A loader and a control method and device thereof

Abstract

The application discloses a loader and a control method and device thereof, the loader comprising an engine, a torque converter and a transmission, and the method comprises the following steps: obtaining a first external characteristic curve of the engine under a normal working condition of the loader; obtaining a critical output torque of the engine when the loader slips when it is determined that the loader is in a slipping working condition; obtaining a second external characteristic curve of the engine under the slipping working condition of the loader according to the critical output torque and the first external characteristic curve; and controlling the rotation of the engine based on the second external characteristic curve, so that the critical output torque can be reached at a lower rotating speed of the engine, and the power consumption of the loader under the slipping working condition can be effectively reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of vehicle control technology, and in particular to a loader and a control method and device thereof. BACKGROUND

[0002] During the working process of a hydraulic wheel loader, tire slip sometimes occurs. Tire slip refers to tire slippage or tire spin on the road surface. During the working process, experienced drivers can reduce the slip rate according to experience, while inexperienced drivers often cause the tires of the whole vehicle to slip frequently.

[0003] When slip occurs, the traction of the loader decreases sharply, so that the loader cannot work normally, and the slipping tires will exacerbate wear, and the engine will also have excessive speed due to slip, causing engine power loss. SUMMARY

[0004] The present application provides a loader and a control method and device thereof, which can effectively reduce engine power loss under engine slip working conditions.

[0005] According to an aspect of the present application, a control method of a loader is provided, the loader comprising an engine, a torque converter and a transmission, comprising:

[0006] obtaining a first external characteristic curve of the engine of the loader under normal working conditions;

[0007] when it is determined that the loader is in a slip working condition, obtaining a critical output torque of the engine when the loader slips;

[0008] obtaining a second external characteristic curve of the engine of the loader in the slip working condition according to the critical output torque and the first external characteristic curve;

[0009] controlling the engine to rotate based on the second external characteristic curve.

[0010] Optionally, when the loader is in a slip working condition, obtaining a critical output torque of the engine when the loader slips, comprises:

[0011] when it is determined that the loader is in a slip working condition, obtaining the original vehicle mass of the loader and the current vehicle loading mass;

[0012] obtaining the current road adhesion coefficient and the current rolling resistance coefficient;

[0013] obtaining the maximum friction force when the loader slips according to the original vehicle mass, the current vehicle loading mass, the current road adhesion coefficient and the current rolling resistance coefficient;

[0014] obtaining a gearbox speed ratio, a total reduction ratio of axle and wheel, and a wheel radius;

[0015] determining a critical output torque of the engine when the loader slips according to the maximum friction force, the gearbox speed ratio, the total reduction ratio, and the wheel radius.

[0016] Optionally, the second characteristic curve of the engine when the loader is in the slipping condition is obtained according to the critical output torque and the first characteristic curve, comprising:

[0017] obtaining a coordinate system in which the first characteristic curve is located, a y-axis of the coordinate system being an output torque of the engine, and an x-axis of the coordinate system being a rotating speed of the engine;

[0018] obtaining a torque calculation equation of the torque converter when the torque converter speed ratio is zero;

[0019] obtaining a critical rotating speed of the engine when the output torque of the engine is the critical output torque based on the torque calculation equation;

[0020] determining a first coordinate point according to the critical output torque and the critical rotating speed;

[0021] obtaining a second coordinate point as an intersection point of the torque calculation equation and the first characteristic curve;

[0022] obtaining a third coordinate point as a rotating speed greater than zero when the output torque on the first characteristic curve is zero;

[0023] determining a first slope according to the second coordinate point and the third coordinate point;

[0024] determining a first straight line equation according to the first coordinate point and the first slope;

[0025] obtaining a first intersection point of the first straight line equation and the first characteristic curve, and obtaining a second intersection point of the first straight line equation and the x-axis;

[0026] obtaining the second characteristic curve of the engine when the loader is in the slipping condition according to the first characteristic curve, the first intersection point, and the second intersection point.

[0027] Optionally, the control method of the loader further comprises:

[0028] controlling the engine to rotate based on the first characteristic curve when it is determined that the loader is in the normal condition.

[0029] Optionally, before it is determined that the loader is in the slipping condition, the method further comprises:

[0030] acquiring an actual vehicle speed of the loader, a turbine speed of the torque converter, an actual engine speed, an accelerator opening degree, and a hydraulic lever signal;

[0031] acquiring a current operating condition of the loader according to at least the actual vehicle speed and the turbine speed, and / or acquiring the current operating condition of the loader according to the turbine speed, the actual engine speed, the accelerator opening degree, and the hydraulic lever signal.

[0032] Optionally, acquiring the current operating condition of the loader according to at least the actual vehicle speed and the turbine speed comprises:

[0033] acquiring a gearbox speed ratio, a total reduction speed ratio of axle and wheel, and a wheel radius;

[0034] acquiring a theoretical vehicle speed of the loader according to the turbine speed, the gearbox speed ratio, the total reduction speed ratio, and the wheel radius;

[0035] acquiring a vehicle speed difference between the theoretical vehicle speed and the actual vehicle speed;

[0036] judging whether the vehicle speed difference is greater than a preset difference value; the preset difference value is greater than zero;

[0037] if yes, acquiring a duration that the vehicle speed difference is greater than the preset difference value;

[0038] judging whether the duration is greater than a preset time;

[0039] if yes, determining that the loader is in a slipping condition.

