Control method and system for hydrostatic loader

Abstract

Disclosed in the present invention are a control method and system for a hydrostatic loader. The control method comprises: determining a speed drop value of an engine on the basis of a requested rotation speed of the engine and the actual rotation speed of the engine; calculating load power of a traveling apparatus; on the basis of the actual rotation speed of the engine, determining power corresponding to the actual rotation speed of the engine; on the basis of the actual rotation speed of the engine, determining a variable-pump control current corresponding to the actual rotation speed of the engine; comparing the load power of the traveling apparatus with the power corresponding to the actual rotation speed of the engine, comparing a vehicle speed with a vehicle speed limit value, comparing the speed drop value of the engine with a speed drop limit value, comparing the actual torque load rate of the engine with a torque load rate limit value, and comparing a load pressure with a load pressure limit value, so as to obtain comparison results; on the basis of the comparison results, determining a variable-pump pre-reduced current and a current change rate; and on the basis of the variable-pump control current corresponding to the actual rotation speed of the engine, the variable-pump pre-reduced current and the current change rate, controlling the variable-pump control current.

Description

Hydrostatic loader control method and system TECHNICAL FIELD

[0001] The present application belongs to the technical field of engineering machinery, and relates to a hydrostatic loader control method and system. BACKGROUND

[0002] The hydrostatic transmission of the loader forms a closed hydraulic circuit by means of a hydraulic variable pump and a hydraulic motor, replaces a traditional torque converter gearbox, realizes travel control functions such as acceleration, deceleration, reversing and gear shifting, and outputs continuous traction, compared with a traditional hydraulic transmission system, can realize continuous stepless speed regulation in a full speed range, large traction at a low engine speed, different traction settings, mechanical lossless braking of the hydraulic anti-drag machine when the accelerator is released during travel, fine control of the vehicle speed and engine speed, quick reversing during travel, and can also integrate constant speed control, constant speed cruise, speed limitation and other electric control functions, and is more efficient and energy-saving in the loading operation mode, and is widely used in small and medium tonnage loaders.

[0003] The prior art has the following problems: the hydrostatic loader completes the operation by cooperation of a travel driving system and a working device, at the moment when the bucket impacts the material, the sudden increase of the load power will cause the engine speed to drop instantaneously, and the excessive drop of the engine speed will easily cause the engine to stall, during the digging operation, on one hand, sufficient traction is required to realize material loading, and on the other hand, the loading operation on the vehicle is required to realize the bucket receiving and the arm lifting, if the travel driving during the digging process occupies a large engine power, the arm lifting of the working device will be difficult, and the problem of cooperation between the travel and the digging operation will be caused.

[0004] SUMMARY

[0005] Object: In view of at least one of the above technical problems, the present application provides a hydrostatic loader control method and system, which solves the problem of engine stall caused by the excessive instantaneous drop of the engine speed.

[0006] Technical solution: To solve the above technical problems, the technical solution adopted by the present application is:

[0007] In a first aspect, a hydrostatic loader control method is provided, the hydrostatic loader comprising a travel device and a working device, the travel device and the working device being driven by an engine, and the control method comprising:

[0008] obtaining an engine request speed, an engine actual speed, an engine actual torque load rate, a load pressure, a variable motor control current, a variable motor speed and a vehicle speed;

[0009] The engine drop speed value is determined according to the engine request speed and the engine actual speed; the variable motor displacement is calculated according to the variable motor control current, the variable motor flow is calculated according to the variable motor displacement and the variable motor speed, and the load power of the walking device is calculated according to the variable motor flow and the load pressure; the engine actual speed corresponding power is determined according to the engine actual speed; the variable pump control current corresponding to the engine actual speed is determined according to the engine actual speed;

[0010] The load power of the walking device is compared with the engine actual speed corresponding power, the vehicle speed is compared with the vehicle speed limit value, the engine drop speed value is compared with the drop speed limit value, the engine actual torque load rate is compared with the torque load rate limit value, and the load pressure is compared with the load pressure limit value to obtain a comparison result;

[0011] According to the comparison result, the variable pump pre-reduction current and the current change rate are determined;

[0012] According to the variable pump control current corresponding to the engine actual speed, the variable pump pre-reduction current and the current change rate, the variable pump control current is controlled.

[0013] In some embodiments, the variable pump control current corresponding to the engine actual speed is determined according to the engine actual speed, comprising:

[0014] The engine actual speed and the variable pump control current have a corresponding relationship, and the variable pump displacement minimum control current to the variable pump displacement maximum control current corresponding to the engine low speed to the engine high speed; if the load mutation causes the engine speed to drop, the corresponding variable pump control current is determined according to the engine actual speed after the drop.

