Single-pump-driven hydraulic traveling transmission system and multi-shaft synchronous control device and method thereof

Abstract

The application discloses a single-pump-driven hydraulic running transmission system and a multi-axle synchronous control device and method thereof. The system comprises two or more hydraulic transmission circuits arranged in different car sections or different trains. The hydraulic transmission circuit comprises an engine, a transfer case and two or more independent running drive branches. The running drive branch comprises a hydraulic pump, a gear box, a transmission shaft, one or two reverse parallel motors and a first proportional valve connected with the hydraulic pump and a second proportional valve connected with the motor. The engine is connected with the transfer case to transmit power to the hydraulic pump. Two or more hydraulic pumps drive the corresponding motors of the respective branches. The motor is disconnected from and combined with the transmission shaft through the gear box. The motor displacement is controlled through the second proportional valve, and the hydraulic pump displacement is controlled through the first proportional valve. The application can solve the technical problem of synchronous running control of the power car in the section or the train and the power car in the other section or the train.

Description

Technical Field

[0001] This application relates to the field of railway engineering machinery technology, and is applied to large railway maintenance machinery, particularly to a single-pump driven hydraulic travel transmission system and its multi-axis workshop synchronous control device and method. Background Technology

[0002] In the field of rail engineering machinery, hydraulic travel transmission is generally used, achieving axle drive through a hydraulically enclosed travel system. When the vehicle is heavy and needs to operate on long, steep slopes, more stringent power requirements are placed. Not only is strong power needed to ensure normal starting on gradients, but for important railway lines, power redundancy is also essential. In this case, a multi-pump, multi-motor system is required to drive multiple drive shafts. Synchronous control of multiple drive shafts is typically achieved through a combination of hydraulic and software-based integrated control.

[0003] However, multi-axis synchronous movement using hydraulic pumps and motors is a complex and large-scale system, involving the control of the displacement, flow rate, power, and torque of multiple hydraulic pumps and motors, as well as the closed-loop and synchronous control of key physical parameters such as travel speed and pressure. The control process is extremely complex. Therefore, achieving multi-axis synchronous movement control using hydraulic transmission is a significant technical challenge in the field of rail engineering machinery. Although some institutions both domestically and internationally are engaged in research on hydraulic transmission movement, multi-pump + multi-motor multi-axis synchronous movement systems are vast and complex, and research generally remains at the level of simulation or small-scale system studies, lacking practical testing on large-scale engineering vehicles. Furthermore, only a few companies and research institutes both domestically and internationally have conducted relevant research on the synchronous control of hydraulic transmission movement.

[0004] Currently, there are several main technical problems with multi-axis synchronous travel using hydraulic transmission: One reason is the dead zone of the traveling hydraulic pump and the differences in the motor, which cause inconsistent starting among multiple drive shafts; Secondly, due to the differences in the various shaft pumps and motors, there is a problem of inconsistent driving pressure during operation; Thirdly, due to the differences between the various shaft pumps and motors, there is a problem of inconsistent speeds of the driving components.

[0005] In the prior art, the following documents are most similar to this application: Document 1 is a Chinese invention application filed by the Wuxi Research Institute of Huazhong University of Science and Technology on October 25, 2023, and published on January 2, 2024, with publication number CN117329181A. This application discloses a hydraulic synchronous control system, belonging to the technical field of fluid pressure actuators. It includes a hydraulic oil suction device connected to a three-position four-way directional valve, which has A, B, P, and T channels. The A channel of the three-position four-way directional valve is connected to a synchronous motor assembly via a first pipe to allow hydraulic oil to flow into the inlet of the synchronous motor assembly. A first one-way throttle valve is installed on the first pipe. At least one throttle control relief valve is installed at the outlet of the synchronous motor assembly. The throttle control relief valve is connected to one end of a hydraulic cylinder. The other end of the hydraulic cylinder is connected to the B channel of the three-position four-way directional valve via a second pipe, on which a second one-way throttle valve is installed. Reference 1 describes a control technology that uses multiple hydraulic motors to synchronously drive multiple hydraulic cylinders. The synchronization of hydraulic cylinders is achieved through a hydraulic device, which is significantly different from the control method and application scope of this application.

[0006] Document 2 is a Chinese invention application filed by the Special Vehicle Technology Center of Hubei Aerospace Technology Research Institute on July 31, 2020, and published on November 3, 2020, with publication number CN111873792A. This application discloses a synchronous drive control method and device. The method includes: acquiring the throttle signal and gear signal of the master vehicle; determining the hydraulic motor displacement and engine speed of each vehicle based on the throttle signal and gear signal; determining the maximum speed that each vehicle can reach; establishing a parallel driving motion model; determining the turning radius of each vehicle based on the parallel driving motion model; determining the synchronous maximum speed of each vehicle; determining the corresponding initial value of the hydraulic pump displacement; adjusting the corresponding hydraulic pump displacement output value based on the actual driving force, target driving force, and initial value of the hydraulic pump displacement of each vehicle; and synchronously controlling the corresponding vehicle based on the hydraulic pump displacement output value, engine speed, and hydraulic motor displacement. Thus, for each vehicle, the corresponding hydraulic pump displacement output value can be adjusted in a closed loop based on the actual driving force, target driving force, and initial value of the hydraulic pump displacement of that vehicle, ensuring that the entire vehicle group has good synchronization characteristics, thereby avoiding cargo slippage and deviation. Reference 2 mainly introduces how to calculate the displacement of hydraulic pumps and motors and the turning radius of vehicles based on speed and vehicle dynamics models for multiple traveling vehicles driven by an engine, hydraulic pump and hydraulic motor. The synchronization control strategy is the synchronization between vehicles, but does not involve the mutual synchronization control system and method between multiple pumps and multiple motors. Summary of the Invention

[0007] In view of this, the purpose of this application is to provide a single-pump driven hydraulic travel transmission system and its multi-axis synchronous control device and method to solve the technical problem of synchronous travel control between the current section or train of power cars and another section or train of power cars.

