A loader distributed electro-hydraulic composite drive hydraulic system and a control method thereof

Abstract

This invention provides a distributed electro-hydraulic hybrid drive hydraulic system for a loader and its control method. It includes a power supply system, a steering drive subsystem, an electro-hydraulic hybrid working subsystem, and a vehicle controller. The steering drive subsystem uses a pure electric cylinder drive and is decoupled from the working system. The electro-hydraulic hybrid working subsystem includes large and small flow motor pump sets, a distribution valve group, working cylinders, and an accumulator. The vehicle controller identifies the working condition based on the collected signals, controlling the small pump to operate independently under low flow conditions, and switching to the large pump or coordinating oil supply under high flow conditions. Pressure energy is recovered through the accumulator, and potential energy is converted into electrical energy using a motor pump with four-quadrant working capability. This application can eliminate steering throttling losses, optimize power matching under all working conditions, achieve multiple composite energy recovery, and significantly improve the overall machine energy efficiency and handling linearity.

Description

Technical Field

[0001] This invention relates to the field of excavating engineering machinery systems, and more specifically, to a distributed electro-hydraulic hybrid drive hydraulic system for a loader and its control method. Background Technology

[0002] In the field of construction machinery, especially in excavation and loading operations, loaders play a crucial role as core equipment. With increasingly stringent global environmental requirements and the transformation of the energy structure, the electrification of loaders has become an inevitable trend in the industry. However, current electric loader technology is still in its early stages. Existing electrification solutions typically simply replace the original engine with an electric motor to drive the traditional hydraulic transmission system. While this approach achieves greening at the power source level, it does not fundamentally solve the problem of the inherent inefficiency of the hydraulic transmission system.

[0003] In actual operation, the lowering of the loader's boom and the movement of the bucket generate a large amount of gravitational potential energy. Due to the limitations of the existing system architecture, this energy is often dissipated as heat through throttling at the valve orifice, making effective energy recovery difficult. This low energy utilization efficiency results in high power consumption for the entire machine. To maintain the necessary operating time, the vehicle must be equipped with a large-capacity battery pack, which not only increases the overall cost and weight of the machine but also limits the range and widespread application of electric loaders. In addition, traditional hydraulic steering systems are usually coupled with the working system, resulting in significant throttling energy loss during steering and making it difficult to achieve high-precision linear control, thus affecting the overall handling performance of the machine.

[0004] Distributed drive systems are considered an ideal solution for improving the energy efficiency of loader working devices and achieving precise power matching. However, there is still a lack of mature distributed drive systems in the domestic and international markets that can be fully applied to the complex operating conditions of loaders. Summary of the Invention

[0005] This invention provides a distributed electro-hydraulic hybrid drive hydraulic system for a loader and its control method, aiming to develop a distributed electro-hydraulic hybrid drive hydraulic system and its control method that can decouple the steering and working systems, have efficient flow regulation capabilities, and effectively recover gravitational potential energy.

[0006] To address the aforementioned technical problems, this invention provides a distributed electro-hydraulic hybrid drive hydraulic system for a loader, comprising an electro-hydraulic hybrid drive hydraulic system body configured in the vehicle. The body includes a power system, a steering drive subsystem, and an electro-hydraulic hybrid working subsystem. The electro-hydraulic hybrid working subsystem includes a hydraulic oil supply component, a work execution component, and an oil tank. The steering drive subsystem and the electro-hydraulic hybrid working subsystem are respectively connected to the power system via a power distribution unit, and the steering drive subsystem and the electro-hydraulic hybrid working subsystem are decoupled. The work execution component is connected to the oil tank via the hydraulic oil supply component.