[0015] In some embodiments, according to the comparison result, the variable pump pre-reduction current and the current change rate are determined, comprising:

[0016] (1) If the load power of the walking device is not greater than the engine actual speed corresponding power, and the engine actual torque load rate is not greater than the set torque load rate limit value, and the engine drop speed value is not greater than the set drop speed limit value, the variable pump pre-reduction current is 0, and the current change rate is determined to be the first change rate based on the first corresponding relationship between the vehicle speed and the current reduction change rate;

[0017] (2) if the load power of the traveling device is greater than the power corresponding to the actual engine speed and the vehicle speed is lower than the vehicle speed limit value, determining the variable pump pre-reduction current to be the first current, setting the action time, and if the load pressure is greater than the second load pressure limit value within the set action time, the variable pump pre-reduction current is the first current, and if the load pressure is not greater than the second load pressure limit value within the set action time, the variable pump pre-reduction current is 0 after the set action time, wherein the first current is a constant; determining the current change rate to be the second change rate based on the second correspondence relationship between the vehicle speed and the current reduction change rate, and the second change rate is greater than the first change rate;

[0018] (3) if the engine actual torque load rate is greater than the set torque load rate limit value and the load pressure is greater than the second load pressure limit value, determining the variable pump pre-reduction current to be the second current, wherein the second current has a corresponding relationship with the actual engine speed; determining the current change rate to be the second change rate based on the second correspondence relationship between the vehicle speed and the current reduction change rate, and the second change rate is greater than the first change rate;

[0019] (4) if the engine speed drop value is greater than the set speed drop limit value and the load pressure is greater than the second load pressure limit value, determining the variable pump pre-reduction current to be the third current, wherein the third current has a corresponding relationship with the engine speed drop value; determining the current change rate to be the second change rate based on the second correspondence relationship between the vehicle speed and the current reduction change rate, and the second change rate is greater than the first change rate;

[0020] (5) if the engine actual torque load rate is greater than the set torque load rate limit value, the engine speed drop value is greater than the set speed drop limit value, and the load pressure is greater than the second load pressure limit value, determining the variable pump pre-reduction current to be the greater of the second current and the third current; determining the current change rate to be the second change rate based on the second correspondence relationship between the vehicle speed and the current reduction change rate, and the second change rate is greater than the first change rate;

[0021] (6) if the load power of the traveling device is greater than the power corresponding to the actual engine speed and the vehicle speed is lower than the vehicle speed limit value, and the engine actual torque load rate is greater than the set torque load rate limit value and the load pressure is greater than the second load pressure limit value, determining the variable pump pre-reduction current to be the greater of the first current and the second current; determining the current change rate to be the second change rate based on the second correspondence relationship between the vehicle speed and the current reduction change rate, and the second change rate is greater than the first change rate;

[0022] (7) if the load power of the traveling device is greater than the power corresponding to the actual engine speed and the vehicle speed is lower than the vehicle speed limit value, and the engine speed drop value is greater than the set speed drop limit value and the load pressure is greater than the second load pressure limit value, determining the variable pump pre-reduction current to be the greater of the first current and the third current; determining the current change rate to be the second change rate based on the second correspondence relationship between the vehicle speed and the current reduction change rate, and the second change rate is greater than the first change rate.

[0023] (8) If the load power of the traveling device is greater than the power corresponding to the actual engine speed and the vehicle speed is lower than the vehicle speed limit value, and the engine actual torque load rate is greater than the set torque load rate limit value, and the engine drop speed value is greater than the set drop speed limit value, and the load pressure is greater than the second load pressure limit value, the variable pump pre-reduction current is determined to be the larger value of the first current, the second current and the third current; based on the second corresponding relationship between the vehicle speed and the current reduction rate, the current rate is determined to be the second rate, and the second rate is greater than the first rate.

[0024] In some embodiments, the variable pump control current is controlled according to the variable pump control current corresponding to the actual engine speed, the variable pump pre-reduction current and the current rate, including:

[0025] The variable pump final control current calculation value is determined according to the variable pump control current corresponding to the actual engine speed and the variable pump pre-reduction current;

[0026] The variable pump control current is controlled according to the variable pump final control current calculation value and the current rate.

[0027] In some embodiments, the variable pump control current is controlled in the process, and further includes limit pressure displacement active restriction control, specifically including:

[0028] If the variable pump final control current calculation value is greater than the variable pump limit pressure displacement current value and the load pressure is greater than the third load pressure limit value, the variable pump final control current is limited to the variable pump limit pressure displacement current value;

[0029] Wherein the variable pump limit pressure displacement current value is the variable pump current value corresponding to the load pressure greater than the third load pressure limit value, and the third load pressure limit value is the limit pressure value of the variable pump.