[0008] To achieve the aforementioned objectives, this application specifically provides a technical solution for a single-pump driven hydraulic travel transmission system for vehicle hydraulic travel transmission, comprising: two or more hydraulic transmission circuits located in different carriages or different trains; each hydraulic transmission circuit includes: an engine, a transfer case, and two or more independent travel drive branches, each travel drive branch including a hydraulic pump, a gearbox, a drive shaft, one or two motors connected in reverse parallel, a first proportional valve connected to the hydraulic pump, and a second proportional valve connected to the motor; the engine is the power source for travel and is mechanically connected to the transfer case, transmitting power to the hydraulic pump connected to the transfer case through the transfer case; the two or more hydraulic pumps drive the motors corresponding to their respective branches, and the motors are disengaged and engaged with the drive shaft through the gearbox; the second proportional valve controls the motor displacement, and the first proportional valve controls the hydraulic pump displacement to adjust the hydraulic pump flow rate, thereby changing the motor speed and achieving control of the drive shaft torque and speed.

[0009] This application also provides a specific technical implementation scheme for a multi-axis synchronous control device based on the above system, including: The control unit performs synchronous control of the vehicle's drive shaft, calculates the displacement of the hydraulic pump and motor, and performs closed-loop speed control based on the collected signals. The human-machine interface terminal connected to the control unit enables the input of the target speed for low constant speed travel, the display of key travel status information and operating conditions; The digital acquisition module connected to the control unit acquires vehicle control signals, travel direction given signals, vehicle speed and motor speed; The digital output module connected to the control unit drives the travel auxiliary switching valve and the enable valve; The analog signal acquisition module connected to the control unit acquires the high and low pressure of the hydraulic pump, as well as the vehicle control traction command, the target speed of high-speed operation, and the traction handle input signal. The analog output module connected to the control unit outputs the opening control signals of the first proportional valve and the second proportional valve. The constant current module connected to the analog output module converts the analog signal output by the analog output module into a dual-channel constant current signal to control the opening degree of the first proportional valve and the second proportional valve. The speed acquisition module, which is connected to the control unit, acquires the vehicle speed and the speed of all motors.

[0010] This application also provides a specific technical implementation scheme for a multi-axle synchronous control method based on the above-mentioned device, including a multi-axle drive force synchronous control process S2 among multiple cars or trains. The multiple cars or trains include two or more power cars, each power car including one master control car and one or more slave control cars. The process includes the following steps: S21) First, determine the traction and braking relationship between the master vehicle and the slave vehicle. This relationship includes: i) The master vehicle pulls the vehicle while the slave vehicle brakes it; ii) The master vehicle brakes, and the slave vehicle pulls; iii) The master control vehicle tows the slave control vehicle; iv) Master-controlled vehicle braking, slave-controlled vehicle braking; S22) Then determine the magnitude of the braking force or traction force of the master vehicle and the slave vehicle when they are both braking or both traction states; S23) By comparing the magnitude of braking force or traction force, calculate the target value and feedback value that need to be adjusted from the driving force of the vehicle control center axis; S24) The target value and feedback value are used to calculate the displacement output value of the hydraulic pump through closed-loop PID control; S25) The displacement output value of the hydraulic pump is converted into the current signal required by the first proportional valve through the analog output module and the constant current module to control the displacement of the hydraulic pump.

[0011] Furthermore, the multi-axle drive force synchronization control process S2 between multiple cars or trains also includes the following steps: When the driving force or braking force is the same, it indicates that the two vehicles are synchronized, and the target value of the closed-loop PID control equals the feedback value, requiring no adjustment. When there is a difference in the driving force or braking force between the two vehicles, the drive output value of the slave vehicle needs to be adjusted to follow the driving force of the master vehicle. When there is a difference in the driving force or braking force, the traction and braking relationship between the master and slave vehicles is determined, comparing which vehicle has a greater driving force or a greater braking force. If both vehicles are in traction mode, and the slave vehicle has a smaller traction force, then the slave vehicle should increase its driving force output. In this case, its closed-loop PID control target value > feedback value, and the output of the closed-loop PID control increases. The error of the closed-loop PID control is the target value minus the feedback value. The target value equals the relatively larger traction force, and the feedback value equals the relatively smaller traction force. Otherwise, if the slave vehicle has a larger traction force, then the target value of the slave vehicle's closed-loop PID control equals the relatively smaller traction force, and the feedback value equals the relatively larger traction force. If both vehicles are braking, and the slave vehicle has a larger braking force, then the slave vehicle should increase its driving force output. Its closed-loop PID control target value is set to the relatively larger braking force, and the feedback value is set to the relatively smaller braking force. Otherwise, if the slave vehicle has a smaller braking force, its closed-loop PID control target value is set to the relatively smaller braking force, and the feedback value is set to the relatively larger braking force. If the master vehicle is in a traction state and the slave vehicle is braking, then the slave vehicle in the braking state needs to increase its driving force output. Its closed-loop PID control target value is set to (traction force + braking force) / 2, and the feedback value is set to 0. Otherwise, if the master vehicle is braking and the slave vehicle is traction, the slave vehicle's closed-loop PID control target value is set to 0, and the feedback value is set to (traction force + braking force) / 2.