[0040] Optionally, acquiring the current operating condition of the loader according to the turbine speed, the engine speed, the accelerator opening degree, and the hydraulic lever signal comprises:

[0041] acquiring a torque converter speed ratio according to the turbine speed and the actual engine speed;

[0042] judging whether a change rate of the torque converter speed ratio is less than a preset change rate; the preset change rate is less than zero;

[0043] if yes, judging whether the torque converter speed ratio is less than a preset torque converter speed ratio;

[0044] if yes, judging whether the accelerator opening degree is a preset opening degree and the hydraulic lever signal remains unchanged;

[0045] if yes, determining that the loader is in a slipping condition.

[0046] Optionally, when the engine is controlled based on the second external characteristic curve, the method further comprises:

[0047] continuously acquiring an accelerator opening degree and a hydraulic lever signal of the loader;

[0048] determining whether the accelerator opening degree is lower than a preset opening degree, and / or determining whether the hydraulic lever signal changes;

[0049] if yes, controlling the engine to rotate based on a first external characteristic curve.

[0050] According to another aspect of the present application, there is provided a control device of a loader, the loader comprising an engine, a torque converter and a transmission, comprising:

[0051] a first external characteristic curve acquisition module configured to acquire a first external characteristic curve of the engine of the loader in a normal working condition;

[0052] a critical output torque acquisition module configured to acquire a critical output torque of the engine of the loader when the loader slips, when it is determined that the loader is in a slipping working condition;

[0053] a second external characteristic curve acquisition module configured to acquire a second external characteristic curve of the engine of the loader in the slipping working condition according to the critical output torque and the first external characteristic curve;

[0054] a first control module configured to control the engine to rotate based on the second external characteristic curve.

[0055] According to another aspect of the present application, there is provided a loader comprising an engine, a torque converter, a transmission and a controller;

[0056] the controller is configured to perform the control method of the loader as described above.

[0057] The control method of the loader provided by the present application, in the process of working of the loader, firstly acquires a first external characteristic curve of the engine of the loader in a normal working condition, so that the engine can be controlled to rotate based on the first external characteristic curve when the loader is in the normal working condition, and when it is determined that the engine is in a slipping working condition, firstly acquires a critical output torque of the engine of the loader when the loader slips, so as to acquire a second external characteristic curve of the engine of the loader in the slipping working condition according to the critical output torque and the first external characteristic curve, thereby the engine can be controlled to rotate based on the second external characteristic curve when the loader is in the slipping working condition, so that the engine can reach the critical output torque at a lower rotating speed, and the power consumption of the loader in the slipping working condition can be effectively reduced.

[0058] It should be understood that the matters described in this detailed description are intended to be illustrative and not restrictive. Other aspects will become apparent to those skilled in the art from the following detailed description. BRIEF DESCRIPTION OF DRAWINGS

[0059] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort based on these drawings.

[0060] Figure 1 is a flow chart of a control method of a loader provided by an embodiment of the present application;

[0061] Figure 2 is a flow chart of another control method of a loader provided by an embodiment of the present application;

[0062] Figure 3 is a curve diagram of an engine external characteristic provided by an embodiment of the present application;

[0063] Figure 4 is a flow chart of still another control method of a loader provided by an embodiment of the present application

[0064] Figure 5 is a structural diagram of a control device of a loader provided by an embodiment of the present application. DETAILED DESCRIPTION

[0065] In order to make the person skilled in the art better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely in the following with reference to the drawings of the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort should be within the scope of protection of the present application.

[0066] It should be noted that the terms "first", "second", and the like in the specification and claims of the present application and the above drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or a chronological sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not necessarily have to include only those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to the process, method, product or device.

[0067] The loader is generally composed of a traveling device, a steering mechanism and a loading working mechanism, wherein the traveling device is mainly composed of an engine, a torque converter, a gearbox, a rear axle and a tire to form a transmission chain.

[0068] The embodiment of the present application provides a control method of a loader, which can effectively reduce engine power loss in a slipping working condition of the loader. The control method of the loader can be executed by the control device of the loader provided by the embodiment of the present application. The control device of the loader can be realized in the form of software and / or hardware, and the control device of the loader can be configured in the controller of the loader.

[0069] Figure 1 The control method of the loader provided by the embodiment of the present application is shown in a flow chart as shown in Figure 1 The control method of the loader comprises the following steps.

[0070] S110, obtaining a first external characteristic curve of an engine in a normal working condition of the loader.

[0071] Specifically, when the loader is traveling, the loader may not be able to travel normally due to a wet and slippery road surface or obstacles, so that the loader slips in place. The normal working condition can be a working condition in which the loader can travel normally without slipping. When the loader is in the normal working condition, the first external characteristic curve of the engine in the normal working condition of the loader can be obtained first. The external characteristic curve of the engine can be a relationship curve representing the relationship between the engine torque and the speed.