[0030] In some embodiments, the variable pump control current is controlled in the process, and further includes pump current increase rate control, specifically including: when the load pressure decreases to not greater than the second load pressure limit value, the variable pump control current stops reducing the pre-reduction current, and starts increasing according to the actual engine speed to the variable pump control current corresponding to the actual engine speed. In the process of increasing the variable pump control current to the variable pump control current corresponding to the actual engine speed, when the load pressure is between the second load pressure limit value and the first load pressure limit value, the current increase rate is the third rate, and when the load pressure is less than the first load pressure limit value, the current increase rate is the fourth rate, and the third rate is less than the fourth rate.

[0031] In a second aspect, a hydrostatic controller is provided, comprising a memory and a processor, the memory being configured to store instructions for controlling the processor to operate to perform the hydrostatic loader control method according to the first aspect.

[0032] In a third aspect, a hydrostatic loader control system is provided, comprising the hydrostatic controller according to the second aspect.

[0033] In some embodiments, the hydrostatic loader control system further comprises an engine, a variable pump, a variable motor, an engine controller, a pump electric proportional control device and a motor electric proportional control device.

[0034] The input shaft end of the variable pump is connected to the output shaft end of the engine, and two oil ports of the variable pump are connected to two oil ports of the variable motor in a pipeline manner; the variable motor is configured to drive the traveling device to travel.

[0035] The engine controller is configured to obtain an actual engine speed and an actual engine torque load rate, and upload the actual engine speed and the actual engine torque load rate to the hydrostatic controller.

[0036] The pump electric proportional control device is configured to control the displacement of the variable pump according to a pump control current output by the hydrostatic controller.

[0037] The motor electric proportional control device is configured to control the displacement of the variable motor according to a motor control current output by the hydrostatic controller.

[0038] In some embodiments, the hydrostatic loader control system further comprises:

[0039] A load pressure sensor is arranged at the two oil ports of the variable pump, and is configured to detect a load pressure and upload the load pressure to the hydrostatic controller.

[0040] A motor speed sensor is arranged at the output shaft end of the variable motor, and is configured to detect a variable motor speed and upload the variable motor speed to the hydrostatic controller.

[0041] An accelerator pedal, and the hydrostatic controller is configured to determine an engine request speed according to a signal of the accelerator pedal.

[0042] In a fourth aspect, a hydrostatic loader is provided, comprising the hydrostatic controller according to the first aspect or the hydrostatic loader control system according to the second aspect.

[0043] Advantages: The hydrostatic loader control method and system provided by the present application has the following advantages:

[0044] (1) EP electric proportional variable pump control is adopted, the pump displacement control is not affected by the engine speed, the pump displacement change rate is adjustable, the pump displacement change speed requirement in different working conditions is realized, the pump displacement corresponds to the control current, and the control is accurate;

[0045] (2) Realize power control of the shovel process, solve the problem of engine speed drop and flameout caused by static hydraulic loader shovel, ensure the continuity of walking drive and shovel operation process, ensure the power output of shovel operation process without interruption, and adapt to different working conditions under different limited conditions;

[0046] (3) Limit the maximum load pressure and the main displacement to ensure the maximum priority power demand on the truck, solve the problem of arm lifting, realize the rapid action of the truck and the energy-saving control of the truck;

[0047] (4) After limiting the shovel displacement, the bucket is closed, the pressure is reduced, the pump displacement is increased, and the change rate is limited to avoid the impact of closing the bucket. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 is a schematic diagram of a static hydraulic loader control system according to an embodiment of the present application. DETAILED DESCRIPTION

[0049] The present application will be further described below in conjunction with the drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present application, and cannot be used to limit the protection scope of the present application.

[0050] In the description of the present application, the meaning of several is more than one, the meaning of multiple is more than two, greater than, less than, more than, etc. are understood as not including the number, above, below, etc. are understood as including the number. If it is described as first, second, it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the sequence of indicated technical features.

[0051] In the description of the present application, the description of the reference terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the exemplary description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0052] The professional terms in this application are explained as follows:

[0053] DA control: speed automatic control, DA control is used for variable pump, the variable control end pressure is directly related to engine speed, and the pump displacement size corresponds to engine speed.

[0054] EP control: electric proportional control, EP control is adopted for variable pump, feedback rod is arranged between pump variable control cylinder and control proportional valve, displacement is not affected by load, rotating speed and the like, pump displacement is completely corresponding to control current.

[0055] CAN communication: it is a kind of broadcast-based serial communication protocol, which is used for connecting various devices in a distributed system to realize data interaction and control among various devices.

