Loader and control method and device thereof

Abstract

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

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle control, and in particular to a loader and a control method and device thereof. Background Art

[0002] During the operation of the hydraulic wheel loader, tire slippage may sometimes occur. Tire slippage refers to the tire sliding or spinning on the road surface. During the operation, experienced drivers can reduce the slippage rate based on their experience, while inexperienced drivers often cause the tires of the entire vehicle to slip frequently.

[0003] When skidding occurs, the traction of the loader drops sharply, making it impossible for the loader to work normally. The slipping tires will wear out more severely, and the engine will also speed up too much due to skidding, causing engine power loss. Summary of the invention

[0004] The present invention provides a loader and a control method and device thereof, which can effectively reduce the engine power loss under the engine slipping condition.

[0005] According to one aspect of the present invention, a control method for a loader is provided, wherein the loader includes an engine, a torque converter and a transmission, including:

[0006] Acquire 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 slipping condition, obtaining a critical output torque of the engine when the loader slips;

[0008] According to the critical output torque and the first external characteristic curve, obtaining a second external characteristic curve of the engine when the loader is in a slipping condition;

[0009] The engine rotation is controlled based on the second external characteristic curve.

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

[0011] When it is determined that the loader is in a slipping condition, obtaining the original vehicle mass and the current vehicle shoveling mass of the loader;

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

[0013] According to the original vehicle mass, the current shovel mass of the vehicle, the current road adhesion coefficient and the current rolling resistance coefficient, the maximum friction force when the loader slips is obtained;

[0014] Obtain the gearbox speed ratio, the total speed ratio of the axle and the wheel, and the wheel radius;

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

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

[0017] Acquire a coordinate system where the first external characteristic curve is located, 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 rotation speed of the engine;

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

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

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

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

[0022] Obtaining a third coordinate point on the first external characteristic curve where the speed is greater than zero when the output torque is zero;

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

[0024] Determine 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 external characteristic curve, and obtaining a second intersection point of the first straight line equation and the x-axis;

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

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

[0028] When it is determined that the loader is in the normal operating condition, the engine rotation is controlled based on the first external characteristic curve.

[0029] Optionally, before determining that the loader is in a slipping condition, the method further includes:

[0030] Real-time acquisition of the actual vehicle speed of the loader, the turbine speed of the torque converter, the actual engine speed, the throttle opening, and the hydraulic handle signal;

[0031] The current operating condition of the loader is obtained at least based on the actual vehicle speed and the turbine speed, and / or the current operating condition of the loader is obtained based on the turbine speed, the actual speed of the engine, the throttle opening and the hydraulic handle signal.

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

[0033] Obtain the gearbox speed ratio, the total speed ratio of the axle and the wheel, and the wheel radius;

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

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

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

[0037] If so, obtaining a duration during which the vehicle speed difference is greater than the preset difference;

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

[0039] If so, it is determined that the loader is in a slipping condition.

[0040] Optionally, obtaining the current operating condition of the loader according to the turbine speed, the engine speed, the throttle opening and the hydraulic handle signal includes:

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

[0042] Determining 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;

[0043] If so, determining whether the torque converter speed ratio is less than a preset torque converter speed ratio;

[0044] If yes, determining whether the throttle opening is a preset opening and whether the hydraulic handle signal remains unchanged;

[0045] If so, it is determined that the loader is in a slipping condition.

[0046] Optionally, when controlling the rotation of the engine based on the second external characteristic curve, the method further includes:

[0047] Continuously obtaining the throttle opening and hydraulic handle signal of the loader;

[0048] Determining whether the throttle opening is lower than a preset opening, and / or determining whether the hydraulic handle signal changes;

[0049] If so, the engine rotation is controlled based on the first external characteristic curve.

