Work machine

Abstract

Provided is a work machine comprising a control device that is capable of accurately adjusting the surplus soil amount in a work device. A controller predicts and calculates the surplus soil amount in the work device from dimensional information and orientation information. The controller displays a predicted value for the calculated surplus soil amount on a monitor and notifies an operator who operates an operation lever of an actuator. Alternatively, the controller automatically controls the operation of the actuator on the basis of the predicted value for the calculated surplus soil amount and performs operation control (orientation control) of the work device.

Description

Work machinery

[0001] The present invention relates to a work machine equipped with a control device that is equipped with a function for measuring the weight of a load inside the work device.

[0002] In recent years, automatic soil dumping technologies have been developed that automatically dump soil loaded in a work device by controlling the operation of the work device of a work machine, with the aim of reducing the operational burden on the operator and improving work efficiency. When dumping soil, for example, it is desirable to be able to accurately determine the weight of the load (cargo) being loaded onto a transport vehicle. Therefore, if the amount of soil loaded in the work device exceeds a specified weight, the excess soil in the work device is dumped in advance to adjust the weight of the soil loaded in the work device. In this automatic soil dumping technology, instead of the operator operating the operating device, a control device calculates the weight of the load in the work device (hereinafter also referred to as the amount of remaining soil) based on the bottom pressure of the lift arm cylinder and changes in the attitude of the work device, and controls the dumping operation (also referred to as the tilting operation) and tilting operation (also referred to as the raising operation or crowding operation) of the work device by controlling the extension and retraction of the lift arm cylinder and bucket cylinder.

[0003] For example, the method described in Patent Document 1 automatically releases soil by controlling the working device to mix according to a mixing pattern until the amount of residual soil in the working device reaches a target weight (see Figure 3, etc.).

[0004] US Patent Application Publication No. 2022 / 0325497

[0005] However, the method described in Patent Document 1 calculates the amount of remaining soil in the working device based on factors such as the pressure of the lift arm cylinder during soil release control, and initiates soil release control termination when the calculated amount of remaining soil reaches a target weight. Therefore, even after the amount of remaining soil reaches the target weight and soil release control termination is initiated, the remaining soil in the working device actually collapses due to gravity and inertial forces acting on the soil, causing soil to fall from the working device, making it inevitable that more soil than the target weight will be released. Furthermore, to reduce the amount of soil falling from the working device after soil release control termination is initiated, it is possible to reduce the amount of movement per unit time (i.e., movement speed) in the control and release the soil over a longer period of time, but this significantly reduces work efficiency. The same issues exist when the operator operates the control lever while viewing the soil weight displayed on a screen. In other words, the conventional method of calculating the amount of remaining soil based on factors such as the pressure of the lift arm cylinder during soil release control and initiating soil release control termination based on the calculated amount of remaining soil cannot accurately release soil.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a work machine equipped with a control device that enables accurate adjustment of the amount of residual soil.

[0007] In order to achieve the above object, the work machine of the present invention comprises a vehicle body, a work device rotatably attached to the vehicle body and capable of loading an object, an actuator that drives the work device, an attitude information detection device that detects attitude information of the work device, and a controller that controls the operation of the actuator and performs release control of the object within the work device, wherein the controller calculates a predicted value of the weight of the object within the work device in a loaded state, estimated based on dimensional information that indicates the geometric shape of the work device and the attitude information, during the release control.

[0008] According to the present invention, it is possible to calculate the amount of residual soil that will be predicted when the suspension of soil release control is initiated, thereby making it possible to accurately adjust the amount of residual soil.

[0009] Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments.

[0010] 1 is an external side view of a wheel loader according to a first embodiment. FIG. 2 is an external perspective view of a wheel loader according to a first embodiment. FIG. 3 is a system configuration diagram of a wheel loader according to a first embodiment. FIG. 4 is a system configuration diagram of predicting the amount of remaining soil in a bucket in soil release control by a controller according to a first embodiment. FIG. 5 is a flowchart of predicting the amount of remaining soil in a bucket in soil release control by a controller according to a first embodiment. FIG. 6 is an explanatory diagram of dimensional information showing the geometric shape of a bucket and physical property values ​​of a loading target in a first embodiment. FIG. 7 is an explanatory diagram of an example of a monitor display in soil release control by a controller according to a first embodiment. FIG. 8 is a system configuration diagram of predicting the amount of remaining soil in a bucket in soil release control by a controller according to a second embodiment. FIG. 9 is a flowchart of predicting the amount of remaining soil in a bucket in soil release control by a controller according to a second embodiment. FIG. 10 is an explanatory diagram of a delay in weight in a bucket according to a second embodiment. FIG. 11 is an explanatory diagram of an example of a monitor display in soil release control by a controller according to a second embodiment. FIG. 12 is a system configuration diagram of predicting the amount of remaining soil in a bucket in soil release control by a controller according to a third embodiment. FIG. 13 is a flowchart of predicting the amount of remaining soil in a bucket in soil release control by a controller according to a third embodiment.

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the description of the drawings, the same elements are given the same reference numerals, and duplicate explanations will be omitted. In the following description, the directions and positions of up / down, left / right, and front / rear are based on the normal use state of the wheel loader, i.e., the state when the wheels are in contact with the ground.

[0012] First Embodiment First, a first embodiment for carrying out the present invention will be described.

[0013] The vehicle body targeted by this invention is assumed to be a work machine such as a shovel that can load earth and sand into a working device and is equipped with a function for measuring the weight of the load inside the working device, but in the embodiment of this invention, it is a wheel loader with a working device. Wheel loaders are machines that run on wheels, are four-wheel drive, and have center-bend steering, and are derivative machines of these.

[0014] The external appearance of the wheel loader is shown in FIGS. 1 and 2.

[0015] The wheel loader 50 has a working machine section 2 mounted in front of a vehicle section 1 (also called a vehicle body or frame), and is equipped with a bucket 3 for scooping up earth and sand.

[0016] The wheel loader 50 is a machine in which an operator sitting in a driver's seat 4B installed on the vehicle controls the height and angle of the bucket 3, as well as the direction and speed at which the wheeled vehicle travels, and performs excavation work to scoop up soil and sand from the ground surface with the bucket 3, transportation work to move the scooped up soil and sand, and loading work to dump the scooped up soil and sand onto the bed of a dump truck.