[0012] Furthermore, when the drive pressure of the drive shafts of multiple trains or multiple cars is inconsistent and needs to be adjusted, the car that obtains control is the master control car, and the other cars are slave control cars. Data communication must be established between the master control car and the slave control cars. The interactive data between the two cars includes: vehicle operating conditions, vehicle control input signals, data communication status, vehicle running system preparation status, the target speed set by the car, and the driving force of the car's central shaft.

[0013] Furthermore, multiple cars or multiple trains include two power cars, #1 and #2, one of which is the main control car and the other is the slave control car, and the system pressure is the pressure of the central shaft.

[0014] Under traction conditions, the traction driving force of vehicle #1 = |pressure of vehicle #1 at port A - pressure of vehicle #1 at port B|; Under traction conditions, the traction driving force of car #2 = |pressure of car #2 at port A - pressure of car #2 at port B|; Under braking conditions, the traction braking force of vehicle #1 = |pressure of vehicle #1 at port A - pressure of vehicle #1 at port B|; Under braking conditions, the traction braking force of vehicle #2 = |pressure of vehicle #2 at port A - pressure of vehicle #2 at port B|.

[0015] Furthermore, the method includes a motor displacement adjustment control process S3, which includes the following steps: S3) The control unit collects the motor's rotational speed and uses an algorithm to maintain the motor's displacement at its maximum before the rotational speed reaches the inflection point, controlling the vehicle to start in a constant maximum torque mode. When the motor's rotational speed reaches the inflection point, the control unit calculates the motor displacement adjustment value based on the motor power and switches to constant power mode control, thereby increasing the motor's rotational speed and increasing the vehicle's speed.

[0016] Furthermore, when a communication failure occurs in either of the two power cars, power is simultaneously cut off in both cars.

[0017] Furthermore, when there are two or more slave cars, it is only necessary to determine whether the communication between the slave car and the master car is normal, and all slave cars maintain consistent driving force with the master car as the target.

[0018] By implementing the technical solution of the single-pump driven hydraulic travel transmission system and its multi-axis synchronous control device and method provided in this application, the following beneficial effects are achieved: (1) The single-pump driven hydraulic travel transmission system and its multi-axis synchronous control device and method of this application can effectively solve the technical problem of insufficient driving force caused by inconsistent driving pressure of multiple transmission shafts in the same car section; (2) The single-pump driven hydraulic travel transmission system and its multi-axis synchronous control device and method of this application can effectively solve the technical problem of asynchronous power in workshops with at least two or more power cars; (3) The single-pump driven hydraulic travel transmission system and its multi-axis synchronous control device and method of this application can fully meet the travel drive requirements of the hydraulic drive network system, solve the technical problem of the modular design of synchronous control of multi-section or multi-train power cars, and make the later expansion and transplantation more efficient. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of a single-pump driven hydraulic travel transmission system of this application, which drives the whole vehicle through multiple drive shafts; Figure 2 This is a schematic diagram of the hydraulic transmission circuit structure of a specific embodiment of the single-pump driven hydraulic travel transmission system of this application; Figure 3 This is a system structure block diagram of a specific embodiment of the multi-axis synchronous control device of this application; Figure 4 This is a flowchart of the process for synchronous control of multi-axle driving force in a single-row or single-section vehicle in a specific embodiment of the multi-axle synchronous control method of this application; Figure 5 This is a flowchart of the process for synchronizing the driving force of multiple axles between multiple cars or multiple trains in a specific embodiment of the multi-axle synchronous control method of this application; Figure 6 This is a block diagram illustrating the control principle of adjusting the hydraulic pump displacement output based on the workshop driving force difference in a specific embodiment of the multi-axis synchronous control method of this application. Figure 7 This is a schematic diagram of the motor displacement adjustment control process in a specific embodiment of the multi-axis synchronous control method of this application. Detailed Implementation

[0021] For the sake of clarity and reference, the technical terms, abbreviations, or acronyms used below will be recorded as follows: Open circuit: In an open circuit, the hydraulic pump draws oil from the tank, drives the actuator (such as a hydraulic cylinder or motor) through hydraulic valves, and then the oil returns to the tank. The tank is connected to the atmosphere through an air filter to balance changes in oil volume within the piping system and actuators. Overall, the system is open and connected to the atmosphere. The advantages of an open circuit are its simple structure, lower requirements for the hydraulic pump compared to a closed circuit, lower cost, applicability to various actuators such as cylinders and motors, and better system adaptability.

[0022] A closed circuit refers to a system where the hydraulic pump's suction line is connected to the actuator's return line. In this system, the hydraulic pump's output oil goes directly into the actuator, and the actuator's return oil goes directly into the hydraulic pump's inlet. The hydraulic fluid is contained within the closed system. Because there is no hydraulic tank to balance changes in oil volume, the actuator in a closed system is often a hydraulic motor, with the same inlet and outlet flow rates.

[0023] Hydraulic pump: A device that drives a pump by drawing in hydraulic oil.

[0024] Hydraulic motor: A device that is driven by hydraulic oil and whose speed and torque can be controlled by adjusting the swashplate angle.

[0025] Hydraulic pump + hydraulic motor closed system: A hydraulic closed system in which hydraulic oil is drawn in by a hydraulic pump and driven by the hydraulic oil to work a hydraulic motor. The hydraulic oil circulates in the closed system, and the pressure of the closed system can be maintained by replenishing oil in case of actual leakage.

