250f, and the position of the center of gravity GC1 of the work implement 203 stored in the memory unit 10j.

[0155] The moment distance calculation unit 250h calculates the horizontal distance from the boom bottom pin 221 to the center of gravity GC1 of the work implement 203. Specifically, the moment distance calculation unit 250h calculates the horizontal distance Xwe from the boom bottom pin 221 to the center of gravity GC1 of the work implement 203.

[0156] In addition, the moment distance calculation unit 250h calculates the horizontal distance Xbucket from the boom bottom pin 221 to the center of gravity GC3 (FIG. 10) of the bucket 214. The moment distance calculation unit 250h calculates the horizontal distance Xtiltrod from the boom bottom pin 221 to the center of gravity of the tilt rod 217.

[0157] In addition, the moment distance calculation unit 250h calculates the horizontal distance Xpin from the boom bottom pin 221 to the support pin 229.

[0158] In addition, the moment distance calculation unit 250h calculates the distance hboom from the boom bottom pin 221 to the boom cylinder 218 in a direction perpendicular to the extension direction of the boom cylinder 218. The moment distance calculation unit 250h calculates the distance hbucket from the support pin 229 to the bucket cylinder 219 in a direction perpendicular to the extension direction of the bucket cylinder 219.

[0159] The moment distance calculation unit 250h outputs these calculated distances to the load weight calculation unit 250i.

[0160] The load weight calculation unit 250i calculates the weight Mpayload of the load loaded in the bucket 214. The load weight calculation unit 250i outputs the calculated weight Mpayload to a display unit 252 outside the controller 250. The display unit 252 may be disposed, for example, in the cab 205 (FIG. 8), or may be disposed in a remote location away from the wheel loader 200. The display unit 252 displays the calculated weight Mpayload on a screen. An operator who operates the wheel loader 200 in the cab 205, an operator who operates the wheel loader 200 in a remote location, or an observer who monitors the operation of the wheel loader 200, can recognize the weight Mpayload of the load loaded in the bucket 214 by looking at the display unit 252.

[0161] Each of the input unit 251 and the display unit 252 may be connected to the controller 250 by wire or wirelessly.

[0162] Hereinafter, a method for calculating the weight Mpayload of the load loaded on the bucket 214 in the fourth embodiment will be described in detail. The load weight calculation unit 250i shown in Fig. 9 reads out a balance equation for the moment around the boom bottom pin 221 from the storage unit 250j. The balance equation for the moment around the boom bottom pin 221 is expressed by the following equation (8).

[0163]

number

[0164] The left side of equation (8) is the moment due to the boom cylinder thrust Fboom. In equation (8), Mpayload is the weight of the load loaded in the bucket 214. Xpayload is the horizontal distance from the boom bottom pin 221 to the center of gravity GC2 of the load loaded in the bucket 214. The first term on the right side of equation (8) is the moment due to the load loaded in the bucket 214.

[0165] The second term MXwe on the right side of equation (8) is the moment due to the weight of the work implement 203. The moment MXwe is calculated by multiplying the sum M1 (FIG. 8) of the weights of the members constituting the work implement 203 and the horizontal distance Xwe from the boom bottom pin 221 to the center of gravity GC1 of the work implement 203.

[0166] Next, the cargo weight calculation unit 250i reads out, from the memory unit 250j, a balance equation for the moment around the support pin 229. Fig. 10 is a schematic diagram showing the balance of the moment around the support pin 229. The balance equation for the moment around the support pin 229 is expressed by the following equation (9).

[0167]

number

[0168] The left side of equation (9) is the moment due to bucket cylinder thrust Fbucket. The first term on the right side of equation (9) is the moment due to the load loaded on the bucket 214. The second term MXwe_pin on the right side of equation (9) is the moment due to the weight of the work machine 203 on the tip side of the work machine 203 relative to the support pin 229. The moment MXwe_pin is calculated by the following equation (10).

[0169]

number

[0170] In formula (10), Mbucket is the weight of bucket 214. Mtiltrod is the weight of tilt rod 217. Each of these weights Mbucket and Mtiltrod is stored in storage unit 250j, for example, by performing an input operation to storage unit 250j at input unit 251 shown in FIG.

[0171] From the simultaneous equations of equations (8) and (9), the following equation (11), which does not depend on the distance Xpayload, can be formulated as an equation for calculating the payload weight Mpayload.

[0172]

number

[0173] Equation (8) includes the distance Xpayload, and equation (9) also includes the distance Xpayload. By solving these two balance equations as simultaneous equations, equation (11) that does not include the distance Xpayload is derived. It becomes possible to calculate the payload weight Mpayload based on equation (11). This makes it possible to eliminate the influence of the shift in the center of gravity position of the load loaded in the bucket 214 and calculate the payload weight Mpayload with higher accuracy.