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

[0018] While traveling, the wheel loader 50 performs steering by changing the angle (bending angle) of the front frame 6 relative to the rear frame 8 by extending and retracting the left and right hydraulic cylinders 10 .

[0019] The work machine section 2 is made up of a bucket 3 and a lift arm 11 for supporting the bucket 3 .

[0020] The lift arms 11 are configured as a pair, left and right, and are connected to (the front end of) the front frame 6 so as to be rotatable (tiltable) up and down about fulcrums 21 spaced apart in the left-right (width) direction. A lift cylinder 12 is connected (interposed) to (the front end of) the front frame 6 and (the middle part of) the lift arm 11 so that the load of the lift arm 11 can be supported by the front frame 6 and the angle (height) of the lift arm 11 relative to the front frame 6 can be varied. The lift cylinder 12 is equipped with a pressure sensor 12b (FIG. 8) that measures the internal pressure on the bottom side of the lift cylinder 12 and a pressure sensor 12r (FIG. 8) that measures the internal pressure on the rod side of the lift cylinder 12. These pressure sensors 12b and 12r may be installed anywhere in the piping where the same pressure is applied.

[0021] The bucket 3 is connected to (the front end of) the lift arm 11 so as to be rotatable (tiltable) in the vertical direction about a fulcrum 13. A bucket cylinder 16 is connected to (the front end of) the front frame 6 via a push rod 14 and a bell crank 15 so as to vary the angle (inclination) of the bucket 3 relative to the lift arm 11. The bucket cylinder 16 is connected to (the front end of) the front frame 6 at a fulcrum 17 (a position different from the fulcrum of the lift cylinder 12 on the front frame 6 side). The bell crank 15 is connected to (the tip of) the bucket cylinder 16 so as to be rotatable about a fulcrum 22. The push rod 14 is connected to (the tip of) the bell crank 15 so as to be rotatable about a fulcrum 24. The bell crank 15 is also connected to (the middle portion of) the lift arm 11 so as to be rotatable about a connection point 25. The bucket 3 is connected to (the tip of) the push rod 14 so as to be rotatable about a fulcrum 23. The push rod 14, bell crank 15, and bucket cylinder 16 are disposed midway between the pair of left and right lift arms 11. The bucket cylinder 16 is fitted with a pressure sensor 16b (FIG. 8) that measures the internal pressure on the bottom side of the bucket cylinder 16 and a pressure sensor 16r (FIG. 8) that measures the internal pressure on the rod side of the bucket cylinder 16. These pressure sensors 16b and 16r may be fitted at any location within the piping where the pressures are the same.

[0022] The height of the bucket 3 can be changed by extending and retracting the lift cylinder 12, and the angle (tilt) of the bucket 3 can be changed by extending and retracting the bucket cylinder 16. In other words, the extension and retraction of the lift cylinder 12 causes the lift arm 11 to rotate vertically, raising and lowering the bucket 3. In addition, a bell crank 15 and a push rod 14 are interposed between the bucket cylinder 16 and the bucket 3, and the bucket cylinder force (extension and retraction force) of the bucket cylinder 16 is transmitted to the bucket 3 via the bell crank 15 and the push rod 14. Therefore, the extension and retraction of the bucket cylinder 16 causes the bucket 3 to rotate vertically via the bell crank 15 and the push rod 14, causing the bucket 3 to tilt (tilt, crowd, or dump).

[0023] A lift arm angle sensor 19, which detects the angle the lift arm 11 makes with respect to the front frame 6 (in other words, the relative position of the lift arm 11 with respect to the front frame 6), is attached to a fulcrum 21, and a bell crank angle sensor 20, which detects the angle the bell crank 15 makes with respect to the lift arm 11 (in other words, the relative position of the bell crank 15 with respect to the lift arm 11), is attached to a connection point 25, and these sensors can obtain the results of the extension and contraction of the lift cylinder 12 and the bucket cylinder 16. In other words, the lift arm angle sensor 19 and the bell crank angle sensor 20 measure the relative position (relative angle) between the lift arm 11 and the front frame 6 and the relative position (relative angle) between the bell crank 15 and the lift arm 11, and these two angle sensors can measure (detect) the relative position (relative angle) of the bucket 3 with respect to the front frame 6.

[0024] The system configuration of the wheel loader 50 will be described with reference to FIG.

[0025] The output shaft 100 of the engine 4 is directly connected to a torque converter 101, a hydraulic pump 102, and a brake pump 103. The rotation speed of the engine 4 is controlled by an electrical signal 105 from an engine controller 104, which in turn indicates the rotation speed of the engine 4 based on the amount of depression of an accelerator pedal 106.

[0026] The output shaft of the torque converter 101 is connected to a drive shaft 108 via a transmission 107 to drive the front and rear wheels. The driving force transmitted from the torque converter 101 to the transmission 107 increases as the rotation speed of the output shaft 100 of the engine 4 increases relative to the output rotation speed of the torque converter 101. By increasing the rotation speed of the engine 4 by depressing the accelerator pedal 106, the driving force output by the torque converter 101 increases.

[0027] The transmission 107 cuts off the connection between the output of the torque converter 101 and the drive shaft 108 to reduce the driving force of the front and rear wheels, or reverses the direction of rotation to change the direction of the driving force of the front and rear wheels, using an electrical signal 110 from the transmission controller 109.

[0028] An electrical signal 110 from the transmission controller 109 is output to cut off the connection when the depression amount of the brake pedal 112 is equal to or greater than a certain amount.

[0029] The hydraulic pump 102 outputs a constant flow rate of pressurized oil for each rotation of the output shaft 100 of the engine 4. The pressurized oil output from the hydraulic pump 102 is supplied to the lift cylinder 12 and the bucket cylinder 16, which serve as hydraulic actuators, via a bucket control hydraulic circuit 113, and causes the lift cylinder 12 and the bucket cylinder 16 to extend and retract.

[0030] The amount of pressurized oil output from the hydraulic pump 102 increases as the rotation speed of the output shaft 100 of the engine 4 increases. Therefore, when the rotation speed of the engine 4 is increased by depressing the accelerator pedal 106, the extension / retraction speed of the lift cylinder 12 and the bucket cylinder 16 (and thus the operating speed of the lift arm 11 or bucket 3) increases.