[0056] For the control of the walking drive of the loader hydrostatic transmission, some schemes set a DA valve on the pump variable control, the DA valve adjusts the variable pump control end pilot pressure according to the engine rotating speed, so as to control the pump displacement, when the load increases and the engine speed drops, the variable pump control end pilot pressure automatically decreases, the variable pump displacement decreases, and the walking power decreases, some technical schemes perform synchronous power control of the upper car and the lower car, when the load pressure is greater than the preset overload pressure and the engine speed drop value is greater than the preset speed drop amplitude, the walking power and the upper car working power are simultaneously reduced, when one of them is satisfied, only the walking power is reduced.

[0057] This technical scheme still has the following shortcomings:

[0058] (1) DA valve control is adopted, the pump displacement completely follows the engine rotating speed, when the shovel excavates and arches the material and needs lower pump displacement control, although the engine rotating speed drops, the pump control end still provides corresponding larger pilot pressure, the walking pump displacement cannot be adjusted to be smaller, the overflow loss is increased, the occupation of the lower car power is increased, and the utilization of the upper car working power such as shovel excavating and arm lifting is affected;

[0059] (2) DA valve control is adopted, due to the limitation of the pilot pressure, the pump large displacement output cannot be realized at low engine rotating speed, and the realization of other functions (such as independent control of engine rotating speed and vehicle speed) is affected;

[0060] (3) DA valve control is adopted, the pump displacement change rate completely follows the engine rotating speed change rate, the displacement change rate is not controlled, and the stability is poor;

[0061] (4) synchronous control of the upper car and the lower car power is adopted, and the control is effected when the speed drop condition or the overload condition is satisfied, single condition satisfaction triggers abnormal action of other working conditions such as high-speed driving, climbing working condition and low-speed heavy load traction, and the upper car power regulation needs the upper car pump to be an electric control pump, which is not suitable for the upper car fixed displacement pump system or the hydraulic control variable pump system, and the application range is limited.

[0062] To this end, the application provides a hydrostatic loader system and control method based on an EP electric proportional control variable pump, which adopts EP electric proportional variable pump control, pump displacement control is not affected by engine speed, pump displacement change rate is adjustable, different working condition displacement change speed requirements are realized, pump displacement corresponds to control current, control is accurate; a static hydraulic drive shovel power control scheme is provided, engine speed drop and flameout problems caused by static hydraulic loader shoveling are solved, continuity of walking driving and shoveling operation process is ensured, power is ensured not to be interrupted during shoveling operation process, different limited conditions adapt to different working condition requirements; during walking and shoveling cooperative operation process, the problem of arm powerlessness during shoveling operation process is solved, fast action of the loader is realized, overflow consumption during getting off is reduced, and energy-saving control of getting off is realized; during walking and shoveling cooperative operation process, bucket displacement change rate is limited, and the problem of shovel bucket impact is solved.

[0063] Embodiment 1: In a first aspect, a hydrostatic loader control method is provided, the hydrostatic loader comprising a walking device and a working device, the walking device and the working device being driven by an engine, the control method comprising:

[0064] obtaining an engine request speed, an engine actual speed, an engine actual torque load rate, a load pressure, a variable motor control current, a variable motor speed and a vehicle speed;

[0065] determining an engine speed drop value according to the engine request speed and the engine actual speed; calculating a variable motor displacement according to the variable motor control current, calculating a variable motor flow according to the variable motor displacement and the variable motor speed, and calculating a load power of the walking device according to the variable motor flow and the load pressure; determining an engine actual speed corresponding power according to the engine actual speed; determining a variable pump control current corresponding to the engine actual speed according to the engine actual speed; comparing the load power of the walking device with the engine actual speed corresponding power, comparing the vehicle speed with a vehicle speed limit value, comparing the engine speed drop value with a speed drop limit value, comparing the engine actual torque load rate with a torque load rate limit value, and comparing the load pressure with a load pressure limit value to obtain a comparison result;

[0066] determining a variable pump pre-reduction current N and a current change rate k according to the comparison result;

[0067] controlling the variable pump control current according to the variable pump control current corresponding to the engine actual speed, the variable pump pre-reduction current N and the current change rate k.

[0068] In some embodiments, obtaining the vehicle speed comprises: calculating the vehicle speed according to the variable motor speed and a determined transmission speed ratio.

[0069] In some embodiments, the load pressure limit value comprises a second load pressure limit value p2.

[0070] In the first load pressure limit p1, the second load pressure limit p2, the third load pressure limit p3 in the embodiment, and p1

[0071] In some embodiments, the engine actual speed corresponding power is determined according to the engine actual speed, comprising:

[0072] The engine speed-power characteristic curve corresponding relationship exists between the engine actual speed and the power, and the engine actual speed corresponding power is obtained according to the engine actual speed and the known engine speed-power characteristic curve.

