A control system for a closed center hydraulic torque converter of a loader

Abstract

The application discloses a control system of a loader closed hydraulic torque converter, and the control system comprises a data sensing layer, an analysis decision layer and a system execution layer; the data sensing layer is used for acquiring operation data and operation data of the loader under different working conditions and transmitting the data to the analysis decision layer; the analysis decision layer determines a required working condition of the hydraulic torque converter through a decision result of a control area decision, and issues a required working condition control instruction to the system execution layer; and the system execution layer receives the control instruction issued by the analysis decision layer, and controls the action of a lock-up clutch in the hydraulic torque converter through an electro-hydraulic execution system. The loader closed hydraulic torque converter slip control system of the application can ensure fuel economy and improve the whole machine driving smoothness, provides a theoretical basis for automatic control of a three-working-condition process of the hydraulic torque converter, and provides technical support for solving the contradiction between fuel economy and driving smoothness of the loader.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of intelligent control, and particularly relates to a control system of a closed hydraulic torque converter of a loader. BACKGROUND

[0002] Engineering machinery is a kind of power equipment widely used in road construction, engineering construction and mine transportation fields, and plays an important role in China's economic and social development, but it has problems such as high energy consumption, low efficiency and poor driving comfort, especially in complex working conditions. As a typical engineering machinery, the mechanical hydraulic transmission system of the loader is composed of engine, hydraulic torque converter, gearbox, drive axle and other components. The hydraulic torque converter transmits power by using the flow of oil, realizes the "flexible" connection between the engine and the gearbox, ensures the smooth starting, speed changing and torque increasing of the loader, attenuates the torsional vibration of the engine and the transmission system, and reduces the impact. However, the biggest disadvantage of hydraulic transmission is low transmission efficiency. Therefore, the closed hydraulic torque converter is widely used in the current loader. The closed hydraulic torque converter adds a lock-up clutch in the hydraulic torque converter, and the working state of the torque converter is converted between hydraulic and mechanical working conditions through lock-up clutch control, so as to improve fuel economy. However, the impact of the lock-up clutch control process is large, which affects the ride comfort of the whole vehicle, that is, there is a contradiction between fuel economy and ride comfort of the loader.

[0003] However, the impact of the lock-up clutch control process is large, which affects the ride comfort of the whole vehicle, that is, there is a contradiction between fuel economy and ride comfort of the loader. SUMMARY

[0004] In order to solve the problems in the prior art, the present application provides a control system of a closed hydraulic torque converter of a loader, which comprises a data perception layer, an analysis and decision layer and a system execution layer,

[0005] The data perception layer is used for acquiring the running data and operation data of the loader under different working conditions, and transmitting the data to the analysis and decision layer,

[0006] The analysis and decision layer comprises a control strategy module of the hydraulic torque converter and a control region decision module. The analysis and decision layer combines the received running data of the loader and is based on the control strategy of the hydraulic torque converter, determines the required working condition of the hydraulic torque converter through the decision result of the control region decision, and issues the required working condition control instruction to the system execution layer,

[0007] The system execution layer comprises an electro-hydraulic execution system, receives the control instruction issued by the analysis and decision layer, and controls the action of the lock-up clutch in the hydraulic torque converter through the electro-hydraulic execution system.

[0008] Further, the data perception layer obtains the operation data of the loader in the three different working conditions of hydraulic, slip and mechanical, including engine speed and vehicle speed, and the operation data generated by the driver operating the loader, including throttle pedal opening and gear position, through the engine speed sensor, throttle pedal opening sensor, gear position sensor and vehicle speed sensor installed in the loader.

[0009] Further, the system execution layer realizes the conversion of the electromagnetic signal through the electromagnetic valve to control the output of the electro-hydraulic execution system to further control the opening and closing of the lock-up clutch friction plate in the hydraulic torque converter,

[0010] When in the hydraulic working condition, the electro-hydraulic execution system drives the lock-up clutch to be in the unlocked state,

[0011] When in the mechanical working condition, the electro-hydraulic execution system drives the lock-up clutch to be in the locked state,

[0012] When in the slip working condition, the electro-hydraulic execution system performs slip control to drive the lock-up clutch to be in the slip state, and the driving and driven discs follow the target slip speed.

[0013] Further, the specific steps of the control strategy of the hydraulic torque converter are:

[0014] First, define Flag = 1, Flag = 2, and Flag = 3 to represent the control instructions of the hydraulic torque converter in the hydraulic, slip, and mechanical working conditions, respectively,

[0015] Then, before starting the control, check whether the engine warm-up signal, sensor fault signal, oil temperature, and gear shifting signal meet the engine starting conditions,

[0016] If the starting conditions are not met, directly output the working condition control instruction Flag = 1 to the electro-hydraulic execution system to drive the lock-up clutch to be in the unlocked state and make the hydraulic torque converter enter the hydraulic working condition,

[0017] If the starting conditions are met, enter the control area decision module and the conversion sub-strategy module, and output the working condition of the hydraulic torque converter at the current time after correction according to the decision results of the two modules, and output the corresponding working condition control instruction,

[0018] When the output working condition control instruction is Flag = 2, indicating that the decision result is the slip working condition, the slip control sub-strategy module needs to be activated to perform fuzzy reasoning neural network slip control on the lock-up clutch of the hydraulic torque converter.

[0019] Further, the specific steps of the decision method of the control area decision module include:

[0020] (1) Determine the control area decision factor set and the evaluation set

[0021] Establishment of factor set:

[0022] Set the factor set as U, then U = {engine speed u1, accelerator pedal opening u2, speed ratio u3, gear u4, vehicle speed u5},

[0023] Establishment of evaluation set:

[0024] Set the evaluation set as V, and the three working conditions of the closed hydraulic torque converter are all regarded as evaluation subsets v j , then

[0025] V = {hydraulic v1, slip v2, mechanical v3};

[0026] (2) Establishment of fuzzy consistency judgment matrix

[0027] Through the dominant role of each factor on the evaluation object, the influence degree of each factor on the evaluation object is compared, and thus the judgment matrix A is constructed i , which is expressed as:

[0028]

[0029] In the formula, r mn represents the importance of the mth factor in the factor set U relative to the nth factor,

[0030] The construction of the judgment matrix may sometimes appear "A is more important than B, B is more important than C, and C is more important than A" abnormal situation, so the consistency of the n-order judgment matrix needs to be checked:

[0031]

[0032] In the formula: n is the number of rows or columns of the judgment matrix; λ max is the maximum eigenvalue of the judgment matrix,

[0033] Calculate the random consistency ratio CR of the judgment matrix:

[0034]

[0035] In the formula, RI is the random consistency index, and when CR < 0.1, it means that the weight coefficient set by the judgment matrix is reasonable.