[0031] The bucket control hydraulic circuit 113, when operated by the operator using the lift lever 114, cuts off the connection between the output of the hydraulic pump 102 and the lift cylinder 12 to stop the operation of the lift arm 11, or reverses the extension / retraction direction to switch the up and down operation of the lift arm 11.

[0032] When the operator operates a bucket lever 115, the bucket control hydraulic circuit 113 cuts off the connection between the output of the hydraulic pump 102 and the bucket cylinder 16 to stop the operation of the bucket 3, or reverses the extension / retraction direction to switch the forward / backward movement of the angle (tilt) of the bucket 3.

[0033] The pressure oil output from the hydraulic pump 102 is connected to the left and right steering cylinders 10 as hydraulic actuators via a steering control hydraulic circuit 116, and causes the left and right steering cylinders 10 to extend and retract.

[0034] When the operator turns the steering wheel 117 to the right, the steering control hydraulic circuit 116 outputs a steering angle signal 116S and simultaneously connects the pressure oil output from the hydraulic pump 102 in the direction that retracts the right steering cylinder 10R and the direction that extends the left steering cylinder 10L, thereby turning the vehicle body to the right.When the operator turns the steering wheel 117 to the left, the steering control hydraulic circuit 116 outputs a steering angle signal 116S and simultaneously connects the pressure oil output from the hydraulic pump 102 in the direction that extends the right steering cylinder 10R and the direction that retracts the left steering cylinder 10L, thereby turning the vehicle body to the left.

[0035] The pressure oil output from the brake pump 103 is stored in an accumulator 118, and the pressure oil stored in the accumulator 118 is passed through a brake control hydraulic circuit 119 to control the braking force of the four wheels.

[0036] The brake control hydraulic circuit 119 adjusts the control pressure (braking force) according to the amount of depression of the brake pedal 112 by the operator.

[0037] The wheel loader 50 is equipped with a controller 120. The controller 120 includes, for example, a central processing unit (CPU), read-only memory (ROM), and random access memory (RAM). The CPU reads and executes program code stored in the ROM, thereby realizing each of the functional blocks described below in the controller 120. The RAM is used as a work area when the CPU executes the program. However, the specific configuration of the controller 120 is not limited to this, and the controller 120 may be realized by hardware such as an application specific integrated circuit (ASIC) or a field-programmable gate array (FPGA).

[0038] The controller 120 is connected to the lift arm angle sensor 19, the bell crank angle sensor 20, the bucket control hydraulic circuit 113, the monitor 123, the soil release start switch 111, and the bucket lever 115. In addition, the values ​​of the lift cylinder rod-side pressure sensor 12r, the bucket cylinder rod-side pressure sensor 16r, the lift cylinder bottom-side pressure sensor 12b, and the bucket cylinder bottom-side pressure sensor 16b are input to the controller 120 via the bucket control hydraulic circuit 113.

[0039] In this embodiment, in response to operation of bucket lever 115 by the operator, for example, controller 120 supplies pressure oil to bucket cylinder 16 via bucket control hydraulic circuit 113, controls extension and contraction of bucket cylinder 16, controls the operation (attitude control) of bucket 3, and controls the release of earth and sand as the object loaded into bucket 3. During this release control, controller 120 calculates a predicted value (hereinafter also referred to as predicted residual earth volume) of the weight of earth and sand in bucket 3 (hereinafter also referred to as residual earth volume) based on part of the input signals, and outputs the calculation result to monitor 123 and part of bucket control hydraulic circuit 113.

[0040] The system configuration for predicting the amount of remaining soil in the bucket 3 during soil release control by the controller 120 will be described with reference to FIG.

[0041] This system is composed of a lift arm angle sensor 19, a bell crank angle sensor 20, a controller 120, and a monitor 123, all of which are connected by electrical wiring for exchanging electrified information. The controller 120 has, as functional blocks for executing calculation processing, a bucket dimension information storage unit 200, a bucket attitude information generation unit 201, and a predicted residual soil volume in bucket calculation unit 202. Note that the bucket dimension information storage unit (bucket dimension information storage device) 200 may be arranged outside the controller 120, as long as it can store dimension information indicating the geometric shape of the bucket 3.

[0042] The controller 120 uses a bucket attitude information generating unit 201 to generate the toe angle of the bucket 3 with respect to the tire contact surface (see FIG. 6 ) as attitude information from the values ​​of the lift arm angle sensor 19 and the bell crank angle sensor 20, which serve as attitude information detection devices that detect attitude information of the bucket 3. The attitude information may be obtained by directly detecting the angle between the bucket 3 and gravity using an IMU sensor (not shown), or may be corrected by placing an IMU sensor inside the driver's seat of the vehicle body to detect whether the tire contact surface is inclined with respect to gravity.

[0043] The controller 120 uses a bucket predicted soil volume calculation unit 202 to calculate the predicted soil volume in the bucket 3 from the bucket 3 dimension information stored in the bucket dimension information storage unit 200 and the bucket 3 attitude information (the angle of the toe of the bucket 3 relative to the tire contact surface) generated by the bucket attitude information generation unit 201. The calculation results are output to the monitor 123. The calculation method will be explained using a flowchart.

[0044] FIG. 5 shows a flowchart of the remaining soil amount prediction of the bucket 3 in the soil release control of the controller 120.

[0045] The controller 120's bucket predicted soil residue volume calculation unit 202 sequentially reads recorded physical property values ​​(S501), calculates the soil residue volume Wp predicted from the toe angle φ of the bucket 3 (S502), determines whether the predicted value is valid or invalid (S503), outputs the display content to the monitor 123 (S504, S505), calculates the soil residue volume Wf predicted from the toe angle change if the toe angle change rate is above a certain level (S506, S507), and outputs the display content to the monitor 123 as the soil residue volume Wf predicted at the time of stoppage (S508).

[0046] In the process of reading recorded physical property values ​​(S501), recorded physical property values ​​of the loading object, such as earth and sand, to be scooped up by the bucket 3 and dumped onto the bed of the dump truck are read.