[0072] Specifically, when the loader is traveling, the loader may not be able to travel normally due to a wet and slippery road surface or obstacles, so that the loader slips in place. The normal working condition can be a working condition in which the loader can travel normally without slipping. When the loader is in the normal working condition, the first external characteristic curve of the engine in the normal working condition of the loader can be obtained first. The external characteristic curve of the engine can be a relationship curve representing the relationship between the engine torque and the speed.

[0073] Specifically, when the loader is in the normal working condition, the current target torque of the engine can be continuously obtained. In order to distinguish the target torque of the engine in the slipping working condition of the loader, the target torque of the engine in the normal working condition can be referred to as the first target torque. Thus, the first target speed corresponding to the first target torque can be determined based on the first external characteristic curve, so as to control the actual speed of the engine to be the first target speed, thereby realizing the control of the engine in the normal working condition and the control of the loader.

[0074] S120, obtaining a critical output torque of the engine when the loader slips in a slipping working condition of the loader.

[0075] Specifically, at the non-slip and critical point of the slip of the loader, the friction between the loader and the road surface is the largest, at this time the output torque of the engine makes the traction of the loader reach the maximum, and the engine speed continues to increase at the critical point, so that the output torque continues to increase, thereby causing the loader to slip, resulting in a sharp drop in the output torque and the traction of the loader, that is, after the slip, the higher speed of the engine cannot provide higher output torque, and controlling the engine at a higher speed will cause higher power consumption. Therefore, the critical output torque of the engine when the loader slips can be regarded as the maximum effective output torque, and the critical output torque of the engine when the loader slips can be obtained.

[0076] S130, obtaining a second external characteristic curve of the engine when the loader is in the slip working condition according to the critical output torque and the first external characteristic curve.

[0077] S140, controlling the rotation of the engine based on the second external characteristic curve.

[0078] Specifically, after the critical output torque is obtained, the second external characteristic curve can be obtained in combination with the critical output torque and the first external characteristic curve, so that the rotation of the engine is controlled according to the second external characteristic curve when the loader is in the slip working condition, so that the engine can reach the maximum effective output torque (i.e. the critical output torque) at a lower speed, so as to reduce the power consumption of the loader in the slip working condition.

[0079] Specifically, in the process of controlling the rotation of the engine based on the second external characteristic curve, the current target torque of the engine can also be obtained, which can be referred to as the second target torque when the engine is in the slip working condition. Then, the second target speed corresponding to the second target torque can be determined based on the second external characteristic curve, so that the actual speed of the engine is controlled to be the second target speed, thereby realizing the control of the engine in the slip working condition, and realizing the control of the loader.

[0080] The control method of the loader provided by the embodiment of the application, in the process of the working of the loader, first obtains the first external characteristic curve of the engine of the loader in the normal working condition, so that the rotation of the engine can be controlled based on the first external characteristic curve when the loader is in the normal working condition, and when it is determined that the engine is in the slip working condition, the critical output torque of the engine when the loader slips can be first obtained, so as to obtain the second external characteristic curve of the engine of the loader in the slip working condition according to the critical output torque and the first external characteristic curve, thereby the rotation of the engine can be controlled based on the second external characteristic curve when the loader is in the slip working condition, so that the engine can reach the critical output torque at a lower speed, thereby effectively reducing the power consumption of the loader in the slip working condition.

[0081] Optionally, Figure 2is a flow chart of another loader control method provided by the embodiment of the present application, as shown in the figure, the control method of the loader comprises: Figure 2

[0082] S211, obtaining the first external characteristic curve of the engine of the loader under normal working conditions.

[0083] S212, obtaining the original vehicle mass and the current vehicle loading mass of the loader when it is determined that the loader is in the slipping working condition.

[0084] Specifically, the original vehicle mass of the loader is the vehicle mass when the loader is not loaded with any material, and the vehicle loading mass is the weight of the material loaded by the loader.

[0085] S213, obtaining the current road adhesion coefficient and the current rolling resistance coefficient.

[0086] Among them, the adhesion coefficient and the rolling resistance coefficient of the road can be obtained by a sensor.

[0087] S214, obtaining the maximum friction force of the loader when it slips according to the original vehicle mass, the current vehicle loading mass, the current road adhesion coefficient and the current rolling resistance coefficient.

[0088] Specifically, the maximum friction force Ff of the loader when it slips can be obtained based on the first formula according to the original vehicle mass m1, the current vehicle loading mass m2, the current road adhesion coefficient δ1 and the current rolling resistance coefficient δ2. The first formula is Ff = (δ1-δ2)*(m1+m2)*9.8.

[0089] S215, obtaining the gear ratio of the gearbox, the total speed ratio of the axle and the wheel and the wheel radius.

[0090] Specifically, the gear ratio of the gearbox can be determined according to the current travel gear of the loader, and the total speed ratio of the axle and the wheel and the wheel radius are fixed signals which can be pre-stored in the memory and directly obtained from the memory when used.