[0073] In some embodiments, the variable pump control current corresponding to the engine actual speed is determined according to the engine actual speed, comprising:

[0074] The engine actual speed and the variable pump control current have a corresponding relationship, and the variable pump control current corresponding to the minimum displacement of the variable pump at low speed to the maximum displacement of the variable pump at high speed; in the current state, the variable pump control current A corresponding to the engine actual speed is set, and if the engine speed drops due to load mutation, the variable pump control current B corresponding to the engine actual speed after dropping is determined.

[0075] In some embodiments, the variable pump pre-reduction current N and the current change rate k are determined according to the comparison result, comprising:

[0076] (1) If the load power of the walking device is not greater than the engine actual speed corresponding power, and the engine actual torque load rate is not greater than the set torque load rate limit, and the engine drop speed value is not greater than the set drop speed limit, the variable pump pre-reduction current N is 0, and the current change rate k is determined as the first change rate k1 based on the first corresponding relationship between the vehicle speed and the current reduction change rate;

[0077] (2) If the load power of the walking device is greater than the engine actual speed corresponding power and the vehicle speed is lower than the vehicle speed limit, the variable pump pre-reduction current N is determined as the first current a, the set action time t1 is set, and the load pressure is greater than the second load pressure limit p2 within the set action time, then the variable pump pre-reduction current N is the first current a, if the load pressure is not greater than the second load pressure limit p2 within the set action time, then after the set action time t1, the variable pump pre-reduction current N is 0, wherein the first current a is a constant; the current change rate k is determined as the second change rate k2 based on the second corresponding relationship between the vehicle speed and the current reduction change rate, and the second change rate k2 is greater than the first change rate k1;

[0078] (3) if the engine actual torque load ratio is greater than the set torque load ratio limit value and the load pressure is greater than the second load pressure limit value, determining the variable pump pre-reduction current N as a second current b, wherein the second current b has a corresponding relationship with the engine actual speed; based on the second corresponding relationship between the vehicle speed and the current reduction rate, determining the current rate of change k as a second rate of change k2, the second rate of change k2 being greater than the first rate of change k1;

[0079] (4) if the engine speed drop value is greater than the set speed drop limit value and the load pressure is greater than the second load pressure limit value, determining the variable pump pre-reduction current N as a third current c, wherein the third current c has a corresponding relationship with the engine speed drop value; based on the second corresponding relationship between the vehicle speed and the current reduction rate, determining the current rate of change k as a second rate of change k2, the second rate of change k2 being greater than the first rate of change k1;

[0080] (5) if the engine actual torque load ratio is greater than the set torque load ratio limit value, the engine speed drop value is greater than the set speed drop limit value, and the load pressure is greater than the second load pressure limit value, determining the variable pump pre-reduction current N as the greater of the second current b and the third current c; based on the second corresponding relationship between the vehicle speed and the current reduction rate, determining the current rate of change k as a second rate of change k2, the second rate of change k2 being greater than the first rate of change k1;

[0081] (6) if the load power of the traveling device is greater than the engine actual speed corresponding power and the vehicle speed is lower than the vehicle speed limit value, and the engine actual torque load ratio is greater than the set torque load ratio limit value and the load pressure is greater than the second load pressure limit value, determining the variable pump pre-reduction current N as the greater of the first current a and the second current b; based on the second corresponding relationship between the vehicle speed and the current reduction rate, determining the current rate of change k as a second rate of change k2, the second rate of change k2 being greater than the first rate of change k1;

[0082] (7) if the load power of the traveling device is greater than the engine actual speed corresponding power and the vehicle speed is lower than the vehicle speed limit value, and the engine speed drop value is greater than the set speed drop limit value and the load pressure is greater than the second load pressure limit value, determining the variable pump pre-reduction current N as the greater of the first current a and the third current c; based on the second corresponding relationship between the vehicle speed and the current reduction rate, determining the current rate of change k as a second rate of change k2, the second rate of change k2 being greater than the first rate of change k1;

[0083] (8) If the load power of the traveling device is greater than the power corresponding to the actual engine speed, the vehicle speed is lower than the vehicle speed limit value, the actual engine torque load rate is greater than the set torque load rate limit value, the engine drop speed value is greater than the set drop speed limit value, and the load pressure is greater than the second load pressure limit value, the variable pump pre-reduction current N is determined as the larger value of the first current a, the second current b, and the third current c; based on the second corresponding relationship between the vehicle speed and the current reduction rate, the current rate k is determined as the second rate k2, which is greater than the first rate k1.

[0084] In some embodiments, the variable pump control current is controlled according to the variable pump control current corresponding to the actual engine speed, the variable pump pre-reduction current N, and the current rate k, including:

[0085] The variable pump final control current calculation value C = B - N is determined according to the variable pump control current B corresponding to the actual engine speed and the variable pump pre-reduction current N.

[0086] The variable pump control current is controlled according to the variable pump final control current calculation value C and the current rate k.