[0050] According to another aspect of the present invention, a control device for a loader is provided, wherein the loader includes an engine, a torque converter and a transmission, including:

[0051] A first external characteristic curve acquisition module, used for acquiring a first external characteristic curve of the engine of the loader under normal working conditions;

[0052] A critical output torque acquisition module, for acquiring a critical output torque of the engine when the loader is in a slipping condition when it is determined that the loader is in a slipping condition;

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

[0054] The first control module is configured to control the engine rotation based on the second external characteristic curve.

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

[0056] The controller is used to execute the above-mentioned loader control method.

[0057] The control method for a loader provided by the present invention first obtains a first external characteristic curve of the engine of the loader under normal working conditions during the operation of the loader, so that the engine rotation can be controlled based on the first external characteristic curve when the loader is in normal working conditions, and when it is determined that the engine is in a slipping condition, the critical output torque of the engine when the loader slips can be first obtained, so as to obtain a second external characteristic curve of the engine when the loader is in a slipping condition based on the critical output torque and the first external characteristic curve, so that the engine rotation can be controlled based on the second external characteristic curve when the loader is in a slipping condition, so that the engine can reach the critical output torque at a lower speed, which can effectively reduce the power consumption of the loader under the slipping condition.

[0058] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

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

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

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

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

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

[0065] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0066] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0067] A loader usually consists of three parts: a traveling device, a steering mechanism and a loading working mechanism. The traveling device mainly consists of a transmission chain composed of an engine, a torque converter, a gearbox, a rear axle and tires.

[0068] An embodiment of the present invention provides a control method for a loader, which can effectively reduce the engine power loss under the engine slip condition. The control method for the loader can be executed by the control device of the loader provided by the embodiment of the present invention. The control device of the loader can be implemented 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 is a flow chart of a control method for a loader provided by an embodiment of the present invention, such as Figure 1 As shown, the control method of the loader includes:

[0070] S110: Obtain a first external characteristic curve of the engine of the loader under normal working conditions.

[0071] Specifically, when the loader is moving, it may not be able to pass normally due to a slippery road or obstacles, causing the loader to slip on the spot. The normal working condition may be a condition in which the loader can move normally without slipping. When the loader is in a normal working condition, the first external characteristic curve of the engine under the normal working condition of the loader may be first obtained. Among them, the external characteristic curve of the engine may be a relationship curve representing the relationship between the engine torque and the speed.

[0072] Exemplarily, when it is determined that the loader is in a normal operating condition, the engine rotation is controlled based on the first external characteristic curve.

[0073] Specifically, when the loader is in normal operating conditions, the current target torque of the engine can be continuously obtained. In order to distinguish it from the target torque when the loader is in a slipping condition, the target torque of the engine under normal operating conditions can be called the first target torque. In this way, the first target speed corresponding to the first target torque can be determined based on the first external characteristic curve, so that the actual speed of the engine is controlled to be the first target speed, thereby achieving control of the engine under normal operating conditions and thus achieving control of the loader.

[0074] S120: When it is determined that the loader is in a slipping condition, a critical output torque of the engine when the loader slips is obtained.

[0075] Specifically, at the critical point between the loader not slipping and slipping, the friction between the loader and the road surface is the largest. At this time, the output torque of the engine makes the loader's traction reach the maximum. At this critical point, the engine speed continues to increase, so that the output torque continues to increase, causing the loader to slip, resulting in a sharp drop in output torque and thus a sharp drop in the loader's traction. That is, after slipping, the higher engine speed cannot provide a 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. Obtain a second external characteristic curve of the engine when the loader is in a slipping condition according to the critical output torque and the first external characteristic curve.

[0077] S140: Control engine rotation based on the second external characteristic curve.

[0078] Specifically, after obtaining the critical output torque, the second external characteristic curve can be obtained by combining the critical output torque and the first external characteristic curve, so that when the loader is in a slipping condition, the engine rotation is controlled according to the second external characteristic curve, 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 slipping condition.

[0079] For example, when controlling the engine rotation based on the second external characteristic curve, the current target torque of the engine can also be obtained. The target torque when the engine is in a slipping condition at this time can be called the second target torque. The second target speed corresponding to the second target torque can be determined based on the second external characteristic curve, so as to control the actual speed of the engine to the second target speed, thereby realizing the control of the engine in a slipping condition and thus realizing the control of the loader.