[0026] Multi-axis synchronization: A method of controlling the driving force to synchronize the driving force when the driving force of multiple drive shafts is inconsistent due to differences in pumps and motors.

[0027] Constant speed driving: A control method in which a target speed is set via a handle or human-machine interface, and the synchronous control system controls the vehicle's running components to adjust the driving force in real time so that the actual speed of the vehicle is close to the target speed.

[0028] AI: Analog In, short for analog signal acquisition.

[0029] DI: Digital In, an abbreviation for digital data acquisition.

[0030] PID: Proportional Integral Derivative.

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. 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.

[0032] As attached Figure 1 To be continued Figure 7 As shown, specific embodiments of the single-pump driven hydraulic travel transmission system and its multi-axis synchronous control device and method of this application are given. The application will be further described below with reference to the accompanying drawings and specific embodiments.

[0033] A single-car power unit only involves speed and pressure control of a single axle and synchronization control between drive shafts. When multiple drive shafts are distributed across at least two car units, synchronization control between the drive shafts of this car and those of other cars becomes involved. Specific embodiments of this application address the technical problem of synchronous running control between this car unit or train and another car unit or train.

[0034] Example 1 As attached Figure 1 As shown, the entire train consists of three cars. Cars A and C are power cars, each with four drive shafts (shafts #1 to #8). Car B is a driven car, with shafts #9 to #12 as driven shafts. The hydraulic travel drive system needs to consider not only the speed and pressure closed-loop control of each shaft (#1 to #4 or #5 to #8) within a single car, but also the synchronization of pressure (driving force) between the four shafts of this car and the four shafts of other cars. This embodiment uses only four shafts as an example to explain in detail how to solve the problem of drive shaft synchronization control within a single car and across multiple cars.

[0035] As attached Figure 2 As shown, an embodiment of the single-pump driven hydraulic travel transmission system of this application is used for the hydraulic travel transmission of multi-axle, multi-car vehicles, and specifically includes: two or more hydraulic transmission circuits set in different car sections or different trains. The hydraulic transmission circuit includes: an engine, a transfer case, and two or more independent travel drive branches. Each travel drive branch includes a hydraulic pump, a gearbox, a drive shaft, one or two motors connected in reverse parallel, a first proportional valve connected to the hydraulic pump, and a second proportional valve connected to the motor. The engine is the power source for travel and is mechanically connected to the transfer case, transmitting power to the hydraulic pump connected to the transfer case. The two or more hydraulic pumps drive the motors corresponding to their respective branches, and the motors are disengaged and engaged with the drive shaft through the gearbox. The second proportional valve controls the motor displacement, and the first proportional valve controls the hydraulic pump displacement to adjust the hydraulic pump flow rate, thereby changing the motor speed and achieving control of the drive shaft torque and speed.

[0036] Engines #1 and #2 may belong to different carriages of the same train, or they may be power sources for different trains. Synchronization control requires addressing the technical challenges of synchronizing the power of this carriage with other carriages, or between this train and other trains. (See appendix...) Figure 2 In this system, engines #1 and #2, serving as power sources, are typically distributed across two cars or two trains, providing power to different cars or trains. The power source for each car / train is divided into multiple hydraulic pumps via a transfer case. Each hydraulic pump, along with one or two motors, forms a closed-loop hydraulic circuit, with each pump driving its own motor. When accommodating both high and low speeds, both hydraulic pumps and motors are typically variable displacement, requiring a first proportional valve for displacement control. Hydraulic pumps #1 (P1) and #2 (P2) have their displacement controlled by the first proportional valve, as do hydraulic pumps #3 (P3) and #4 (P4). Motors #1 (M1) and #2 (M2) have their displacement controlled by a second proportional valve, as do motors #3 (M3) and #4 (M4). Each hydraulic transmission circuit is equipped with a pressure acquisition sensor on the high-pressure / low-pressure side. The high-pressure sensor for hydraulic pump #1 circuit is acquired by sensor F1A, and the low-pressure sensor for hydraulic pump #1 circuit is acquired by sensor F1B. The high-pressure sensor for hydraulic pump #2 circuit is acquired by sensor F2A, and the low-pressure sensor for hydraulic pump #2 circuit is acquired by sensor F2B.

[0037] Example 2 As attached Figure 3 As shown, a multi-axis synchronous control device based on the system described in Embodiment 1 of this application specifically includes: The control unit performs synchronous control of the vehicle's drive shaft, calculates the displacement of the hydraulic pump and motor, and performs closed-loop speed control based on the collected signals. Through a human-machine interface terminal connected to the control unit via an industrial Ethernet bus, but not limited to, the target speed input for low constant speed driving, key driving status information (control, direction, vehicle speed, motor speed, hydraulic pump drive pressure, etc.) and the display of working conditions can be realized. The digital acquisition module connected to the control unit acquires vehicle control signals, travel direction setting signals, vehicle speed, and motor speed. The digital output module connected to the control unit drives the travel auxiliary switching valve and the enable valve; The analog signal acquisition module connected to the control unit acquires the high and low pressure of the hydraulic pump, as well as the vehicle control traction command, the target speed for high-speed operation, and the traction handle input signal (the target vehicle speed input can also be set through the human-machine interface terminal). The analog output module connected to the control unit outputs the opening control signals of the first proportional valve and the second proportional valve. The constant current module connected to the analog output module converts the analog signal (including but not limited to -5~5V or -10V~10V analog signal) output by the analog output module into a dual-channel constant current signal to control the opening of the first proportional valve and the second proportional valve. It is generally equipped with a potentiometer that can adjust the maximum and minimum current to adjust the ratio between the input voltage and the output current and the range of the output value. The speed acquisition module, connected to the control unit, acquires the vehicle speed and the speed of all motors.

