Multi-pump parallel hydraulic traveling transmission system and multi-shaft synchronous control device and method thereof

Abstract

The application discloses a kind of multi-pump parallel hydraulic running transmission system and its multi-axis synchronous control device and method, system includes: engine, transfer case, gear box, transmission shaft, two or more above running pump and two or more above motor. Engine is running power source, with transfer case mechanical connection, power is transmitted to running pump connected with transfer case by transfer case. Two or more above running pump parallel drive two or more parallel motor work, motor is realized with transmission shaft by gear box and is combined with the separation. System also includes first proportional valve connected with running pump, and second proportional valve connected with motor. The displacement of motor is controlled by second proportional valve, and the flow of running pump is adjusted by controlling the displacement of running pump by first proportional valve, so as to change the rotating speed of motor, realize the control of transmission shaft torque and rotating speed. The application can solve the technical problems of inconsistent starting, driving force and speed between transmission shafts in the existing running transmission mode.

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 multi-pump parallel hydraulic travel transmission system and its multi-axis 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; Fourth, it uses multiple pumps and multiple motors to drive multiple transmission shafts, which makes the synchronous control algorithm complex, has many control parameters, and requires a long time to debug for matching. Fifth, the system has low reliability, lacks power redundancy, and is neither flexible nor convenient to disconnect or add power.

[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 multi-pump parallel hydraulic travel transmission system and its multi-axis synchronous control device and method, so as to solve the technical problem of inconsistent starting, driving force and speed between transmission shafts in the existing hydraulic travel transmission method.

[0008] To achieve the aforementioned objectives, this application specifically provides a technical solution for a multi-pump parallel hydraulic travel transmission system for vehicle hydraulic travel transmission, comprising: an engine, a transfer case, a gearbox, a drive shaft, two or more travel pumps, and two or more motors. The engine serves as the power source for travel and is mechanically connected to the transfer case, transmitting power to the travel pumps connected to the transfer case. Two or more travel pumps drive two or more parallel motors, with the motors being disengaged and engaged with the drive shaft via the gearbox. The system also includes a first proportional valve connected to the travel pumps and a second proportional valve connected to the motors. The second proportional valve controls the motor displacement, while the first proportional valve controls the travel pump displacement to adjust the flow rate of the travel pumps, thereby changing the motor speed and controlling the torque and speed of the drive shaft.

[0009] Furthermore, when there is only one engine, the engine transmits power to two or more travel pumps connected to the transfer case via a transfer case, and the motors are connected to their respective drive shafts via their respective gearboxes.

[0010] Furthermore, when the number of engines is N or more, where N≥2, each engine operates independently and is connected to its own travel pump via a transfer case, dividing the power into N independent groups. Each group of power is connected to two or more travel pumps, which are then connected in parallel through a manifold valve to form a main hydraulic circuit, which in turn drives two or more motors. Each motor is connected to its corresponding driveshaft via its own gearbox. Each motor or several motors form a group that drives one driveshaft, and multiple driveshafts work together to drive the vehicle.

[0011] Furthermore, when there are two engines, the two engines operate independently, each connected to its own travel pump via a transfer case, resulting in two independent power groups. The flow control valves include a first flow control valve, a second flow control valve, a third flow control valve, and a fourth flow control valve. One end of two or more travel pumps belonging to one power group is connected in parallel to one side of the transmission system circuit via the first flow control valve, and one end of two or more travel pumps belonging to the other power group is connected in parallel to one side of the transmission system circuit via the second flow control valve. The other end of two or more travel pumps belonging to one power group is connected in parallel to the other side of the transmission system circuit via the third flow control valve, and the other end of two or more travel pumps belonging to the other power group is connected in parallel to the other side of the transmission system circuit via the fourth flow control valve. By controlling the opening and closing of the first, second, third, or fourth flow control valves, the two power groups can be engaged or disengaged. When one power group needs to be engaged, the first and third flow control valves are opened simultaneously; otherwise, they are closed. When the other power group needs to be engaged, the second and fourth flow control valves are opened simultaneously; otherwise, they are closed.

[0012] Furthermore, the motor is a variable displacement motor.