[0080] The control method for a loader provided in an embodiment of the present invention first obtains a first external characteristic curve of the engine of the loader under normal working conditions during the operation of the loader. In this way, the engine rotation can be controlled based on the first external characteristic curve when the loader is in normal working conditions. When it is determined that the engine is in a slipping condition, the critical output torque of the engine when the loader slips can be first obtained, so as to obtain a second external characteristic curve of the engine when the loader is in a slipping condition based on the critical output torque and the first external characteristic curve. Therefore, the engine rotation can be controlled based on the second external characteristic curve when the loader is in a slipping condition, so that the engine can reach the critical output torque at a lower speed, which can effectively reduce the power consumption of the loader under slipping conditions.

[0081] Optional, Figure 2is a flow chart of another loader control method provided by an embodiment of the present invention. Figure 2 As shown, the control method of the loader includes:

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

[0083] S212: When it is determined that the loader is in a slipping condition, the original vehicle mass of the loader and the current vehicle shoveling mass are obtained.

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

[0085] S213: Obtain the current road adhesion coefficient and the current rolling resistance coefficient.

[0086] Among them, the adhesion coefficient and rolling resistance coefficient of the road surface can be obtained through sensors.

[0087] S214: Obtain the maximum friction force when the loader slips according to the original vehicle mass, the current vehicle shovel mass, the current road adhesion coefficient, and the current rolling resistance coefficient.

[0088] Specifically, based on the first formula, the maximum friction force Ff when the loader slips can be obtained according to the original vehicle mass m1, the current vehicle shovel 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: Obtain the transmission speed ratio, the total speed ratio of the axle and the wheel, and the wheel radius.

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

[0091] S216. 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 of the reduction gear, and the wheel radius.

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

[0093] S217: Obtain the coordinate system where the first external characteristic curve is located.

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

[0095] Specifically, Figure 3 is a curve diagram of an engine external characteristic provided by an embodiment of the present invention, such as Figure 3 As shown, a coordinate system can be established with the engine speed rpm as the x-axis and the engine output torque Nm as the y-axis. Based on the coordinate system, the corresponding relationship between the engine speed and the output torque 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 can be directly obtained from the memory when used.

[0096] S218. Obtain 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. When the traction is maximum, the loader is at the critical point between normal working condition and slipping condition. In the traveling device of the loader, the torque output by the engine is transmitted to the torque converter for deceleration and torque reduction. Therefore, in order to obtain the engine speed when the output torque of the engine is the critical output torque, it can be obtained based on the torque converter torque calculation equation when the speed ratio of the torque converter is zero. Among them, the torque calculation equation of the torque converter can be MB=C*n 2 , and its curve is shown as L2 in the figure. Among them, C is a constant that changes according to the speed ratio of the torque converter. When the speed ratio of the torque converter is zero, the constant C can be calculated by the formula C=ρ*g*Y*d, where ρ is the working oil density of the torque converter, g is the acceleration of gravity, Y is the torque coefficient of the pump wheel, and d is the diameter of the pump wheel.

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

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

[0100] S220: Determine a first coordinate point according to a critical output torque and a critical speed.

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

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

[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 the second coordinate point H = (n2, M2).

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

[0105] For details, please refer to Figure 3 The third coordinate point on the first external characteristic curve L1 where the speed is greater than zero when the output torque is zero is denoted as B=(n3, 0).

[0106] S223. Determine a first slope 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. Determine a first straight line equation according to the first coordinate point and the first slope.

[0109] Specifically, according to the point-slope principle, the equation of 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 equation of the first straight line 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 first external characteristic curve L1 part, so that the external characteristic curve for controlling the engine rotation under the slipping condition can be determined with reference to the slope, thereby improving the reliability of the control process of the engine under the slipping condition of the loader.