[0007] The work execution components include a bucket cylinder and a boom cylinder; The hydraulic oil supply assembly includes a high-flow working motor pump group, a low-flow working motor pump group, a first relief valve, a second relief valve, a distribution valve group, and an accumulator. The oil inlets of the high-flow-rate pump set and the low-flow-rate pump set are respectively connected to the oil tank; the oil outlets of the high-flow-rate pump set and the low-flow-rate pump set are both connected to the oil inlet of the distribution valve set, and the oil outlet of the high-flow-rate pump set is connected to the oil inlet of the first relief valve, while the oil outlet of the low-flow-rate pump set is connected to the oil inlet of the second relief valve; the return ports of the first and second relief valves are both connected to the oil tank. The working oil port of the distribution valve group is connected to the control oil port of the boom cylinder and the bucket cylinder respectively, and the return oil port of the distribution valve group is connected to the oil tank. It also includes a vehicle controller, which is configured to acquire the vehicle's operating signals and status parameters, identify the vehicle's operating conditions, and coordinate the power output of the hydraulic oil supply components and the operation of the steering drive subsystem based on the operating conditions.

[0008] As a further optimization, the flow distribution valve group includes a boom flow distribution valve, a boom potential energy recovery control valve, a bucket potential energy recovery control valve, and a bucket flow distribution valve. The inlet of the boom flow distribution valve is connected to the outlet of the high-flow working motor pump group and the low-flow working motor pump group respectively, and the working port of the boom flow distribution valve is connected to the boom cylinder. The inlet of the bucket flow distribution valve is connected to the outlet of the high-flow working motor pump group and the low-flow working motor pump group respectively, and the working port of the bucket flow distribution valve is connected to the bucket cylinder. The boom potential energy recovery control valve is equipped with a floating working position; The accumulator is used to recover and store the hydraulic energy returned from the boom cylinder and bucket cylinder during boom lowering and bucket lowering operations. The rodless chamber oil port of the bucket cylinder is connected to the oil inlet of the bucket potential energy recovery control valve, and the oil outlet of the bucket potential energy recovery control valve is connected to the accumulator. The rodless chamber port of the boom cylinder is connected to the inlet of the boom potential energy recovery control valve, and the outlet of the boom potential energy recovery control valve is connected to the accumulator.

[0009] As a further optimization, the power system includes a power management subsystem, a power distribution unit, a battery pack, a charging socket, and a battery thermal management system, wherein the power management subsystem is connected to the power distribution unit, the battery pack, the charging socket, and the battery thermal management system, respectively.

[0010] As a further optimization, the steering drive subsystem includes a steering motor and a steering cylinder. The steering motor is electrically connected to the power distribution unit of the power system, and the steering cylinder is driven by the steering motor.

[0011] As a further optimization, the vehicle controller is equipped with a data acquisition unit, which is used to acquire: handle signal, steering wheel signal, accelerator pedal signal, brake pedal signal, large and small chamber pressures of boom cylinder and bucket cylinder, outlet pressure of high-flow working motor pump group, outlet pressure of low-flow working motor pump group, motor speed and torque of high-flow working motor pump group, motor speed and torque of low-flow working motor pump group, steering motor speed of steering drive subsystem, and outlet pressure of accumulator; The vehicle controller is also configured to: calculate the target working speed of the boom cylinder, bucket cylinder, and steering drive subsystem based on the signals and status parameters acquired by the acquisition unit, and identify the working conditions of the entire vehicle; The vehicle controller is also configured to: calculate the required flow rate of the hydraulic oil supply components based on the target operating speed of the boom cylinder and bucket cylinder; and calculate the target speed of the steering motor based on the target operating speed of the steering drive subsystem.

[0012] As a further optimization, the vehicle controller is also configured to: calculate the target speed and target displacement of the high-flow-rate motor pump group and the target speed and target displacement of the low-flow-rate motor pump group based on the required flow rate of the hydraulic oil supply components and the identified vehicle operating conditions; Specifically, under low flow conditions, the low flow working motor pump set is controlled to work independently to supply oil to the hydraulic oil supply component; under high flow conditions, the high flow working motor pump set is controlled to work independently to supply oil to the hydraulic oil supply component. The signal output terminal of the vehicle controller is electrically connected to the high-flow working motor pump group, the low-flow working motor pump group and the steering motor of the steering drive subsystem, respectively. The vehicle controller is also configured to: send the calculated target speed and target displacement to the corresponding high-flow working motor pump group and low-flow working motor pump group; and send the calculated target speed of the steering drive subsystem to the steering motor so that the boom cylinder, bucket cylinder and steering electric cylinder can reach the target working speed.