[0047] In the calculation process (S502) of the residual soil volume Wp predicted based on the tip angle φ of the bucket 3, the following calculation formula (1) is used, which uses the dimensional information, attitude information, and physical property values. This calculation formula (1) is used to calculate the residual soil volume Wp (predicted value) in the bucket 3, which predicts the loading state (according to the attitude information) based on the dimensional information, attitude information, and physical property values ​​(in other words, the predicted loading state) (see also FIG. 6). <Equation 1> Residual soil volume Wp = N(φ) = radius R × radius R × (angle of repose θ + tip angle φ) × π / 360 × depth D × density ρ... formula (1)

[0048] Here, the function N(φ) is the amount of residual soil (predicting the loading state) at the toe angle φ. Here, the calculation of the internal volume of bucket 3, an example of a work tool, has been simplified and expressed as radius R and angle, but of course, if the shape or dimensions of the work tool are different, the formula should be adjusted accordingly.

[0049] In formula (1), the radius R and depth D are values ​​determined by the shape and dimensions of the work equipment; for example, the radius R = 1.2 m and the depth D = 2.8 m. The angle of repose θ and density ρ are physical properties that represent the characteristics of the material assumed to be loaded; for example, assuming dry soil and sand, the angle of repose θ = 35° and density ρ = 1.7 t / m^3. For example, using these values, formula (1) can be simplified to the following formula (2). Residual soil volume Wp = N(φ) ≒ 0.06(35 + φ) [t] ... formula (2)

[0050] Furthermore, due to the nature of wheel loader work, although the amount of remaining soil Wp inside the work equipment may fall off the equipment and decrease from time to time, the amount of soil inside the work equipment will not increase except during specific work operations, so it is advisable to reset the amount of remaining soil Wp to its maximum value when a loading operation (not shown), a weighing start operation, an engine on operation, or when the toe angle φ approaches its maximum value, and thereafter update the value only in the decreasing direction until it is reset again.

[0051] In the process of determining whether the predicted value is valid or invalid (S503), if the toe angle φ is equal to or less than the threshold A, the result is affirmative, and the remaining soil volume Wp is displayed on the monitor 123 as a valid predicted value (S504). If the toe angle φ is greater than the threshold A, the predicted value is invalid, and a message indicating that there is no valid predicted value is output to the monitor 123, and the process ends (S505). Here, threshold A is an angle threshold corresponding to a physical property value and determines whether the surface of the soil inside the work implement (bucket 3) is a repose angle surface. When the bucket 3, an example of a work implement, tilts forward, the toe angle formed when the rear end of the bucket 3 is positioned at the angle of repose θ relative to the front end of the soil flowing down (see the dotted-line box in Figure 5 ) can be set as threshold A. That is, threshold A is the angle at which the amount of soil inside the bucket 3 is supported at the front end by the angle of repose θ. Therefore, if the toe angle φ is equal to or less than threshold A, the calculation of Equation (1) is valid. Therefore, although it depends on the shape of the bucket 3, threshold A is, for example, 50 degrees. That is, in the process of determining whether the predicted value is valid or invalid (S503), the angle corresponding to the physical property value (threshold value A) is compared with the posture information of the bucket 3 (toe angle φ) to determine whether the predicted value of the residual soil volume Wp is valid or invalid (a valid / invalid determination is made).

[0052] When the toe angle change rate is determined to be equal to or greater than a certain level (S506), if the toe angle change rate is equal to or greater than the threshold F, the result is affirmative and the process proceeds to the remaining soil volume Wf calculation step (S507), whereas if the toe angle change rate is less than the threshold F and the result is negative, the process ends. In other words, it is determined whether or not to calculate the remaining soil volume Wf depending on the toe angle change rate. Here, the threshold F can be set to a toe angle change rate that is greater than a value expected due to noise or vibration of the vehicle body contained in the values ​​output by the lift arm angle sensor 19 and the bell crank angle sensor 20 used to calculate the posture information. For example, the threshold F can be set to 5 degrees / s.

[0053] The calculation process (S507) for the remaining soil volume Wf predicted based on the change in the toe angle calculates the remaining soil volume Wf using the following equation (3), which uses ts as the estimated time until the current toe angle change rate dφ / s reaches 0. Here, ts represents the time it takes for the vehicle to actually come to a stop when the operator attempts to change the vehicle from a forward tilt operation command state using the bucket lever 115 to a stopped state. Therefore, it is a value calculated based on the characteristics of the hydraulic circuit, and represents, for example, the total time consisting of the reaction time from when the operator looks at the screen to when they operate the vehicle, and the response time from when the bucket control hydraulic circuit 113 is connected by operating the bucket lever 115 to when they stop operating the bucket lever 115 and the connection is broken. For example, ts is 1 second, which is the sum of the operator reaction time of 0.5 seconds and the machine response time of 0.5 seconds. Remaining soil amount Wf=N(φ+dφ / s*ts) = Radius R×Radius R×(Angle of repose θ+Toe angle (φ+dφ / s*ts))×π / 360×Depth D×Density ρ…Equation (3)

[0054] Thus, equation (3) is a calculation using the predicted value of the toe angle φ+dφ / s*ts after time ts seconds. In other words, the amount of remaining soil Wf calculated by equation (3) is a predicted value of the amount of remaining soil in the bucket 3, including the change in weight of the object in the bucket 3 due to the change in the toe angle (φ+dφ / s*ts) that can be predicted (until the bucket comes to a stop) from the current operating state of the bucket 3 (according to the operating speed dφ / s).

[0055] Wf is a value different from Wp, and either one, for example, only Wf, may be selected and displayed on the monitor 123, or Wp and Wf may be displayed separately on the monitor 123 (S508). By displaying Wp and Wf on the monitor 123 and informing the operator who operates the control lever of the hydraulic actuator, the operator can obtain information about Wp and Wf. Figure 7 shows an example of a display on the monitor 123 during soil release control by the controller 120.

[0056] When displayed on the monitor 123, it is not the amount of soil remaining inside the bucket 3 that is displayed, but rather the amount of soil remaining inside the bucket 3, which corresponds to the amount of soil discharged from inside the bucket 3 or the amount loaded onto the dump truck, so it may be converted into the amount of soil discharged, etc. and displayed on the monitor 123.