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

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

[0112] S227. Control the engine rotation based on the second external characteristic curve.

[0113] Specifically, after determining the equation of the first straight line, the equation of the first straight line and the equation of the first external characteristic curve can be used to jointly calculate the first intersection point E, and the second intersection point F between the equation of the first straight line and the x-axis when y=0 can be calculated. Thus, the second external characteristic curve L3 can be determined to be a curve including points A, E, k, and F. Among them, the AE segment curve can be the same as the AE segment curve in the first external characteristic curve L1. In this way, when the loader is not slipping, the engine rotation is controlled according to the AE segment curve, and when the loader is in a slipping condition, the engine rotation is controlled according to the EF segment straight line. Combined with reference Figure 3 Compared with controlling the engine rotation according to the first external characteristic curve L1 under the slipping condition, the engine rotation is controlled according to the EF segment straight line of the second external characteristic curve after the loader is in the slipping condition. When the same output torque is achieved, the target speed of the engine is smaller when the engine is controlled according to the EF segment straight line of the second external characteristic curve, thereby effectively reducing the power loss of the engine of the loader under the slipping condition.

[0114] Optional, Figure 4 is a flow chart of another method for controlling a loader provided by an embodiment of the present invention, such as Figure 4 As shown, the control method of the loader includes:

[0115] S311. Obtain a first external characteristic curve of the engine of the loader under normal working conditions.

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

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

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

[0119] Specifically, the current operating condition of the loader can be obtained at least according to the actual vehicle speed and turbine speed, or according to the turbine speed, the actual engine speed, the throttle opening and the hydraulic handle signal. In another feasible embodiment, the current operating condition of the loader can be obtained according to the actual vehicle speed and turbine speed at the same time, and according to the turbine speed, the actual engine speed, the throttle opening and the hydraulic handle signal. As long as at least one of the two determines that the loader is in a slipping condition, the operating condition of the loader is determined to be a slipping condition.

[0120] Exemplarily, when obtaining the current operating condition of the loader based on at least the actual vehicle speed v1 and the turbine speed n4, the gearbox speed ratio ig, the total deceleration speed ratio i0 of the axle and the wheel radius r can be obtained first; then, based on the turbine speed n4, the gearbox speed ratio ig, the total deceleration speed ratio i0 and the wheel radius r, the theoretical vehicle speed v2 of the loader can be obtained. 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 speed difference between the theoretical speed v2 and the actual speed v1 is obtained, and it is determined whether the speed difference v2-v1 is greater than the preset difference, and the preset difference is greater than zero; if it is determined that the speed difference is greater than the preset difference, it means that the current actual speed is much less than the theoretical speed, and the duration of the speed difference greater than the preset difference can be taken, and it is determined whether the duration is greater than the preset time; if it is determined whether the duration is the preset time, it can be determined that the actual speed of the loader is much less than the theoretical speed due to slippage, which can avoid misjudgment of the slippage condition and improve the accuracy of slippage detection. At this time, it can be determined that the loader is in a slippage condition. When the speed difference is less than or equal to the preset difference, or when the speed difference is greater than the preset difference for a duration of rain or equal to the preset time, it can be determined that the loader is in a normal condition.

[0121] When obtaining the current operating condition of the loader based on the turbine speed, the actual engine speed, the throttle opening and the hydraulic handle signal, the torque converter speed ratio i1 can be first obtained based on the turbine speed n4 and the actual engine speed n5; determine 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 so, determine whether the torque converter speed ratio is less than the preset torque converter speed ratio; if so, determine whether the throttle opening is the preset opening and whether the hydraulic handle signal remains unchanged; if so, determine that the loader is in a slipping condition.