[0087] Further, in some embodiments, the process of controlling the variable pump control current also includes active limit control of the limit pressure displacement, specifically including:

[0088] If the variable pump final control current calculation value C is greater than the variable pump limit pressure displacement current value D and the load pressure is greater than the third load pressure p3, the variable pump final control current is limited to the variable pump limit pressure displacement current value D.

[0089] The variable pump limit pressure displacement current value D is the variable pump current value corresponding to the load pressure greater than the third load pressure limit value p3, and the third load pressure limit value p3 is the limit pressure value of the variable pump.

[0090] The above-mentioned active limit control of the limit pressure displacement makes the pump only reach the minimum displacement required to ensure the continuous establishment of traction when the load pressure reaches the third load pressure limit value, without causing additional overflow consumption, achieving energy-saving control when the vehicle is off, while ensuring the work power when the vehicle is on, and realizing the rapid action of the vehicle when it is on.

[0091] Further, in some embodiments, the control process of the variable pump control current further comprises pump current increasing rate control, specifically comprising: when the load pressure p decreases to not more than the second load pressure limit p2, the variable pump control current stops decreasing the pre-decrease current N, and starts to increase according to the engine actual speed to the variable pump control current B corresponding to the engine actual speed, and during the process of increasing the variable pump control current to B, when the load pressure p is between the second load pressure limit p2 and the first load pressure limit p1 (p2≥p≥p1), the current increasing rate is the third rate k3, and when the load pressure p is less than the first load pressure limit p1 (p

[0092] Embodiment 2: In a second aspect, there is provided a hydrostatic controller comprising a memory and a processor, the memory being configured to store instructions for controlling the processor to operate to perform the method of controlling a hydrostatic loader according to the first aspect.

[0093] In some embodiments, the hydrostatic controller is a hydrostatic control unit 10 as shown in FIG. 1.

[0094] Embodiment 3: In a third aspect, there is provided a hydrostatic loader control system comprising a hydrostatic controller according to the second aspect.

[0095] In some embodiments, as shown in FIG. 1, a hydrostatic loader control system comprises the above-mentioned hydrostatic controller 10, and further comprises an engine 3, a variable pump 1, a variable motor 5, an engine controller 4, a pump electric proportional control device 2, and a motor electric proportional control device 6.

[0096] The input shaft end of the variable pump 1 is connected to the output shaft end of the engine 3, and the two oil ports of the variable pump 1 are connected to the two oil ports of the variable motor 5 in pipeline; the variable motor 5 is used to drive the walking device to walk;

[0097] The engine controller 4 acquires the engine actual speed and the engine actual torque load rate, and uploads them to the hydrostatic controller;

[0098] The pump electric proportional control device 2 is used to control the displacement of the variable pump according to the pump control current output by the hydrostatic controller;

[0099] The motor electric proportional control device 6 is used to control the displacement of the variable motor according to the motor control current output by the hydrostatic controller.

[0100] In some embodiments, the hydrostatic loader control system further comprises:

[0101] Load pressure sensors 9-1, 9-2 are arranged at two oil port positions of the variable pump 1 to detect load pressure and upload to the hydrostatic controller;

[0102] A motor speed sensor 7 is arranged at an output shaft end of the variable motor 5 to detect variable motor speed and upload to the hydrostatic controller;

[0103] A throttle pedal 11, and the hydrostatic controller determines engine request speed according to the signal of the throttle pedal.

[0104] In some embodiments, the variable motor 5 is drivingly connected to the reduction device 8, and the variable motor 5 drives the walking device to walk through the reduction device 8.

[0105] In some embodiments, the hydrostatic loader control system further comprises a handle FNR button 12, and the hydrostatic controller determines forward and reverse gear signals according to the handle FNR button 12.

[0106] In some embodiments, the working method of the hydrostatic loader control system comprises:

[0107] As shown in FIG. 1, when the handle FNR button 12 is in the F position, the engine speed increases after the throttle pedal 11 is actuated, the pump electric proportional control device 2 is actuated, the variable pump 1 changes in displacement, the output hydraulic oil drives the variable motor 5 to rotate, and the vehicle is driven to walk through the reduction device 8 to perform forward digging operation, the hydrostatic controller 10 determines the engine request speed according to the signal of the throttle pedal 11, obtains the actual engine speed and torque load rate of the engine 3 in real time through the CAN bus, obtains the load pressure in real time through the load pressure sensor, calculates the variable motor displacement through the actual control current value of the control end of the motor electric proportional control device 6, and determines the variable motor speed through the motor speed sensor 7. The hydrostatic controller determines the engine speed drop value according to the engine request speed and the actual engine speed, and compares it with the set speed drop limit value; the hydrostatic controller compares the actual torque load rate of the engine with the set torque load rate limit value; the hydrostatic controller compares the load pressure with the preset first, second and third load pressure limit values; the hydrostatic controller calculates the variable motor flow according to the variable motor displacement and the variable motor speed, and calculates the load power of the walking device according to the collected load pressure, and compares it with the actual engine speed corresponding power (obtained according to the engine actual speed and engine speed power characteristic curve).