[0013] As a further optimization, both the high-flow-rate working motor pump set and the low-flow-rate working motor pump set are equipped with a motor pump that can operate in four quadrants, so as to convert the hydraulic energy of the oil return from the oil cylinder into electrical energy and store it in the battery pack during the boom lowering and bucket lowering operations.

[0014] As a further optimization, both the bucket potential energy recovery control valve and the boom potential energy recovery control valve are two-position two-way proportional control valves, so that the control flow of each hydraulic circuit can be linearly adjusted through the two-position two-way proportional control valve.

[0015] The present invention also provides a control method for the distributed electro-hydraulic hybrid drive hydraulic system of a loader as described above, comprising the following steps: S1. Signal Acquisition: The control signals and status parameters of the entire vehicle are acquired through the acquisition unit. The control signals include handle signals, steering wheel signals, accelerator pedal signals, and brake pedal signals. The status parameters include the pressure of the large and small chambers of the boom cylinder and bucket cylinder, the outlet pressure of the high-flow working motor pump group, the outlet pressure of the low-flow working motor pump group, the motor speed and torque of the high-flow working motor pump group, the motor speed and torque of the low-flow working motor pump group, the steering motor speed of the steering drive subsystem, and the outlet pressure of the accumulator. S2. Working Condition Identification and Target Calculation: Based on the control signals and state parameters obtained in step S1, calculate the target working speed of the boom cylinder, bucket cylinder, and steering drive subsystem, and identify the working condition of the entire vehicle. S3. Demand Calculation: Calculate the required flow rate of the hydraulic oil supply components based on the target operating speed of the boom cylinder and bucket cylinder; calculate the target speed of the steering motor based on the target operating speed of the steering drive subsystem. S4. Power Parameter Matching: Based on the required flow rate of the hydraulic oil supply components and the identified vehicle operating conditions, calculate the target speed and target displacement of the high-flow working motor pump set and the target speed and target displacement of the low-flow working motor pump set; in the low-flow condition, match the parameters of the low-flow working motor pump set working alone; in the high-flow condition, match the parameters of the high-flow working motor pump set working alone. S5. Closed-loop execution: The target speed and target displacement obtained in step S4 are sent to the corresponding high-flow working motor pump group and low-flow working motor pump group. The target speed of the steering motor obtained in step S3 is sent to the steering motor of the steering drive subsystem to control the boom cylinder, bucket cylinder and steering electric cylinder to run to the target working speed respectively.

[0016] As a further optimization, the high-flow-rate working motor pump set and the low-flow-rate working motor pump set can operate in four quadrants, recovering energy from the high-pressure hydraulic oil returning from the cylinder during boom lowering and bucket lowering operations, converting hydraulic energy into electrical energy and storing it in the battery pack; the accumulator can also recover energy from the high-pressure hydraulic oil returning from the cylinder during boom lowering and bucket lowering operations, storing the hydraulic energy; the energy recovery of the accumulator and the energy recovery of the high-flow-rate working motor pump set and the low-flow-rate working motor pump set can be carried out simultaneously.

[0017] By adopting the above technical solution, the present invention can achieve the following technical effects: First, it achieves complete decoupling and efficient operation of the steering system. By separating the steering drive subsystem from the traditional hydraulic cycle and using pure electric cylinder drive, the energy loss from hydraulic throttling during steering is completely eliminated. Steering actions are no longer affected by pressure fluctuations in the working circuit, significantly improving the linearity and response accuracy of steering control, while reducing the system's standby power consumption.

[0018] Secondly, it achieves power source efficiency optimization across the entire operating range. By configuring two sets of working motor pumps, one with a high flow rate and the other with a low flow rate, and cooperating with the intelligent switching logic of the vehicle controller, it solves the problem of low efficiency of traditional single pump sources under low flow rate conditions. The system can automatically select the optimal pump combination according to actual load requirements, ensuring that the motor and pump always operate within the high-efficiency characteristic range, thereby reducing losses in the process of converting electrical energy into hydraulic energy at the source.