[0013] Furthermore, the travel pump is a variable pump. When the engine speed is constant, the flow rate of the travel pump is controlled by controlling the displacement of the travel pump, thereby changing the speed of the motor and realizing the control of the torque and speed of the drive shaft.

[0014] 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 travel 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 analog signal acquisition module connected to the control unit acquires the high and low pressure of the travel pump, as well as the vehicle control traction command, the target speed of high-speed operation, and the hand 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, connected to the control unit, acquires the vehicle speed and the speed of all motors; The digital output module connected to the control unit controls the opening and closing of the flow combiner valve, enabling the individual or simultaneous activation of N power groups, and the isolation of faulty power.

[0015] This application also provides a technical implementation scheme for a multi-axis synchronous control method based on the above-mentioned device. The control method includes a traveling pump displacement adjustment control process, which includes the following steps: The control unit first acquires the motor's rotational speed, calculates it using the gearbox's high and low speed ratio coefficients and the motor's gear ratio, and compares it with the target speed to calculate the speed error of the drive shaft. Based on this speed error, it performs closed-loop PID control to calculate the speed loop output value. The speed loop output value is then converted into the current signal required by the first proportional valve via an analog output module and a constant current module, controlling the displacement of the travel pump. With a constant motor flow rate, adjusting the motor's displacement changes its rotational speed, thereby changing the vehicle's speed. The motor's rotational speed is taken as the average of the rotational speeds of all engaged motors. When a motor malfunction is detected, that motor is disabled, and the average rotational speed is recalculated based on the number of engaged motors.

[0016] Furthermore, the control method includes a motor displacement adjustment control process, which includes the following steps: 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.

[0017] Furthermore, the control method includes a minimum drive displacement calibration process for the traveling pump, which includes the following steps: Open the human-machine interface terminal's operating mode, select the vehicle's direction of travel, click "Start Calibration," and select one of the travel pumps. The corresponding button will flash; only one travel pump can be calibrated at a time. At this point, the output valve on the travel pump's minimum drive displacement calibration interface will display 0% output. Slowly increase the output threshold until a pressure differential begins to build up, then slowly decrease the output threshold until the pressure differential reaches 0. Repeat this adjustment 2-3 times to confirm the travel pump's minimum drive displacement output value, and then save the calibration. Use this process to calibrate each subsequent travel pump.

[0018] Furthermore, the control method includes a calibration process for the maximum drive displacement output value of the traveling pump, which includes the following steps: Open the human-machine interface terminal, select the vehicle's direction of travel, and click "Start Calibration." Select one of the travel pumps; the corresponding button will flash. Only one travel pump can be calibrated at a time. At this point, the output valve on the travel pump's maximum drive displacement calibration interface will display 0% output. Slowly increase the output threshold until the vehicle speed stabilizes and stops increasing. Then slowly decrease the output threshold until the vehicle speed decreases slightly. Repeat this adjustment 2-3 times to confirm the travel pump's maximum drive displacement output value, and then save the calibration. Use this process to calibrate each subsequent travel pump.

[0019] Furthermore, the displacement of the traveling pump is set to be consistent.

[0020] Furthermore, the displacement of the motor is set to be consistent.

[0021] By implementing the technical solution of the multi-pump parallel 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 multi-pump parallel hydraulic travel transmission system and its multi-axis synchronous control device and method of this application can fully meet the drive requirements of the system technical solution based on different travel pumps + motors, and avoid the technical problem of inconsistent multi-axis travel start; (2) The multi-pump parallel hydraulic travel transmission system and its multi-axis synchronous control device and method of this application can effectively solve the technical problems of asynchronous starting of multiple travel pumps due to differences and asynchronous travel speed of multiple axes, and can effectively meet the hydraulic drive constant speed control (including at least two modes: high-speed travel and low constant speed operation). (3) The multi-pump parallel 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 different transmission shafts during travel, and thus solve the technical problem of insufficient starting power, especially insufficient starting power on slopes. (4) The multi-pump parallel hydraulic travel transmission system and its multi-axis synchronous control device and method of this application can overcome the defect of inconsistent driving pressure of multi-axis synchronous travel, avoid individual shafts being dragged back or even damaged due to asynchrony, and control the synchronous travel of each shaft to give full play to the maximum driving force of the hydraulic travel system. (5) The multi-pump parallel hydraulic travel transmission system and its multi-axis synchronous control device and method of this application effectively avoid the complex synchronous control algorithm and parameter matching adjustment problem, simplify the control algorithm and logic, reduce the control parameters and system control complexity, and shorten the debugging cycle; (6) The multi-pump parallel hydraulic travel transmission system and its multi-axis synchronous control device and method of this application have the functions of simultaneous input of multiple power groups and individual fault isolation, and have power redundancy, which greatly improves the safety and reliability of the system. Attached Figure Description