[0108] Embodiment 4: In a fourth aspect, a hydrostatic loader is provided, comprising the hydrostatic controller of the first aspect or the hydrostatic loader control system of the second aspect.

[0109] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks or in conjunction with the flowcharts.

[0110] These computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instructions which implement the function specified in the flowchart block or blocks or in conjunction with the flowcharts.

[0111] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks or in conjunction with the flowcharts.

[0112] The above only is the preferred embodiment of the present application, it should be pointed out that for those skilled in the technical field, without departing from the principles of the present application, can also make a number of improvements and refinements, these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A control method for a hydrostatic loader, the hydrostatic loader comprising a traveling device and a working device, wherein the traveling device and the working device are driven by an engine, characterized in that... The control method includes: Obtain the engine requested speed, engine actual speed, engine actual torque load rate, load pressure, variable motor control current, variable motor speed, and vehicle speed; The engine speed drop value is determined based on the requested engine speed and the actual engine speed; the variable motor displacement is calculated based on the variable motor control current; the variable motor flow rate is calculated based on the variable motor displacement and variable motor speed; the load power of the travel device is calculated based on the variable motor flow rate and load pressure; the power corresponding to the actual engine speed is determined based on the actual engine speed; the variable pump control current corresponding to the actual engine speed is determined based on the actual engine speed. The comparison results are obtained by comparing the load power of the traveling device with the power corresponding to the actual engine speed, comparing the vehicle speed with the vehicle speed limit, comparing the engine speed drop value with the speed drop limit, comparing the actual engine torque load rate with the torque load rate limit, and comparing the load pressure with the load pressure limit. Based on the comparison results, determine the pre-reduction current and current change rate of the variable pump; The variable pump control current is controlled based on the variable pump control current corresponding to the actual engine speed, the variable pump pre-reduction current, and the current change rate.

2. The hydrostatic loader control method according to claim 1, characterized in that, The variable pump control current corresponding to the actual engine speed is determined based on the actual engine speed, including: There is a corresponding relationship between the actual engine speed and the variable pump control current. The change from low engine speed to high engine speed corresponds to the change from the minimum control current of the variable pump displacement to the maximum control current of the variable pump displacement. If a sudden change in load causes the engine speed to drop, the corresponding variable pump control current is determined based on the actual engine speed after the speed drop.

3. The hydrostatic loader control method according to claim 1, characterized in that, Based on the comparison results, the pre-reduction current and current change rate of the variable pump are determined, including: If the load power of the traveling device is not greater than the power corresponding to the actual engine speed, and the actual engine torque load rate is not greater than the set torque load rate limit, and the engine speed drop value is not greater than the set speed drop limit, the variable pump pre-reduction current is 0. Based on the first correspondence between vehicle speed and current reduction rate, the current change rate is determined to be the first change rate. If the load power of the traveling device is greater than the power corresponding to the actual engine speed and the vehicle speed is lower than the vehicle speed limit, the variable pump pre-reduction current is determined to be the first current, and an action time is set. If the load pressure is greater than the second load pressure limit within the set action time, then the variable pump pre-reduction current is the first current. If the load pressure is not greater than the second load pressure limit within the set action time, then the variable pump pre-reduction current is 0 after the set action time. Here, the first current is a constant. Based on the second correspondence between vehicle speed and the rate of change of current reduction, the rate of change of current is determined to be the second rate of change. The second rate of change is greater than the first rate of change; If the actual torque load rate of the engine is greater than the set torque load rate limit and the load pressure is greater than the second load pressure limit, the variable pump pre-reduction current is determined to be the second current, wherein the second current has a corresponding relationship with the actual engine speed; based on the second correspondence between vehicle speed and the rate of change of current reduction, the rate of change of current is determined to be the second rate of change, and the second rate of change is greater than the first rate of change; If the engine speed drop value is greater than the set speed drop limit and the load pressure is greater than the second load pressure limit, the variable pump pre-reduction current is determined to be the third current, wherein the third current has a corresponding relationship with the engine speed drop value; based on the second correspondence between vehicle speed and current reduction rate of change, the current change rate is determined to be the second change rate, which is greater than the first change rate; If the actual torque load rate of the engine is greater than the set torque load rate limit, and the engine speed drop value is greater than the set speed drop limit and the load pressure is greater than the second load pressure limit, the variable pump pre-reduction current is determined to be the larger value between the second current and the third current; based on the second correspondence between vehicle speed and current reduction rate, the current change rate is determined to be the second change rate, which is greater than the first change rate. If the load power of the traveling device is greater than the power corresponding to the actual engine speed and the vehicle speed is lower than the vehicle speed limit, and the actual engine torque load rate is greater than the set torque load rate limit and the load pressure is greater than the second load pressure limit, the variable pump pre-reduction current is determined to be the larger of the first current and the second current; based on the second correspondence between vehicle speed and current reduction rate, the current change rate is determined to be the second change rate, which is greater than the first change rate. If the load power of the traveling device is greater than the power corresponding to the actual engine speed and the vehicle speed is lower than the vehicle speed limit, and the engine speed drop value is greater than the set speed drop limit and the load pressure is greater than the second load pressure limit, the variable pump pre-reduction current is determined to be the larger value between the first current and the third current; based on the second correspondence between vehicle speed and current reduction rate, the current change rate is determined to be the second change rate, which is greater than the first change rate. If the load power of the traveling device is greater than the power corresponding to the actual engine speed and the vehicle speed is lower than the vehicle speed limit, the actual engine torque load rate is greater than the set torque load rate limit, the engine speed drop value is greater than the set speed drop limit, and the load pressure is greater than the second load pressure limit, the variable pump pre-reduction current is determined to be the larger of the first current, the second current, and the third current; based on the second correspondence between vehicle speed and current reduction rate, the current change rate is determined to be the second change rate, which is greater than the first change rate.

