KR20160133324A - Method of controlling wheel loader - Google Patents

Abstract

In a control method of a wheel loader, signals indicating the operation state are received from sensors mounted on a wheel loader. Among the received signals, signals necessary to determine at least one among the low, middle, or high load state defined based on the load consumed for each work by the wheel loader are selected. For the selected signals, a learned prediction algorithm is performed to calculate output values each of which indicates the low load state, the middle load state, and the high load state, respectively. Through analysis of the calculated output values, it is determined whether the current operation state is excavation. If the operation state by the wheel loader is determined as excavation, the number of rotations of an engine is controlled to limit the maximum rotation in an engine.

Description

{METHOD OF CONTROLLING WHEEL LOADER}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wheel loader control method, and more particularly, to a wheel loader control method for automatically controlling a wheel loader by determining an operation state of the wheel loader.

Wheel loaders are widely used in construction sites to load and unload cargoes such as dump trucks by digging and transporting soil, sand, and the like.

The working load of the wheel loader is changed according to the working state of the wheel loader, and by sensing the working load, the engine or the transmission of the wheel loader is automatically controlled so that the fuel consumption can be reduced and the working efficiency can be prevented from lowering. Therefore, there is a need for a technique for automatically detecting the current work state and the work load state in real time and automatically controlling the wheel loader based on the detection.

An object of the present invention is to provide a wheel loader control method capable of reducing fuel consumption and improving operation efficiency when a wheel loader is operated.

In order to accomplish one aspect of the present invention, there is provided a method of controlling a wheel loader according to exemplary embodiments, the method comprising receiving signals indicative of a work state from sensors mounted on a wheel loader. A signal required for judging at least a low load, a heavy load and a heavy load state, which are classified according to a load required in a series of operations performed by the wheel loader, among the received signals. The prediction algorithms learned for the selected signals are performed to calculate output values indicating whether the loads are low load state, heavy load state, and high load state. And analyzes the calculated output values to determine whether the current work state is an excavating operation. When the work state performed by the wheel loader is determined as an excavating operation, the engine speed is controlled so as to limit the maximum number of revolutions of the engine.

In the exemplary embodiments, the limited engine maximum engine speed may be set to the engine speed at the intersection where the torque converter output torque line and the maximum output torque line meet.

In exemplary embodiments, the method may include analyzing the calculated output values to determine whether the current work state is a backward running work, and if the work state performed by the wheel loader is determined to be a backward running work , And controlling the engine speed so as to have a maximum rotation speed limited to be smaller than the maximum rotation speed of the engine.

In the exemplary embodiments, the step of controlling the engine speed in the reverse travel operation may include the steps of: setting the maximum engine speed of the engine to the first limit speed when the reverse first stage is selected; Setting the maximum rotation number of the engine to a second limit rotation number that is larger than the first limit rotation number and when the reverse third rotation is selected, To a larger third limit rotational speed.

In exemplary embodiments, at least one of the boom cylinder pressure signal, the FNR signal, the main pressure signal of the hydraulic pump, the vehicle speed signal, the boom position signal, and the torque converter speed ratio signal indicates whether the wheel loader is in a low- And at least one of the main pressure signal, the vehicle speed signal, the boom position signal, and the torque converter speed ratio signal of the hydraulic pump may be used to determine whether the wheel loader is in a heavy load state.

In exemplary embodiments, performing the pre-learned predictive algorithm may comprise performing a neural network algorithm.

According to exemplary embodiments, it is possible to determine whether a work state of the wheel loader is an excavation work or a backward running work by using a pre-learned predictive algorithm such as a neural network algorithm, The number of revolutions of the engine can be controlled so as to limit the number.

Accordingly, it is possible to reduce the time and burden required for the calculation for determining the work state of the wheel loader, and improve the accuracy of the judgment. Further, by efficiently controlling the number of revolutions of the engine in accordance with the finally determined workload state, work performance can be improved and fuel consumption can be improved.

However, the effects of the present invention are not limited to the above-mentioned effects, and may be variously expanded without departing from the spirit and scope of the present invention.

1 is a side view of a wheel loader in accordance with exemplary embodiments;
Fig. 2 is a block diagram showing the control system of the wheel loader of Fig. 1; Fig.
3 is a block diagram illustrating a control device of a wheel loader according to exemplary embodiments.
4 is a block diagram showing a workload determination unit of the control apparatus of FIG.
5 is a diagram showing an individual neural network circuit of the individual load judgment unit of FIG.
Fig. 6 is a diagram showing the signal transfer formula in each layer of the individual neural network circuit of Fig. 5; Fig.
7 is a graph showing an engine torque diagram of a wheel loader and an output diagram of a torque converter.
8 is a flowchart showing a method of controlling the wheel loader according to the exemplary embodiments.
9 is a diagram illustrating V-type operation of a wheel loader in accordance with exemplary embodiments.
FIG. 10 is a graph showing output values representing individual load states in each operation of the V-shaped operation of FIG.
11 is a graph showing the final workload state obtained by analyzing the output values of FIG.
12 is a flowchart showing an engine control method of a wheel loader according to exemplary embodiments.