[0022] 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.

[0023] Figure 1 This is a schematic diagram of the hydraulic transmission circuit structure of a specific embodiment of the multi-pump parallel hydraulic travel transmission system of this application; Figure 2 This is a schematic diagram of the hydraulic transmission circuit structure of another specific embodiment of the multi-pump parallel 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 block diagram illustrating the principle of travel pump displacement adjustment control in a specific embodiment of the multi-axis synchronous control method of this application. Figure 5 This is a schematic diagram of the travel motor displacement adjustment control in a specific embodiment of the multi-axis synchronous control method of this application; Figure 6 This is a schematic diagram of the minimum displacement drive value calibration interface of the traveling pump in a specific embodiment of the multi-axis synchronous control method of this application; Figure 7 This is a schematic diagram of the calibration interface for the maximum displacement drive value of the traveling pump in a specific embodiment of the multi-axis synchronous control method of this application. Detailed Implementation

[0024] 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.

[0025] 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.

[0026] Hydraulic pump: A device that drives a pump by drawing in hydraulic oil.

[0027] Hydraulic motor: A device that is driven by hydraulic oil and whose speed and torque can be controlled by adjusting the swashplate angle.

[0028] 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.

[0029] 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.

[0030] AI: Analog In, an abbreviation for analog signal acquisition.

[0031] DI: Digital In, an abbreviation for digital data acquisition.

[0032] PID: Proportional Integral Derivative.

[0033] 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.

[0034] As attached Figure 1 To be continued Figure 7 The accompanying drawings illustrate a specific embodiment of the multi-pump parallel hydraulic travel transmission system and its multi-axis synchronous control device and method of this application. The system employs hydraulic transmission to achieve synchronous travel control of multiple drive shafts, including a hydraulic transmission system, hardware control device, and a control method integrating hydraulics and software, thereby realizing functions such as synchronous control of the travel driving force of multiple drive shafts. The following description, in conjunction with the accompanying drawings and specific embodiments, further illustrates this application.

[0035] Example 1 An embodiment of the multi-pump parallel hydraulic travel transmission system of this application is used for vehicle hydraulic travel transmission. Specifically, it includes: an engine, a transfer case, a gearbox, a drive shaft, two or more travel pumps (specifically hydraulic pumps), and two or more motors (specifically hydraulic motors). The engine is the power source for travel and is mechanically connected to the transfer case, transmitting power to the travel pumps connected to the transfer case. The two or more travel pumps drive two or more parallel motors, with the motors being disengaged and engaged with the drive shaft via the gearbox. The system also includes a first proportional valve connected to the travel pumps and a second proportional valve connected to the motors. The second proportional valve controls the motor displacement, and the first proportional valve controls the travel pump displacement to adjust the flow rate of the travel pumps, thereby changing the motor speed and controlling the torque and speed of the drive shaft.

[0036] As attached Figure 1 As shown, when there is only one engine, the engine transmits power to two or more travel pumps connected to the transfer case via a transfer case. Each motor is connected to its corresponding driveshaft via its own gearbox. When there are N or more engines (N≥2), each engine operates independently, connected to its own travel pump via a transfer case, dividing the power into N independent groups. Each group of power is connected to two or more travel pumps, which are then connected in parallel through a manifold valve to form a main hydraulic circuit, driving two or more motors. Each motor is connected to its corresponding driveshaft via its own gearbox. Each motor or several motors form a group driving one driveshaft, and multiple driveshafts work together to drive the vehicle.