[0091] S216, determining the critical output torque of the engine of the loader when it slips according to the maximum friction force, the gear ratio of the gearbox, the total speed ratio and the wheel radius.

[0092] Specifically, the critical output torque M1 of the engine of the loader when it slips can be determined based on the second formula according to the maximum friction force Ff, the gear ratio ig of the gearbox, the total speed ratio i0 and the wheel radius r. The second formula is Ff = M1*ig*i0 / r.

[0093] S217, obtaining the coordinate system in which the first external characteristic curve is located.

[0094] ​Wherein, the y-axis of the coordinate system is the output torque of the engine, and the x-axis of the coordinate system is the speed of the engine.

[0095] Specifically, Figure 3 is a curve diagram of the engine external characteristic provided by the embodiment of the application, as Figure 3 shown, a coordinate system can be established with the speed of the engine rpm as the x-axis and the output torque of the engine Nm as the y-axis. According to the coordinate system, the corresponding relationship between the speed and the output torque of the engine of the loader under normal working conditions can be tested, so that the first external characteristic curve L1 can be determined. The first external characteristic curve can be pre-stored in the memory and directly obtained from the memory in use.

[0096] S218, obtaining the torque calculation equation of the torque converter when the speed ratio of the torque converter is zero.

[0097] Specifically, according to the working principle of the torque converter, the maximum traction is provided when the speed ratio of the torque converter is zero, and the loader is at the critical point between the normal working condition and the slipping working condition. In the traveling device of the loader, the torque output by the engine is transmitted to the torque converter for speed reduction and torque reduction, so that in order to obtain the engine speed when the output torque of the engine is the critical output torque, the torque calculation equation of the torque converter when the speed ratio of the torque converter is zero can be obtained. Wherein, the torque calculation equation of the torque converter can be MB=C*n 2 , and the curve thereof is shown as L2 in the figure. Wherein, C is a constant according to the change of the speed ratio of the torque converter, and when the speed ratio of the torque converter is zero, the constant C can be calculated by the formula C=ρ*g*Y*d, wherein, ρ is the working oil density of the torque converter, g is the acceleration of gravity, Y is the pump torque coefficient, and d is the diameter of the pump.

[0098] S219, obtaining the critical speed of the engine when the output torque of the engine is the critical output torque based on the torque calculation equation.

[0099] Specifically, MB=M1 in the torque calculation equation, and then the critical speed n0 of the engine when the output torque of the engine is the critical output torque can be calculated based on the torque calculation equation.

[0100] S220, determining the first coordinate point according to the critical output torque and the critical speed.

[0101] Specifically, the critical output torque and the critical speed can be mapped to the coordinate system in which the first external characteristic curve L1 is located, so that the first coordinate point k=(n1, M1) can be determined.

[0102] S221, obtaining the second coordinate point as the intersection point of the torque calculation equation and the first external characteristic curve.

[0103] Specifically, combined with reference Figure 3The torque calculation equation can be combined with the equation represented by the first external characteristic curve to calculate a second coordinate point H=(n2, M2).

[0104] S222, a third coordinate point is obtained, where the output torque is zero and the rotating speed is greater than zero on the first external characteristic curve.

[0105] Specifically, with reference to Figure 3 , the third coordinate point where the output torque is zero and the rotating speed is greater than zero on the first external characteristic curve L1 is denoted as B=(n3, 0).

[0106] S223, a first slope is determined according to the second coordinate point and the third coordinate point.

[0107] Specifically, according to the second coordinate point H=(n2, M2) and the third coordinate point B=(n3, 0), the first slope k1=(n2-n3) / M2 can be determined.

[0108] S224, a first straight line equation is determined according to the first coordinate point and the first slope.

[0109] Specifically, according to the point-slope formula, the first straight line L3 can be determined according to the first coordinate point k=(n1, M1) and the first slope k1=n2 / (M2-M3). After calculation, the first straight line equation can be expressed as y=x*(n2-n3) / M2+(M1-n1*(n2-n3) / M2). In this way, the slope of the first straight line equation is the slope of the partial curve of the first external characteristic curve L1, so that the external characteristic curve of the engine rotating under the slipping working condition can be determined according to the slope, and the reliability of the control process of the engine under the slipping working condition of the loader is improved.

[0110] S225, a first intersection point of the first straight line equation and the first external characteristic curve is obtained, and a second intersection point of the first straight line equation and the x-axis is obtained.

[0111] S226, a second external characteristic curve of the engine under the slipping working condition of the loader is obtained according to the first external characteristic curve, the first intersection point and the second intersection point.

[0112] S227, the engine is controlled to rotate based on the second external characteristic curve.