[0036] (3) Establishment of factor set weight vector

[0037] The characteristic vector corresponding to the maximum eigenvalue of the judgment matrix is normalized to obtain the weight vector A i of the influencing factor,

[0038]

[0039] (4) Fuzzy synthesis algorithm for the control area

[0040] First, establish the fuzzy relation matrix of the control region.

[0041] A fuzzy relation matrix reflects a fuzzy relationship between a factor set U and an evaluation set V. The key to establishing a fuzzy relation matrix is ​​to determine the membership degree of each factor relative to the evaluation set. If for any element x in the universe of discourse U, there is a number A(x) ∈ (0,1), then A(x) is called the membership degree of x to A, where A is a fuzzy set in the universe of discourse U, and A(x) represents the degree to which x belongs to A.

[0042] For the i-th factor u in the factor set i When making an evaluation, its relative evaluation set V contains the j-th element v. j The membership degree is r ij , to combine the various factors u i Convert to membership vector R i , represented as:

[0043] R i =(r i1 ,r i2 ,Lr ij )

[0044] Establish a fuzzy relation matrix R, represented as follows:

[0045]

[0046] Secondly, fuzzy comprehensive evaluation is based on the fuzzy relation matrix R, and considers the weights A of each factor. i To reflect the combined effect of all factors, it is represented as B:

[0047]

[0048] Where o is the comprehensive evaluation operator,

[0049] Using the maximum membership principle and considering the contribution of the largest index, the demand condition decision result S(t) of the lock-up hydraulic torque converter at the current moment is determined:

[0050] S(t) = v j (t)=maxb j (t)

[0051] If S(t) = v2(t), the decision result of the demand condition of the loader's lock-up hydraulic torque converter is the slip condition. Slip control is performed in this region, which is also called the slip control region.

[0052] If S(t)=v1(t), the decision result of the loader closed hydraulic torque converter demand condition is hydraulic condition, the area is unlocked control, and the area is also called hydraulic control area;

[0053] If S(t)=v3(t), the decision result of the loader closed hydraulic torque converter demand condition is mechanical condition, the area is locked control, and the area is also called mechanical control area.

[0054] Further, the implementation process of the control method of the fuzzy reasoning neural network slip control is as follows:

[0055] When the slip control sub-strategy module receives the slip condition control instruction and is activated, the actual slip speed of the hydraulic torque converter and the opening value of the throttle at the current time are read out, input into the fuzzy reasoning system of the target slip speed, and the expected target slip speed is output as the target quantity of the BP neural network controller. The deviation value e obtained by operating the expected target slip speed and the actual slip speed is input into the BP neural network controller to follow the expected value of the slip speed, and the slip control of the loader closed hydraulic torque converter is realized.

[0056] Further, the specific steps of the conversion sub-strategy method of the conversion sub-strategy module are as follows:

[0057] According to the output of the fuzzy comprehensive algorithm of the control area of the control area strategy, the demand condition S(t) of the hydraulic torque converter at the current time is output, T is the signal sampling interval, the demand condition S(t-T) at the last sampling time and the slip friction work W of the lock-up clutch in the slip control stage are combined to realize the conversion between different conditions through logical judgment,

[0058] It is set that the hydraulic condition must pass through the slip condition to the mechanical condition, so as to reduce the impact degree when the lock-up clutch is engaged. In the slip condition, in order to prolong the service life of the lock-up clutch, the allowable slip friction work [W] is used as a judgment signal. If the slip friction work W of the lock-up clutch in the slip control stage exceeds the allowable slip friction work [W], the hydraulic torque converter exits the slip condition and immediately converts to the hydraulic condition. The lock-up clutch is prohibited from being started again before the oil temperature of the lock-up clutch reaches the normal range.

[0059] The condition control instruction of the hydraulic torque converter after the output conversion sub-strategy is corrected to determine the condition of the hydraulic torque converter at the current time.

[0060] Further, the electro-hydraulic execution sub-strategy module in the electro-hydraulic execution system receives the condition control instruction of the hydraulic torque converter at the current time output from the control area decision and conversion sub-strategy module, and outputs the duty cycle signal in the form of the corresponding PWM wave.

[0061] When the control instruction is the slip condition of Flag=2, the torque control amount signal of the slip control sub-strategy is input, the slip torque formula when the lock-up clutch is in the slip state and the function relationship between the engagement pressure of the electro-hydraulic execution system and the duty cycle are combined, and the duty cycle signal under the slip condition is obtained through mathematical conversion calculation;

[0062] When the control instruction is the hydraulic condition of Flag=1, PWM=0 is output,

[0063] When the control instruction is the mechanical condition of Flag=3, PWM=1 is output,

[0064] By inputting the PWM signal to the electromagnetic valve of the electro-hydraulic execution system, the control electrical signal is converted into a pressure signal through the hydraulic execution circuit, the oil filling pressure of the lock-up clutch is adjusted, and the working condition control of the closed lock-up hydraulic torque converter of the loader is realized.

[0065] Compared with the prior art, the beneficial effects of the present application are:

[0066] (1) In view of the fact that the current closed lock-up hydraulic torque converter of the loader has only two working conditions of "hydraulic-mechanical", the present application adds a slip condition to the closed lock-up hydraulic torque converter of the loader, and proposes a three-working-condition control region decision method, a slip condition control method and a control strategy of the three-working-condition slip control system of the closed lock-up hydraulic torque converter of the loader.

[0067] (2) In view of the problem that the control region boundaries of the hydraulic, slip and mechanical three working conditions of the hydraulic torque converter are not clear, a five-parameter control region fuzzy comprehensive decision method of the hydraulic torque converter is proposed by comprehensively considering the engine speed, the accelerator pedal opening degree, the speed ratio, the gear position and the vehicle speed, an intelligent black box model from the five parameters of the loader to the output of the required working condition of the hydraulic torque converter is established, and dynamic decision of the required working condition of the closed lock-up hydraulic torque converter is realized.

[0068] (3) In view of the problem that the lock-up clutch of the hydraulic torque converter has large engagement impact and the slip control of the loader requires high requirements, a fuzzy reasoning neural network slip control method is proposed, and compared with the neural network control method, it is found that the maximum value of the lock-up clutch engagement impact of the hydraulic torque converter can be reduced by 79.95% through the fuzzy reasoning neural network control method.

[0069] (4) Using fuzzy comprehensive evaluation method, using engine speed, throttle pedal opening, speed ratio, gear and vehicle speed five parameters to decide the working condition of the closed hydraulic torque converter of the loader; using fuzzy reasoning method, controlling target quantity through actual slip speed and throttle pedal opening fuzzy reasoning, to reduce the impact degree in slip working condition, combining BP neural network PID to realize slip control; the conversion principle of "hydraulic-slip-mechanical" three working conditions is researched, combining the above working condition fuzzy comprehensive decision method and fuzzy reasoning neural network slip control method, the control strategy of the control system is established.

