Composite action cooperative control method for hydraulic system

Abstract

The invention relates to a hydraulic system compound action cooperative control method, which relates to the technical field of hydraulic system control, and comprises the following steps: S1, acquiring the rotating speed of an engine and the displacement parameter of a hydraulic pump in real time, and calculating the actual output flow of the current system; s2, receiving an input signal of an operation handle, and analyzing to obtain respective demand flow and total demand flow of the walking mechanism and the working mechanism; s3, whether the total required flow exceeds the actual output flow or not is judged, and if yes, the rotating speed of the engine is increased till the maximum rotating speed threshold value is reached; and S4, when the engine reaches the maximum rotating speed threshold value and still has a flow gap, flow sharing control is started. The method has the advantages that the machine is allowed to do composite actions, the working efficiency can be improved, meanwhile, the danger caused by action incoordination due to insufficient flow is avoided, the priority or the priority proportion can be set for each action according to the requirements of different machine types, hardware does not need to be changed, and extra cost does not exist.

Description

Technical Field

[0001] This application relates to the technical field of hydraulic system control, and particularly to a method for coordinated control of composite actions of a hydraulic system, which is especially applicable to the flow distribution and coordinated control when the traveling mechanism and the working mechanism of construction machinery act simultaneously. Background Art

[0002] The inherent flow rate of the pump cannot meet the requirements of the simultaneous operation of the traveling and working mechanisms. In case of composite actions, since the flow rate always preferentially supplies low-load actions, the actions of the traveling and working mechanisms become uncoordinated. Especially for a bilaterally driven traveling system, there is also a problem that the vehicle may deviate due to the difference in bilateral driving forces.

[0003] In a traditional hydraulic system, when the traveling mechanism and the working mechanism act simultaneously, the output flow rate of the hydraulic pump often cannot meet the requirements of composite actions, resulting in the following problems: Uneven flow distribution: Low-load actions preferentially obtain the flow rate, causing uncoordinated actions. For example, the vehicle may deviate due to the flow rate difference in the bilateral traveling mechanisms (the deviation exceeds 0.5 meters when traveling 50 meters); Operation restrictions: An interlock mechanism is adopted to prohibit composite actions, reducing the operation efficiency; Hardware dependence: Some solutions require modifying the structure of the multi-way valve or increasing the hardware cost; The driver can only adopt an operation mode in which the traveling and working mechanisms do not act simultaneously. An interlock mechanism is adopted in the vehicle control program. When traveling, the control of the working mechanism is invalid. Conversely, when operating the working mechanism, the traveling control is invalid. This ensures that the two working conditions work independently without interference, but the disadvantage is that the working efficiency is reduced. Summary of the Invention

[0004] The purpose of this application is to provide a method for coordinated control of composite actions of a hydraulic system, which solves the problem of flow conflict during composite actions and improves the operation efficiency and safety.

[0005] A method for coordinated control of composite actions of a hydraulic system provided by this application adopts the following technical solutions: (1) Open system flow sharing technology: Dynamically detect the flow demand and supply, and automatically adjust the engine speed; When the flow rate is insufficient, allocate the flow rate according to priority or proportion, and generate an override control signal to replace the handle input.

[0006] (2) Valve post-compensation mechanism: Set a damping plug (aperture 0.8 - 1.2 mm) in the LS signal channel of the multi-way valve to isolate the common pressure compensation channel; Force all valve plates to reduce the flow rate at the same ratio to ensure the coordination of composite actions.

[0007] Specifically, a hydraulic system composite action collaborative control method provided by the present application includes the following steps: S1. Obtain the engine speed and hydraulic pump displacement parameters in real time, and calculate the actual output flow rate of the current system; S2. Receive the input signal of the operation handle, and parse to obtain the required flow rates of the traveling mechanism and the working mechanism respectively and the total required flow rate; S3. Determine whether the total required flow rate exceeds the actual output flow rate. If it exceeds, increase the engine speed until the maximum speed threshold is reached; S4. When there is still a flow gap when the engine reaches the maximum speed threshold, start the flow sharing control: S41. Calculate the difference between the actual output flow rate and the total required flow rate; S42. According to the preset action priority ratio and the operation signal strength, allocate the available flow rate to each actuator proportionally; S43. Reverse calculate the hydraulic control valve opening degree according to the allocated flow rate, and generate the corresponding over-authority control current; S5. Output the over-authority control current to the solenoid valve to replace the original handle control signal.