[0122] Specifically, the torque converter speed ratio i1 may be the ratio of the turbine speed n4 to the actual speed n5 of the engine, that is, i1=n4 / n5. Assuming that the speed ratio of the transmission at the current moment is i1(t1), and the speed ratio of the transmission at the previous moment is i1(t0), the change rate of the torque converter speed ratio i1 may be expressed as [i1(t1)-i1(t0)] / (t1-t0), and the preset change rate may be set to a value less than zero according to demand. 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 is reduced instantaneously. In this case, it is possible to continue to detect whether the reduced torque converter speed ratio is less than the preset torque converter speed ratio. Under normal working conditions, the speed ratio of the torque converter is between 0.6 and 0.8, and the preset torque converter speed ratio may be 0.3. If the torque converter speed ratio i1 is reduced to less than 0.3 instantaneously, it is possible to detect whether the throttle opening remains unchanged at the preset opening, and whether the hydraulic handle signal remains unchanged. The preset opening can be the maximum opening of the throttle. If the throttle opening remains unchanged at the preset opening and the hydraulic handle signal remains unchanged, it means that the loader has slipped and the driver has not actively processed the slip condition. At this time, it can be determined that the loader is in a slip 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 decreases or the hydraulic handle signal changes, it can be determined that the loader is in a normal condition.

[0123] In this way, the operating condition of the loader can be detected from two angles, which can effectively improve the detection efficiency of the slipping condition.

[0124] S314, determine whether the operating condition is a slipping condition; if so, execute step S316; if not, execute step S320.

[0125] S315: Obtain the critical output torque of the engine when the loader slips.

[0126] S316. Obtain a second external characteristic curve of the engine when the loader is in a slipping condition according to the critical output torque and the first external characteristic curve.

[0127] S317: Control the engine rotation based on the second external characteristic curve.

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

[0129] S329, determine whether the throttle opening is lower than the preset opening, and / or determine whether the hydraulic handle signal changes; if so, execute step S320; if not, execute step S317.

[0130] S320: Control engine rotation based on the first external characteristic curve.

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

[0132] Based on the same inventive concept, an embodiment of the present invention further provides a control device for a loader, which is used to execute the control method for a loader provided by any embodiment of the present invention. The control device for a loader can be implemented by software and / or hardware. Therefore, the control device for a loader provided by an embodiment of the present invention includes the technical features of the control method for a loader provided by any embodiment of the present invention, and can achieve the beneficial effects of the control method for a loader provided by any embodiment of the present invention. The similarities can be referred to the above description of the control method for a loader provided by an embodiment of the present invention, and will not be repeated here.

[0133] The loader consists of an engine, a torque converter and a transmission. Figure 5 is a structural schematic diagram of a loader control device provided by an embodiment of the present invention, such as Figure 5 As shown, the loader control device includes: a first external characteristic curve acquisition module 100, used to obtain the first external characteristic curve of the engine of the loader under normal working conditions; a critical output torque acquisition module 200, used to obtain the critical output torque of the engine when the loader slips when it is determined that the loader is in a slipping condition; a second external characteristic curve acquisition module 300, used to obtain the second external characteristic curve of the engine when the loader is in a slipping condition based on the critical output torque and the first external characteristic curve; a first control module 400, used to control the engine rotation based on the second external characteristic curve.

[0134] The loader control device provided by the embodiment of the present invention first obtains the first external characteristic curve of the engine of the loader under normal working conditions through the first external characteristic curve acquisition module during the operation of the loader. In this way, the engine rotation can be controlled based on the first external characteristic curve when the loader is in normal working conditions. When it is determined that the engine is in a slipping condition, the critical output torque of the engine when the loader slips can be first obtained through the critical output torque acquisition module, and the second external characteristic curve of the engine when the loader is in a slipping condition can be obtained through the second external characteristic curve acquisition module based on the critical output torque and the first external characteristic curve. Therefore, when the loader is in a slipping condition, the engine rotation can be controlled based on the second external characteristic curve through the first control module, so that the engine can reach the critical output torque at a lower speed, which can effectively reduce the power consumption of the loader under slipping conditions.