For the embodiments of the invention disclosed herein, specific structural and functional descriptions are set forth for the purpose of describing an embodiment of the invention only, and it is to be understood that the embodiments of the invention may be practiced in various forms, The present invention should not be construed as limited to the embodiments described in Figs.

The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It is to be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but on the contrary, is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms may be used for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between. Other expressions that describe the relationship between components, such as "between" and "between" or "neighboring to" and "directly adjacent to" should be interpreted as well.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprise", "having", and the like are intended to specify the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, , Steps, operations, components, parts, or combinations thereof, as a matter of principle.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be construed as meaning consistent with meaning in the context of the relevant art and are not to be construed as ideal or overly formal in meaning unless expressly defined in the present application .

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

1 is a side view of a wheel loader in accordance with exemplary embodiments; Fig. 2 is a block diagram showing the control system of the wheel loader of Fig. 1; Fig.

1 and 2, the wheel loader 10 may include a front vehicle body 12 and a rear vehicle body 14 rotatably connected to each other. The front vehicle body 12 may include a working device and a front wheel 160. The rear vehicle body 14 may include a cab 40, an engine room 50, and a rear wheel 162.

The working device may include a boom (20) and a bucket (30). The boom 20 can be freely rotatably attached to the front vehicle body 12 and the bucket 30 can be freely rotatably attached to one end of the boom 20. [ The boom 20 is connected to the front vehicle body 12 by a pair of boom cylinders 22 and the boom 20 can be rotated up and down by driving the boom cylinder 22. [ The tilt arm 34 is attached so as to freely rotate on substantially the center of the arm 20 and one end of the tilt arm 34 and the front body 12 are connected by a pair of bucket cylinders 32, The bucket 30 connected to the other end of the tilt arm 34 by the tilt rod can be rotated (dumped or crowded) in the vertical direction by driving the bucket cylinder 32.

The front vehicle body 12 and the rear vehicle body 14 are rotatably connected to each other by a center pin 16 and the front vehicle body 12 is extended to the rear vehicle body 14 by a stretching and shrinking cylinder As shown in Fig.

A traveling device for traveling the wheel loader 10 may be mounted on the rear body 14. The engine 100 is disposed in the engine room 50 and can supply a power output to the traveling device. The traveling device may include a torque converter 120, a transmission 130, a propeller shaft 150, axles 152 and 154, and the like. The power output of the engine 100 is transmitted to the front wheel 160 and the rear wheel 162 via the torque converter 120, the transmission 130, the propeller shaft 150 and the axles 152 and 154, 10).

Specifically, the power output of the engine 100 may be transmitted to the transmission 130 via the torque converter 120. The input shaft of the torque converter 120 is connected to the output shaft of the engine 100 and the output shaft of the torque converter 120 may be connected to the transmission 130. The torque converter 120 may be a fluid clutch device having an impeller, a turbine, and a stator. The transmission 130 may include hydraulic clutches for shifting speed stages between first through fourth speeds and the rotation of the output shaft of the torque converter 120 may be shifted by the transmission 130. [ The shifted rotation is transmitted to the front wheel 160 and the rear wheel 162 via the propeller shaft 150 and the axles 152 and 154 so that the wheel loader can travel.

The torque converter 120 may have the function of increasing the output torque to the input torque, that is, the function of making the torque ratio 1 or more. The torque ratio decreases as the torque converter speed ratio e (= Nt / Ni), which is the ratio of the number of rotations Ni of the input shaft of the torque converter 120 to the number of rotations Nt of the output shaft. For example, when the running load increases during traveling while the engine speed is constant, the number of revolutions of the output shaft of the torque converter 120, that is, the vehicle speed decreases and the torque converter speed ratio decreases. At this time, since the torque ratio increases, the vehicle can be driven with a larger driving force.

The transmission 130 may include a forward hydraulic clutch, a reverse reverse hydraulic clutch, and first to fourth speed hydraulic clutches. Each of the hydraulic clutches can be engaged or released by a pressure oil (clutch pressure) supplied through a transmission control unit (TCU) That is, when the clutch pressure supplied to the hydraulic clutch increases, the hydraulic clutch is engaged and released when the clutch pressure decreases.

When the running load is lowered and the torque converter speed ratio (e) increases and becomes equal to or higher than the predetermined value (eu), the speed stage is shifted up by one stage. Conversely, when the running load increases and the torque converter speed ratio e becomes less than the preset value ed, the speed stage is downshifted by one stage.

The transmission 130 may have a manual mode or a plurality of automatic shift modes. The shift modes may be converted by operation of a mode changeover switch (not shown). For example, the transmission 130 may include a manual mode, a 1-4 auto mode, and a 1-3 auto mode. When set to manual mode, the speed step selected by the shift selector lever can be applied. 1-4 auto mode or 1-3 auto mode, it can be automatically shifted between the speed stages below the speed stage selected by the shift selector lever.