[0019] Third, a multi-layered, composite gravitational potential energy recovery system was constructed. The system innovatively integrates two mechanisms: physical recovery via an accumulator and electrical recovery via a four-quadrant motor pump. The accumulator can quickly respond to small-amplitude adjustments and absorb system impact pressure, while the four-quadrant motor pump efficiently converts hydraulic energy into electrical energy during large-scale potential energy release. This composite recovery mode significantly improves the recovery rate of gravitational potential energy, effectively extending the driving range of the electric loader.

[0020] Fourth, it improves the overall machine's operational performance and handling quality. Based on the distributed collaborative control of the vehicle controller, precise decoupling and synchronous control of the boom, bucket, and steering movements are achieved. Through a closed-loop adjustment mechanism, the system can compensate for speed deviations caused by load fluctuations, enabling the loader to maintain stable handling characteristics even in complex operating environments. While reducing the overall machine's energy consumption, it improves the efficiency of the work cycle, reduces reliance on large-capacity battery packs, and provides reliable technical support for the lightweighting and cost reduction of electric loaders.

[0021] In summary, this invention, through a distributed electro-hydraulic composite drive architecture, deeply optimizes the hydraulic system of loaders from multiple dimensions such as system topology, power matching, flow control, and energy recovery, solving the core pain point of improving the energy efficiency of electromechanical equipment. It has extremely high practical value and broad application prospects. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the structure of a distributed electro-hydraulic hybrid drive hydraulic system for a loader according to the present invention; Figure 2 This is a schematic diagram of the electro-hydraulic composite working subsystem of the present invention; Figure 3 This is a flowchart illustrating a control method for a distributed electro-hydraulic hybrid drive hydraulic system for a loader according to the present invention. Marked in the image: 100. Power system; 110. Charging socket; 120. Battery pack; 130. Power management subsystem; 140. Power distribution unit; 150. Battery thermal management system; 200. Steering drive subsystem; 210. Steering motor; 220. Steering electric cylinder; 400. Electro-hydraulic composite working subsystem; 410. Hydraulic oil supply assembly; 411. High-flow working motor pump set; 412. Low-flow working motor pump set; 413. First relief valve; 414. Second relief valve; 415. Flow distribution valve assembly; 4151. Boom flow distribution valve; 4152. Boom potential energy recovery control valve; 4153. Bucket potential energy recovery control valve; 4154. Bucket flow distribution valve; 416. Accumulator; 421. Boom cylinder; 422. Bucket cylinder; 430. Oil tank. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention 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 the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0025] like Figures 1-2 As shown, this embodiment of the invention provides a distributed electro-hydraulic hybrid drive hydraulic system for a loader. This system is built on the loader's vehicle platform and utilizes electronic control and hydraulic transmission technology to optimize energy management during loader operation. The core architecture of the system consists of a power system 100, a steering drive subsystem 200, a vehicle controller, and an electro-hydraulic hybrid working subsystem 400. In the physical layout of the vehicle, the power system 100 serves as the energy center, responsible for the storage, distribution, and safe management of electrical energy. The steering drive subsystem 200 and the electro-hydraulic hybrid working subsystem 400 are electrically connected in parallel through a power distribution unit 140, but are completely independent at the mechanical execution and hydraulic circuit levels. This decoupled configuration eliminates the power coupling interference between steering actions and working device actions, thereby improving the system's response speed and energy utilization efficiency.

[0026] The power system 100 comprises a charging socket 110, a battery pack 120, a power management subsystem 130, a power distribution unit 140, and a battery thermal management system 150. The charging socket 110 is used to connect to an external charging station to replenish power. The battery pack 120 provides DC high-voltage power to the vehicle. The power management subsystem 130 monitors the voltage, current, state of charge, and health status of the battery pack 120 in real time using high-precision sensors and executes safety protection logic such as overcharge, over-discharge, and short circuit protection. The power distribution unit 140 distributes the high-voltage DC power to the motor drivers of the steering drive subsystem 200 and the electro-hydraulic hybrid operating subsystem 400 according to instructions from the vehicle controller. The battery thermal management system 150 includes a cooling water pump, a radiator, and an electric fan, which circulates coolant to remove the heat generated by the battery pack 120 during charging and discharging, ensuring the battery pack operates within its optimal temperature range. This is prior art and will not be elaborated further.