[0070] (5) Through the control system of the application, the slip control system of the closed hydraulic torque converter of the loader can ensure fuel economy while improving the riding comfort of the whole machine, providing a theoretical basis for the automatic control of the three working conditions of the hydraulic torque converter, and providing technical support for solving the contradiction between fuel economy and riding comfort of the loader. BRIEF DESCRIPTION OF DRAWINGS

[0071] Figure 1 is the hierarchical architecture schematic diagram of the closed hydraulic torque converter control system of the application;

[0072] Figure 2 is the schematic diagram of the control strategy of the closed hydraulic torque converter control system of the application;

[0073] Figure 3 is the schematic diagram of the control region decision and conversion sub-strategy of the closed hydraulic torque converter control system of the application;

[0074] Figure 4 is the schematic diagram of the factor set weight in the control region decision of the closed hydraulic torque converter control system of the application;

[0075] Figure 5 is the hydraulic torque converter efficiency curve diagram of the closed hydraulic torque converter control system of the application;

[0076] Figure 6 is the conversion principle diagram of the three working conditions in the closed hydraulic torque converter control system of the application;

[0077] Figure 7 is the schematic diagram of the slip control sub-strategy of the closed hydraulic torque converter control system of the application;

[0078] Figure 8 is the schematic diagram of the fuzzy reasoning neural network slip control method of the closed hydraulic torque converter control system of the application;

[0079] Figure 9 is the schematic diagram of the fuzzy reasoning system of the target slip speed of the closed hydraulic torque converter control system of the application;

[0080] Figure 10This is the membership diagram of the throttle pedal opening in the lock-up hydraulic torque converter control system of the present invention.

[0081] Figure 11 This is the membership diagram of the actual slip speed of the lock-up hydraulic torque converter control system of the present invention;

[0082] Figure 12 This is the target slip speed membership diagram of the lock-up hydraulic torque converter control system of the present invention;

[0083] Figure 13 This is a fuzzy inference diagram of the target slip speed of the lock-up hydraulic torque converter control system of the present invention;

[0084] Figure 14 This is a schematic diagram of the electro-hydraulic actuation sub-strategy of the lock-up hydraulic torque converter control system of the present invention. Detailed Implementation

[0085] The present invention will be further explained and described below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0086] Combined with appendix Figure 1 The present invention provides a control system for a lock-up hydraulic torque converter in a loader. The control system includes a data perception layer, an analysis and decision-making layer, and a system execution layer. The data perception layer acquires operational data of the loader under different working conditions and transmits the data to the analysis and decision-making layer. The data perception layer primarily relies on various sensors in the loader, including engine speed sensors, throttle pedal opening sensors, gear position sensors, and vehicle speed sensors, to acquire objective data of the loader under various working conditions and subjective operational data of the driver. The analysis and decision-making layer includes a control strategy module and a control area decision-making module for the hydraulic torque converter. Based on the received loader operational data and the control strategy of the hydraulic torque converter, it determines the required operating conditions of the hydraulic torque converter through the decision results of the control area decision-making, and sends the required operating condition control commands to the system execution layer. It also utilizes a slip control algorithm to implement the slip condition of the hydraulic torque converter. The system execution layer includes an electro-hydraulic execution system that receives the control commands sent by the analysis and decision-making layer and controls the action of the lock-up clutch in the hydraulic torque converter.

[0087] According to an embodiment of the present invention, the operating data, i.e., objective data, includes engine speed, vehicle speed, and speed ratio, as well as the operating data generated by the driver's subjective operation of the loader, including accelerator pedal opening and gear position.

[0088] According to an embodiment of the present invention, in conjunction with the appendixFigure 2 The schematic diagram of the control strategy of the hydraulic torque converter is shown in the figure, which calls control area decision and conversion sub-strategy, slip control sub-strategy and electro-hydraulic execution sub-strategy to meet the needs of the closed hydraulic torque converter slip control system and cope with complex loader working conditions. The specific steps are as follows:

[0089] Firstly, define Flag=1, Flag=2 and Flag=3 to represent the control instructions of the hydraulic, slip and mechanical working conditions of the hydraulic torque converter respectively, and the specific meanings are shown in Table 1.

[0090] Table 1 meanings of working condition control instructions of the closed hydraulic torque converter

[0091]

[0092] Then, the pre-check before starting the control is carried out to analyze whether the engine warm-up signal, sensor fault signal, oil temperature and gear shift signal meet the starting conditions of the engine. If the starting conditions are not met, the working condition control instruction Flag=1 is directly output to the electro-hydraulic execution sub-strategy of the electro-hydraulic execution system, so that the master and driven discs of the lock-up clutch of the hydraulic torque converter are kept in a completely separated state, or the lock-up clutch is forced to separate from the sliding friction state or the completely engaged state, so that the hydraulic torque converter enters the hydraulic working condition.

[0093] If the starting conditions are met, the control area decision and conversion sub-strategy established based on the fuzzy comprehensive decision of the control area is used to output the working condition of the hydraulic torque converter required after the control strategy correction according to the decision result of the module.

[0094] When the output working condition control instruction is Flag=2, it indicates that the decision result is the slip working condition, and at this time, the slip control sub-strategy module needs to be activated to perform fuzzy reasoning neural network slip control on the lock-up clutch of the hydraulic torque converter.

[0095] If the decision result is the hydraulic or mechanical working condition, the slip control sub-strategy is skipped, and the electro-hydraulic execution sub-strategy module is directly entered to realize the hydraulic and closed control.

[0096] The hydraulic, slip and mechanical working conditions of the hydraulic torque converter are finally passed through the electro-hydraulic execution sub-strategy module, and the corresponding oil filling pressure is applied to the lock-up clutch through electro-hydraulic signal conversion to realize the working condition control of the closed hydraulic torque converter.

[0097] According to the embodiments of the present application, combined with the accompanying Figure 3The diagram shown illustrates the control region decision-making and switching sub-strategy of the lock-up hydraulic torque converter control system of the present invention. The function of the control region decision-making and switching sub-strategy module is to determine the required operating conditions of the hydraulic torque converter, control the transitions between the three operating conditions of "hydraulic-slip-mechanical," and further correct the control signal after fuzzy comprehensive decision-making to avoid problems such as frequent operating condition switching and excessively long slip time, which contradict the established three-operating-condition strategy. The control region decision-making and switching sub-strategy module takes engine speed, throttle pedal opening, speed ratio, gear position, and vehicle speed signals as inputs. It uses the control region fuzzy comprehensive decision-making algorithm of the control region decision-making module to obtain the required operating condition S(t) at the current moment. Combined with the required operating condition S(tT) at the previous sampling moment and parameters such as slip friction work, it performs logical judgments on the transitions between the three operating conditions and outputs the corrected operating condition control command for the hydraulic torque converter to determine the operating condition of the hydraulic torque converter at the current moment.