[0037] As attached Figure 2As shown, when there are two engines, the two engines are independent of each other and are connected to their respective travel pumps through a transfer case. The power is divided into two independent groups (including Group I power and Group II power). The flow control valves include a first flow control valve, a second flow control valve, a third flow control valve, and a fourth flow control valve. One end of two or more travel pumps belonging to one group of power (Group I power) (Group I power source travel pumps, including travel pump 1# and travel pump 2#) is connected in parallel to one side of the transmission system circuit (i.e., side A, also known as the upper side) through the first flow control valve (flow control valve 1). One end of two or more travel pumps belonging to the other group of power (Group II power) (Group II power source travel pumps, including travel pump 3# and travel pump 4#) is connected in parallel to one side of the transmission system circuit (i.e., side A, also known as the upper side) through the second flow control valve (flow control valve 2). Two or more traveling pumps belonging to one power group (Group I power source traveling pumps, including traveling pump 1# and traveling pump 2#) are connected in parallel to the other side of the transmission system circuit (i.e., side B, also known as the lower side) via a third combiner valve (combiner valve 3). Two or more traveling pumps belonging to another power group (Group II power source traveling pumps, including traveling pump 3# and traveling pump 4#) are connected in parallel to the other side of the transmission system circuit (i.e., side B, also known as the lower side) via a fourth combiner valve (combiner valve 4). The activation or deactivation of the two power groups is achieved by controlling the opening and closing of the first, second, third, or fourth combiner valves. When one power group (e.g., Group I power) needs to be activated, both the first and third combiner valves (combiner valve 1 and combiner valve 3) are opened simultaneously; otherwise, they are closed. When another power group (e.g., Group II power) needs to be activated, both the second and fourth combiner valves (combiner valve 2 and combiner valve 4) are opened simultaneously; otherwise, they are closed.

[0038] After the traveling pumps are connected in parallel, they simultaneously drive multiple (traveling hydraulic) motors. These motors can be either fixed-displacement or variable-displacement motors; for applications requiring both high and low-speed operation, variable-displacement motors are generally used. The traveling pumps themselves are variable-displacement pumps. With a constant engine speed, the flow rate of the traveling pumps is controlled by adjusting their displacement, thereby changing the motor speed and controlling the torque and speed of the drive shaft. The motors are then disengaged and engaged with the (traveling) drive shaft via a gearbox.

[0039] The advantage of using multiple pumps in parallel (at least two pumps) to drive multiple motors (at least two motors), and then having multiple motors drive multiple shafts, is that: 1) The number of detection sensors in the system was reduced, thereby lowering design costs and saving vehicle layout space; 2) Since multiple pumps are connected in parallel, the pressure in the high and low pressure pipelines is consistent, thus avoiding the complex technical problems of synchronous control of pressure driven by multiple shafts, which can reduce the product design and commissioning cycle. 3) Multiple motors are also driven by the same pipeline pressure in parallel, avoiding the technical problem of inconsistent input pressure of the drive motor; 4) If multiple pumps connected in parallel are used as variable pumps, the control variable of the variable pump can be reduced from multiple to one because the high and low pressure circuits are connected in parallel, thus reducing the complexity of control. 5) Multiple motors can be connected in parallel, or multiple variable pumps can be connected in parallel, which can reduce multiple control variables to one, thus reducing the complexity of motor control.