[0008] Preferably, the actual flow rate calculation formula in step S1 is: wherein, ( ) is the engine speed (rpm), ( ) is the pump displacement (cc / rev), and ( ) is the pump volumetric efficiency (default 0.92 - 0.98).

[0009] Preferably, a gradient speed increase strategy is adopted when increasing the engine speed in step S3, which specifically includes: when a flow gap is detected, increase the speed at a rate of 200 rpm / second; when the speed increases to the economic speed range, reduce the speed to 50 rpm / second and continue to increase until the maximum speed threshold is reached.

[0010] Preferably, the preset action priority ratio in step S42 includes: setting a bilateral flow deviation threshold according to the bilateral drive characteristics of the traveling mechanism. When the flow distribution causes the bilateral flow difference to exceed the set threshold, forcefully correct the flow distribution ratio to make the bilateral flow difference return to the threshold range.

[0011] Preferably, when generating the unauthorized control current in step S43, a dynamic safety factor is introduced for compensation calculation. The safety factor is dynamically adjusted according to the hydraulic pump volumetric efficiency curve and the current oil pressure parameters. The safety factor includes a hydraulic pump volumetric efficiency correction value α and a solenoid valve response delay correction value β, where α = 0.9 - 1.1, β = 1.05 - 1.2, and when the oil temperature is lower than 20 °C, a low-temperature compensation factor γ = 1.15 - 1.3 is activated.

[0012] Preferably, the distribution flow process in step S43 is implemented by a post-valve compensation mechanism, including: setting a damping plug between the LS signal channel and the pressure compensation common channel of the multi-way valve; isolating the LS signal of the valve plate from the pressure compensation common channel; and applying the same LS signal pressure to the pressure compensation spring chambers of all multi-way valves.

[0013] Preferably, the synchronous control of the pressure compensation spring chambers enables all valve plates to reduce the output flow in the same proportion during compound actions.

[0014] Preferably, the aperture of the damping plug is set to 0.8 - 1.2 mm, and a pressure drop range of 0.2 - 0.5 MPa is formed in the LS signal channel. The pressure drop value is jointly calibrated through oil circuit simulation calculation and bench test.

[0015] Preferably, the preset action priority ratio includes a default equal distribution mode. When no specific priority is set, the available flow is distributed proportionally according to the signal intensity of each operation handle.

[0016] Preferably, the control method is implemented through the PLUS+1 software platform, loaded in the form of a software module in the original control system, and the output response time of the unauthorized control current ≤ 50 ms.

[0017] Preferably, the hardware implementation details are as follows: Damping plug installation process: A damping hole with a diameter of Φ1.0 ± 0.05 mm is machined in the LS oil passage of the valve block, and cemented carbide material is used to prevent erosion and deformation; After installation, a pulse pressure test (0 - 10 MPa, 10^5 cycles) is required to ensure that the pressure drop stability error < ±0.02 MPa.

[0018] Sensor configuration scheme: Required sensors: engine speed sensor (magnetic-electric type, accuracy ±1 rpm), pump displacement angular displacement sensor (potentiometer type, linearity 0.5%); Optional sensors: oil temperature sensor (PT100, -40 °C ~ 120 °C), spool displacement sensor (LVDT, resolution 0.1 mm).

[0019] Preferably, the software implementation details are as follows: Optimization of the control period: The main control loop period is set to 10 ms, where: The first 2 ms: data acquisition and filtering (using moving average filtering, window size = 5); The middle 5 ms: flow calculation and distribution decision-making; The last 3 ms: unauthorized current output and anomaly detection.

[0020] Fault tolerance mechanism: Signal anomaly handling: If the handle signal is lost, switch to the preset safe mode (e.g., the traveling mechanism maintains the last valid signal, and the working mechanism unloads slowly); Timeout protection: If the unauthorized control lasts for more than 30 seconds without being released, trigger a system alarm and downgrade to the interlock mode.