[0098] According to an embodiment of the present invention, the specific steps of the decision-making method of the control area decision module include:

[0099] (1) Determine the set of decision factors and evaluation set for the control area

[0100] Establishment of the factor set:

[0101] Let the set of factors be U, then U = {engine speed u1, accelerator pedal opening u2, speed ratio u3, gear position u4, vehicle speed u5}.

[0102] Establishment of the evaluation set:

[0103] The evaluation set is defined as V, and the three operating conditions of the lock-up hydraulic torque converter are all taken as evaluation subsets v. j ,but,

[0104] V = {hydraulic v1, slip v2, mechanical v3};

[0105] like Figure 4 The schematic diagram of the decision hierarchy model of the control area of ​​the lock-up hydraulic torque converter shows the influence of five factors on the operating conditions of the lock-up hydraulic torque converter: engine speed u1, throttle pedal opening u2, speed ratio u3, gear position u4, and vehicle speed u5.

[0106] (2) Establish a fuzzy consistency judgment matrix

[0107] By evaluating the dominant influence of the evaluated object on each factor, and comparing the pairwise influence of each factor on the evaluated object, a judgment matrix A is constructed. i , is represented as:

[0108]

[0109] In the formula, r mnThe relative importance of the mth factor in the factor set U relative to the nth factor, with the relative importance measured by a scale of 1-9

[30] As shown in the analytic hierarchy process scale of Table 2.

[0110] Table 2 Analytic hierarchy process scale

[0111]

[0112] Consistency check of the judgment matrix:

[0113] The construction of the judgment matrix sometimes has abnormal conditions such as "A is more important than B, B is more important than C, and C is more important than A", so the consistency of the n-order judgment matrix needs to be checked:

[0114]

[0115] In the formula: n is the number of rows or columns of the judgment matrix; λ max is the maximum eigenvalue of the judgment matrix.

[0116] The value of RI is determined by the average random consistency index of the 1-9 order matrix in Table 3:

[0117] Table 3 Average random consistency index of 1-9 order matrix

[0118]

[0119] Calculate the random consistency ratio CR of the judgment matrix:

[0120]

[0121] In the formula, RI is the random consistency index, and when CR<0.1, it means that the weight coefficient set by the judgment matrix is reasonable.

[0122] The consistency of the judgment matrix is verified by specific examples as follows.

[0123] According to the definition of the relative importance judgment scale of the analytic hierarchy process, the influence degree of engine speed, throttle opening degree, speed ratio, gear position, and vehicle speed on the working condition decision of the hydraulic torque converter is compared by studying the relative importance, and the judgment matrix A1 of the starting, braking, and uniform speed stages is established by taking the loader V-type operation cycle as a specific example, which is expressed as:

[0124]

[0125] The maximum eigenvalue of A1 Consistency check:

[0126]

[0127] Since the loader as a construction machinery, different from the road vehicle, its working condition also exists the shovel stage, under the shovel stage, the load changes dramatically, often accompanied by the driver large throttle opening, high engine speed, large torque, and low speed, at this time the influence degree of each parameter on the working condition state decision of the torque converter changes, and the judgment matrix A2 of this stage needs to be separately formulated, which is represented as:

[0128]

[0129] Similarly, the maximum eigenvalue of the matrix A2 can be obtained CR=0.038<0.1, which meets the consistency.

[0130] (3) Establish the factor set weight vector

[0131] The weight vector A of the influence factor is obtained by normalizing the characteristic vector corresponding to the maximum eigenvalue of the judgment matrix. i ,

[0132]

[0133] The characteristic vector and weight vector of the judgment matrix A1 and the judgment matrix A2 are obtained from the specific examples.

[0134] The characteristic vector W1 of the matrix A1 T =(0.8176, 0.0699, 0.1528, 0.2679, 0.4811), and the weight vector of A1 is obtained by normalizing processing:

[0135]

[0136] The characteristic vector of the matrix A2 The weight vector of A2 is obtained by normalizing processing:

[0137]

[0138] (4) Fuzzy comprehensive algorithm of control region

[0139] Firstly, the fuzzy relationship matrix of the control region is established,

[0140] The fuzzy relationship matrix reflects a fuzzy relationship between the factor set U and the evaluation set V. The key to establishing the fuzzy relationship matrix is to determine the membership degree of each factor with respect to the evaluation set. If any element x in the domain U has a number A(x) in (0, 1), then A(x) is called the membership degree of x to A, and A is a fuzzy set of the domain U. A(x) represents the degree of x belonging to A, and its characteristic is that the evaluation result is represented by a fuzzy set, not an absolute affirmation or negation. The present application determines the membership degree of each factor by using the fuzzy statistical method.

[0141] The following is the establishment of the five parameters of the membership degree of the factors of the present application

[0142] 1) Engine speed u1

[0143] The establishment of the control region should take into account the engine speed and its torque fluctuation. When the vehicle is running at low speed, there is a large speed difference between the driving and driven discs of the lockup clutch of the torque converter, and if the lockup clutch is engaged at this time, it will cause the engine speed to drop, resulting in engine stall and torque fluctuation.

[0144] When the slip control region is established, the following principles should be followed between the engine speeds:

[0145] 1.1) When the engine is at low speed, the torque converter should be in the hydrodynamic working condition to isolate the engine torque fluctuation at low speed.

[0146] 1.2) When the engine is at medium-high speed, the working condition of the torque converter is related to the torque fluctuation of the engine. When the torque fluctuation of the engine is small, the torque converter tends to be in the mechanical working condition to improve the efficiency of the transmission system. When the torque fluctuation is not obvious, the torque converter can be in the slip working condition.

[0147] Considering that when the engine is at high speed, it is the working condition of the loader that requires large traction power

[32] Therefore, when the engine is at high speed, the lockup clutch tends to be fully engaged to transmit large traction power. Conversely, when the engine is at low speed, the torque converter is in the hydrodynamic working condition, and the lockup clutch is separated at this time to reduce power loss.

[0148] Therefore, according to the torsional vibration characteristic curve of the diesel engine under the action of different orders of excitation, when the engine speed is lower than 1100 r / min, the engine speed is near the idle speed, and slip control in this area is easy to cause engine stall, so slip control should not be performed in this area, and the state of the torque converter should tend to be in the hydrodynamic working condition; when the engine speed is greater than 1400 r / min, the torsional vibration of the engine begins to rise, producing a resonance peak, so this area tends to be in the lockup control to improve the efficiency of the transmission system; when the engine speed is between 1100 r / min and 1400 r / min, the degree of change of the torsional vibration is small, and it is considered that this area tends to be in the slip control. The engine speed membership degree established based on the above analysis is shown in Table 4.