[0040] Example 2 As attached Figure 3 As shown in the diagram, on the left side, the engine's power is divided into multiple components via a transfer case, connecting to several travel pumps. These travel pumps are then connected in parallel through a manifold valve to form a main hydraulic circuit, which drives multiple motors. Each motor or several motors form a group driving a driveshaft, and the multiple driveshafts collectively drive the vehicle. The travel pumps are divided into groups I and II based on the engine's power source. Each group has a manifold valve for both high and low pressure. By controlling these manifold valves, the system can activate equipment from both power sources, increasing power and providing power redundancy to enhance system reliability and safety. An embodiment of a multi-axis synchronous control device based on the system described in Embodiment 1 of this application specifically includes: The control unit implements the synchronous control logic algorithm for the vehicle's drive shaft based on the collected signals, including the calculation of the displacement of the travel pump and motor, as well as speed closed-loop control, etc. Through a human-machine interface terminal connected to the control unit via an industrial Ethernet bus, the system can realize the input of target speed for low constant speed travel, display of key travel status information and operating conditions. The analog acquisition (DI) module connected to the control unit acquires the high and low pressure of the travel pump (drive pressure = |high pressure - low pressure|), and also acquires the vehicle control traction command, the target speed for high-speed operation, and the hand lever 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, including but not limited to outputting signals of -10V to 10V. 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 (generally equipped with a potentiometer that can adjust the maximum and minimum current to adjust the ratio of input voltage to output current and the range of output value), thereby realizing the opening control of the first proportional valve and the second proportional valve. The speed acquisition module (usually a pulse acquisition module) connected to the control unit collects the vehicle speed and the speed of all motors; The digital output module connected to the control unit controls the opening and closing of the flow combiner valve, enabling the individual or simultaneous activation of N power groups, and the isolation of faulty power.

[0041] Configure the corresponding sensor and drive valve: 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). Each drive shaft is equipped with a speed sensor to detect the motor speed Vx (x = 1 to n, where n is the number of motors connected in parallel).

[0042] Configure hydraulic pump and motor displacement controllers (and first and second proportional valves): the driving displacement of the traveling pump is P (the displacement control of all hydraulic pumps is the same), and the driving displacement of the motor is M (the displacement control of all hydraulic motors is the same).

[0043] Example 3 The multi-pump parallel drive multi-motor multi-axis synchronous control scheme solves the problem of inter-pump pressure synchronization control in single-pump single-axis operation, but the synchronization problem of pumps and motors during startup still exists. Because the start-up signals of each pump and motor differ, if the same control signal is output, some will always be on while others are in the process of starting. This will result in the starting power not reaching its maximum. Therefore, this embodiment proposes to calibrate the effective operating range of the traveling pumps and motors to address the differences in their operating ranges.

[0044] As attached Figure 4 As shown, an embodiment of the multi-axis synchronous control method based on the device described in Embodiment 2 of this application includes a traveling pump displacement adjustment control process, which includes the following steps: The control unit first acquires the motor's rotational speed, calculates it using the gearbox's high and low speed ratio coefficients and the motor's gear ratio, and compares it with the target speed to calculate the speed error of the drive shaft. Based on this speed error, it performs closed-loop PID control to calculate the speed loop output value. The speed loop output value is then converted into the current signal required by the first proportional valve via an analog output module and a constant current module, controlling the displacement of the travel pump. With a constant motor flow rate, adjusting the motor's displacement changes its rotational speed, thereby changing the vehicle speed. The motor's rotational speed is the average of all engaged motors. When a motor malfunctions, it is disabled, and the average rotational speed is recalculated based on the number of engaged motors. For example, in this embodiment, there are four motors; the motor feedback speed = (V1 + V2 + V3 + V4) / 4. When the control unit detects a motor malfunction, it should disable that motor, and the average speed should be recalculated based on the number of engaged motors.

[0045] The target vehicle speed Vt is set via a handle or human-machine interface terminal. The feedback vehicle speed Vf, calculated from the motor speed, can be used to calculate the first proportional valve control value of the pump displacement through speed closed-loop PID control. The speed feedback value Vf during speed closed-loop control needs to be calculated based on the gearbox ratio and motor gear ratio coefficient. If the conversion coefficient is K, then the feedback speed Vf = V * K, where V is the motor speed.

[0046] As attached Figure 5 As shown, the multi-axis synchronous control method also includes a motor displacement adjustment control process, which further includes the following steps: 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 (maximum torque during start-up, using constant torque mode). This ensures the vehicle starts in a constant maximum torque mode. When the motor 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, enabling rapid increase in motor speed and a gradual increase in vehicle speed.

[0047] When multiple traveling pumps are connected in parallel to drive multiple motors, since the pressure of the traveling pumps is combined, there is only one system high pressure FA and low pressure FB. This means that there is no pressure difference between the traveling pumps, so the displacement of the traveling pumps can be designed to be the same, i.e., M1=M2=M3=M4=M. Because the driving force of the motors is also driven by the traveling pumps connected in parallel, and the driving force is consistent, the displacement of the motors can also be designed to be the same, i.e., P1=P2=P3=P4=P.