[0021] In summary, the present application includes at least one of the following beneficial technical effects: 1. Allowing the machine to perform composite actions can improve work efficiency, and at the same time avoid the danger caused by uncoordinated actions due to insufficient flow. The priorities or priority ratios of each action can be set according to the requirements of different machine models without the need to change the hardware and without additional costs; 2. When the flow is insufficient, without manual intervention, the system automatically slows down the action rate according to the set priority or proportional value scheme, so that each action can still cooperate with each other, avoiding the danger that a certain action may accelerate due to a small load and cause disharmony with other actions, such as product collision; 3. The function is triggered only when the maximum engine speed still does not meet the requirement: When the engine speed is low and insufficient flow is detected, the engine speed is automatically increased to make the flow meet the demand, reducing the driver's operation; 4. The priorities and ratios between each action can be freely set by the manufacturer according to the characteristics of different machines, and the default is an equal ratio for all actions; 5. There is no need to perform hardware processing and transformation, which reduces costs. Only the PLUS+1 software is used, and this function can be added to the original control system program. Description of the Drawings

[0022] Figure 1 is the flow chart of the cooperative control method for the composite actions of the hydraulic system of the present application; Figure 2 is the hydraulic schematic diagram for distributing the flow of the present application; Description of the reference numerals: A, pressure compensation common channel; B, damping plug; C, LS signal channel of the multi-way valve. Detailed implementation manners

[0023] The following combines the attached Figure 1 - attached Figure 2, the present application is further described in detail.

[0024] The present application provides a cooperative control method for compound actions of a hydraulic system, including the following steps: S1. Obtain the engine speed and hydraulic pump displacement parameters in real time, and calculate the actual output flow of the current system; S2. Receive the input signal of the operation handle, and analyze to obtain the required flow rates of the traveling mechanism and the working mechanism respectively, as well as the total required flow rate; S3. Determine whether the total required flow rate exceeds the actual output flow rate. If it exceeds, increase the engine speed until the maximum speed threshold is reached; S4. When there is still a flow gap when the engine reaches the maximum speed threshold, start the flow sharing control: S41. Calculate the difference between the actual output flow rate and the total required flow rate; S42. According to the preset action priority ratio and the operation signal strength, allocate the available flow rate to each actuator proportionally; S43. Calculate the hydraulic control valve opening degree by inverse deduction according to the allocated flow rate, and generate the corresponding over-authority control current; S5. Output the over-authority control current to the solenoid valve to replace the original handle control signal.

[0025] Among them, the actual flow rate calculation formula in step S1 is: Among them, ( ) is the engine speed (rpm), ( ) is the pump displacement (cc / rev), ( ) is the pump volumetric efficiency (default 0.92 - 0.98); Effect: By calculating the actual flow rate in real time, it provides an accurate benchmark for subsequent allocation, with an error ≤ 3%.

[0026] In step S2, the required flow rate analysis adopts linear mapping: Among them, ( ) is the handle signal - flow conversion coefficient (for example, for the traveling mechanism = 2.5 L / min / %, for the working mechanism = 1.8 L / min / %), ( ) is the handle opening degree (0 - 100%); Implementation: Establish a K value mapping table for each actuator through calibration experiments and store it in the controller EEPROM.

[0027] Among them, when increasing the engine speed in step S3, a gradient speed increase strategy is adopted, which specifically includes: when a flow gap is detected, the speed is increased at a rate of 200 rpm / second to avoid engine surge caused by sudden speed changes; when the speed is increased to the economic speed range (for example, 1800 - 2200 rpm for a diesel engine), the speed reduction is to 50 rpm / second and continue to increase until the maximum speed threshold is reached; Combined with the PID control algorithm, compared with the traditional step - up speed, the fuel consumption is reduced by 15% (see the following table).

[0028] Speed-up strategy Time taken to reach 2500 rpm (s) Fuel consumption (mL) Step-by-step 5 520 Gradient type 8 442 Among them, the preset action priority ratio in step S42 includes: setting a bilateral flow deviation threshold according to the bilateral drive characteristics of the traveling mechanism. When the flow distribution causes the bilateral flow difference to exceed the set threshold, the flow distribution ratio is forcibly corrected to make the bilateral flow difference return to the threshold range.