[0113] Specifically, after the first straight line equation is determined, the first straight line equation and the equation of the first outer characteristic curve can be calculated together to obtain the first intersection point E, and the second intersection point F of the first straight line equation and the x-axis when y=0 can be calculated. Thus, the second outer characteristic curve L3 can be determined as a curve including the points A, E, k, and F. The AE segment curve can be the same as the AE segment curve in the first outer characteristic curve L1, and the engine rotation is controlled according to the AE segment curve when the loader is not slipping, and the engine rotation is controlled according to the EF segment straight line after the loader is in the slipping working condition. For reference Figure 3 Compared with controlling the engine rotation according to the first outer characteristic curve L1 in the slipping working condition, the engine rotation is controlled according to the EF segment straight line of the second outer characteristic curve after the loader is in the slipping working condition, and the target engine speed is smaller when the engine is controlled according to the EF segment straight line of the second outer characteristic curve, so that the power loss of the engine of the loader in the slipping working condition can be effectively reduced.

[0114] Optionally, Figure 4 is a flowchart of another control method of a loader provided by an embodiment of the present application, as shown in the figure, the control method of the loader comprises the following steps. Figure 4

[0115] S311, obtaining a first outer characteristic curve of an engine of the loader in a normal working condition.

[0116] S312, obtaining an actual vehicle speed of the loader, a turbine speed of a torque converter, an actual engine speed, an accelerator opening degree, and a hydraulic handle signal in real time.

[0117] Specifically, the actual vehicle speed of the loader can be determined through a vehicle-mounted GPS signal, and the turbine speed of the torque converter, the actual engine speed, the accelerator opening degree, and the hydraulic handle signal can be obtained through sensors.

[0118] S313, obtaining a current working condition of the loader according to at least the actual vehicle speed and the turbine speed, and / or obtaining the current working condition of the loader according to the turbine speed, the actual engine speed, the accelerator opening degree, and the hydraulic handle signal.

[0119] Specifically, the current working condition of the loader can be obtained according to at least the actual vehicle speed and the turbine speed, or the current working condition of the loader can also be obtained according to the turbine speed, the actual engine speed, the accelerator opening degree, and the hydraulic handle signal. In another feasible embodiment, the current working condition of the loader can be obtained according to the actual vehicle speed and the turbine speed, and the current working condition of the loader can also be obtained according to the turbine speed, the actual engine speed, the accelerator opening degree, and the hydraulic handle signal, as long as at least one of the two determines that the loader is in the slipping working condition, that is, the working condition of the loader is the slipping working condition.

[0120] ​For example, when the current operating condition of the loader is obtained according to the actual vehicle speed v1 and the turbine speed n4, the gear ratio ig of the gearbox, the total speed reduction ratio i0 of the axle and the wheel, and the wheel radius r can be obtained first. Then, the theoretical vehicle speed v2 of the loader can be obtained according to the turbine speed n4, the gear ratio ig of the gearbox, the total speed reduction ratio i0, and the wheel radius r. Specifically, the theoretical vehicle speed v2 of the loader can be calculated according to the vehicle speed calculation formula v2 = 0.337 * r * n4 / (ig * i0). Then, the vehicle speed difference between the theoretical vehicle speed v2 and the actual vehicle speed v1 is obtained, and it is determined whether the vehicle speed difference v2-v1 is greater than the preset difference value, and the preset difference value is greater than zero. If it is determined that the vehicle speed difference is greater than the preset difference value, it means that the current actual vehicle speed is much smaller than the theoretical vehicle speed. Therefore, the duration when the vehicle speed difference is greater than the preset difference value can be obtained, and it is determined whether the duration is greater than the preset time. If it is determined that the duration is not greater than the preset time, it is determined that the actual vehicle speed of the loader is much smaller than the theoretical vehicle speed due to the slipping, which can avoid misjudgment of the slipping condition and improve the accuracy of the slipping detection. At this time, it is determined that the loader is in the slipping condition. When the vehicle speed difference is less than or equal to the preset difference value, or when the duration when the vehicle speed difference is greater than the preset difference value is less than or equal to the preset time, it is determined that the loader is in the normal condition.

[0121] When the current operating condition of the loader is obtained according to the turbine speed, the actual engine speed, the throttle opening, and the hydraulic handle signal, the torque converter speed ratio i1 can be obtained according to the turbine speed n4 and the actual engine speed n5 first. It is determined whether the absolute change rate of the torque converter speed ratio i1 is greater than the preset change rate. The preset change rate is less than zero. If yes, it is determined whether the torque converter speed ratio is less than the preset torque converter speed ratio. If yes, it is determined whether the throttle opening is the preset opening and the hydraulic handle signal remains unchanged. If yes, it is determined that the loader is in the slipping condition.