4. The hydrostatic loader control method according to claim 1, 2, or 3, characterized in that, The variable pump control current is controlled based on the variable pump control current corresponding to the actual engine speed, the variable pump pre-reduction current, and the current change rate, including: The final calculated value of the variable pump control current is determined based on the variable pump control current corresponding to the actual engine speed and the variable pump pre-reduction current. The control current of the variable pump is controlled based on the calculated value of the final control current of the variable pump and the rate of change of the current.

5. The hydrostatic loader control method according to claim 4, characterized in that, The process of controlling the control current of a variable pump also includes active limit pressure displacement control, specifically including: If the calculated value of the final control current of the variable pump is greater than the limit pressure displacement current value of the variable pump and the load pressure is greater than the third load pressure limit, then the final control current of the variable pump will be limited to the limit pressure displacement current value of the variable pump. The variable pump ultimate pressure displacement current value is the variable pump current value when the load pressure is greater than the third load pressure limit value, and the third load pressure limit value is the ultimate pressure value of the variable pump.

6. The hydrostatic loader control method according to claim 4, characterized in that, The process of controlling the variable pump control current also includes controlling the rate of change of the pump current. Specifically, when the load pressure decreases to no more than the second load pressure limit, the variable pump control current stops decreasing the pre-decrease current and starts increasing to the variable pump control current corresponding to the actual engine speed according to the actual engine speed. During the process of the variable pump control current increasing to the variable pump control current corresponding to the actual engine speed, when the load pressure is between the second load pressure limit and the first load pressure limit, the rate of change of the current increase is the third rate of change. When the load pressure is less than the first load pressure limit, the rate of change of the current increase is the fourth rate of change, and the third rate of change is less than the fourth rate of change.

7. A hydrostatic controller, characterized in that, It includes a memory and a processor, the memory being used to store instructions for controlling the processor to operate in order to execute the hydrostatic loader control method according to any one of claims 1 to 6.

8. A hydrostatic loader control system, characterized in that, Includes the hydrostatic controller according to claim 7.

9. The hydrostatic loader control system according to claim 8, characterized in that, It also includes the engine, variable pump, variable motor, engine controller, pump electro-proportional control device, and motor electro-proportional control device; The input shaft of the variable pump is connected to the output shaft of the engine; the two oil ports of the variable pump are connected to the two oil port pipelines of the variable motor. The variable motor is used to drive the walking device to move. The engine controller is used to obtain the actual engine speed and the actual engine torque load rate, and then upload them to the hydrostatic controller. The pump-electric proportional control device is used to control the displacement of the variable pump based on the pump control current output by the hydrostatic controller. The motor electro-proportional control device is used to control the displacement of the variable displacement motor based on the motor control current output by the hydrostatic controller.

10. The hydrostatic loader control system according to claim 9, characterized in that, Also includes: The load pressure sensor is set at both oil ports of the variable pump to detect the load pressure and transmit it to the hydrostatic controller. A motor speed sensor is installed at the output shaft end of the variable motor to detect the speed of the variable motor and transmit the data to the hydrostatic controller. The accelerator pedal is used as the reference point, and the hydrostatic controller determines the engine's requested speed based on the signal from the accelerator pedal.

11. A hydrostatic loader, characterized in that, Includes the hydrostatic controller as described in claim 7 or the hydrostatic loader control system as described in any one of claims 8 to 10.

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