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

[0136] Optionally, the second external characteristic curve acquisition module includes: a coordinate system acquisition unit, used to acquire the coordinate system where the first external characteristic curve is located, 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; a torque calculation equation acquisition unit, used to acquire the torque calculation equation of the torque converter when the speed ratio of the torque converter is zero; a critical speed acquisition unit, used to acquire the critical speed of the engine when the output torque of the engine is the critical output torque based on the torque calculation equation; a first coordinate point determination unit, used to determine the first coordinate point according to the critical output torque and the critical speed; a second coordinate point acquisition unit, used to acquire the intersection of the torque calculation equation and the first external characteristic curve The point is the second coordinate point; the third coordinate point acquisition unit is used to acquire the third coordinate point on the first external characteristic curve where the speed is greater than zero when the output torque is zero; the first slope determination unit is used to determine the first slope according to the second coordinate point and the third coordinate point; the first straight line equation determination unit is used to determine the first straight line equation according to the first coordinate point and the first slope; the intersection acquisition unit is used to acquire the first intersection point of the first straight line equation and the first external characteristic curve, and to acquire the second intersection point of the first straight line equation and the x-axis; the second external characteristic curve acquisition unit is used to acquire the second external characteristic curve of the engine when the loader is in a slipping condition according to the first external characteristic curve, the first intersection point and the second intersection point.

[0137] Optionally, the control device of the loader further includes a second control module, which is used to control the engine rotation based on the first external characteristic curve when it is determined that the loader is in a normal operating condition.

[0138] Optionally, the control device of the loader also includes a first signal acquisition module, which is used to obtain 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 before determining that the loader is in a slipping condition; a working condition acquisition module, which is used to obtain the current operating condition of the loader based on at least the actual vehicle speed and the turbine speed, and / or, to obtain the current operating condition of the loader based on the turbine speed, the actual speed of the engine, the throttle opening and the hydraulic handle signal.

[0139] Optionally, the control device of the loader also includes a second signal acquisition module, used to continuously acquire the throttle opening and hydraulic handle signal of the loader; a judgment module, used to judge whether the throttle opening is lower than a preset opening, and / or, judge whether the hydraulic handle signal changes; the second control module is also used to control the engine rotation based on the first external characteristic curve when the throttle opening of the judgment module is lower than a preset opening, and / or the hydraulic handle signal changes.

[0140] Based on the same inventive concept, an embodiment of the present invention further provides a loader, which includes an engine, a torque converter, a transmission and a controller, wherein the controller is used to execute the control method of the loader provided by any embodiment of the present invention. Therefore, the loader provided by the embodiment of the present invention includes the technical features of the control method of the loader provided by any embodiment of the present invention, and can achieve the beneficial effects of the control method of the loader provided by any embodiment of the present invention. The similarities can be referred to the above description of the control method of the loader provided by the embodiment of the present invention, and will not be repeated here.

[0141] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0142] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A control method for a loader, the loader comprising an engine, a torque converter and a transmission, characterized in that: include: Acquire a first external characteristic curve of the engine of the loader under normal working conditions; When it is determined that the loader is in a slipping condition, obtaining a critical output torque of the engine when the loader slips; According to the critical output torque and the first external characteristic curve, obtaining a second external characteristic curve of the engine when the loader is in a slipping condition; The engine rotation is controlled based on the second external characteristic curve.

2. The control method of a loader according to claim 1, characterized in that: When it is determined that the loader is in a slipping condition, obtaining a critical output torque of the engine when the loader slips, comprises: When it is determined that the loader is in a slipping condition, obtaining the original vehicle mass and the current vehicle shoveling mass of the loader; Get the current road adhesion coefficient and the current rolling resistance coefficient; According to the original vehicle mass, the current shovel mass of the vehicle, the current road adhesion coefficient and the current rolling resistance coefficient, the maximum friction force when the loader slips is obtained; Obtain the gearbox speed ratio, the total speed ratio of the axle and the wheel, and the wheel radius; The critical output torque of the engine when the loader slips is determined according to the maximum friction force, the gearbox speed ratio, the total speed ratio of the reduction gear, and the wheel radius.