The rear body 14 may be provided with a variable displacement hydraulic pump 200 for supplying pressurized oil to the boom cylinder 22 and the bucket cylinder 32 of the working device. The variable displacement hydraulic pump 200 can be driven using a part of the power output from the engine 100. [ The output of the engine 100 is transmitted to the hydraulic pump 200 for the working device through a power transmission device PTO such as a gear train 110 installed between the engine 100 and the torque converter 120. [ And a steering hydraulic pump (not shown).

A pump control device is connected to the variable displacement hydraulic pump 200, and the discharge flow rate of the variable displacement hydraulic pump 200 can be controlled by the pump control device. A main control valve (MCV) such as a boom control valve 210 and a bucket control valve 212 may be installed on the hydraulic circuit of the hydraulic pump 200. The discharged oil of the hydraulic pump 200 is supplied to the boom cylinder 22 and the bucket cylinder 32 through the boom control valve 210 and the bucket control valve 212 provided in the hydraulic line 202 at the previous stage of the main control valve . The main control valve MCV can supply the hydraulic fluid discharged from the hydraulic pump 200 to the boom cylinder 22 and the bucket cylinder 32 in accordance with the pilot pressure inputted from the operation lever. The boom 20 and the bucket 30 can be driven by the hydraulic pressure of the hydraulic oil discharged from the hydraulic pump 200. [

A driving operation device may be provided in the cab 40. The driving operation device may include operating pedals 142, brake pedal 144, and operating levers for actuating cylinders such as the FNR traveling lever and the boom cylinder 22 and the bucket cylinder 32.

As described above, the wheel loader 10 includes a traveling system for driving the traveling device through the power transmission device PTO and a working device such as a boom 20 and a bucket 30, And a hydraulic system for driving the hydraulic system.

The rear vehicle body 14 may be mounted with a control device 300 of the wheel loader 10 as a part of the vehicle control device VCU or as a separate controller. The control device 300 may include an arithmetic processing unit having a CPU for executing a program, a storage device such as a memory, and other peripheral circuits.

The control device 300 may receive signals from various sensors mounted on the wheel loader 10. For example, the control device 300 includes an engine speed sensor 102 for detecting the engine speed, a traveling pedal detection sensor 143 for detecting the amount of operation of the traveling pedal 142, and an operation amount of the brake pedal 144 (Shift lever) position for detecting the operating position of the shift lever for selecting the speed limit, forward (F), neutral (N) and reverse (R) of the transmission 130, The detection sensor 146, and a parking detection sensor that detects whether or not a parking switch is connected.

The control device 300 further includes a rotation number detection sensor 122a for detecting the rotation number Ni of the input shaft of the torque converter 120 and a rotation number detection sensor 122b for detecting the rotation number Nt of the output shaft of the torque converter 120 A rotational speed detecting sensor 122b and a vehicle speed detecting sensor 132 for detecting the rotational speed of the output shaft of the transmission 130, that is, the vehicle speed v.

The control device 300 further includes a pressure sensor 204 installed in the hydraulic line 202 at the front end of the main control valve MCV for detecting the discharge pressure of the hydraulic pump 200, And may be connected to a boom cylinder pressure sensor 222 for detecting pressure. The control device 300 may also be connected to a boom angle sensor 224 for detecting the rotational angle of the boom 20 and a bucket angle sensor 234 for detecting the rotational angle of the bucket 30.

Signals detected by the sensors mounted on the wheel loader 10 may be input to the control device 300 as indicated by the dotted arrow in FIG. As will be described later, the control device 300 selects specific signals from the signals received from the sensors mounted on the wheel loader 10 and performs a learned prediction algorithm such as a neural network algorithm, And determine the current workload state or the current workload state of the wheel loader 10. [0050] Further, the control device 300 may be connected to an engine control unit (ECU), a transmission control unit (TCU) 140, the pump control unit, and the like to output a control signal, The engine 100, the transmission 130, the hydraulic pump 200, and the like of the loader 10 can be selectively controlled.

Hereinafter, the wheel loader control device will be described.

3 is a block diagram illustrating a control device of a wheel loader according to exemplary embodiments. 4 is a block diagram showing a workload determination unit of the control apparatus of FIG. 5 is a diagram showing an individual neural network circuit of the individual load judgment unit of FIG. Fig. 6 is a diagram showing the signal transfer formula in each layer of the individual neural network circuit of Fig. 5; Fig. 7 is a graph showing an engine torque diagram of a wheel loader and an output diagram of a torque converter.

3 to 7, the wheel loader control apparatus 300 may include a work load determination unit 310, a control signal output unit 320, and a storage unit 330.

The work load determination unit 310 can determine the load status of the current job or the current job status performed by the wheel loader 10 from the sensors mounted on the wheel loader 10. [ The control signal output unit 320 selects and executes a control type to be performed such as, for example, output torque control of the engine, rpm control of the engine, shift control of the transmission, etc., according to the determined load state or work state of the current job A signal can be output. The storage unit 330 stores data necessary for an operation such as learning for a predictive model performed by the workload determination unit 310, neural network algorithm execution, and the like, a control map for determining a control signal in the control signal output unit 320, And so on.

In the exemplary embodiments, the workload determination unit 310 may include a signal receiving unit 312, a signal selecting unit 314, an individual load determining unit 316, and a load state determining unit 318.