[0038] In addition, corresponding sensors are configured to detect the corresponding signals: Install and collect the drive pressure of each drive shaft; Two hydraulic pressure sensors are installed in the closed-loop system corresponding to each drive shaft to detect the high pressure FxA and low pressure FxB of the hydraulic system respectively (x=1~N, where N is the number of drive shafts). Install speed sensors on each drive shaft to detect the motor speed Vx (X=1~n, where n is the number of motors); Install vehicle speed sensors to collect current vehicle speed.

[0039] Example 3 As attached Figure 4 As shown, a multi-axle synchronous control method based on the device described in Embodiment 2 of this application includes a multi-axle drive force synchronous control process S1 within a single train or single car section. This process specifically includes the following steps: S1) In a single - column or single - section vehicle, select a drive shaft in a non - neutral gear as the central shaft, and compare the driving forces of other drive shafts with this drive shaft as the center. If the driving force of a certain drive shaft is less than that of the central shaft, it is considered that the driving force of this drive shaft is too small, and the displacement of the corresponding hydraulic pump needs to be increased. If the driving force of a certain drive shaft is greater than that of the central shaft, it is considered that the driving force of this drive shaft is too large, and the displacement of the corresponding hydraulic pump needs to be reduced. Convert the driving - force difference between the two shafts into the fine - tuning coefficient of the hydraulic pump for other drive shafts, and adjust the opening of the first proportional valve according to the fine - tuning coefficient of the hydraulic pump, thereby adjusting the displacement output value of the hydraulic pump. Complete the synchronization of the driving forces of all drive shafts according to the above process, and the driving forces of the drive shafts in a single train or single - section vehicle will tend to be consistent after a certain period of adjustment. For example: If the driving pressure of the #2 drive shaft is less than the central shaft (#1 drive shaft), it means that the driving force of the #2 drive shaft is too small, and the displacement of the hydraulic pump needs to be increased. If the driving pressure of the #2 drive shaft is greater than the central shaft (#1 drive shaft), it means that the driving force of the #2 drive shaft is too large, and the displacement of the hydraulic pump needs to be reduced. In this way, the driving pressures in a single train or single - section vehicle will tend to be consistent after a certain period of adjustment.

[0040] When there are multiple trains or multiple sections of vehicles, there may be inconsistent driving pressures of the central shafts of each train or each section, and adjustment is required. Synchronization of multiple sections of vehicles involves which vehicle is the master - control vehicle and which vehicle is the slave - control vehicle. Generally, the vehicle that obtains control rights is the master - control vehicle, and other vehicles are slave - control vehicles, and data communication must be established between the two vehicles. Multiple - section vehicles or multiple trains include two powered vehicles, vehicle #1 and vehicle #2, where one is the master - control vehicle and the other is the slave - control vehicle, and the system pressure is the absolute value of the difference between the system pressure at port A and the system pressure at port B of the hydraulic transmission circuit.

[0041] For example, the vehicle hydraulic system is designed as follows: When driving in the forward direction for traction, the system pressure at port A of the hydraulic transmission circuit of vehicle #1 ≥ the system pressure at port B, and the system pressure at port B of the hydraulic transmission circuit of vehicle #2 ≥ the system pressure at port A; When driving in the reverse direction for traction, the system pressure at port A of the hydraulic transmission circuit of vehicle #1 < the system pressure at port B, and the system pressure at port B of the hydraulic transmission circuit of vehicle #2 < the system pressure at port A; Then: When driving in the forward direction, if the system pressure at port A of the hydraulic transmission circuit of vehicle #1 ≥ the system pressure at port B, then vehicle #1 is in the traction state; When driving in the forward direction, if the system pressure at port B of the hydraulic transmission circuit of vehicle #2 ≥ the system pressure at port A, then vehicle #2 is in the traction state; When driving in the reverse direction, if the system pressure at port A of the hydraulic transmission circuit of vehicle #1 < the system pressure at port B, then vehicle #1 is in the traction state; When driving in the reverse direction, if the system pressure at port B of the hydraulic transmission circuit of vehicle #2 < the system pressure at port A, then vehicle #2 is in the traction state; In the forward direction, if the system pressure at port A of the hydraulic transmission circuit of vehicle #1 < the system pressure at port B, then vehicle #1 is in the braking state; In the forward direction, if the system pressure at port B of the hydraulic transmission circuit of vehicle #2 < the system pressure at port A, then vehicle #2 is in the braking state; In the reverse direction, if the system pressure at port A of the hydraulic transmission circuit of vehicle #1 ≥ the system pressure at port B, then vehicle #1 is in the braking state; In the reverse direction, if the system pressure at port B of the hydraulic transmission circuit of vehicle #2 ≥ the system pressure at port A, then vehicle #2 is in the braking state; In the traction state, the traction driving force of vehicle #1 = |the system pressure at port A of vehicle #1 - the system pressure at port B of vehicle #1| = the system pressure at port A of vehicle #1 - the system pressure at port B of vehicle #1; In the traction state, the traction driving force of vehicle #2 = |the system pressure at port A of vehicle #2 - the system pressure at port B of vehicle #2| = the system pressure at port B of vehicle #2 - the system pressure at port A of vehicle #2; In the braking state, the traction braking force of vehicle #1 = |the system pressure at port A of vehicle #1 - the system pressure at port B of vehicle #1| = the system pressure at port B of vehicle #1 - the system pressure at port A of vehicle #1; In the braking state, the traction braking force of vehicle #2 = |the system pressure at port A of vehicle #2 - the system pressure at port B of vehicle #2| = the system pressure at port A of vehicle #2 - the system pressure at port B of vehicle #2.