[0048] The minimum drive current of the traveling pump determines the minimum current required for the pump dead zone to open, which is crucial for consistent start-up. Since the first proportional valve of the traveling pump is typically controlled by a constant current module, the software displacement control value (0-100%) is converted to a hardware constant current module output value (0-1000mA). Therefore, the calibration of the minimum and maximum displacement of the traveling pump drive is also called the calibration of the minimum and maximum drive current.

[0049] As attached Figure 6 As shown, the minimum displacement drive value calibration interface can be set in the software of the host computer (i.e., the human-machine interaction terminal). The minimum displacement drive value calibration interface includes, but is not limited to, the following: Disable calibration: Disables the calibration function; Cancel calibration: Do not update the current calibration value; Store calibration: Stores the current calibration value; Differential pressure bar: After the dead zone of each travel pump is opened, oil flows out to drive the motor, and the oil pressure will start to build up. Output valve %: Used to input the first proportional valve control value for directly setting the displacement of the traveling pump, expressed in 0-100; Minimum forward displacement: The travel pump rotates in a direction, and the forward and backward directions are different. Here it refers to the minimum displacement control value of the travel pump in the forward direction. Minimum backwards: The travel pump rotates in a direction, and the forward and backward directions are different. Here it refers to the minimum displacement control value of the travel pump drive in the backward direction. #1~#n pumps: Selected according to system design, where n is the number of traveling pumps. When each traveling pump is calibrated, only one traveling pump is put into operation through software or hardware.

[0050] The multi-axis synchronous control method also includes a minimum drive displacement calibration process for the traveling pump, which further includes the following steps: Open the human-machine interface terminal's operating mode, select the vehicle's direction of travel, click "Start Calibration," and select one of the travel pumps. The corresponding button will flash (e.g., set to flashing orange). Only one travel pump can be calibrated at a time. At this point, the output valve on the travel pump's minimum drive displacement calibration interface will display 0% output. Slowly increase the output threshold until a pressure differential begins to build up (indicating that the selected pump's dead zone has opened and pressure is building up). Then slowly decrease the output threshold until the pressure differential is 0. Repeat this adjustment 2-3 times to confirm the travel pump's minimum drive displacement output value, and then save the calibration. Perform this process to calibrate each subsequent travel pump.

[0051] As attached Figure 7 As shown, the calibration interface for the maximum drive displacement output value of the traveling pump includes, but is not limited to, the following: Disable calibration: Disables the calibration function; Cancel calibration: Do not update the current calibration value; Store calibration: Stores the current calibration value; Speed ​​(km / h): When the travel pump outputs a certain value, the vehicle speed will gradually increase. The vehicle speed read here is the vehicle speed. Output valve %: Used to input the first proportional valve control value for directly setting the displacement of the traveling pump, expressed in 0-100; Maximum forward displacement %: The travel pump rotates in a direction, and the forward and backward directions are different. Here it refers to the maximum displacement control value of the travel pump in the forward direction. Maximum Reverse %: The travel pump rotates in a direction, and the forward and reverse directions are different. Here it refers to the maximum displacement control value of the travel pump drive in the reverse direction. #1~#n pumps: Selected according to system design, where n is the number of traveling pumps. When each traveling pump is calibrated, only one traveling pump is put into operation through software or hardware.