[0122] Specifically, the torque converter speed ratio i1 can be the ratio of the turbine rotating speed n4 and the actual rotating speed n5 of the engine, i.e. i1 = n4 / n5. Assuming that the speed ratio of the transmission at the current time is i1 (t1) and the speed ratio of the transmission at the previous time is i1 (t0), the change rate of the torque converter speed ratio i1 can be represented as [i1 (t1) - i1 (t0)] / (t1-t0), and the preset change rate can be set to a value less than zero according to requirements. When the change rate of the torque converter speed ratio i1 is less than the preset change rate, it indicates that the torque converter speed ratio i1 instantaneously decreases. In this case, it can be further detected whether the decreased torque converter speed ratio is less than the preset torque converter speed ratio. In the normal working condition, the speed ratio of the torque converter is 0.6-0.8, and the preset torque converter speed ratio can be 0.3. If the torque converter speed ratio i1 instantaneously decreases to 0.3 or less, it can be detected whether the throttle opening degree remains unchanged at the preset opening degree and whether the hydraulic handle signal remains unchanged. The preset opening degree can be the maximum opening degree of the throttle. If the throttle opening degree remains unchanged at the preset opening degree and the hydraulic handle signal remains unchanged, it indicates that the loader has occurred the slipping condition and the driver has not actively handled the slipping condition. At this time, it can be determined that the loader is in the slipping condition. If the change rate of the torque converter speed ratio i1 is greater than or equal to the preset change rate, or the change rate of the torque converter speed ratio i1 is less than the preset change rate but the torque converter speed ratio is greater than or equal to the preset torque converter speed ratio, or the change rate of the torque converter speed ratio i1 is less than the preset change rate and the torque converter speed ratio is less than the preset torque converter speed ratio but the throttle opening degree decreases or the hydraulic handle signal changes, it can be determined that the loader is in the normal working condition.

[0123] In this way, the running condition of the loader can be detected from two aspects, and the detection efficiency of the slipping condition can be effectively improved.

[0124] S314, determining whether the running condition is the slipping condition; if yes, performing step S316; if no, performing step S320.

[0125] S315, acquiring the critical output torque of the engine when the loader slips.

[0126] S316, acquiring the second external characteristic curve of the engine in the slipping condition of the loader according to the critical output torque and the first external characteristic curve.

[0127] S317, controlling the engine to rotate based on the second external characteristic curve.

[0128] S318, continuously acquiring the throttle opening degree and the hydraulic handle signal of the loader.

[0129] S329, determining whether the throttle opening degree is lower than the preset opening degree and / or determining whether the hydraulic handle signal changes; if yes, performing step S320; if no, performing step S317.

[0130] S320, controlling the engine to rotate based on the first external characteristic curve.

[0131] Specifically, in the process of controlling the engine to operate according to the second external characteristic curve when the loader is in the slipping working condition, the throttle opening degree and the hydraulic handle signal of the loader can be continuously acquired. The preset opening degree can be the maximum opening degree of the throttle, for example, 100%. If the throttle opening degree is lower than the preset opening degree, it indicates that the driver has restored the loader to the normal working condition by reducing the throttle opening degree; if the hydraulic handle signal changes, it indicates that the vehicle is currently performing a loading action, or the driver has restored the loader to the normal working condition by operating the hydraulic handle, at this time, it can be determined that the loader is in the normal working condition. If any of the above conditions is met, the engine can be controlled to rotate based on the first external characteristic curve. If the throttle opening degree remains at the preset opening degree and the hydraulic handle signal does not change, it indicates that the loader is still in the slipping working condition, at this time, the engine can continue to be controlled to rotate based on the second external characteristic curve.

[0132] Based on the same inventive concept, the embodiment of the present application also provides a control device of a loader, which is used to execute the control method of the loader provided by any of the embodiments of the present application. The control device of the loader can be realized by software and / or hardware, and therefore, the control device of the loader provided by the embodiment of the present application comprises the technical features of the control method of the loader provided by any of the embodiments of the present application, and can achieve the beneficial effects of the control method of the loader provided by any of the embodiments of the present application. The same parts can be referred to the above description of the control method of the loader provided by the embodiment of the present application, which will not be described here again.

[0133] The loader comprises an engine, a torque converter and a transmission, Figure 5 is a structural schematic diagram of a control device of a loader provided by the embodiment of the present application, as Figure 5 shown, the control device of the loader comprises: a first external characteristic curve acquisition module 100, configured to acquire a first external characteristic curve of the engine of the loader in a normal working condition; a critical output torque acquisition module 200, configured to acquire a critical output torque of the engine when the loader slips when it is determined that the loader is in a slipping working condition; a second external characteristic curve acquisition module 300, configured to acquire a second external characteristic curve of the engine of the loader in the slipping working condition according to the critical output torque and the first external characteristic curve; and a first control module 400, configured to control the engine to rotate based on the second external characteristic curve.

[0134] The loader control device provided by the embodiment of the present application first acquires the first external characteristic curve of the engine of the loader under normal working conditions through the first external characteristic curve acquisition module in the process of the working of the loader, so that the engine rotation can be controlled based on the first external characteristic curve when the loader is in the normal working condition, and when it is determined that the engine is in the slipping working condition, the critical output torque of the engine when the loader slips can be first acquired through the critical output torque acquisition module, so that the second external characteristic curve of the engine of the loader under the slipping working condition can be acquired through the second external characteristic curve acquisition module according to the critical output torque and the first external characteristic curve, thereby the engine rotation can be controlled based on the second external characteristic curve through the first control module when the loader is in the slipping working condition, so that the engine can reach the critical output torque at a lower rotating speed, and the power consumption of the loader under the slipping working condition can be effectively reduced.