[0149] Table 4 Engine speed membership degree

[0150]

[0151] 2) Throttle pedal opening degree u2

[0152] From the economy of the vehicle equipped with the closed torque converter, the smaller the throttle pedal opening, the smaller the vibration and impact of the clutch when engaged, and the lower the impact of the clutch. When the throttle pedal opening is large, the clutch should be in the unlocked state in order to obtain a larger torque.

[0153] When the slip area is set, the throttle pedal opening should follow the principle that:

[0154] 2.1) The lower the throttle pedal opening, the more the torque converter tends to be in the slip or mechanical working condition.

[0155] 2.2) The larger the throttle pedal opening, the more the torque converter tends to be in the hydraulic working condition.

[0156] Although the closed lock can improve the efficiency, it will cause the impact of the transmission system when the throttle pedal opening is small, so the throttle pedal opening threshold value needs to be set, and only when it exceeds the threshold value, the slip or closed lock is allowed, and the present application sets it to 30%.

[0157] Based on the above analysis, the throttle pedal opening membership degree is shown in Table 5 according to the V-shaped operation cycle throttle opening curve of the loader researched by the present application.

[0158] Table 5 Throttle pedal opening membership degree

[0159]

[0160]

[0161] 3) Speed ratio u3

[0162] In order to improve the efficiency of the transmission system, a locking clutch is added in the torque converter. From the economy of the vehicle equipped with the closed torque converter, since the efficiency in the hydraulic working condition is always less than 1, the lower the slip and closed lock point of the locking clutch, the higher the efficiency of the transmission system, and the better the fuel economy. The efficiency curve of the closed torque converter of the loader researched by the present application is shown in Figure 5 The starting speed ratio i0 of the high efficiency interval is i0=0.47. i1 is the highest efficiency point of the torque converter, and the speed ratio of the highest efficiency closed lock point is i1=0.69. i2 is the coupling point of the torque converter, and the speed ratio of the coupling point is i2=0.88.

[0163] When the slip area is set, the speed ratio follows the principle that:

[0164] 3.1) The starting point i0 of the high efficiency interval is used as the closed lock point, which can improve the fuel economy.

[0165] 3.2) The highest efficiency point i1 is closed, which can expand the high efficiency range and prevent the efficiency from falling before the coupling point.

[0166] 3.3) With the coupling point i2 as the lock-up point, the torque jump can be reduced, and the self-adaptability of the torque converter can be utilized.

[0167] Before reaching the high efficiency region, the speed ratio is relatively small, and according to the original characteristic curve of the torque converter, the torque multiplication coefficient K is large, indicating that the vehicle is in a high load state. Under this working condition, the lock-up clutch should be unlocked to fully utilize the torque increasing effect of the torque converter. In the high efficiency region, the torque multiplication coefficient of the torque converter begins to decrease gradually, indicating that the torque demand of the vehicle is decreasing. At this time, the slip control is performed in the first half of the high efficiency region i0-i1 to achieve vibration reduction and torque increase while further improving the efficiency of the torque converter. From the end of the high efficiency region to the coupling point i1-i2 of the torque converter, the torque demand of the vehicle further decreases, and the working condition should be shifted from slip to mechanical as soon as possible. In the last region i2-1, the speed ratio exceeds the coupling point, and the transmission efficiency of the torque converter is independent of the action of the clutch, and the mechanical working condition is maintained. The speed ratio membership degree established based on the above analysis is shown in Table 6.

[0168] Table 6 Speed ratio membership degree

[0169]

[0170] 4) Gear position

[0171] Generally speaking, the lower the gear position, the better the power performance of the vehicle, and the greater the vibration and impact of the transmission system. The higher the gear position, the worse the power performance of the vehicle, and the smaller the vibration and impact of the transmission system. Therefore, in order to achieve good vehicle power performance and minimize vibration and impact, the determination of the required working condition of the lock-up torque converter is also related to the gear position.

[0172] When the slip control region is determined, the gear position should follow the following principles:

[0173] 4.1) The higher the gear position, the easier it is for the torque converter to be in the slip or mechanical working condition.

[0174] 4.2) The lower the gear position, the easier it is for the torque converter to be in the hydraulic working condition.

[0175] 4.3) When shifting, the torque converter must be in the hydraulic working condition.

[0176] Forward one and two gears are usually the traction gears of the loader, and three and four gears are the traveling gears. In the traction working condition, the periodic variable load will impact the transmission system. In order to improve the output torque of the loader in this working condition and enhance the adaptability of the transmission system to the periodic variable load impact, when the loader is in one or two gears, the hydraulic torque converter should tend to be in the hydraulic working condition in order to obtain greater torque for starting, climbing and working. When the loader is in three or four gears, the external load changes little in the traveling process, and in order to make the vehicle obtain higher speed and greater power utilization rate, the hydraulic torque converter should tend to be in the mechanical working condition at this time to improve the transmission efficiency. The gear membership degree established based on the above analysis is shown in Table 7.

[0177] Table 7 Gear membership degree

[0178]

[0179] 5) Vehicle speed

[0180] From the fuel economy of the loader equipped with the lock-up hydraulic torque converter, since the efficiency in the hydraulic working condition is always less than 1, the lower the slip of the lock-up clutch and the lock-up vehicle speed, the higher the efficiency of the transmission system and the better the fuel economy of the whole machine.

[0181] When the slip area is determined, the principles that the vehicle speed should follow are:

[0182] 5.1) The higher the vehicle speed, the easier the hydraulic torque converter is in the slip or mechanical working condition.

[0183] 5.2) The lower the vehicle speed, the easier the hydraulic torque converter is in the hydraulic working condition.

[0184] Considering that the loader is in the low-speed working condition for a relatively longer time, and its vehicle speed in the typical V-shaped working cycle is generally lower than 12 km / h, therefore, when the detected vehicle speed is lower than this speed, the hydraulic torque converter should tend to be in the hydraulic working condition to meet the traction demand. When the vehicle speed is higher than 12 km / h, the loader is generally in the non-working high-speed traveling working condition, and the traction demand is small, at this time, the lock-up clutch should be locked as soon as possible to improve the fuel economy of the whole machine. The vehicle speed membership degree established based on the above analysis is shown in Table 8.