[0057] With the configuration and method described above, the amount of remaining soil that will be predicted if the release control is stopped during release can be calculated and displayed on the monitor 123, so the operator operating the control lever can obtain information via the monitor 123 as to whether the desired loading amount can be achieved by returning the control lever to neutral now, or whether it is necessary to continue dumping and increase the loading amount, and by operating the control lever at the appropriate timing, the amount of remaining soil can be accurately adjusted to load the target amount of soil. In particular, for vehicles with a long machine response time, predicting when the release control will be stopped makes it easier to operate the control lever at the appropriate timing.

[0058] [Embodiment 2] Embodiment 2, which is different from Embodiment 1 of the present invention, will be described with reference to Figure 8 in terms of additions and modifications made to the above-described Embodiment 1. The system configuration diagram of Embodiment 2 will be described using the system configuration diagram of Figure 8, rather than Figure 4 used in Embodiment 1. Compared to Figure 4, Figure 8 adds lift cylinder bottom-side pressure sensor 12b, lift cylinder rod-side pressure sensor 12r, bucket cylinder bottom-side pressure sensor 16b, bucket cylinder rod-side pressure sensor 16r, and a bucket weight calculation unit 204 as a functional block of controller 120.

[0059] In the bucket weight calculation unit 204, the controller 120 acquires load information from the values ​​of the lift cylinder 12, which serves as a hydraulic actuator that drives the bucket 3 (rotates it relative to the vehicle body), and the pressure sensors 12b, 12r, 16b, and 16r, which serve as load information detection devices that detect load information (cylinder load) applied to the bucket cylinder 16.

[0060] In the bucket weight calculation unit 204, the controller 120 calculates the (current) bucket weight (actual measured value) from the load information acquired from the four types of pressure sensors and the attitude information generated by the bucket attitude information generation unit 201. The calculated bucket weight is output to the predicted bucket residual soil volume calculation unit 202. The bucket weight can be found because the force of gravity acting on the soil in the bucket 3 appears as the difference from the pressure sensor value when the bucket is in the same attitude but with no soil loaded.

[0061] The flowchart in the second embodiment will be described using the flowchart in Fig. 9 instead of Fig. 5 used in the first embodiment. Compared to Fig. 5, Fig. 9 adds the following steps to calculate the weight Wr in the bucket using the cylinder load (S901), update the physical property values ​​(S902 to S907), recalculate the amount of remaining soil Wp predicted based on the toe angle φ of the bucket 3 (S908), and display Wr (S909).

[0062] In the process of calculating the weight Wr in the bucket using the cylinder load (S901), the (actual measured value) (current) weight Wr in the bucket is calculated based on the load information and attitude information, as described above.

[0063] The physical property update process (S902 to S907) determines whether the update condition is met when the toe angle φ is equal to or less than threshold A (yes in S503), and the toe angle change rate dφ / s is equal to or less than threshold S, ensuring stable measurement of the bucket weight Wr (S902). Stable measurement here means obtaining the samples necessary for accurate measurement while suppressing the effects of sensor noise and other factors. For example, if a measurement system, such as an angle sensor, can obtain measurement samples every 0.1 seconds, and averaging 10 measurement samples is sufficient for measurement accuracy, and the angular velocity at which stable measurement is possible is 10 degrees / second, then threshold A can be set to 50 degrees and threshold S to 10 degrees / second. The angular velocity at which stable measurement is possible may be determined, for example, based on a value expected when the operator tilts the bucket lever 115 by approximately 10% to 50% to determine whether the control valve is stably held in the dump position. Furthermore, by adding a step of determining whether the toe angle φ is equal to or greater than threshold value B (S903), and setting threshold value B to -10 degrees, for example, as the value for determining whether the bottom of the bucket 3 and the sediment surface have approached each other, it is possible to prevent the value from being updated if, for example, when the toe angle φ is small at the start of processing, the toe angle φ decreases too much before sufficient measurement samples are obtained, which could cause sediment to stick to the bucket 3. After determining threshold values ​​A, S, and B, the measurement value is stable and is recorded (S904), and a step of determining whether the number of records is equal to or greater than threshold value C as the number of measurements (S905) is added, and by setting threshold value C to 20, for example, as a sufficient number of samples, it is possible to move on to updating the physical property values ​​once 20 samples have been obtained. Conversely, it is possible not to update the physical property values ​​if sufficient samples have not been obtained. Furthermore, by adding a step S906 to determine whether the width φL of the toe angle values ​​included in the measured toe angle φ is equal to or greater than a threshold value D, and setting the threshold value D to, for example, 20 degrees, it is possible to provide a minimum width (= difference) to the average value when performing simultaneous calculations in updating the physical property values, which makes it less likely that the physical property values ​​will become biased due to the influence of noise, etc.

[0064] As a result, in the physical property update process (S902-S907), if threshold A is 50 degrees, threshold S is 10 degrees / second, and the toe angle changes at a constant rate of 10 degrees / second, 10 samples of 50 degrees, 49 degrees, ..., 41 degrees are obtained in the one second after the toe angle reaches 50 degrees, and the average of these samples is a toe angle of 45.5 degrees. Similarly, the average of the subsequent 10 samples is 35.5 degrees. This process would be similar if threshold B were -10 degrees, threshold C was 20 degrees, and threshold D was 20 degrees, since these thresholds are met. When thresholds C and D are used, it is recommended to calculate the average using the samples obtained at the time they are met. For example, it is recommended to calculate the average using half of the samples with the largest toe angle φ included in the record, and then calculate the average using the remaining half.

[0065] The angle of repose θ and density ρ can be calculated (corrected) by simultaneously solving the obtained values ​​so that the residual soil volume Wp (predicted value) calculated using equation (1) matches the weight inside the bucket Wr (actual value) calculated using the cylinder load at that time. For example, when using the calculated values ​​for the attitudes of 45.5 degrees and 35.5 degrees, which are the average values ​​as explained above, the angle of repose θ and density ρ can be calculated (corrected) by simultaneously solving the following two equations (4). <Equation 4> N(φ=45.5 degrees)=Wr(average of measured values ​​at 50 degrees, 49 degrees...41 degrees) N(φ=35.5 degrees)=Wr(similarly, average of measured values ​​at 40 degrees, 39 degrees...31 degrees)...Equation (4)

[0066] The recorded physical properties are updated with the calculated angle of repose θ and density ρ (S907), and the residual soil volume Wp is calculated (recalculated) again using the updated physical properties in equation (1) (S908). Also, when the process is repeated in the order of the flowchart thereafter, the updated values ​​are read as the physical properties recorded in the first step (S501).