The signal receiving unit 312 may receive signals indicating the operation state from the sensors mounted on the wheel loader 10. [ For example, the signal receiving section 312 receives the boom cylinder pressure signal from the pressure sensor 222 provided on the head side of the boom cylinder 22, the FNR signal from the FNR lever position detecting sensor 146, The vehicle speed signal from the vehicle speed detection sensor 132, the boom position signal from the boom angle sensor 224, the rotation speed detection sensors 122a and 122b of the torque converter 120, the main pressure signal of the hydraulic pump from the pressure sensor 204, A torque converter speed ratio signal, an accelerator pedal position signal from the traveling pedal detection sensor 145, and the like can be received. It will be appreciated that the signals received by the signal receiver 312 are not limited thereto and may receive various signals that may be used to determine the workload state or operational state of the wheel load.

The signal receiving unit 312 may include a data preprocessing unit. The data preprocessor may filter the input sensor signals to remove noise and normalize the noise signals.

The signal selector 314 selects a signal that can determine a plurality of individual load states, for example, load states classified into at least four of the received signals, and outputs the selected signal to the corresponding individual load NN_2, NN_3, and NN_4 of the determination unit 316, respectively. The signal selector 314 can select a signal necessary to determine at least the first to fourth individual load states classified according to the load required in the series of operations performed by the wheel loader. For example, the individual load states can be classified into a low load state, a heavy load state, a high load state, and an acceleration / slope state depending on a load required in a series of operations performed by the wheel loader.

The signal selected from the received signals is transmitted to the wheel loader 10 at least one of a specific load state required for a specific operation performed by the wheel loader 10, that is, a low load state, a heavy load state, a high load state, Can be an index that can effectively represent the load state of the vehicle.

The boom cylinder pressure signal can be an indicator that can directly indicate the workload state of the current wheel loader depending on the weight of the load placed on the bucket 30, the height of the boom 20, and the like. The boom cylinder pressure signal can be used to determine the traveling operation state of the wheel loader and the combined operation (traveling boomup) state.

The FNR signal may be an indicator for distinguishing the switching between operations such as the start of the backward operation after the completion of the excavation work or the switching of the forward or backward operation during the traveling operation. The FNR signal can be used to determine the traveling operation state of the wheel loader and the combined operation (traveling boomup) state.

Unlike the boom cylinder pressure, the main pressure signal of the hydraulic pump, that is, the MCV input pressure, maintains the basic pressure state without operation of the boom / bucket by the driver. Therefore, It can be an index indicating any one of the operations. The main pressure signal of the hydraulic pump can be used to determine the running state of the wheel loader, the combined operation (traveling boom up) state, and the excavating operation state.

The vehicle speed signal may be indicative of the running speed of the wheel loader. The vehicle speed signal can be used to determine the traveling operation state of the wheel loader, the combined operation (traveling boom up) state, and the excavation operation state.

The boom position signal may be an index for distinguishing the operation of the wheel loader from the boom position during excavation work and the boom position during the vehicle dump operation. The boom position signal can be used to determine the traveling operation state of the wheel loader, the combined operation (traveling boomup) state, and the excavation operation state.

The torque converter speed ratio signal may indicate an excavation operation state and a slope running state as an index indicating a running load of the vehicle. The torque converter speed ratio signal can be used to determine the traveling operation state of the wheel loader, the combined operation (traveling boom up) state, the excavation operation state, and the acceleration operation state.

The accelerator pedal position signal may be an index indicating an acceleration intention of the driver. The accelerator pedal position signal may be used to determine an accelerating operation state.

The individual load determination unit 316 may include a plurality of individual determination circuit units. Specifically, the individual load determination unit 316 may include first to fourth individual determination circuit units. The first to fourth individual determination circuit units may perform output of the output signals that represent the first to fourth individual load states by performing a pre-learned prediction algorithm on the selected signals.

In the exemplary embodiments, the first individual decision circuit includes a low load neural network determiner NN_1 for calculating an output value indicating a low load state by performing a neural network algorithm on the input signals . The low load neural network determination unit NN_1 receives the boom cylinder pressure signal, the FNR signal, the main pressure signal of the hydraulic pump, the vehicle speed signal, the boom position signal, and the torque converter speed ratio signal from the signal selection unit 314 . The low load neural network determiner NN_1 may perform a neural network algorithm on the received signals to calculate an output value indicating whether the current wheel loader operation is a low load state.

 The second individual decision circuit part may include a heavy-load neural network determiner (NN_2) for performing a neural network algorithm on the input signals and calculating an output value indicating a heavy load state. The heavy load network determination unit NN_2 may receive the main pressure signal, the vehicle speed signal, the boom position signal, and the torque converter speed ratio signal of the hydraulic pump from the signal selection unit 314. The heavy load network determination unit NN_2 may perform a neural network algorithm on the received signals to calculate an output value indicating whether the work of the current wheel loader is in a heavy load state.