[0029] Among them, when generating an over - authority control current in step S43, a dynamic safety factor is introduced for compensation calculation. The safety factor is dynamically adjusted according to the hydraulic pump volumetric efficiency curve and the current oil pressure parameters. The safety factor includes the hydraulic pump volumetric efficiency correction value α and the solenoid valve response delay correction value β, where α = 0.9 - 1.1, β = 1.05 - 1.2, and when the oil temperature is lower than 20 °C, the low - temperature compensation factor γ = 1.15 - 1.3 is activated; the dynamic safety factor compensation formula is as follows: Calculation of α (pump volumetric efficiency correction): Obtained by looking up the table from the pump performance curve; Calculation of β (solenoid valve delay compensation): is the spool action delay time, in ms; Trigger condition of γ: When the oil temperature T < 20 °C: T is in °C; Effect: The flow control error after compensation is reduced from ±8% to ±3% (improved from ±15% to ±5% under low - temperature conditions).

[0030] Among them, the process of distributing flow in step S43 is realized by a post - valve compensation mechanism, including: setting a damping plug B between the LS signal channel C of the multi - way valve and the pressure compensation common channel A; isolating the LS signal of the valve plate from the pressure compensation common channel A; making the same LS signal pressure act on the pressure compensation spring chambers of all multi - way valves.

[0031] Among them, the synchronous control of the pressure compensation spring chamber enables all valve plates to reduce the output flow in the same proportion during the composite action. The formula for the reduction ratio of the valve plate flow is as follows: Among them, is the load-sensitive pressure, is the pressure difference corresponding to the pre-tightening force of the compensation spring; Effect: The flow ratio of the bilateral travel motors is always maintained at 1±0.02, and the deviation amount ≤ 0.5 m / 50 m.

[0032] Among them, the aperture of the damping plug B is set to 0.8 - 1.2 mm, and a pressure drop range of 0.2 - 0.5 MPa is formed on the LS signal channel. The pressure drop value is jointly calibrated through oil circuit simulation calculation and bench test. The optimization of the aperture of the damping plug B is as follows: Determine the pressure drop - aperture relationship through CFD simulation: Among them, is the reference aperture, is the actual aperture, The unit is MPa; Verification by bench test: When = 1.0 mm, = 0.3 MPa, the flow synchronization error ≤ 2%.

[0033] Among them, the preset action priority ratio includes the default equal distribution mode. When no specific priority is set, the available flow is distributed proportionally according to the signal strength of each operation handle. The default equal distribution algorithm is as follows: For example: the travel demand is 120 L / min, the working demand is 80 L / min, and the actual flow is 180 L / min, then the distribution is as follows: Among them, the control method is implemented through the PLUS+1 software platform, loaded in the form of a software module in the original control system, and the output response time of the over - authority control current ≤ 50 ms, and the code is optimized: the key functions are written in assembly language, and the loop body adopts the pre - loaded cache technology.

[0034] Among them, the hardware implementation details are as follows: Installation process of the damping plug B: Machine a damping hole with a diameter of Φ1.0±0.05 mm in the LS oil passage of the valve block, and use cemented carbide material to prevent erosion and deformation; After installation, pulse pressure testing (0 - 10 MPa, 10^5 cycles) is required to ensure that the pressure drop stability error < ±0.02 MPa.

[0035] Sensor configuration scheme: Required sensors: engine speed sensor (magnetoelectric type, accuracy ±1 rpm), pump displacement angular displacement sensor (potentiometer type, linearity 0.5%); Optional sensors: oil temperature sensor (PT100, -40°C ~ 120°C), spool displacement sensor (LVDT, resolution 0.1 mm).

[0036] Among them, the software implementation details are as follows: Control cycle optimization: The main control cycle period is set to 10 ms, where: The first 2 ms: data acquisition and filtering (using moving average filtering, window size = 5); The middle 5 ms: flow calculation and distribution decision-making; The last 3 ms: unauthorized current output and anomaly detection.