[0027] Preferably, the steering drive subsystem 200 adopts a pure electric drive scheme, which consists of a steering motor 210 and a steering cylinder 220. Unlike traditional hydraulic steering systems, in this embodiment, the steering motor 210 is directly controlled by commands issued by the vehicle controller. An internal inverter converts the DC power provided by the power distribution unit 140 into three-phase AC power to drive the steering motor 210 to rotate. The output shaft of the steering motor 210 is connected to the lead screw mechanism of the steering cylinder 220, converting the rotational motion into linear reciprocating motion, thereby driving the loader's articulated frame to steer. This pure electric drive architecture completely eliminates the steering pump, steering priority valve, and complex hydraulic lines, eliminating throttling and overflow losses of hydraulic oil during pipeline flow. Due to the extremely high control precision of the steering motor 210, the system achieves linear control of the steering angle. The steering angle signal input by the driver through the steering wheel is mapped to the displacement of the electric cylinder, significantly improving the smoothness of handling.

[0028] Preferably, the electro-hydraulic composite working subsystem 400 is the main body for performing loading operations, and it includes a hydraulic oil supply component 410, a working execution component, and an oil tank 430. The working execution component consists of a boom cylinder 421 and a bucket cylinder 422, which are responsible for raising and lowering the boom and tilting the bucket, respectively. The hydraulic oil supply component 410, as the power source, adopts a distributed dual-pump configuration, specifically including a high-flow working motor pump group 411 and a low-flow working motor pump group 412. Both pump groups are driven by independent permanent magnet synchronous motors. The oil inlets of both the high-flow working motor pump group 411 and the low-flow working motor pump group 412 are connected to the oil tank 430 through oil suction pipes. To achieve flexible flow regulation, the oil outlets of the two pump groups converge to the oil inlet of the distribution valve group 415. In terms of safety protection, the outlet of the high-flow working motor pump set 411 is connected in parallel with a first relief valve 413, and the outlet of the low-flow working motor pump set 412 is connected in parallel with a second relief valve 414. When the system pressure exceeds the set threshold due to a sudden change in external load, the relief valve opens to guide the high-pressure oil back to the oil tank 430, preventing damage to hydraulic components.

[0029] Furthermore, the flow distribution valve assembly 415 is the core control unit for realizing complex action logic. It integrates the boom flow distribution valve 4151, the boom energy recovery control valve 4152, the bucket energy recovery control valve 4153, and the bucket flow distribution valve 4154. Both the boom flow distribution valve 4151 and the bucket flow distribution valve 4154 are high-frequency response proportional directional valves, with their valve core opening controlled by the proportional current signal output from the vehicle controller. The working port of the boom flow distribution valve 4151 is connected to the rod-side and rodless-side chambers of the boom cylinder 421, respectively, achieving boom lifting, lowering, pressure holding, and floating functions by changing the flow direction. The bucket flow distribution valve 4154 controls the bucket retraction and unloading actions of the bucket cylinder 422. Specifically, the boom energy recovery control valve 4152 and the bucket energy recovery control valve 4153 are two-position two-way proportional control valves, specifically used to manage the energy recovery flow direction of the return oil circuit. In addition, the hydraulic supply assembly 410 also includes an accumulator 416, which, as a physical energy storage element, is connected to a potential energy recovery control valve via a pipeline to absorb and release hydraulic energy.

[0030] Preferably, the vehicle controller is equipped with a data acquisition unit, which acquires the vehicle's operating signals and status parameters in real time through analog input interfaces, digital input interfaces, and a CAN bus interface. These parameters include: operating handle signals, steering wheel signals, accelerator pedal signals, and brake pedal signals from the cab; pressure sensor signals from the large and small chambers of the boom cylinder 421 and bucket cylinder 422 mounted on the actuators; outlet pressure sensor signals from the high-flow-rate working motor pump group 411 and the low-flow-rate working motor pump group 412; speed and torque signals fed back from the encoders of each motor; real-time current and speed signals from the steering motor 210; and pressure sensor signals from the outlet of the accumulator 416.