The third individual decision circuit may include a high load neural network determiner (NN_3) for performing a neural network algorithm on the input signals to calculate an output value indicating a high load state. The high load neural network determination unit NN_3 receives the boom cylinder pressure signal, the FNR signal, the main pressure signal of the hydraulic pump, the vehicle speed signal, the boom position signal, and the torque converter speed ratio signal from the signal selection unit 314 can do. The high load network determining unit NN_3 may perform a neural network algorithm on the received signals to calculate an output value indicating whether the current wheel loader job is in a high load state.

The fourth individual decision circuit may include an acceleration / deceleration load neural network determiner (NN_4) for calculating an output value indicating an acceleration / declination load state by performing a neural network algorithm on the input signals. The acceleration / slope load neural network determiner NN_4 may receive the torque converter speed ratio signal and the accelerator pedal position signal from the signal selector 314. [ The acceleration / deceleration load neural network determiner NN_4 may perform a neural network algorithm on the received signals to calculate an output value indicating whether the current wheel loader operation is an acceleration / declination load state.

In the exemplary embodiments, the low load neural network determiner NN_1, the heavy load neural network determiner NN_2, the high load neural network determiner NN_3, and the accelerator / ramp load neural network determiner NN_4, And a neural network circuit for calculating an output value indicating the individual load state.

As shown in FIGS. 5 and 6, the neural network circuit may have a multi-layer perceptron structure having a multi-layer input layer, a hidden layer, and an output layer. Neurons are arranged in each layer, and neurons in each layer can be connected by connection weights. That is, input data may be input to the neurons of the input layer and transmitted to the output layer through the hidden layer.

Learning in the neural network algorithm may be a process of adjusting a weight between nodes so that an error between an output value and an expected value derived by a neural network algorithm according to a specific input (actual measurement data) is minimized. For example, the neural network algorithm of the neural network circuit can be learned by a back propagation learning method. Therefore, the neural network circuits of the individual neural network determinators NN_1, NN_2, NN_3, and NN_4 adjust the weights connecting the input layer, the hidden layer, and the output layer using the data pre-collected for each individual neural network decision unit, The neural network algorithm can be established.

Therefore, the neural network circuit has a learned neural network algorithm, and can perform an output neural network algorithm on input signals to calculate an output value indicating whether or not the neural network circuit is in an individual load state.

The load state determination unit 318 may analyze the output values calculated by the first to fourth individual determination circuit units to determine the current workload state or the work state of the wheel loader 10. [ The load state determiner 318 may calculate a final result after performing post-processing such as applying a weight to output values input from the individual neural network determinators NN_1, NN_2, NN_3, and NN_4.

For example, the load state determiner 318 may analyze the output values to determine the current workload state of the wheel loader 10. [ Therefore, the load state determination unit 318 can determine that the current work load state of the wheel loader 10 is any one of a low load state, a heavy load state, a high load state, and an acceleration / slope load state.

The load state determiner 318 may additionally consider other signals received from the sensors mounted on the wheel loader 10 to determine the current operation state of the wheel loader 10. [ For example, the load state determination unit 318 can determine the current workload state of the wheel loader 10 and the current work state.

The control signal output unit 320 outputs the control signal to the engine 100 and the transmission 130 of the wheel loader 10 in consideration of the current or past work load state or the work state of the wheel loader determined by the work load determination unit 310. [ The hydraulic pump 200, and the like. For example, the control signal output section 320 can output a control signal for controlling the engine output torque, the engine speed (rpm), the speed change stage, the shifting time, and the like.

The storage unit 330 is connected to the workload determination unit 310 and is connected to the first storage unit 332 and the control signal output unit 320 for storing data for determining the workload, And a second storage unit 334 for determining the second storage unit 334. The first storage unit 332 may store data necessary for an operation such as learning for a prediction model, performing a neural network algorithm, and the like. The second storage unit 334 may store an engine torque map, an engine rpm map, a transmission shift control map, and the like necessary for determining a control signal. 7, the second storage portion 334 may store the maximum torque Tmax, the torque converter output torque Tt, and the engine torque curve T1 according to the engine speed control mode .

In the exemplary embodiments, the control signal output unit 320 determines whether the determined operation state corresponds to which of the traveling operation and the excavation operation, and controls the maximum rotation number of the engine in accordance with the determination result It is possible to output an engine speed control signal which can be output.

The control signal output unit 320 may output a first engine speed control signal for performing the engine speed control mode to the engine control unit ECU when the current working state of the wheel loader is determined as an excavation work. The engine control unit ECU can receive the first engine speed control signal and adjust the fuel injection amount and the like to control the engine speed so as to have the maximum engine speed smaller than the maximum engine speed.

7, the maximum torque line Tmax represents the maximum output torque of the engine, and the torque converter output torque line Tt represents a torque converter output torque when the torque converter speed ratio e is 0 And the torque curve T1 can show the control torque curve in the excavating operation of the wheel loader or the inclined traveling operation. The engine speed at the intersection A where the torque converter output torque Tt and the maximum output torque Tmax meet is Np, which represents the maximum engine output (rated output) at the rated rotation speed Nr.