[0042] The actual design may also be: when traction driving in the forward direction, the system pressure at port A of the hydraulic transmission circuit of vehicle #1 < the system pressure at port B, and the system pressure at port B of the hydraulic transmission circuit of vehicle #2 < the system pressure at port A; when traction driving in the reverse direction, the system pressure at port A of the hydraulic transmission circuit of vehicle #1 ≥ the system pressure at port B, and the system pressure at port B of the hydraulic transmission circuit of vehicle #2 ≥ the system pressure at port A.

[0043] It may also be: when traction driving in the forward direction, the system pressure at port A of the hydraulic transmission circuit of vehicle #1 ≥ the system pressure at port B, and the system pressure at port A of the hydraulic transmission circuit of vehicle #2 ≥ the system pressure at port B; when traction driving in the reverse direction, the system pressure at port A of the hydraulic transmission circuit of vehicle #1 < the system pressure at port B, and the system pressure at port A of the hydraulic transmission circuit of vehicle #2 < the system pressure at port B.

[0044] The multi-axis synchronous control method further includes the multi-axis driving force synchronous control process S2) between multiple cars or multiple trains. Multiple cars or multiple trains include two or more powered cars. The powered car includes one master control car and one or more slave control cars. This process further includes the following steps: S21) First, judge the traction and braking state relationship between the master control car and the slave control car. This relationship includes: ⅰ) The master control car is in traction and the slave control car is in braking; ⅱ) The master control car is in braking and the slave control car is in traction; iii) The master control vehicle tows the slave control vehicle; iv) Master-controlled vehicle braking, slave-controlled vehicle braking; S22) Then determine the magnitude of the braking force or traction force of the master vehicle and the slave vehicle when they are both braking or tractioning; S23) By comparing the magnitude of braking force or traction force, calculate the target value and feedback value that need to be adjusted from the driving force of the vehicle control center axis; S24) The target value and feedback value are used to calculate the displacement output value of the hydraulic pump through closed-loop PID control; S25) The hydraulic pump's displacement output value is converted into the current signal required by the first proportional valve via the analog output module and constant current module to control the hydraulic pump's displacement, as shown in the attached diagram. Figure 5 As shown.

[0045] As attached Figure 6 As shown, the multi-axle drive force synchronization control process S2 between multiple cars or multiple trains also includes the following steps: When the driving force or braking force is the same, it indicates that the two vehicles are synchronized, and the target value of the closed-loop PID control equals the feedback value, requiring no adjustment. When there is a difference in the driving force or braking force between the two vehicles, the drive output value of the slave vehicle needs to be adjusted to follow the driving force of the master vehicle. When there is a difference in the driving force or braking force, the traction and braking relationship between the master and slave vehicles is determined, comparing which vehicle has a greater driving force or a greater braking force. If both vehicles are in traction mode, and the slave vehicle has a smaller traction force, then the slave vehicle should increase its driving force output. In this case, the target value of its closed-loop PID control will be greater than the feedback value, and the output of the closed-loop PID control will increase. The error of the closed-loop PID control is the target value minus the feedback value. The target value equals the relatively larger traction force, and the feedback value equals the relatively smaller traction force. Otherwise, if the slave vehicle has a larger traction force, then the target value of the slave vehicle's closed-loop PID control equals the relatively smaller traction force, and the feedback value equals the relatively larger traction force. If both vehicles are braking, and the slave vehicle has a larger braking force, it should increase its driving force output. Its closed-loop PID control target value is set to the relatively larger braking force, and the feedback value to the relatively smaller braking force. Otherwise, if the slave vehicle has a smaller braking force, its closed-loop PID control target value is set to the relatively smaller braking force, and the feedback value to the relatively larger braking force. If the master vehicle is in traction mode and the slave vehicle is braking, the slave vehicle in braking mode needs to increase its driving force output. Its closed-loop PID control target value is set to (traction force + braking force) / 2, and the feedback value is set to 0. Otherwise, if the master vehicle is braking and the slave vehicle is traction, the slave vehicle's closed-loop PID control target value is set to 0, and the feedback value is set to (traction force + braking force) / 2. In the diagram, mark = 511 indicates that both vehicles are in traction drive mode, with the traction force of the master vehicle being greater than that of the slave vehicle, but the error is within the dead zone; mark = 521 indicates that both vehicles are in braking mode, with the braking force of the slave vehicle being greater than that of the master vehicle, but the error is within the dead zone; mark = 522 indicates that both vehicles are in braking mode, with the braking force of the master vehicle being greater than that of the slave vehicle, but the error is within the dead zone; mark = 512 indicates that both vehicles are in traction drive mode, with the traction force of the slave vehicle being greater than that of the master vehicle, but the error is within the dead zone.

[0046] As attached Figure 7 As shown, the multi-axis synchronous control method also includes a motor displacement adjustment control process (S3). The motor displacement control is adjusted using either software or hardware methods based on the vehicle's operating mode. This process further includes the following steps: S3) In normal network operation, the control unit collects the motor's rotational speed and uses an algorithm to maintain the motor's displacement at its maximum before the speed reaches the inflection point, controlling the vehicle to start in a constant maximum torque mode. When the motor's speed reaches the inflection point, the control unit calculates the motor displacement adjustment value based on the motor power and switches to constant power mode control, thereby increasing the motor speed and vehicle speed. The motor's inflection point speed is adjusted according to the motor's characteristics to meet the differentiated needs of different motors. In emergency driving mode, the motor displacement is adjusted through hardware circuitry to meet emergency driving requirements.