[0037] Fault tolerance mechanism: Signal anomaly handling: If the handle signal is lost, switch to the preset safety mode (e.g., the traveling mechanism maintains the last valid signal, and the working mechanism unloads slowly); Timeout protection: If the unauthorized control lasts for more than 30 seconds without being lifted, trigger a system alarm and downgrade to the interlock mode.

[0038] Example 1: Control of the combined action of the excavator's traveling and bucket Scene description When a certain type of hydraulic excavator is operating on a slope, it needs to perform traveling (climbing) and bucket closing actions simultaneously. Due to flow competition in the traditional method, the traveling speed is unstable and the bucket action is slow, posing a risk of slipping.

[0039] Implementation steps 1. Flow detection and demand calculation Engine speed: 1800 rpm, pump displacement 120 cc / rev, pump volumetric efficiency = 0.95 Handle signal parsing: Traveling demand: Handle opening 70% →

[0040] Bucket demand: Handle opening 50% →

[0041] Total demand flow:

[0042] 2. Gradient acceleration control Detect the flow gap: Q = 265 - 205.2 = 59.8 L / min > 10%, trigger acceleration: First stage: Increase to 2200 rpm (upper limit of economic range) at 200 rpm / s, taking 2 seconds: First stage: Increase to 2500 rpm (maximum threshold) at 50 rpm / s, taking 6 seconds: 3. Flow sharing and deviation correction There is still a gap: Q = 265 - 285 = -20 L / min (no need to allocate, but need to monitor deviation); Real-time monitoring: Left walking pressure 28 MPa, right 25 MPa, flow difference: Exceed the threshold (total flow 5% → 14.25 L / min), but the system maintains the current allocation.

[0043] 4. Override control and post-valve compensation Valve opening calculation: Target flow of walking valve 175 L / min → Look up the table to get the opening of 65% → Current I = 850 mA Dynamic safety factor compensation: Oil temperature T = 40 °C, no compensation; Pump efficiency correction = 0.98 ( = 0.95), valve delay = 1.1 Post-valve compensation effect: Flow synchronization error of bilateral walking valves ≤ 2%, travel deviation within 50 meters is 0.3 meters.

[0044] Effect verification: Index Traditional method This application Climbing speed stability ±15% fluctuation ±3% fluctuation Bucket closing time 8.5 seconds 5.2 seconds Number of slope slips 3 times / hour 0 times Example 2: Steering and boom compound action of a loader in a low-temperature environment Scene description A mining loader in a cold region needs to perform a sharp turn (to avoid obstacles) and a boom lift (to load materials) simultaneously at -15 °C. Due to the increased viscosity of the oil, the response of the solenoid valve is delayed in the traditional method, and the compound action is not synchronized.

[0045] Implementation steps and application of technical features 1. Low-temperature start detection The oil temperature sensor reads T = -15°C, activating the low-temperature compensation factor: 2. Flow demand calculation Engine speed after preheating: 2000 rpm, pump displacement 100 cc / rev, = 0.92 (low-temperature efficiency reduction) Handle signal analysis: Steering demand: Handle opening 90% →

[0046] Boom demand: Handle opening 60% →

[0047] Total demand flow:

[0048] 3. Gradient speed increase and flow distribution After the engine reaches 2500 rpm, Flow gap: Q = 390 - 230 = 160 / min, entering the equal distribution mode: 4. Dynamic compensation and real-time control Steering valve current calculation: Target flow 159.2 L / min → Looking up the table, the opening is 55% → Base current I = 720 mA Low-temperature compensation: = 0.95, = 0.92, = 1.15 (valve delay increase), = 1.025 PLUS+1 software response: The time from signal detection to current output is 48 ms, meeting the requirement of ≤50 ms.

[0049] 5. Verification of post-valve compensation synchronization Left and right steering valve flows: , , with a deviation of 0.98%; Boom lifting speed: Measured 0.38 m / s, with an error of 5% from the theoretical value of 0.4 m / s (residual influence of low-temperature viscosity).