[0052] The multi-axis synchronous control method also includes a calibration process for the maximum drive displacement output value of the traveling pump, which further includes the following steps: Open the human-machine interface terminal's operating mode, select the vehicle's direction of travel, click "Start Calibration," and select one of the travel pumps. The corresponding button will flash; only one travel pump can be calibrated at a time. At this point, the output valve on the travel pump's maximum drive displacement calibration interface will display 0% output. Slowly increase the output threshold until the vehicle speed stabilizes and no longer increases (indicating that the travel pump's displacement has reached its maximum and cannot be increased further). Then, slowly decrease the output threshold until the vehicle speed decreases slightly. Repeat this adjustment 2-3 times to confirm the travel pump's maximum drive displacement output value and save the calibration. Perform this process to calibrate each subsequent travel pump.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] By implementing the technical solutions of the multi-pump parallel 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 multi-pump parallel 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 drive requirements of the system technical solution based on different travel pumps + motors, and avoid the technical problem of inconsistent multi-axis travel start; (2) The multi-pump parallel 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 problems of asynchronous starting of multiple travel pumps due to differences and asynchronous travel speed of multiple axes, and can effectively meet the hydraulic drive constant speed control (including at least two modes: high-speed travel and low constant speed operation). (3) The multi-pump parallel 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 different transmission shafts during travel, and thus solve the technical problem of insufficient starting power, especially insufficient starting power on slopes. (4) The multi-pump parallel hydraulic travel transmission system and its multi-axis synchronous control device and method described in the specific embodiments of this application can overcome the defect of inconsistent driving pressure of multi-axis synchronous travel, avoid individual shafts being dragged back or even damaged due to asynchrony, and control the synchronous travel of each shaft to give full play to the maximum driving force of the hydraulic travel system. (5) The multi-pump parallel hydraulic travel transmission system and its multi-axis synchronous control device and method described in the specific embodiments of this application effectively avoid the complex synchronous control algorithm and parameter matching adjustment problem, simplify the control algorithm and logic, reduce the control parameters and system control complexity, and shorten the debugging cycle; (6) The multi-pump parallel hydraulic travel transmission system and its multi-axis synchronous control device and method described in the specific embodiments of this application have the functions of simultaneous input of multiple power groups and individual fault isolation, and have power redundancy, which greatly improves the safety and reliability of the system.

[0059] 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.

[0060] The above description is merely a preferred embodiment of this application and is not intended to limit this application in any way. Although this application has been disclosed above with reference to preferred embodiments, it is not intended to limit this 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 multi-pump parallel hydraulic travel transmission system, characterized in that, This system is used for hydraulic travel transmission in vehicles and includes: an engine, a transfer case, a gearbox, a drive shaft, two or more travel pumps, and two or more motors. The engine is the power source for travel and is mechanically connected to the transfer case, transmitting power to the travel pumps connected to the transfer case. The two or more travel pumps drive two or more parallel motors, which are connected and disconnected from the drive shaft via the gearbox. The system also includes a first proportional valve connected to the travel pumps and a second proportional valve connected to the motors. The second proportional valve controls the motor displacement, and the first proportional valve controls the travel pump displacement to adjust the flow rate of the travel pumps, thereby changing the motor speed and controlling the torque and speed of the drive shaft.

2. The multi-pump parallel hydraulic travel transmission system according to claim 1, characterized in that: When there is one engine, the engine transmits power to two or more travel pumps connected to the transfer case through the transfer case, and the motors are connected to the corresponding drive shafts through their respective gearboxes.

3. The multi-pump parallel hydraulic travel transmission system according to claim 1, characterized in that: When the number of engines is N or more, and N≥2, each engine is independent and connected to its own travel pump through a transfer case, dividing the power into N independent groups. Each group of power is connected to two or more travel pumps, which are connected in parallel through a manifold valve to form a total hydraulic circuit, which then drives two or more motors. Each motor is connected to its corresponding drive shaft through its own gearbox. Each motor or several motors form a group that drives one drive shaft, and multiple drive shafts work together to drive the vehicle.

4. The multi-pump parallel hydraulic travel transmission system according to claim 3, characterized in that: When there are two engines, the two engines are independent of each other and are connected to their respective travel pumps through a transfer case, with the power divided into two independent groups. The flow control valves include a first flow control valve, a second flow control valve, a third flow control valve, and a fourth flow control valve. One end of two or more travel pumps belonging to one group of power is connected in parallel to one side of the transmission system circuit through the first flow control valve, and one end of two or more travel pumps belonging to the other group of power is connected in parallel to one side of the transmission system circuit through the second flow control valve. The other end of two or more travel pumps belonging to one group of power is connected in parallel to the other side of the transmission system circuit through the third flow control valve, and the other end of two or more travel pumps belonging to the other group of power is connected in parallel to the other side of the transmission system circuit through the fourth flow control valve. By controlling the opening and closing of the first, second, third, or fourth flow control valves, the two groups of power can be engaged or disengaged. When one group of power needs to be engaged, the first and third flow control valves are opened simultaneously; otherwise, they are closed. When the other group of power needs to be engaged, the second and fourth flow control valves are opened simultaneously; otherwise, they are closed.