[0047] When the drive pressure of the drive shafts of multiple trains or cars is inconsistent and needs to be adjusted, the car that gains control becomes the master control car, and the other cars become slave control cars. Data communication must be established between the master control car and the slave control cars. The interactive data between the two cars further includes: vehicle operating conditions, vehicle control input signals, data communication status, vehicle running system readiness status, the target speed set by the car, and the drive force of the car's central shaft.

[0048] When two power cars experience a communication failure, both power cars will simultaneously lose power; otherwise, the master and slave cars will be dragged in opposite directions, which could easily cause wheel rubbing. When there are more than two slave cars, it is only necessary to determine whether the communication between the slave cars and the master car is normal. All slave cars will maintain consistent driving force with the master car as the target.

[0049] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0050] In the description of this application, it should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly set on the other element or indirectly set on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0051] It should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0052] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" or "several" means two or more, unless otherwise explicitly specified.

[0053] It should be noted that the structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only used to complement the content disclosed in the specification for those skilled in the art to understand and read, and are not intended to limit the conditions under which this application can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and purposes that this application can produce, should still fall within the scope of the technical content disclosed in this application.

[0054] By implementing the technical solutions of the single-pump driven hydraulic travel transmission system and its multi-axis synchronous control device and method described in the specific embodiments of this application, the following technical effects can be achieved: (1) The single-pump driven hydraulic travel transmission system and its multi-axis synchronous control device and method described in the specific embodiments of this application can effectively solve the technical problem of insufficient driving force caused by inconsistent driving pressure of multiple transmission shafts in the same car section; (2) The single-pump driven hydraulic travel transmission system and its multi-axis synchronous control device and method described in the specific embodiments of this application can effectively solve the technical problem of asynchronous power in workshops with at least two or more power cars; (3) The single-pump driven hydraulic travel transmission system and its multi-axis synchronous control device and method described in the specific embodiments of this application can fully meet the travel drive requirements of the hydraulic drive network system, solve the technical problem of the modular design of synchronous control of multiple sections or multiple trains of power cars, and make subsequent expansion and transplantation more efficient.

[0055] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0056] The above description is merely a preferred embodiment of this application and is not intended to limit the application in any way. Although this application has been disclosed above with reference to preferred embodiments, it is not intended to limit the application. Any person skilled in the art can make many possible variations and modifications to the technical solutions of this application using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the spirit and technical essence of this application. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of this application without departing from the content of the technical solutions of this application shall still fall within the protection scope of the technical solutions of this application.

Claims

1. A single-pump driven hydraulic travel transmission system, characterized in that, For vehicle hydraulic travel transmission, comprising: two or more hydraulic transmission circuits located in different carriages or different trains; each hydraulic transmission circuit includes: an engine, a transfer case, and two or more independent travel drive branches, each travel drive branch including a hydraulic pump, a gearbox, a drive shaft, one or two motors connected in opposite parallel, a first proportional valve connected to the hydraulic pump, and a second proportional valve connected to the motor; the engine is the power source for travel and is mechanically connected to the transfer case, transmitting power to the hydraulic pump connected to the transfer case through the transfer case; the two or more hydraulic pumps drive the motors corresponding to their respective branches, and the motors are disengaged and engaged with the drive shaft through the gearbox; the second proportional valve controls the motor displacement, and the first proportional valve controls the hydraulic pump displacement to adjust the hydraulic pump flow rate, thereby changing the motor speed and achieving control of the drive shaft torque and speed.

2. A multi-axis synchronous control device based on the system of claim 1, characterized in that, include: The control unit performs synchronous control of the vehicle's drive shaft, calculates the displacement of the hydraulic pump and motor, and performs closed-loop speed control based on the collected signals. The human-machine interface terminal connected to the control unit enables the input of the target speed for low constant speed travel, the display of key travel status information and operating conditions; The digital acquisition module connected to the control unit acquires vehicle control signals, travel direction given signals, vehicle speed and motor speed; The digital output module connected to the control unit drives the travel auxiliary switching valve and the enable valve; The analog signal acquisition module connected to the control unit acquires the high and low pressure of the hydraulic pump, as well as the vehicle control traction command, the target speed of high-speed operation, and the traction handle input signal. The analog output module connected to the control unit outputs the opening control signals of the first proportional valve and the second proportional valve. The constant current module connected to the analog output module converts the analog signal output by the analog output module into a dual-channel constant current signal to control the opening degree of the first proportional valve and the second proportional valve. The speed acquisition module, which is connected to the control unit, acquires the vehicle speed and the speed of all motors.

3. A multi-axis synchronous control method based on the device described in claim 2, characterized in that, This includes a multi-axle drive force synchronization control process S1 within a single train or single car section, which comprises the following steps: S1) Within a single train or car, a non-neutral driveshaft is selected as the central shaft, and the driving forces of other driveshafts are compared with this central shaft. If the driving force of a certain driveshaft is less than that of the central shaft, it is considered that the driving force of that driveshaft is too small, and the displacement of the corresponding hydraulic pump needs to be increased. If the driving force of a certain driveshaft is greater than that of the central shaft, it is considered that the driving force of that driveshaft is too large, and the displacement of the corresponding hydraulic pump needs to be reduced. The difference in driving force between the two shafts is converted into the hydraulic pump fine-tuning coefficient of the other driveshafts. The opening of the first proportional valve is adjusted according to the hydraulic pump fine-tuning coefficient, thereby adjusting the displacement output value of the hydraulic pump. By synchronizing the driving force of all driveshafts according to the above process, the driving force of the driveshafts within a single train or car tends to be consistent after a certain period of adjustment.