[0067] Here, it is advisable to reflect in the calculation of the measured value of Wr the amount of delay until the soil and sand flows out from inside the bucket 3. For example, if the movement of soil and sand flowing out from inside the bucket 3 due to gravity is expressed by the following equation (5), then if the length from the front end to the rear end inside the bucket 3 is assumed to be 1.2 m, the time required for the soil and sand to fall completely is calculated as m = 1.4 seconds, and it takes 1.4 seconds for the predicted value to become Wr ​​after the attitude has changed (see also Figure 10). <Equation 5> Acceleration a = g (sin θ - arctan θ cos θ) ... equation (5)

[0068] Wr can be calculated as the total weight of the posture 1.4 seconds ago plus the dynamic weight based on the posture changes over the last 1.4 seconds (the delay in Wr caused by the posture changes over the last 1.4 seconds).

[0069] Assuming that the attitude change is constant, Wr can be calculated using the following equation (6). That is, Wr calculated using equation (6) is a value that includes the delay that occurs in the actual measurement value due to the most recent attitude information change. <Equation 6> Wr(t)=(N(φ(tm))+N(φ(t))) / 2...Equation (6)

[0070] If the attitude change is not constant, it is advisable to calculate and integrate the amount of soil released at each moment using equation (5).Instead of calculating the delay amount in this way to increase accuracy, it is also possible to set the threshold value S to a value small enough that the time m required for all the soil to fall can be ignored.

[0071] In the display process of Wr (S909), the calculated Wr is displayed (basically always displayed) as a current measurement value on the monitor 123. Fig. 11 shows an example of a display on the monitor 123 during soil release control by the controller 120.

[0072] With the configuration and method described above, the angle of repose θ and density ρ, which are physical properties, can be determined using the results of calculating the weight Wr inside the bucket using the cylinder load. Therefore, even if the physical properties recorded at the start of processing differ from the physical properties of the soil stored in the work device, the amount of remaining soil is calculated using the physical properties of the soil stored in the work device, so a more accurate amount of remaining soil can be calculated and displayed on monitor 123, allowing the operator to adjust the amount of remaining soil more accurately.

[0073] [Embodiment 3] Additions and changes from the above-mentioned embodiment 2 will be described for embodiment 3, which is different from embodiment 2 of the present invention, using Figure 12. The system configuration diagram for embodiment 3 will be described using the system configuration diagram of Figure 12, rather than Figure 8 used in embodiment 2. Compared to Figure 8, Figure 12 adds a release start switch 111, and a release start command determination unit 206, a target residual soil volume reception unit 207, a control command unit 208, and a bucket control hydraulic circuit 113 as functional blocks of the controller 120.

[0074] The discharge start command determination unit 206 determines whether or not a discharge start command (discharge start information) instructing the start of discharge of the bucket 3 has been input in response to an input from the discharge start switch 111 (output). The discharge start command may also be output by inputting an operation signal for the bucket lever 115, etc. The target residual soil volume reception unit 207 receives (accepts) input of target residual soil volume information, which is a target value for the amount of weight change from the bucket 3, from the monitor 123. Instead of the target residual soil volume information, input of target discharge volume information may be accepted.

[0075] The control command unit 208 outputs a bucket control command as an electronic control command to the bucket control hydraulic circuit 113 to electronically control the control valves that control the charging and discharging of pressure oil to the lift cylinder 12 and the bucket cylinder 16 as hydraulic actuators.

[0076] The flowchart in the third embodiment will be explained using the flowchart in Fig. 13 instead of Fig. 9 used in the second embodiment. Compared to Fig. 9, Fig. 13 adds the following processes: reception process of target residual soil volume Wt (S1301), reception process of discharge start command (S1302), calculation process of residual soil volume Wc based on stop control command (S1303), comparison process of Wc with target residual soil volume Wt (S1304), comparison process of Wr with target residual soil volume Wt (S1305), output process of stop control command (S1306), and output process of discharge control command (S1307).

[0077] In the process for receiving the target soil volume Wt (S1301), the monitor 123 accepts the target soil volume input (specified) by the operator. The rated load weight of the dump truck to be unloaded can be registered in advance, and the target soil volume can be calculated to correspond to that load weight. For example, if a dump truck has a rated load weight of 2 tons and the wheel loader's bucket has a load of 3 tons, and the target soil volume is set to 2 tons, the unloading process (described later) will unload soil until the soil volume in the bucket reaches 2 tons. Therefore, all 2 tons of soil can be loaded onto the dump truck. On the other hand, a possible use is to start loading soil into the dump truck when the wheel loader's bucket has a load of 3 tons. In this case, if the target soil volume is set to 1 t, the unloading process (described later) will load 2 tons of soil into the dump truck until the soil volume in the bucket reaches 1 t, i.e., from 3 to 1 t. The operator can set which method to use on the monitor 123. In the latter case, the amount of residual soil can be determined by using the weight inside the bucket Wr as the weight inside the wheel loader bucket.The same applies to a hopper instead of a dump truck as the target for soil release.

[0078] In the process of receiving the discharge start command (S1302), the operator moves to a location suitable for discharging the soil and sand, and then operates the bucket lever 115, the discharge start switch 111, etc., to receive the discharge start command.

[0079] In the calculation process (S1303) for the residual soil volume Wc due to the stop control command, if the stop control command includes a control to tilt the bucket 3 backward, the residual soil volume N (toe angle φ of the final posture) will not be the volume predicted at the toe angle of the final posture. This is because soil and sand that has fallen from the bucket 3 once will not return to the bucket 3. Therefore, it is advisable to calculate the weight of soil that will be released during the stop control command. For example, the residual soil volume predicted at the final posture is calculated using the following equation (7). Here, the stop control command is set to tilt the bucket 3 sufficiently backward at the same angular velocity as the release control command to tilt the bucket 3 forward. <Equation 7> Wc=(N(φ(-m / 2+tc))+N(φ(tc))) / 2...Equation (7)

[0080] Here, φ(tc) represents the toe angle at which the machine is most tilted forward during stop control. If the machine's response delay is 0.5 seconds, this is the toe angle 0.5 seconds after the start of stop control. On the other hand, -m / 2+tc is the sum of half of the machine's response time tc and the negative value of -m, which is the time it takes for the soil to fall. This is the value 0.2 seconds before the start of stop control. As shown in equation (7), this is the average of the predicted toe angle at which the machine is most tilted forward and the predicted toe angle at -m / 2+tc, which is the same as the toe angle at which the soil release is finally completed (m / 2+tc). This can be explained by the fact that the predicted soil volume at a toe angle of m / 2+tc is completely released, while the predicted soil volume at the most tilted toe angle is not released at all due to tilting, and this is the average volume (see Figure 14).