[0031] Based on the above hardware architecture, embodiments of the present invention provide a control method for a distributed electro-hydraulic hybrid drive hydraulic system of a loader, such as... Figure 3 As shown, this method is executed cyclically through the following logical steps.

[0032] S1. Signal Acquisition: The vehicle controller acquires all the aforementioned control signals and status parameters at millisecond intervals through the acquisition unit. These data constitute the raw input for operating condition identification.

[0033] S2. Working Condition Recognition and Target Calculation: The vehicle controller has a pre-stored loader dynamics model and working condition feature library. Through real-time analysis of the displacement of the handle signal, pedal opening, and cylinder pressure change rate, the controller executes working condition recognition logic to determine whether the loader is currently in a specific operating stage, such as unloaded driving, light-load material loading, heavy-load shoveling, full-load lifting, or gravity lowering. Simultaneously, based on the input of the handle and steering wheel signals, the controller calculates the target working speeds of the boom cylinder 421, bucket cylinder 422, and steering drive subsystem 200 through a lookup table mapping method.

[0034] S3. Demand Calculation: After obtaining the target speed, the vehicle controller, in conjunction with the piston area geometry parameters of the boom cylinder 421 and bucket cylinder 422, calculates the total required flow rate of the hydraulic system. Simultaneously, for steering requirements, the target speed required for the steering motor 210 is calculated to ensure that the extension and retraction speed of the steering cylinder 220 meets the driver's control expectations.

[0035] S4. Power Parameter Matching: The vehicle controller, based on the total demand flow, calls the efficiency map of the motor-pump unit in real time and executes optimized allocation logic. When a light-load, low-flow condition is identified, the controller outputs control commands to start the low-flow motor-pump unit 412 independently and adjusts its speed according to the demand flow, while the high-flow motor-pump unit 411 remains shut down, thus eliminating the losses caused by the large pump operating in the low-efficiency range. When a heavy-load, high-flow condition is identified, the controller activates the high-flow motor-pump unit 411, or controls both pumps to supply oil in parallel simultaneously under extremely high flow demand. Through this distributed dynamic matching, it is ensured that the power source always operates in the high-efficiency range.

[0036] S5. Closed-Loop Execution: The vehicle controller sends the calculated target speed and displacement commands to the corresponding motor controller via the CAN bus. The motor controller drives the high-flow working motor pump group 411, the low-flow working motor pump group 412, and the steering motor 210. Simultaneously, the controller adjusts the valve core positions of each proportional valve in the distribution valve group 415 to guide the pressurized oil to the target cylinder chamber. The system uses real-time speed and pressure feedback from sensors to perform PID closed-loop regulation, ensuring that the actual operating speed of the actuator accurately approximates the target speed.

[0037] To more clearly illustrate the system operation process, the following detailed description is provided in conjunction with actual operating scenarios. When the loader is performing light-load, low-flow operations, such as micro-loading of light materials in the bucket or minor adjustments to the boom position, the vehicle controller acquires the small-stroke signal of the handle and the low-opening signal of the accelerator pedal. Through the operating condition identification algorithm, the controller determines that the system's required flow rate is lower than the rated flow rate of the large pump. At this time, the controller only sends operating commands to the small-flow working motor pump unit 412, adjusting its motor speed to output a precise small flow rate. Because the small pump has a lower rated power and lower inertia, its efficiency at low flow output is higher than that of the large pump, thereby reducing power consumption during standby and micro-movement conditions.

[0038] When the loader is performing heavy-load, high-flow-rate operations, such as the rapid lifting of the boom during a full-load loading process, the vehicle controller collects the full-stroke signal of the handle and the high-opening signal of the throttle pedal. At this time, the controller recognizes the heavy-load condition and immediately starts the high-flow-rate work motor pump unit 411. Based on real-time feedback from the pressure sensor, it adjusts the motor speed to achieve constant power output or constant flow output to overcome heavy-load resistance and maintain rapid response. Meanwhile, the low-flow-rate work motor pump unit 412 switches to a standby state to reduce unnecessary idling losses. The boom flow distribution valve 4151 in the distribution valve group 415 is fully open, providing a high-flow-rate, high-pressure hydraulic oil to the boom cylinder 421 to ensure smooth loading operations.