4. The multi-axis synchronous control method according to claim 2 or 3, characterized in that, The process includes a multi-axle drive force synchronization control process (S2) among multiple cars or trains. The multiple cars or trains include two or more power cars, each power car comprising one master control car and one or more slave control cars. This process includes the following steps: S21) First, determine the traction and braking relationship between the master vehicle and the slave vehicle. This relationship includes: i) The master vehicle pulls the vehicle while the slave vehicle brakes it; ii) The master vehicle brakes, and the slave vehicle pulls; iii) The master control vehicle tows the slave control vehicle; iv) Master-controlled vehicle braking, slave-controlled vehicle braking; S22) Then determine the magnitude of the braking force or traction force of the master vehicle and the slave vehicle when they are both braking or both traction states; S23) By comparing the magnitude of braking force or traction force, calculate the target value and feedback value that need to be adjusted from the driving force of the vehicle control center axis; S24) The target value and feedback value are used to calculate the displacement output value of the hydraulic pump through closed-loop PID control; S25) The displacement output value of the hydraulic pump is converted into the current signal required by the first proportional valve through the analog output module and the constant current module to control the displacement of the hydraulic pump.

5. The multi-axis synchronous control method according to claim 4, characterized in that, The multi-axle drive force synchronization control process S2 between multiple cars or trains also includes the following steps: When the driving force or braking force is the same, it indicates that the two vehicles are synchronized, and the target value of the closed-loop PID control equals the feedback value, requiring no adjustment. When there is a difference in the driving force or braking force between the two vehicles, the drive output value of the slave vehicle needs to be adjusted to follow the driving force of the master vehicle. When there is a difference in the driving force or braking force, the traction and braking relationship between the master and slave vehicles is determined, comparing which vehicle has a larger driving force or a larger braking force. If both vehicles are in traction mode, and the slave vehicle has a smaller traction force, then the slave vehicle should increase its driving force output. In this case, the target value of its closed-loop PID control will be greater than the feedback value, and the output of the closed-loop PID control will increase. The error of the closed-loop PID control is the target value minus the feedback value, where the target value equals the relatively larger traction force, and the feedback value equals the relatively smaller traction force. Otherwise, if the slave vehicle has a larger traction force, then the slave vehicle's closed-loop PID control... The target value of the D control is a relatively small traction force, and the feedback value is a relatively large traction force. If both vehicles are braking, and the slave vehicle has a larger braking force, then the slave vehicle should increase its driving force output. Its closed-loop PID control target value is a relatively large braking force, and the feedback value is a relatively small braking force. Otherwise, if the slave vehicle has a smaller braking force, its closed-loop PID control target value is a relatively small braking force, and the feedback value is a relatively large braking force. If the master vehicle is in a traction state and the slave vehicle is braking, then the slave vehicle in the braking state needs to increase its driving force output. Set its closed-loop PID control target value to (traction force + braking force) / 2, and the feedback value to 0. Otherwise, if the master vehicle is braking and the slave vehicle is in a traction state, set the slave vehicle's closed-loop PID control target value to 0, and the feedback value to (traction force + braking force) / 2.

6. The multi-axis synchronous control method according to claim 3 or 5, characterized in that: When the drive pressure of the drive shafts of multiple trains or multiple cars is inconsistent and needs to be adjusted, the car that obtains control shall be the master control car and the other cars shall be the slave control cars. Data communication must be established between the master control car and the slave control cars. The interactive data between the two vehicles includes: vehicle operating conditions, vehicle control input signals, data communication status, vehicle running system readiness status, target speed set by the vehicle, and driving force of the vehicle's central axis.

7. The multi-axis synchronous control method according to claim 6, characterized in that: Multiple cars or multiple trains include two power cars, #1 and #2, one of which is the main control car and the other is the slave control car. The system pressure is the pressure of the central shaft. Under traction conditions, the traction driving force of vehicle #1 = |pressure of vehicle #1 at port A - pressure of vehicle #1 at port B|; Under traction conditions, the traction driving force of car #2 = |pressure of car #2 at port A - pressure of car #2 at port B|; Under braking conditions, the traction braking force of vehicle #1 = |pressure of vehicle #1 at port A - pressure of vehicle #1 at port B|; Under braking conditions, the traction braking force of vehicle #2 = |pressure of vehicle #2 at port A - pressure of vehicle #2 at port B|.

8. The multi-axis synchronous control method according to claim 3, 5, or 7, characterized in that, This includes the motor displacement adjustment control process S3, which includes the following steps: S3) The control unit collects the motor speed and uses an algorithm to keep the motor displacement at its maximum before the speed reaches the inflection point, so that the vehicle starts in a constant maximum torque mode when starting. When the motor speed reaches the inflection point, the control unit calculates the motor displacement adjustment value based on the motor power and switches to constant power mode control to increase the motor speed and increase the vehicle speed.

9. The multi-axis synchronous control method according to claim 8, characterized in that: When a communication failure occurs in either of the two power cars, power is simultaneously cut off in both cars.

10. The multi-axis synchronous control method according to claim 9, characterized in that: When there are two or more slave cars, it is only necessary to determine whether the communication between the slave car and the master car is normal, and all slave cars maintain consistent driving force with the master car as the target.

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