[0081] The comparison process with the target soil volume Wt (S1304, S1305) uses the result of the judgment (S503) of whether the soil surface is in a state where it forms a repose angle plane using threshold A. If the toe angle φ is less than threshold A and the predicted value is valid, Wc is compared with the target soil volume Wt (S1304). Otherwise (if the toe angle φ is greater than threshold A and the predicted value is invalid), Wr is compared with the target soil volume Wt (S1305). If Wc or Wr is less than the target soil volume Wt, a stop control command is issued (S1306). Otherwise (if Wc or Wr is greater than the target soil volume Wt), a soil release control command is issued (S1307). Here, the soil release control command is a bucket control command output from the controller 120 (control command unit 208) to the bucket control hydraulic circuit 113, corresponding to the operator's operation of the bucket lever 115 in the dump direction.

[0082] That is, after determining that there is an earth discharge start command (earth discharge start information), the control command unit 208 of the controller 120 controls an electronic control command (bucket control command) that electronically controls the control valves of the lift cylinder 12 and the bucket cylinder 16 (S1306, S1307) based on a judgment based on the target residual soil volume Wt (or target earth discharge volume) and the predicted value after the weight change of the object in the bucket 3 (residual soil volume Wc) (S1304).

[0083] The configuration and method described above makes it possible to accurately adjust the amount of residual soil using the amount of residual soil predicted when the suspension of soil release control is initiated by the control rather than the operator, thereby having the effect of not being affected by the operator's reaction speed.

[0084] Summary of Examples 1 to 3 As described above, the work machine (wheel loader 50) of this example is a work machine comprising a vehicle body, a work implement (bucket 3) rotatably attached to the vehicle body and capable of loading an object, an actuator that drives (rotates) the work implement, an attitude information detection device (lift arm angle sensor 19, bell crank angle sensor 20) that detects attitude information of the work implement, and a controller (120) that controls the operation of the actuator and controls the release of the object within the work implement, and during the release control, the controller (120) calculates a predicted value (predicted residual soil volume Wp) of the weight of the object within the work implement (in the estimated loading state) in an estimated loading state (according to the attitude information) based on dimensional information that indicates the geometric shape of the work implement and the attitude information.

[0085] The controller (120) calculates a predicted value (predicted residual soil volume Wp) of the weight of the object in the work device in a loaded state estimated based on the dimensional information, the posture information, and the physical properties of the object (angle of repose θ, density ρ).

[0086] The controller (120) determines whether the predicted value is valid or invalid based on the angle (threshold A) corresponding to the physical property value and the attitude information (S503 in FIG. 5, etc.).

[0087] The controller (120) determines that the predicted value is valid when the posture information is equal to or smaller than the angle (threshold A) corresponding to the physical property value, and determines that the predicted value is invalid when the posture information is greater than the angle (threshold A) corresponding to the physical property value (S503 to S505 in FIG. 5).

[0088] The controller (120) calculates a predicted value of the weight of the object in the work device (predicted residual soil volume Wf), including the change in weight of the object in the work device due to a change in posture information (change in toe angle) that can be predicted from the current operating state of the work device.

[0089] The controller (120) calculates a predicted value of the weight of the object in the work device (predicted residual soil volume Wf), including the change in weight of the object in the work device due to changes in posture information from the current operating state of the work device to the stopped state.

[0090] The controller (120) determines whether to calculate a predicted value of the weight of the object in the work device (predicted residual soil volume Wf) based on the rate of change of the posture information (time change in the claw angle) including the change in the weight of the object in the work device due to a change in posture information that can be predicted from the current operating state of the work device (S506 in Figure 5, etc.).

[0091] When the rate of change of the posture information (time change in the claw angle) is equal to or greater than a predetermined rate of change (threshold F), the controller (120) calculates a predicted value of the weight of the object in the work device (predicted residual soil volume Wf), including the change in weight of the object in the work device due to a change in posture information that can be predicted from the current operating state of the work device (S506, S507 in Figure 5, etc.).

[0092] The work machine is equipped with a load information detection device (pressure sensors 12b, 12r, 16b, 16r) that detects load information applied to the cylinders (lift cylinder 12, bucket cylinder 16) that serve as the actuators, and the controller (120) calculates the actual measured value (Wr) of the weight of the object in the (current) work device based on the load information and the posture information during the release control, corrects the physical property values ​​(angle of repose θ, density ρ) so that the predicted value (Wp) matches the actual measured value (Wr), and calculates (recalculates) the predicted value of the weight of the object in the work device (predicted residual soil volume Wp) (Example 2).

[0093] The controller (120) corrects the physical property values ​​(angle of repose θ, density ρ) only when the rate of change of the posture information is equal to or less than a predetermined rate of change (threshold S) (S902 in FIG. 9, etc.) (Example 2).

[0094] The controller (120) calculates the actual measurement value (Wr) including a delay that occurs in the actual measurement value due to a change in the attitude information (Example 2).

[0095] The controller (120) displays the predicted value (predicted residual soil volume Wp) on a monitor (123) to notify the operator operating the actuator operating device (operation lever), thereby adjusting the weight (remaining soil volume) of the object in the working device.

[0096] The controller (120) automatically controls the operation of the actuator based on the predicted value (predicted residual soil volume Wp) and controls the operation of the work device (dumping operation and tilting operation) to adjust the weight of the object (residual soil volume) within the work device.