When the excavating operation is performed, the maximum engine speed in the engine speed control mode may have a limited engine speed so as to be smaller than the maximum engine speed Nmax. That is, the limited maximum engine speed of the engine speed control mode may be set to be limited to a specific ratio (X%) of the maximum engine speed Nmax. For example, the limited maximum engine speed of the engine speed control mode may be determined based on the engine speed Np at the intersection A where the torque converter output torque Tt and the engine torque Tmax meet, And can be set to a specific engine speed. The engine speed Np may be greater than the rated speed Nr.

After outputting the first engine speed control signal, the control signal output unit 320 determines whether or not the engine speed control release condition is satisfied. If the release condition is satisfied, the control signal output unit 320 outputs the first engine speed The control signal can be released. For example, when the vehicle speed is equal to or higher than a predetermined speed (for example, 3 km / h), a control signal for releasing the engine speed control signal can be outputted. With this control signal, the engine maximum rotation number can be reset to the first engine maximum rotation number Nmax.

The control signal output unit 320 outputs a second engine speed control signal for performing the engine speed control mode to the engine control unit (ECU) when it is determined that the current working state of the wheel loader is the backward traveling work state can do. The engine control unit ECU can receive the second engine speed control signal and adjust the fuel injection amount and the like to control the engine speed so as to have the maximum engine speed smaller than the maximum engine speed.

In the exemplary embodiments, when the reverse first stage is selected by the shift lever, the maximum number of revolutions of the engine can be set to the first limit number of revolutions (for example, 1800 rpm). When the reverse second stage is selected by the shift lever, the maximum engine speed of the engine may be set to a second limit engine speed (e.g., 1900 rpm) that is greater than the first engine speed limit. When the third reverse stage is selected by the shift lever, the maximum engine speed of the engine may be set to a third limit engine speed (for example, 2000 rpm) which is greater than the second engine speed limit.

Considering the work characteristics of the wheel loader, excavation may require higher torque than speed. The operator steps the accelerator pedal as much as possible to obtain a high output at the beginning of the excavation work, and the engine operates at an unnecessarily high number of revolutions (rpm) until the desired high torque is actually obtained. The actual machine can output the maximum output at the engine speed where the engine torque line and the torque converter output line meet. Therefore, by limiting the number of revolutions of the engine at a specific speed (for example, 3 km / h or less) at the time of excavation work to a point at which the actual equipment can output the maximum output, the fuel consumption performance can be improved. Further, since the operator runs at a lower speed on average than the forward running on the basis of the visibility and the controllability in the backward running, unnecessary fuel loss can be prevented by restricting the number of revolutions of the engine in the backward running.

As described above, the wheel loader control device 300 controls the wheel loader 10 so that the wheel loader 10 is in a state of discrete load (low load, heavy load, high load, acceleration / ) And can determine the current workload state or the current workload state of the wheel loader 10 using a pre-learned predictive algorithm such as a neural network algorithm. In addition, the wheel loader control device 300 determines whether the divided work state is a traveling operation, an excavation work, or a traveling boom up operation, and determines a maximum rotation number limited by the maximum rotation number of the engine It is possible to output an engine speed control signal capable of controlling the engine speed.

Accordingly, it is possible to reduce the time and burden required for the calculation for determining the work state of the wheel loader, and improve the accuracy of the judgment. In addition, by efficiently controlling the engine speed according to the finally determined work state, work performance can be improved and fuel economy can be improved.

Hereinafter, a method of controlling the wheel loader using the wheel loader control apparatus of FIG. 3 will be described.

8 is a flowchart showing a method of controlling the wheel loader according to the exemplary embodiments.

Referring to FIGS. 3, 4, and 8, first, signals indicating a work state of the wheel loader may be received (S100).

The control device 300 of the wheel loader can receive signals indicating the operation state from the sensors mounted on the wheel loader. For example, the signal receiving unit 312 of the work load determining unit 310 receives the boom cylinder pressure signal, the FNR signal, the main pressure signal of the hydraulic pump, the vehicle speed signal, the boom position signal, the torque converter speed ratio signal, And the like. The input sensor signals may be filtered through a preprocessing operation and normalized.

Then, from among the received signals, a signal necessary for judging a plurality of individual load conditions can be selected (S110).

The signal selection unit 314 of the workload determination unit 310 selects a signal capable of determining at least four workload states (the first to fourth individual load states) And output the selected signal to the individual determination circuit units NN_1, NN_2, NN_3, and NN_4 of the individual load determination unit 316 corresponding thereto.

The first to fourth individual load states may correspond to a low load state, a heavy load state, a high load state, and an acceleration / slope state, respectively, according to the load required in the series of operations performed by the wheel loader. The received signals effectively indicate at least one of the load conditions required for a specific operation performed by the wheel loader, that is, at least one of a low load state, a heavy load state, a high load state, and an acceleration / Whether or not it is possible.