[0174] The distance Xpayload can be calculated by substituting the load weight Mpayload calculated according to equation (11) into equation (8) or equation (9). In addition, an equation that does not depend on the load weight Mpayload can be formulated as an equation for calculating the distance Xpayload from the simultaneous equations of equations (8) and (9). The position of the center of gravity of the load loaded in the bucket 214 can be corrected according to the calculated distance Xpayload.

[0175] In the wheel loader 200 shown in the fourth embodiment, by calculating the weight of the load while the wheel loader 200 is moving backward with a load loaded in the bucket 214, it is possible to calculate the weight of the load with greater accuracy.

[0176] In the above embodiment, the controller 10 uses two of the moment balance equations for each of the multiple links of the work machine as the relational equations for calculating the weight of the load. The relational equations are not limited to the moment balance equations, and may be equations of motion for each of the multiple links. The equations of motion may be set up using information from pressure sensors and position sensors, similar to the balance equations.

[0177] Although the embodiment has been described above, the disclosed embodiment is illustrative in all respects and should not be considered as being limiting. The scope of the present invention is indicated by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0178] 1 Traveling body, 2 Swinging body, 2a Cab, 3,203 Work machine, 3a,215 Boom, 3b Arm, 3c,214 Bucket (attachment), 3d Bucket link, 3da First link member, 3db Second link member, 3dc Bucket cylinder top pin, 3dd First link pin, 3de Second link pin, 4a,218 Boom cylinder (boom hydraulic cylinder), 4aa Cylinder, 4ab Cylinder rod, 4b Arm cylinder (arm hydraulic cylinder), 4c,219 Bucket cylinder (attachment hydraulic cylinder), 5a,221 Boom bottom pin (first rotation center), 5b,222 Boom top pin (second rotation center), 5c Arm top pin (third rotation center), 6a,6b,6c,6d,6e,6f,231b,231h,232b,232h Pressure sensor, 7a, 7b, 7c, 235, 236 Stroke sensor, 9a, 9b, 9c Angle sensor (sensor, position sensor), 10, 250 Controller, 10a, 250a Boom cylinder thrust calculation unit, 10b Arm cylinder thrust calculation unit, 10c, 250c Bucket cylinder thrust calculation unit, 10d, 250d Boom angle calculation unit, 10e Arm angle calculation unit, 10f, 250f Bucket angle calculation unit, 10g, 250g Center of gravity position calculation unit, 10h, 250h Moment distance calculation unit, 10i, 250i Load weight calculation unit, 10j, 250j Memory unit, 11, 251 Input unit, 12, 252 Display unit, 40 Actuator, 100 Hydraulic excavator, 103 Lifting magnet, 104 Support unit, 105 Main body unit, 200 Wheel loader, 202 body frame, 204 running gear, 205 cab, 216 bell crank, 217 tilt rod, 229 support pin, 233, 234 potentiometer, L load.

Claims

1. A calculation device for calculating a weight of a load carried by a work machine equipped with a work implement, comprising: The work machine includes: The car body and A boom bottom pin supported on the vehicle body; a boom rotatably connected to the vehicle body by the boom bottom pin; A boom top pin attached to a tip of the boom; an arm rotatably connected to the boom by the boom top pin; An arm top pin attached to a tip of the arm; an attachment rotatably connected to the arm by the arm top pin; a calculation device that calculates the weight of the load from any two of the balance equations of the moment around the boom bottom pin, the balance equation of the moment around the boom top pin, and the balance equation of the moment around the arm top pin.

2. The work machine includes: an actuator that generates a thrust force that rotates the boom relative to the vehicle body; a sensor that detects an angle of the boom relative to the vehicle body, 2. The computing device according to claim 1, further comprising: a balance equation for a moment around the boom bottom pin based on the thrust generated by the actuator and the detection result of the sensor.

3. The work machine includes: an actuator that generates a thrust force that rotates the arm relative to the boom; a sensor that detects an angle of the arm relative to the boom, 2. The computing device according to claim 1, further comprising: a balance equation for a moment around the boom top pin based on the thrust generated by the actuator and the detection result of the sensor.

4. The work machine includes: an actuator that generates a thrust force that rotates the attachment relative to the arm; a sensor that detects an angle of the attachment relative to the arm, 2. The computing device according to claim 1, further comprising: a balance equation for a moment around the arm top pin based on a thrust generated by the actuator and a detection result of the sensor.

5. The work machine further includes a link member connecting the actuator and the arm, The computing device according to claim 4 , wherein the sensor is attached to the link member.

6. The computing device according to claim 1 , wherein the attachment is a lifting magnet.

7. 7. The calculation device according to claim 1, wherein the position of the center of gravity of the load is calculated from any two of the balance equations.