[0097] The controller (120) comprises a reception unit (target residual soil amount reception unit 207) that receives target weight change amount information (target soil discharge amount information or target residual soil amount information), which is a target value for the amount of weight change from the work device; a judgment unit (soil discharge start command judgment unit 206) that judges whether or not there is release start information (soil discharge start command) that instructs the start of release (soil discharge) of the work device; and a control command unit (208) that controls a control valve that controls the charging and discharging of pressurized oil to and from the hydraulic cylinders (lift cylinder 12, bucket cylinder 16) that serve as the actuators. After judging that there is the release start information, the control command unit (208) controls the control valve based on the target weight change amount information and the predicted value after the weight change of the object in the work device (S1304 in Figure 13) (Example 3).

[0098] In other words, the work machine (wheel loader 50) of this embodiment predicts the amount of remaining soil in the work device (bucket 3) from dimensional information and posture information so that the amount of remaining soil in the work device (bucket 3) of the work machine (wheel loader 50) can be accurately adjusted.

[0099] According to this embodiment, it is possible to calculate the amount of residual soil that will be predicted when the suspension of soil release control is initiated, and therefore it is possible to accurately adjust the amount of residual soil.

[0100] It should be noted that the present invention is not limited to the above-described embodiment, and includes various modifications. For example, the above-described embodiment has been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to an embodiment having all of the described configurations.

[0101] Furthermore, the above-described configurations, functions, processing units, processing means, etc. may be partially or entirely implemented in hardware, for example, by designing them as integrated circuits. The above-described configurations, functions, etc. may also be implemented in software, with a processor interpreting and executing a program that implements each function. Information such as the programs, tables, and files that implement each function can be stored in a memory, a storage device such as a hard disk or SSD (Solid State Drive), or a recording medium such as an IC card, SD card, or DVD.

[0102] In addition, the control lines and information lines shown are those that are considered necessary for the explanation, and do not necessarily show all the control lines and information lines in the product. In reality, it can be assumed that almost all components are interconnected.

[0103] REFERENCE SIGNS LIST 1 Vehicle section (vehicle body) 2 Work machine section 3 Bucket (working device) 4 Engine 4A Engine compartment 4B Driver's seat 5 Front wheels 6 Front frame 7 Rear wheels 8 Rear frame 9 Center pin 10 Hydraulic cylinder (steer cylinder or steering cylinder) 11 Lift arm 12 Lift cylinder 12b Lift cylinder bottom side pressure sensor (load information detection device) 12r Lift cylinder rod side pressure sensor (load information detection device) 14 Push rod 15 Bell crank 16 Bucket cylinder 16b Bucket cylinder bottom side pressure sensor (load information detection device) 16r Bucket cylinder rod side pressure sensor (load information detection device) 19 Lift arm angle sensor (posture information detection device) 20 Bell crank angle sensor (posture information detection device) 50 Wheel loader (working machine) 120 Controller 111 Soil discharge start switch 113 Bucket control hydraulic circuit 123 Monitor

Claims

1. A work machine comprising: a vehicle body; a working device rotatably attached to the vehicle body and capable of loading an object; an actuator for driving the working device; an attitude information detection device for detecting attitude information of the working device; and a controller for controlling the operation of the actuator and performing release control of the object within the working device, wherein the controller calculates a predicted value of the weight of the object within the working device in a loaded state estimated based on dimensional information indicating the geometric shape of the working device and the attitude information during the release control.

2. A work machine as described in claim 1, characterized in that the controller calculates a predicted value of the weight of the object within the work device in a loaded state estimated based on the dimensional information, the attitude information and the physical properties of the object.

3. A work machine as claimed in claim 2, characterized in that the controller determines whether the predicted value is valid or invalid based on the angle corresponding to the physical property value and the attitude information.

4. A work machine as described in claim 3, characterized in that the controller determines the predicted value to be valid when the posture information is equal to or less than an angle corresponding to the physical property value, and determines the predicted value to be invalid when the posture information is greater than an angle corresponding to the physical property value.

5. A work machine as described in claim 1, characterized in that the controller calculates a predicted value of the weight of the object within the work device, including a change in the weight of the object within the work device due to a change in posture information that is predictable from the current operating state of the work device.

6. A work machine as described in claim 5, characterized in that the controller calculates a predicted value of the weight of the object within the work device, including the change in weight of the object within the work device due to changes in posture information from the current operating state of the work device to the state where the work device is stopped.

7. A work machine as described in claim 5, characterized in that the controller determines whether or not to calculate a predicted value of the weight of the object within the work device, including the change in weight of the object within the work device due to a change in posture information that is predictable from the current operating state of the work device, depending on the rate of change of the posture information.

8. A work machine as described in claim 7, characterized in that, when the rate of change of the posture information is equal to or greater than a predetermined rate of change, the controller calculates a predicted value of the weight of the object within the work device, including a change in the weight of the object within the work device due to a change in posture information that is predictable from the current operating state of the work device.

9. A work machine as claimed in claim 2, further comprising a load information detection device for detecting load information acting on a cylinder serving as the actuator, wherein the controller calculates an actual measured value of the weight of the object within the work device based on the load information and the attitude information during the release control, corrects the physical property value so that the predicted value coincides with the actual measured value, and calculates a predicted value of the weight of the object within the work device.

10. A work machine as claimed in claim 9, characterized in that the controller corrects the physical property value only when the rate of change of the attitude information is equal to or less than a predetermined rate of change.

11. A work machine according to claim 9, characterized in that the controller calculates the actual measurement value including a delay caused in the actual measurement value by a change in the posture information.

12. A work machine according to claim 1, wherein said controller displays said predicted value on a monitor and notifies an operator who operates an operating device for said actuator.

13. A work machine as claimed in claim 1, characterized in that the controller automatically controls the operation of the actuator based on the predicted value and controls the operation of the work device, thereby adjusting the weight of the object within the work device.

14. A work machine as described in claim 13, wherein the controller comprises a receiving unit which receives target weight change amount information, which is a target value for the amount of weight change from the work device, a judgment unit which judges whether or not there is release start information which instructs the start of release of the work device, and a control command unit which controls a control valve which controls the charging and discharging of pressurized oil to and from a hydraulic cylinder serving as the actuator, wherein the control command unit, after determining that there is the release start information, controls the control valve based on the target weight change amount information and the predicted value after the weight change of the object in the work device.

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