3. The control method of a loader according to claim 1, characterized in that: According to the critical output torque and the first external characteristic curve, obtaining a second external characteristic curve of the engine when the loader is in a slipping condition includes: Acquire a coordinate system where the first external characteristic curve is located, 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 rotation speed of the engine; Obtaining a torque calculation equation of the torque converter when the speed ratio of the torque converter is zero; Based on the torque calculation equation, obtaining a critical speed of the engine when the output torque of the engine is the critical output torque; Determining a first coordinate point according to the critical output torque and the critical speed; Obtaining an intersection point of the torque calculation equation and the first external characteristic curve as a second coordinate point; Obtaining a third coordinate point on the first external characteristic curve where the speed is greater than zero when the output torque is zero; determining a first slope according to the second coordinate point and the third coordinate point; Determine 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 obtaining a second intersection point of the first straight line equation and the x-axis; A second external characteristic curve of the engine when the loader is in a slipping condition is obtained according to the first external characteristic curve, the first intersection point and the second intersection point.

4. The control method of a loader according to claim 1, characterized in that: Also includes: When it is determined that the loader is in the normal operating condition, the engine rotation is controlled based on the first external characteristic curve.

5. The control method of a loader according to claim 1, characterized in that: Before determining that the loader is in a slipping condition, the method further includes: Real-time acquisition of the actual vehicle speed of the loader, the turbine speed of the torque converter, the actual engine speed, the throttle opening, and the hydraulic handle signal; The current operating condition of the loader is obtained at least based on the actual vehicle speed and the turbine speed, and / or the current operating condition of the loader is obtained based on the turbine speed, the actual speed of the engine, the throttle opening and the hydraulic handle signal.

6. The control method of a loader according to claim 5, characterized in that: Acquiring the current operating condition of the loader at least according to the actual vehicle speed and the turbine speed, including: Obtain the gearbox speed ratio, the total speed ratio of the axle and the wheel, and the wheel radius; Obtaining a theoretical vehicle speed of the loader according to the turbine speed, the gearbox speed ratio, the total speed ratio of the reduction gear, and the wheel radius; Obtaining a vehicle speed difference between the theoretical vehicle speed and the actual vehicle speed; Determining whether the vehicle speed difference is greater than a preset difference; the preset difference is greater than zero; If so, obtaining a duration during which the vehicle speed difference is greater than the preset difference; Determine whether the duration is greater than a preset time; If so, it is determined that the loader is in a slipping condition.

7. The control method of a loader according to claim 5, 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 handle signal, including: obtaining a torque converter speed ratio according to the turbine speed and the actual speed of the engine; Determining 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 so, determining whether the torque converter speed ratio is less than a preset torque converter speed ratio; If yes, determining whether the throttle opening is a preset opening and whether the hydraulic handle signal remains unchanged; If so, it is determined that the loader is in a slipping condition.

8. The control method of a loader according to claim 1, characterized in that: When controlling the engine rotation based on the second external characteristic curve, the method further includes: Continuously obtaining the throttle opening and hydraulic handle signal of the loader; Determining whether the throttle opening is lower than a preset opening, and / or determining whether the hydraulic handle signal changes; If so, the engine rotation is controlled based on the first external characteristic curve.

9. A control device for a loader, the loader comprising an engine, a torque converter and a transmission, characterized in that: include: A first external characteristic curve acquisition module, used for acquiring a first external characteristic curve of the engine of the loader under normal working conditions; A critical output torque acquisition module, for acquiring a critical output torque of the engine when the loader is in a slipping condition when it is determined that the loader is in a slipping condition; A second external characteristic curve acquisition module, configured to acquire a second external characteristic curve of the engine when the loader is in a slipping condition according to the critical output torque and the first external characteristic curve; The first control module is configured to control the engine rotation based on the second external characteristic curve.

10. A loader, characterized in that: Includes engine, torque converter, transmission and controller; The controller is used to execute the control method of the loader according to any one of claims 1 to 8.

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