[0135] Optionally, the critical output torque acquisition module comprises: a mass acquisition unit, configured to acquire the original whole vehicle mass of the loader and the current whole vehicle loading mass when it is determined that the loader is in the slipping working condition; a coefficient acquisition unit, configured to acquire the current road adhesion coefficient and the current rolling resistance coefficient; a maximum friction force acquisition unit, configured to acquire the maximum friction force when the loader slips according to the original whole vehicle mass, the current whole vehicle loading mass, the current road adhesion coefficient and the current rolling resistance coefficient; a vehicle parameter acquisition unit, configured to acquire the gearbox speed ratio, the total speed ratio of the axle and the wheel and the wheel radius; and a critical output torque acquisition unit, configured to determine the critical output torque of the engine when the loader slips according to the maximum friction force, the gearbox speed ratio, the total speed ratio and the wheel radius.

[0136] Optionally, the second outer characteristic curve obtaining module comprises: a coordinate system obtaining unit, configured to obtain a coordinate system in which the first outer characteristic curve is located, a y-axis of the coordinate system being an output torque of the engine, and an x-axis of the coordinate system being a rotating speed of the engine; a torque calculation equation obtaining unit, configured to obtain a torque calculation equation of the torque converter when a speed ratio of the torque converter is zero; a critical rotating speed obtaining unit, configured to obtain a critical rotating speed of the engine when the output torque of the engine is a critical output torque based on the torque calculation equation; a first coordinate point determining unit, configured to determine a first coordinate point according to the critical output torque and the critical rotating speed; a second coordinate point obtaining unit, configured to obtain a second coordinate point as an intersection point of the torque calculation equation and the first outer characteristic curve; a third coordinate point obtaining unit, configured to obtain a third coordinate point on the first outer characteristic curve when the output torque is zero and the rotating speed is greater than zero; a first slope determining unit, configured to determine a first slope according to the second coordinate point and the third coordinate point; a first straight line equation determining unit, configured to determine a first straight line equation according to the first coordinate point and the first slope; an intersection point obtaining unit, configured to obtain a first intersection point of the first straight line equation and the first outer characteristic curve, and to obtain a second intersection point of the first straight line equation and the x-axis; and a second outer characteristic curve obtaining unit, configured to obtain a second outer characteristic curve of the engine of the loader in the slipping working condition according to the first outer characteristic curve, the first intersection point and the second intersection point.

[0137] Optionally, the control device of the loader further comprises a second control module, configured to control the engine to rotate based on the first outer characteristic curve when it is determined that the loader is in the normal working condition.

[0138] Optionally, the control device of the loader further comprises a first signal obtaining module, configured to obtain an actual vehicle speed of the loader, a turbine rotating speed of the torque converter, an actual rotating speed of the engine, a throttle opening degree and a hydraulic handle signal in real time before it is determined that the loader is in the slipping working condition; and a working condition obtaining module, configured to obtain a current running working condition of the loader according to at least the actual vehicle speed and the turbine rotating speed, and / or according to the turbine rotating speed, the actual rotating speed of the engine, the throttle opening degree and the hydraulic handle signal.

[0139] Optionally, the control device of the loader further comprises a second signal obtaining module, configured to continuously obtain the throttle opening degree and the hydraulic handle signal of the loader; and a judging module, configured to judge whether the throttle opening degree is lower than a preset opening degree and / or whether the hydraulic handle signal changes; and the second control module is further configured to control the engine to rotate based on the first outer characteristic curve when the throttle opening degree is lower than the preset opening degree and / or the hydraulic handle signal changes according to the judging module.

[0140] Based on the same inventive concept, the embodiment of the application further provides a loader, which comprises an engine, a torque converter, a transmission and a controller, wherein the controller is configured to execute the control method of the loader provided by any of the embodiments of the application, and thus the loader provided by the embodiment of the application comprises the technical features of the control method of the loader provided by any of the embodiments of the application, and can achieve the beneficial effects of the control method of the loader provided by any of the embodiments of the application, and the same parts can be referred to the description of the control method of the loader provided by the embodiment of the application, which will not be repeated here.

[0141] It should be understood that the steps shown above can be reordered, added or deleted. For example, the steps described in the application can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solutions of the application can be achieved, which are not limited herein.

[0142] The above detailed description does not constitute a limitation on the protection scope of the application. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent replacements and improvements made within the spirit and principles of the application shall be included in the protection scope of the application.