[0185] Table 8 Vehicle speed membership degree

[0186]

[0187] Then, the establishment of the fuzzy relationship matrix of the control area is followed. The fuzzy relationship matrix reflects a fuzzy relationship between the factor set U and the evaluation set V. When the i-th factor u i in the factor set is evaluated, its membership degree to the j-th element v j in the relative evaluation set V is r ij , and the membership degrees of various factors ui Convert to membership vector R i , represented as:

[0188] R i =(r i1 ,r i2 ,Lr ij )

[0189] Establish a fuzzy relation matrix R, represented as follows:

[0190]

[0191] Secondly, fuzzy comprehensive evaluation is based on the fuzzy relation matrix R, and considers the weights A of each factor. i To reflect the combined effect of all factors, it is represented as B:

[0192]

[0193] Where o is the comprehensive evaluation operator,

[0194] This invention adopts the maximum membership principle, considering the contribution of the largest index, to determine the demand condition decision result S(t) of the lock-up hydraulic torque converter at the current moment:

[0195] S(t) = v j (t)=maxb j (t)

[0196] If S(t) = v2(t), the decision result of the loader's lock-up hydraulic torque converter for the required operating condition is slip condition, and slip control is performed in this region.

[0197] If S(t) = v1(t), the decision result of the loader's lock-up hydraulic torque converter for the required operating condition is the hydraulic operating condition, and unlocking control is performed in this region.

[0198] If S(t) = v3(t), the decision result of the loader's lock-up hydraulic torque converter for the required operating condition is the mechanical operating condition, and lock-up control is performed in this region.

[0199] According to embodiments of the present invention, as shown in the appendix Figure 6 The diagram shown illustrates the switching principle of the three operating conditions in the lock-up hydraulic torque converter control system of the present invention.

[0200] The three-condition switching of the lock-up hydraulic torque converter studied in this invention is based on the output of the fuzzy comprehensive decision algorithm of the control region studied. It combines the current demand condition S(t) of the hydraulic torque converter with T as the signal sampling interval and combines the demand condition S(tT) of the previous sampling time. The switching of the condition is realized through logical judgment.

[0201] (1) The time limit of slip working condition. If the time of lock-up clutch slip is too long, the heat generated by the clutch will be too much, which will cause the performance of the clutch to decline. Therefore, the time of slip working condition needs to be controlled to avoid the lock-up clutch working in slip condition for a long time.

[0202] (2) Avoid frequent switching of hydraulic torque converter working condition. The switching between hydraulic, slip and mechanical working conditions needs to establish certain conditions. There should be a certain interval between the hydraulic and mechanical working conditions. The slip work is used as an additional judgment parameter between the hydraulic and slip working conditions, and the mechanical to slip working condition jump is prohibited, etc. to avoid frequent switching of working condition in unstable working condition, which affects the fuel economy and ride comfort of the vehicle.

[0203] Based on the established three working condition strategy, it is set that the lock-up clutch must pass through the slip working condition from the hydraulic working condition to the mechanical working condition, so as to reduce the impact degree when the lock-up clutch is engaged, and fully play the advantages of slip control, such as buffering and damping reduction and high efficiency. The mechanical working condition is directly converted into the hydraulic working condition instead of the decision result from mechanical to slip working condition, so as to improve the unlocking efficiency. In the slip working condition, in order to prolong the service life of the lock-up clutch, the allowable slip work [W] is used as a judgment signal. If the slip work W of the clutch slip control stage exceeds this limit value, the hydraulic torque converter exits the slip working condition and immediately converts to the hydraulic working condition, and the start is prohibited again before the oil temperature of the clutch reaches the normal range.

[0204] And when the slip work W is less than the allowable slip work [W], the slip working condition is converted to the mechanical working condition.

[0205] According to the embodiment of the present application, as shown in the schematic diagram of the slip control sub-strategy of the lock-up hydraulic torque converter control system of the present application Figure 7 and as shown in the schematic diagram of the fuzzy reasoning neural network slip control method of the lock-up hydraulic torque converter control system of the present application Figure 8 , after receiving the slip working condition control instruction is activated, the actual slip speed and the throttle pedal opening value of the hydraulic torque converter at the current time are read in and input to the fuzzy reasoning system of the target slip speed studied by the present application, and the expected target slip speed is output as the target quantity of the BP neural network controller. The deviation value e after the output value is operated with the actual slip speed is input to the BP neural network controller together. The follow-up of the expected value of the slip speed is carried out to realize the slip control of the lock-up hydraulic torque converter of the loader.

[0206] According to the embodiment of the present application, the actual slip speed can reflect the working condition of the lock-up clutch of the hydraulic torque converter in the transmission system of the loader. The throttle pedal opening can represent the driving intention of the driver and reflect the change of the actual slip speed. Therefore, the actual slip speed ω r and the throttle pedal opening α are used as input quantities, and the fuzzy reasoning system of the target slip speed is established as shown in Figure 9 .

[0207] According to the embodiment of the present application, the established target slip speed fuzzy reasoning method step includes: (1) fuzzification of input and output language values, (2) establishment of membership functions.

[0208] (1) Fuzzification of input and output language values

[0209] Actual slip speed ω r The basic domain is [0, 850], if outside the range, 0 or 850 is selected. The discrete range is [0, 5], the quantization factor k r = 5 / 850 = 0.0059. The discrete range is divided into 5 fuzzy languages: {very small (VS), small (S), moderate (M), large (B), very large (VB)}.

[0210] The basic domain of the accelerator pedal opening α is [0, 1], the discrete range is [0, 1], and the quantization factor k α = 1. The discrete range is divided into 5 fuzzy languages: {very small (VS), small (S), moderate (M), large (B), very large (VB)}.

[0211] The basic range of the target slip speed ω a is [20, 100], if outside the range, the adjacent maximum value 20 or 100 is used. The discrete range is [0, 8], and the proportion factor k a = 80 / 8 = 10. The discrete range is divided into 9 fuzzy languages: {very small (VS), small (NS), slightly small (PS), slightly small (S), moderate (M), slightly large (B), larger (PB), large (NB), very large (VB)}.

[0212] (2) Establishment of membership functions

[0213] The membership function is a mapping between fuzzy language values and fuzzy subsets, mainly including trapezoidal, triangular and Gaussian types. Different membership functions have different effects on the performance of the system. The flatter the membership curve, the better the stability of the system, and the steeper the membership curve, the higher the sensitivity of the system. Considering comprehensively, the membership functions of input and output quantities are selected as Gaussian type, such as Figure 10 is the accelerator pedal opening membership graph, Figure 11 is the actual slip speed membership graph, Figure 12 is the target slip speed membership graph.