For example, among the received signals, the boom cylinder pressure signal, the FNR signal, the main pressure signal of the hydraulic pump, the vehicle speed signal, the boom position signal, and the torque converter speed ratio signal are transmitted to the wheel loader And may be input to the low load neural network determiner NN_1 and the high load neural network determiner NN_3 of the individual load determiner 316. [

The main pressure signal, the vehicle speed signal, the boom position signal, and the torque converter speed ratio signal of the hydraulic pump among the received signals may be signals for determining whether the wheel loader is in a heavy load state, And may be input to the heavy load network determination unit NN_2 of the determination unit 316. [

Among the received signals, the torque converter speed ratio signal and the accelerator pedal position signal may be signals for determining whether an acceleration / deceleration load state is present, and the acceleration / (NN_4).

Thereafter, the prediction algorithms learned for the selected signals may be performed to determine a plurality of individual load states (S120).

The low load neural network determiner NN_1, the heavy load neural network determiner NN_2, the high load neural network determiner NN_3 and the acceleration / ramp load neural network determiner NN_4 of the individual load determiner 316 calculate The output neural network algorithm can be used to calculate output values indicating the low load state, the heavy load state, the high load state, and the acceleration / slope load state, respectively.

Next, the output values may be analyzed to determine the current operation state of the wheel loader (S130).

The load state determiner 318 may analyze the output values and determine that the current work load state of the wheel loader is any one of a low load state, a heavy load state, a high load state, and an acceleration / slope load state.

In addition, the load state determiner 318 may additionally consider other signals received from the sensors mounted on the wheel loader to determine the current work load state of the wheel loader as well as the current work load state.

Next, the number of revolutions of the wheel loader may be controlled according to whether the current operation state of the wheel loader is a driving operation or an excavation operation (S140). The method of controlling the engine speed of the wheel loader according to the exemplary embodiments will be described later with reference to FIG.

Hereinafter, a method for determining the workload state of the V-type operation of the wheel loader using the wheel loader control method of Fig. 8 will be described.

9 is a diagram illustrating V-type operation of a wheel loader in accordance with exemplary embodiments. FIG. 10 is a graph showing output values representing individual load states in each operation of the V-shaped operation of FIG. 11 is a graph showing the final workload state obtained by analyzing the output values of FIG. 10 and 11 together show a graph showing the boom cylinder pressure value with time in the V-type operation for reference.

9 to 11, the wheel loader 10 can perform a V-type operation of digging an object material such as the soil S and loading it into the dump truck T. For the V-type operation, the wheel loader 10 performs the forward traveling operation (a), the excavation operation (b), the backward traveling operation (c), the forward traveling boom up operation (d), the dump operation And the boom-down operation f can be performed sequentially.

As shown in FIG. 10, it is possible to determine whether or not the respective load states corresponding to the respective operations of the V-type operation are respectively determined. The low load neural network determiner NN_1 can calculate an output value indicating whether or not the load is low for a series of jobs a to f. The heavy neutral network determination unit NN_2 may calculate an output value indicating whether the heavy load state is present or not for a series of jobs a to f. The high load neural network determination unit NN_3 can calculate an output value indicating whether or not the workload a to f is in a high load state. The acceleration / deceleration load neural network determiner NN_4 can calculate an output value indicating whether the acceleration / declination load state is present or not for a series of jobs (a to f).

As shown in FIG. 11, the current workload state can be determined by comprehensive analysis of the calculated output values. The load state determination unit 318 can determine that the workload state of each of the series of operations (a to f) is any one of the low load state, the heavy load state, the high load state, and the acceleration / .

The forward traveling operation (a), the backward traveling operation (c), the dump operation (e) and the backward traveling boom down operation (f) are judged to be in a low load state in the V-type operation of the wheel loader, b is judged to be in the heavy load state, and the forward travel boomup operation (d) can be judged to be in the high load state. Also, among the operations performed by the wheel loader, the slope traveling operation and the vehicle acceleration operation can be determined as an acceleration / slope load state defined between the heavy load state and the heavy load state.

However, the present invention is not limited to the V-type operation of the wheel loader. For example, the load-and-carry operation, the I-cross operation, It will be understood that the invention may be practiced.

12 is a flowchart showing an engine control method of a wheel loader according to exemplary embodiments.

Referring to FIGS. 3, 4, 7, and 12, it can be determined whether the current work state of the wheel loader corresponds to a traveling operation or an excavating operation (S141, S143).

In the exemplary embodiments, the tasks performed by the wheel loader can be distinguished using pre-learned prediction algorithms such as neural network algorithms. The workload determination unit 310 can distinguish the work statuses performed by the wheel loader from the sensors mounted on the wheel loader in real time. It is possible to determine whether the current operation state is a traveling operation or an excavating operation by analyzing the output values calculated from the low load neural network determiner NN_1, the heavy load neural network determiner NN_2 and the high load neural network determiner NN_3.

Next, when it is determined that the work state performed by the wheel loader is an excavation work, the engine speed control mode may be performed (S142).

The control signal output unit 320 may output an engine speed control signal for performing the engine speed control mode to the engine control unit ECU when it is determined that the current working state of the wheel loader is the excavation work state. The engine control unit ECU can receive the engine speed control signal and adjust the fuel injection amount and the like to control the engine speed so as to have a limited maximum engine speed smaller than the maximum engine speed.