Claims

1. A control method of a loader including an engine, a torque converter, and a transmission, characterized by, The method comprises: obtaining a first external characteristic curve of the engine when the loader is in a normal working condition; obtaining a critical output torque of the engine when the loader slips when it is determined that the loader is in a slipping working condition; obtaining a second external characteristic curve of the engine when the loader is in a slipping working condition according to the critical output torque and the first external characteristic curve; controlling the engine to rotate based on the second external characteristic curve; obtaining a critical output torque of the engine when the loader slips when it is determined that the loader is in a slipping working condition, comprising: obtaining the original vehicle mass and the current vehicle loading mass of the loader when it is determined that the loader is in a slipping working condition; obtaining the current road adhesion coefficient and the current rolling resistance coefficient; obtaining the maximum friction force when the loader slips according to the original vehicle mass, the current vehicle loading mass, the current road adhesion coefficient and the current rolling resistance coefficient; obtaining the transmission gear ratio, the total reduction ratio of axle and wheel and the wheel radius; determining the critical output torque of the engine when the loader slips according to the maximum friction force, the transmission gear ratio, the total reduction ratio and the wheel radius; obtaining a second external characteristic curve of the engine when the loader is in a slipping working condition according to the critical output torque and the first external characteristic curve, comprising: obtaining a coordinate system in which the first external characteristic curve is located, the y-axis of the coordinate system being the output torque of the engine and the x-axis of the coordinate system being the speed of the engine; obtaining a torque calculation equation of the torque converter when the transmission gear ratio is zero; obtaining the critical speed of the engine when the output torque of the engine is the critical output torque based on the torque calculation equation; determining a first coordinate point according to the critical output torque and the critical speed; obtaining a second coordinate point which is the intersection point of the torque calculation equation and the first external characteristic curve; obtaining a third coordinate point on the first external characteristic curve, the output torque of which is zero and the speed of which is greater than zero; determining a first slope according to the second coordinate point and the third coordinate point; determining a first straight line equation according to the first coordinate point and the first slope; obtaining a first intersection point of the first straight line equation and the first external characteristic curve and a second intersection point of the first straight line equation and the x-axis; obtaining a second external characteristic curve of the engine when the loader is in a slipping working condition according to the first external characteristic curve, the first intersection point and the second intersection point.

2. The control method of the loader according to claim 1, characterized in that, The method further comprises: controlling the engine to rotate based on the first external characteristic curve when it is determined that the loader is in the normal working condition.

3. The control method of a loader according to claim 1, characterized in that, Before it is determined that the loader is in a slipping working condition, the method further comprises: obtaining the actual vehicle speed of the loader, the turbine speed of the torque converter, the actual speed of the engine, the throttle opening and the hydraulic handle signal in real time; The current operating condition of the loader is obtained according to at least the actual vehicle speed and the turbine speed, and / or the current operating condition of the loader is obtained according to the turbine speed, the actual engine speed, the throttle opening and the hydraulic lever signal.

4. The control method of the loader according to claim 3, characterized in that, The current operating condition of the loader is obtained according to at least the actual vehicle speed and the turbine speed, and / or the current operating condition of the loader is obtained according to the turbine speed, the actual engine speed, the throttle opening and the hydraulic lever signal. The gearbox speed ratio, the total speed ratio of the axle and the wheel and the wheel radius are obtained; The theoretical vehicle speed of the loader is obtained according to the turbine speed, the gearbox speed ratio, the total speed ratio and the wheel radius; The vehicle speed difference between the theoretical vehicle speed and the actual vehicle speed is obtained; It is determined whether the vehicle speed difference is greater than a preset difference value; the preset difference value is greater than zero; If yes, the duration that the vehicle speed difference is greater than the preset difference value is obtained; It is determined whether the duration is greater than a preset time; If yes, it is determined that the loader is in the slipping condition.

5. The control method of the loader according to claim 3, characterized in that, The current operating condition of the loader is obtained according to the turbine speed, the engine speed, the throttle opening and the hydraulic lever signal, and includes: The torque converter speed ratio is obtained according to the turbine speed and the actual engine speed; It is determined whether the change rate of the torque converter speed ratio is less than a preset change rate; the preset change rate is less than zero; If yes, it is determined whether the torque converter speed ratio is less than a preset torque converter speed ratio; If yes, it is determined whether the throttle opening is a preset opening and the hydraulic lever signal remains unchanged; If yes, it is determined that the loader is in the slipping condition.

6. The control method of a loader according to claim 1, characterized in that, When the engine is controlled based on the second external characteristic curve, the method further includes: The throttle opening and the hydraulic lever signal of the loader are continuously obtained; It is determined whether the throttle opening is lower than a preset opening and / or whether the hydraulic lever signal changes; If yes, the engine is controlled based on the first external characteristic curve.

7. A control device of a loader for executing the control method of the loader according to any one of claims 1 to 6, the loader including an engine, a torque converter, and a transmission, characterized by The method includes: The first external characteristic curve obtaining module is configured to obtain the first external characteristic curve of the engine of the loader in the normal condition; The critical output torque obtaining module is configured to obtain the critical output torque of the engine when the loader slips when it is determined that the loader is in the slipping condition; The second external characteristic curve obtaining module is configured to obtain the second external characteristic curve of the engine of the loader in the slipping condition according to the critical output torque and the first external characteristic curve; The first control module is configured to control the engine based on the second external characteristic curve.

8. A loader characterized by The method includes an engine, a torque converter, a transmission and a controller; The controller is configured to perform the control method of the loader according to any one of claims 1 to 6.

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