[0214] The target slip speed fuzzy reasoning rule is:

[0215] The fuzzy inference is a rule-based inference, and the establishment of the fuzzy inference rule needs to consider the change of the input variable itself and the influence of the impact degree and the slip work. According to the theoretical research on the influence factors of the target slip speed decision, the fuzzy inference rule of the target slip speed decision is established as follows:

[0216] 1) In the initial engagement stage, if the actual slip speed is large, a larger target slip speed should be output to reduce the impact degree when the target slip speed is small, so as to reduce the slip speed change rate. When the actual slip speed is small, the slip speed change rate is also small, and a large impact will not be caused. When the actual slip speed is 0, even if the clutch is engaged at the fastest speed, no impact will be caused. If the accelerator pedal opening degree is small, the target slip speed can be appropriately reduced to reduce the slip work. If the accelerator pedal opening degree is large, the target slip speed should be further increased.

[0217] 2) In the late engagement stage, the change rate of the actual slip speed is small, the impact degree is small, and a smaller target slip speed should be output to reduce the slip work. When the accelerator pedal opening degree is large, the engine speed is increased, the driving disc speed of the lock-up clutch is increased, and the actual slip speed is increased. If the target slip speed is not changed at this time, a large impact degree will be caused, and the target slip speed should be increased at this time. When the accelerator pedal opening degree is small, the actual slip speed is reduced, and the target slip speed should be reduced to further reduce the slip work and improve the transmission system efficiency.

[0218] The lock-up clutch outputs the corresponding target slip speed according to the actual slip speed and the accelerator pedal opening degree in each working condition. In the inference, 25 kinds of input conditions are formed according to the fuzzy language of the input quantities of the fuzzy inference device, the actual slip speed and the accelerator pedal opening degree. According to the research on the above fuzzy inference rules, the fuzzy inference rule of the target slip speed is shown in Table 9, and the fuzzy inference diagram is shown in Figure 13 .

[0219] Table 9 Fuzzy inference rule table of target slip speed

[0220]

[0221]

[0222] According to the embodiment of the present application, the neural network in the present application is a BP neural network PID controller.

[0223] According to the embodiment of the present application, as Figure 14The figure shows the electro-hydraulic execution sub-strategy of the closed hydraulic torque converter control system of the application. The electro-hydraulic execution sub-strategy receives the working condition control instruction of the hydraulic torque converter from the control area decision and conversion sub-strategy module, and outputs the duty cycle signal in the form of corresponding PWM wave. In the Flag=2 slip working condition, the torque control signal from the slip control sub-strategy is input, the slip friction torque formula when the lock-up clutch is in the slip friction state and the functional relationship between the engagement pressure of the electro-hydraulic execution system and the duty cycle are combined, and the duty cycle signal in the slip working condition is calculated through mathematical conversion; in the Flag=1 hydraulic working condition, PWM=0 is output; in the Flag=3 mechanical working condition, PWM=1 is output. By inputting the PWM signal to the electromagnetic valve of the electro-hydraulic execution system, the control electrical signal is converted into a pressure signal through the hydraulic execution circuit, the oil filling pressure of the lock-up clutch is adjusted, and the working condition control of the closed hydraulic torque converter of the loader is realized.

[0224] The maximum supply oil pressure of the electro-hydraulic execution system is 0.7MPa. Through fitting of the simulation data of the system, the relationship between the duty cycle of the electromagnetic valve and the oil filling pressure of the lock-up clutch of the hydraulic torque converter is obtained, that is, when the duty cycle=0, the oil filling pressure of the lock-up clutch is 0, and the hydraulic torque converter is unlocked; when the duty cycle is 100%, the oil filling pressure of the lock-up clutch is 0.7MPa, and the hydraulic torque converter is locked, when the duty cycle is 0-100%, the oil filling pressure of the lock-up clutch is between 0-0.70.7MPa, at this time, the hydraulic torque converter is in the slip working condition, and the oil pressure of the lock-up clutch is changed by controlling the input duty cycle of the electromagnetic valve of the hydraulic execution system, so as to track the target slip speed and realize the control of the slip speed of the hydraulic torque converter.

[0225] The application uses the fuzzy comprehensive evaluation method to use five parameters of engine speed, throttle pedal opening, speed ratio, gear and vehicle speed to decide the working condition of the closed hydraulic torque converter of the loader; the fuzzy reasoning method is used to control the target amount through actual slip speed and throttle pedal opening fuzzy reasoning, so as to reduce the impact degree in the slip working condition, and the BP neural network PID is combined to realize the slip control; the conversion principle of the "hydraulic-slip-mechanical" three working conditions is studied, the control strategy of the control system is established by combining the above working condition fuzzy comprehensive decision method and the fuzzy reasoning neural network slip control method. The slip control system of the closed hydraulic torque converter of the loader improves the riding comfort while ensuring the fuel economy, provides a theoretical basis for the automatic control of the three working conditions of the hydraulic torque converter, and provides technical support for solving the contradiction between the fuel economy and the riding comfort of the loader.