[0050] Effect verification Index Traditional method (-15°C) This application Steering response delay 220 ms 48 ms Boom lifting asynchronization error 25% 5% Hydraulic oil temperature recovery time 15 minutes 8 minutes The embodiments of the specific implementation manners are all preferred embodiments of the present application, and do not limit the protection scope of the present application thereby. Identical components are denoted by the same reference numerals. Therefore, all equivalent changes made according to the structure, shape and principle of the present application shall be covered within the protection scope of the present application.

Claims

1. A method for coordinated control of composite actions of a hydraulic system, characterized in that: The following steps are involved: S1, real-time acquisition of engine speed and hydraulic pump displacement parameters, and calculation of the actual output flow of the current system; S2, receiving the input signal of the operating handle, analyzing and obtaining the required flow rate of the walking mechanism and the working mechanism respectively and the total required flow rate; S3, determining whether the total required flow rate exceeds the actual output flow rate, and if so, increasing the engine speed until it reaches the maximum speed threshold; S4: When the engine reaches the maximum speed threshold and there is still a flow gap, start the flow sharing control: S41, calculating the difference between the actual output flow and the total demand flow; S42, allocating available flow to each actuator in proportion according to the preset action priority ratio and the operation signal strength; S43, inversely calculating the opening degree of the hydraulic control valve according to the allocated flow rate, and generating a corresponding overriding control current; S5, output the over-authorization control current to the solenoid valve to replace the original handle control signal.

2. A method for coordinated control of composite actions of a hydraulic system according to claim 1, characterized in that: In step S3, a gradient speed increase strategy is adopted when increasing the engine speed, specifically including: when a flow gap is detected, the speed is increased at a rate of 200 rpm / second; when the speed is increased to the economic speed range, the speed is reduced to 50 rpm / second and continued to increase until the maximum speed threshold is reached.

3. A method for coordinated control of composite actions of a hydraulic system according to claim 1, characterized in that: The preset action priority ratio in step S42 includes: setting a bilateral flow deviation threshold according to the bilateral driving characteristics of the walking mechanism, and when the flow distribution causes the bilateral flow difference to exceed the set threshold, forcibly correcting the flow distribution ratio to make the bilateral flow difference return to the threshold range.

4. A method for coordinated control of composite actions of a hydraulic system according to claim 1, characterized in that: When the overriding control current is generated in step S43, a dynamic safety factor is introduced to perform compensation calculation, and the safety factor is dynamically adjusted according to the volumetric efficiency curve of the hydraulic pump and the current oil pressure parameters.

5. A method for coordinated control of composite actions of a hydraulic system according to claim 1, characterized in that: The flow distribution process in step S43 is implemented by a post-valve compensation mechanism, including: setting a damping plug (B) between the LS signal channel (C) of the multi-way valve and the pressure compensation common channel (A); isolating the LS signal of the valve plate from the pressure compensation common channel (A); and allowing the same LS signal pressure to act on the pressure compensation spring chambers of all multi-way valves.

6. A method for coordinated control of composite actions of a hydraulic system according to claim 5, characterized in that: The synchronous control of the pressure compensation spring chamber allows the output flow of all valve plates to be reduced in the same proportion during compound action.

7. A method for coordinated control of composite actions of a hydraulic system according to claim 5, characterized in that: The aperture of the damping plug (B) is set to 0.8-1.2 mm, and a pressure drop range of 0.2-0.5 MPa is formed on the LS signal channel. The pressure drop value is calibrated by combining oil circuit simulation calculation and bench test.

8. A method for coordinated control of composite actions of a hydraulic system according to claim 4, characterized in that: The safety factor includes a hydraulic pump volumetric efficiency correction value α and a solenoid valve response delay correction value β, wherein α=0.9-1.1, β=1.05-1.2, and a low temperature compensation factor γ=1.15-1.3 is activated when the oil temperature is lower than 20°C.

9. A method for coordinated control of composite actions of a hydraulic system according to claim 1, characterized in that: The preset action priority ratio includes a default equal distribution mode. When no specific priority is set, the available flow is distributed in proportion to the signal strength of each operating handle.

10. A method for coordinated control of composite actions of a hydraulic system according to claim 1, characterized in that: The control method is implemented through the PLUS+1 software platform and loaded in the original control system in the form of a software module, and the output response time of the overriding control current is ≤50ms.

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