8. A calculation device for calculating a weight of a load carried by a work machine equipped with a work implement, comprising: The work machine includes: The car body and A boom bottom pin supported on the vehicle body; a boom rotatably connected to the vehicle body by the boom bottom pin; A boom top pin attached to a tip of the boom; an attachment rotatably connected to the boom by the boom top pin; a rotating member supported by the boom and rotatable relative to the boom together with the attachment, a calculation device that calculates the weight of the load from two balance equations, namely, a balance equation for the moment around the boom bottom pin and a balance equation for the moment around the rotation center of the rotating member.

9. The work machine includes: an actuator that generates a thrust force that rotates the boom relative to the vehicle body; a sensor that detects an angle of the boom relative to the vehicle body, 9. The computing device according to claim 8, further comprising: a balance equation for a moment around the boom bottom pin based on the thrust generated by the actuator and the detection result of the sensor.

10. The work machine includes: an actuator that generates a thrust force that rotates the attachment relative to the boom; a sensor that detects an angle of the attachment relative to the boom, 9. The computing device according to claim 8, further comprising: a balance equation for the moment about the center of rotation based on the thrust generated by the actuator and the detection result of the sensor.

11. 11. The computing device according to claim 8, wherein the position of the center of gravity of the load is calculated from the two balance equations.

12. A calculation device for calculating a weight of a load carried by a work machine equipped with a work implement, comprising: The work machine includes: The car body and A boom bottom pin supported on the vehicle body; a boom having one end rotatably connected to the vehicle body by the boom bottom pin; A boom top pin attached to the other end of the boom; an arm having one end rotatably connected to the other end of the boom by the boom top pin; an arm top pin attached to the other end of the arm; an attachment having one end rotatably connected to the other end of the arm by the arm top pin; A boom hydraulic cylinder that drives the boom to perform a rotational operation; an arm hydraulic cylinder that drives the arm to rotate it; An attachment hydraulic cylinder that drives the attachment to rotate it; a pressure sensor including at least two sensors among a boom pressure sensor attached to the boom hydraulic cylinder and outputting hydraulic oil pressure information of the boom hydraulic cylinder, an arm pressure sensor attached to the arm hydraulic cylinder and outputting hydraulic oil pressure information of the arm hydraulic cylinder, and an attachment pressure sensor attached to the attachment hydraulic cylinder and outputting hydraulic oil pressure information of the attachment hydraulic cylinder; a boom position sensor that outputs boom information for obtaining a position of the boom relative to the vehicle body, an arm position sensor that outputs arm information for obtaining a position of the arm relative to the boom, and an attachment position sensor that outputs attachment information for obtaining a position of the attachment relative to the arm, Calculating a weight of the load from any two of the following relational expressions: a first relational expression generated from the hydraulic oil pressure information of the boom hydraulic cylinder and the boom information, a second relational expression generated from the hydraulic oil pressure information of the arm hydraulic cylinder and the arm information, and a third relational expression generated from the hydraulic oil pressure information of the attachment hydraulic cylinder and the attachment information in transporting the load; The pressure sensor includes at least two sensors corresponding to the two relational expressions.

13. the boom position sensor is a sensor that detects an angle of the boom with respect to the vehicle body, the arm position sensor is a sensor that detects an angle of the arm with respect to the boom, The computing device according to claim 12 , wherein the attachment position sensor is a sensor that detects an angle of the attachment relative to the arm.

14. The first relational expression is a balance expression of a moment around the boom bottom pin when the load is transported, the second relational expression is a balance expression for a moment around the boom top pin when the load is transported, 14. The arithmetic device according to claim 12, wherein the third relational expression is a balance expression for a moment around the arm top pin when the load is transported.

15. A calculation method for calculating a weight of a load carried by a work machine equipped with a work machine, comprising: The working machine has, as members, a boom that rotates about a first rotation center, an arm that rotates about a second rotation center, and an attachment that rotates about a third rotation center, formulating a relational equation for a motion of the member about any two of the first rotation center, the second rotation center, and the third rotation center; Obtaining the weight and center of gravity position of each of said members; Obtaining a position of the member during transportation of the load; Obtaining a thrust force corresponding to the motion of the relational expression; calculating horizontal distances between the center of gravity of each of the members and the corresponding first rotation center, second rotation center, and third rotation center during transport of the load from the center of gravity of the members and the positions of the members; calculating a weight of the load transported by the work machine using the relational equation, the acquired information, and the calculated information.

16. The method according to claim 15 , wherein the position of the member is obtained from an angle indicative of an attitude of the member.

17. 17. The calculation method according to claim 15, wherein the relational expression is a balance expression of a moment about a center of rotation of the motion.

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