5. The multi-pump parallel hydraulic travel transmission system according to any one of claims 1-4, characterized in that: The motor is a variable displacement motor.

6. The multi-pump parallel hydraulic travel transmission system according to claim 5, characterized in that: The travel pump is a variable pump. When the engine speed is constant, the flow rate of the travel pump is controlled by controlling the displacement of the travel pump, thereby changing the speed of the motor and realizing the control of the torque and speed of the drive shaft.

7. A multi-axis synchronous control device based on the system according to any one of claims 1-6, characterized in that, include: The control unit performs synchronous control of the vehicle's drive shaft, calculates the displacement of the travel 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 analog signal acquisition module connected to the control unit acquires the high and low pressure of the travel pump, as well as the vehicle control traction command, the target speed of high-speed operation, and the hand 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, connected to the control unit, acquires the vehicle speed and the speed of all motors; The digital output module connected to the control unit controls the opening and closing of the flow combiner valve, enabling the individual or simultaneous activation of N power groups, and the isolation of faulty power.

8. A multi-axis synchronous control method based on the device of claim 7, characterized in that, This includes the travel pump displacement adjustment control process, which includes the following steps: The control unit first acquires the motor's rotational speed, calculates it using the gearbox's high and low speed ratio coefficients and the motor's gear ratio, and compares it with the target speed to calculate the speed error of the drive shaft. Based on this speed error, it performs closed-loop PID control to calculate the speed loop's output value. The speed loop's output value is then converted into the current signal required by the first proportional valve via an analog output module and a constant current module, controlling the displacement of the travel pump. With a constant motor flow rate, the vehicle speed is changed by adjusting the motor's displacement. The motor's rotational speed is taken as the average of all engaged motors' rotational speeds. When a motor malfunction is detected, that motor is disabled, and the average rotational speed is recalculated based on the number of engaged motors.

9. The multi-axis synchronous control method according to claim 8, characterized in that, The control method includes a motor displacement adjustment control process, which includes the following steps: 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 to increase the motor's rotational speed, thereby increasing the vehicle's speed.

10. The multi-axis synchronous control method according to claim 8 or 9, characterized in that, The control method includes a minimum drive displacement calibration process for the traveling pump, which includes the following steps: Turn on the human-machine interface terminal, select the vehicle's direction of travel, click "Start Calibration," and select one of the travel pumps. The corresponding button will flash. Only one travel pump can be calibrated at a time. At this time, the output valve on the travel pump's minimum drive displacement calibration interface will display 0% output. Slowly increase the output threshold until the pressure difference begins to build up, then slowly decrease the output threshold until the pressure difference is 0. Repeat this adjustment 2-3 times to confirm the minimum drive displacement output value of the travel pump, and then press "Store Calibration." Use this process to calibrate each subsequent travel pump.

11. The multi-axis synchronous control method according to claim 10, characterized in that, The control method includes a calibration process for the maximum drive displacement output value of the traveling pump, which includes the following steps: Turn on the human-machine interface terminal, select the vehicle's direction of travel, click "Start Calibration," and select one of the travel pumps. The corresponding button will flash. Only one travel pump can be calibrated at a time. At this time, the output valve on the travel pump's maximum drive displacement calibration interface will display 0% output. Slowly increase the output threshold until the vehicle speed is constant and no longer increases. Then slowly decrease the output threshold until the vehicle speed decreases slightly. Repeat this adjustment 2-3 times to confirm the maximum drive displacement output value of the travel pump and press "Store Calibration." Use this process to calibrate each subsequent travel pump.

12. The multi-axis synchronous control method according to claim 8, 9 or 11, characterized in that: Set the displacement of the traveling pump to be consistent.

13. The multi-axis synchronous control method according to claim 12, characterized in that: Set the displacement of the motor to be consistent.

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