[0226] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A control system for a closed center hydraulic torque converter of a loader, characterized by, The control system includes: a data perception layer, an analysis and decision-making layer, and a system execution layer. The data perception layer is used to acquire the loader's operating and control data under different working conditions and transmit the data to the analysis and decision-making layer. The analysis and decision-making layer, including the control strategy module and control area decision-making module of the hydraulic torque converter, combines the received loader operation data and, based on the control strategy of the hydraulic torque converter, determines the required operating conditions of the hydraulic torque converter through the decision results of the control area decision, and then sends the required operating condition control commands to the system execution layer. The system execution layer, including the electro-hydraulic actuator, receives control commands from the analysis and decision-making layer and controls the action of the lock-up clutch in the hydraulic torque converter through the electro-hydraulic actuator. The specific steps of the control strategy for the hydraulic torque converter are as follows: First, we define Flag=1, Flag=2, and Flag=3 to represent the control commands for the hydraulic, slip, and mechanical operating conditions of the hydraulic torque converter, respectively. Next, a pre-check is performed before control is activated to analyze whether the engine warm-up signal, sensor fault signal, oil temperature and shift signal meet the engine starting conditions. If the starting conditions are not met, the operating condition control command Flag=1 is directly output to the electro-hydraulic actuator to unlock the drive lock-up clutch and allow the hydraulic torque converter to enter hydraulic operating condition. If the startup conditions are met, the system enters the control area decision module and the conversion sub-strategy module. Based on the decision results of the two modules, it outputs the corrected operating condition of the hydraulic torque converter at the current moment and outputs the corresponding operating condition control commands. When the output operating condition control command is Flag=2, it indicates that the decision result is slip condition. At this time, the slip control sub-strategy module needs to be activated to perform fuzzy inference neural network slip control on the hydraulic torque converter lock-up clutch. The specific steps of the decision-making method in the control area decision module include: (1) Determine the set of decision factors and evaluation set for the control area Establishment of the factor set: Let the set of setting factors be U, then, U = {engine speed u 1 , accelerator pedal opening u 2 , speed ratio u 3 , gear position u 4 , vehicle speed u 5} Establishment of the evaluation set: The evaluation set is set as V, and three working conditions of the closed hydraulic torque converter are regarded as evaluation subsets v j Then, ； (2) Establish the judgment matrix of fuzzy consistency By evaluating the object of the dominant role of each factor, the impact of each factor between the two, thus forming a judgment matrix A i , expressed as: In the formula, denotes the importance of the mth factor in the factor set U relative to the nth factor. The construction of the judgment matrix can sometimes result in anomalies such as "A is more important than B, B is more important than C, and C is more important than A". Therefore, it is necessary to perform a consistency check on the n-order judgment matrix. In the formula, n is the number of rows or columns of the judgment matrix; is the maximum eigenvalue of the judgment matrix, Calculate the random consistency ratio CR of the judgment matrix: In the formula, RI is a random consistency index, when CR <0.1, it indicates that the weight coefficient set by the judgment matrix is reasonable. (3) Establish factor weight vector Normalizing the eigenvector corresponding to the maximum eigenvalue of the judgment matrix to obtain a weight vector of the influence factor A i , ， (4) Fuzzy synthesis algorithm for the control region First, establish the fuzzy relation matrix of the control region. The fuzzy relation matrix reflects the factor set. U and evaluation set V A fuzzy relationship exists between them. The key to establishing the fuzzy relationship matrix is ​​determining the membership degree of each factor relative to the evaluation set. If the universe of discourse... U any element x There is a number A If (x)∈(0,1), then it is called A (x) represents x pairs A membership degree A It is the domain U fuzzy sets, using A (x) indicates that x belongs to A The degree of The membership degree of the first element in the relative evaluation set R is i u i The membership degree of the first element in the relative evaluation set R is V j v j The membership degree of the first element in the relative evaluation set R is r ij The membership degree of the first element in the relative evaluation set R is u i The membership degree of the first element in the relative evaluation set R is i The membership degree of the first element in the relative evaluation set R is​​​ Establish a fuzzy relation matrix R, represented as: Secondly, fuzzy comprehensive evaluation is based on the fuzzy relation matrix R, considering the weight of each factor A i to reflect the comprehensive influence of all factors, expressed as B: Where o is the comprehensive evaluation operator, The maximum membership principle is adopted to determine the decision result of the demand working condition of the closed torque converter at the current time by considering the contribution of the maximum index : If , the decision result of the loader closed torque converter demand working condition is the slip working condition, the area carries on the slip control, If , the decision result of the demand working condition of the closed hydraulic torque converter of the loader is the hydraulic working condition, the unlocking control is performed in this area, If , the decision result of the demand working condition of the closed hydraulic torque converter of the loader is the mechanical working condition, and the closed control is performed in this area.

2. The control system for a lock-up torque converter of a loader as set forth in claim 1, wherein, The data perception layer acquires the loader's operating data under three different working conditions—hydraulic, slip, and mechanical—through engine speed sensors, throttle pedal opening sensors, gear position sensors, and vehicle speed sensors installed in the loader. This includes engine speed and vehicle speed, as well as operating data generated by the driver operating the loader, including throttle pedal opening and gear position.

3. The control system for a lock-up torque converter of a loader as set forth in claim 1, wherein, The system execution layer uses solenoid valves to convert electromagnetic signals and control the output oil filling pressure of the electro-hydraulic execution system to further control the opening and closing of the lock-up clutch friction plates in the hydraulic torque converter. When in hydraulic operation, the electro-hydraulic actuator will drive the lock-up clutch to the unlocked state. When in mechanical working condition, the electro-hydraulic execution system drives the lock-up clutch to be in the locked state, When in slip working condition, the electro-hydraulic execution system carries out slip control, drives the lock-up clutch to be in the slip state, and the driving disc and the driven disc rotate at the target slip speed.

4. The control system for a lock-up torque converter of a loader as set forth in claim 1, wherein, The implementation process of the control method of the fuzzy inference neural network slip control is as follows: When the slip control sub-strategy module is activated by receiving the slip working condition control instruction, the actual slip speed of the hydraulic torque converter and the opening value of the accelerator pedal at the current time are read out and input into the fuzzy inference system of the target slip speed, and the expected target slip speed is output as the target quantity of the BP neural network controller. The deviation value e obtained by operating the expected target slip speed and the actual slip speed is input into the BP neural network controller, the slip speed expectation value is followed, and the slip control of the loader lock-up hydraulic torque converter is realized.

5. The control system for a lock-up torque converter of a loader as set forth in claim 4, wherein, The specific steps of the conversion sub-strategy method of the conversion sub-strategy module are as follows: The output of the fuzzy comprehensive algorithm of the control area of the control area strategy is used as the basis to output the required working condition of the hydraulic torque converter at the current time , and T the signal sampling interval is combined with the required working condition at the previous sampling time and the slip work W of the lock-up clutch in the slip control stage to realize the conversion between different working conditions through logical judgment, It is stipulated that the slip working condition must be passed from the hydraulic working condition to the mechanical working condition, so as to reduce the impact degree when the lock-up clutch is engaged. In the slip working condition, in order to prolong the service life of the lock-up clutch, the allowable slip power [W] is used as a judgment signal. If the slip power W of the lock-up clutch in the slip control stage exceeds the allowable slip power [W], the hydraulic torque converter exits the slip working condition and immediately converts to the hydraulic working condition. Before the oil temperature of the lock-up clutch reaches the normal range, it is prohibited to start again, The working condition control instruction of the hydraulic torque converter after the output conversion sub-strategy is used to determine the working condition of the hydraulic torque converter at the current time.

6. The control system for a lock-up torque converter of a loader as set forth in claim 5, wherein, The electro-hydraulic execution sub-strategy module in the electro-hydraulic execution system receives the working condition control instruction of the hydraulic torque converter at the current time output from the control area decision and conversion sub-strategy module, and outputs the duty cycle signal in the form of a corresponding PWM wave, When the control instruction is the slip working condition of Flag=2, the torque control signal of the slip control sub-strategy is used as the input, the slip torque formula when the lock-up clutch is in the slip state is combined, and the function relationship between the engagement pressure of the electro-hydraulic execution system and the duty cycle is calculated through mathematical conversion to obtain the duty cycle signal in the slip working condition; When the control instruction is the hydraulic working condition of Flag=1, PWM=0 is output, When the control instruction is the mechanical working condition of Flag=3, PWM=1 is output, By inputting the PWM signal into the electromagnetic valve of the electro-hydraulic execution system, the control electric signal is converted into a pressure signal through the hydraulic execution circuit, the oil filling pressure of the lock-up clutch is adjusted, and the working condition control of the loader lock-up hydraulic torque converter is realized.

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