The maximum engine speed of the engine speed control mode may have a limited engine speed so as to be less than the maximum engine speed Nmax. That is, the limited maximum engine speed of the engine speed control mode may be set to be limited to a specific ratio (X%) of the maximum engine speed Nmax. For example, the limited maximum engine speed of the engine speed control mode is set to the engine speed Np at the intersection A where the torque converter output torque line Tt and the engine torque line Tmax meet . The engine speed Np may be greater than the rated speed Nr.

Next, if it is determined that the work state performed by the wheel loader is the backward travel operation, the engine speed control mode may be performed (S144).

The control signal output unit 320 may output an output control signal for performing the engine speed control mode to the engine control unit ECU when it is determined that the current operation state of the wheel loader is the reverse travel operation state. The engine control unit ECU can receive the engine output control signal and control the engine speed so as to adjust the fuel injection amount or the like to have the maximum engine speed smaller than the maximum engine speed.

In the exemplary embodiments, when the reverse first stage is selected by the shift lever, the maximum number of revolutions of the engine can be set to the first limit number of revolutions (for example, 1800 rpm). When the reverse second stage is selected by the shift lever, the maximum engine speed of the engine may be set to a second limit engine speed (e.g., 1900 rpm) that is greater than the first engine speed limit. When the third reverse stage is selected by the shift lever, the maximum engine speed of the engine may be set to a third limit engine speed (for example, 2000 rpm) which is greater than the second engine speed limit.

As described above, it is possible to determine the working state and the load state of the wheel loader by using a pre-learned prediction algorithm such as a neural network algorithm, and to automatically control the engine speed according to the determination result.

Accordingly, it is possible to reduce the time and burden required for the calculation for determining the work state of the wheel loader, and improve the accuracy of the judgment. Further, by efficiently controlling the engine in accordance with the finally determined work state, the work performance can be improved and the fuel consumption can be improved.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the following claims. It can be understood that it is possible.

10: Wheel loader 12: Front bodywork
14: rear body 20: boom
22: boom cylinder 30: bucket
32: bucket cylinder 34: tilt arm
40: cab 50: engine room
100: engine 102: engine speed sensor
110: Gear train 120: Torque converter
122a, 122b: rotation speed detecting sensor 130: transmission
132: vehicle speed detecting sensor 140: transmission control device
142: Travel pedal 143: Travel pedal detection sensor
144: Brake pedal 145: Brake pedal detection sensor
146: FNR lever position detection sensor 150: Propeller shaft
152, 154: axle 160: front wheel
162: rear wheel 200: hydraulic pump
202: Hydraulic line 204: Pressure sensor
210: Boom control valve 212: Bucket control valve
222: Boom cylinder pressure sensor 224: Boom angle sensor
234: Bucket angle sensor 300: Control device
310: workload determination unit 312: signal reception unit
314: Signal selection unit 316: Individual load determination unit
318: Load state determination unit 320: Control signal output unit
330: storage unit 332: first storage unit
334: Second storage unit

Claims (6)

Receiving signals indicative of a work state from sensors mounted on the wheel loader;
Selecting a signal necessary for determining at least a low load, a heavy load and a heavy load state, which are classified according to a load required in a series of operations performed by the wheel loader, among the received signals;
Calculating output values each indicating whether a low load state, a heavy load state, and a high load state, by performing a pre-learned prediction algorithm on the selected signals;
Analyzing the calculated output values to determine whether a current work state is an excavating operation; And
And controlling the engine speed so as to limit the maximum number of revolutions of the engine when the work state performed by the wheel loader is determined as an excavating operation. The control method of a wheel loader according to claim 1, wherein the limited engine maximum rotational speed is set to an engine rotational speed at an intersection where a torque converter output torque line and a maximum output torque line meet. The method of claim 1, further comprising: analyzing the calculated output values to determine whether a current operation state is a reverse travel operation; And
Further comprising the step of controlling the engine speed so as to have a limited maximum speed so as to be smaller than the maximum speed of the engine when the work state of the wheel loader is determined to be the backward traveling work Way. 4. The method according to claim 3, wherein the step of controlling the engine speed in the reverse travel operation
Setting a maximum rotation speed of the engine to a first limit rotation speed when the reverse first stage is selected;
Setting a maximum rotational speed of the engine to a second limit rotational speed that is larger than the first limit rotational speed when the reverse second stage is selected; And
And setting the maximum rotation number of the engine to a third limit rotation number that is larger than the second limit rotation number when the third reverse rotation is selected. 2. The wheel loader according to claim 1, wherein at least one of the boom cylinder pressure signal, the FNR signal, the main pressure signal of the hydraulic pump, the vehicle speed signal, the boom position signal and the torque converter speed ratio signal indicates whether the wheel loader is in a low- Wherein at least one of the main pressure signal, the vehicle speed signal, the boom position signal, and the torque converter speed ratio signal of the hydraulic pump is used for determining whether the wheel loader is in a heavy load state or not Control method of wheel loader. 2. The method of claim 1, wherein performing the pre-learned predictive algorithm comprises performing a neural network algorithm.

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