[0039] Preferably, this system improves the utilization rate of gravitational potential energy through a combined physical and electrical recovery mode. During operation, when the boom or bucket is lowered, the vehicle controller executes the corresponding recovery strategy based on the lowering speed and load pressure. When a small-amplitude lowering or fine-tuning condition is detected, the controller outputs a signal to open the corresponding boom potential energy recovery control valve 4152 or bucket potential energy recovery control valve 4153. At this time, the high-pressure hydraulic oil generated by gravity compression in the rodless chamber of the cylinder does not return to the oil tank 430 through the reversing valve, but enters the accumulator 416 through the potential energy recovery control valve. The bladder inside the accumulator 416 is compressed, converting hydraulic energy into gas pressure energy for storage. In subsequent lifting conditions or auxiliary circuit requirements, the controller reverses the valve opening, releasing the energy in the accumulator 416 back to the system to compensate for the pump flow, thereby reducing the burden on the motor.

[0040] Furthermore, when a rapid, large-amplitude lowering of the boom is detected, the system activates the energy recovery mode. Both the high-flow-rate working motor pump group 411 and the low-flow-rate working motor pump group 412 are equipped with motor pumps capable of operating in all four quadrants. At this time, the vehicle controller adjusts the distribution valve group 415, causing the high-pressure hydraulic oil in the cylinder return oil circuit to flow to the outlet end of the motor pump. Under the action of the pressure difference, the hydraulic pump switches to hydraulic motor mode, driving the motor to rotate in reverse. Since the motor controller has an energy feedback function, the motor enters generator mode at this time, converting mechanical energy into electrical energy. The generated current is rectified by the inverter and fed back to the battery pack 120 for storage through the power distribution unit 140. This energy recovery method handles the release of high-power potential energy, with high recovery efficiency and is not limited by the accumulator capacity. The accumulator 416 absorbs the pressure shock during the commutation process, protecting the hydraulic components.

[0041] The steering control process also demonstrates the system's superiority. When the driver turns the steering wheel, the vehicle controller analyzes the pulse signals from the steering wheel angle sensor in real time. Based on the angle and rotation frequency, the controller calculates the torque and speed required by the steering motor 210. The steering motor 210 drives the steering cylinder 220 to precisely extend and retract. Because the steering system is completely decoupled from the working hydraulic system, the speed of steering action is unaffected by boom lifting or bucket movement, solving the problem of heavy or sluggish steering in traditional loaders during heavy-load lifting. Furthermore, by eliminating the continuous idling of the hydraulic steering pump, the system's energy consumption under straight-line driving conditions is significantly reduced.

[0042] In summary, the distributed electro-hydraulic hybrid drive hydraulic system for loaders provided by this invention provides stable power through the power supply system 100 and achieves zero-throttling-loss steering through the pure electric drive of the steering drive subsystem 200. Through intelligent coordination by the vehicle controller, the high-flow working motor pump group 411 and the low-flow working motor pump group 412 are directed to perform power matching under different working conditions. Hydraulic energy recovery achieved by the distribution valve group 415 and the accumulator 416, and electrical energy recovery achieved by the four-quadrant motor pump, construct a multi-dimensional energy management system. This system improves the range of electric loaders and also achieves high-precision decoupled control of operating actions through a distributed architecture, enhancing the overall operating efficiency and user experience. This electro-hydraulic hybrid drive mode provides a technical solution for the green and intelligent transformation of construction machinery. In practical applications, the system dynamically adjusts the energy recovery intensity based on the state of charge of the battery pack 120. When the battery pack is close to saturation, the absorption ratio of the accumulator 416 is increased; when the battery pack is low, energy recovery is prioritized. This flexible strategy ensures the operational safety and energy balance of the entire vehicle. Through the implementation of this system, the overall energy efficiency of the loader is greatly improved compared to traditional solutions, demonstrating significant practical value.

[0043] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A distributed electro-hydraulic hybrid drive hydraulic system for a loader, comprising an electro-hydraulic hybrid drive hydraulic system body configured in the vehicle, characterized in that, The main body includes: a power system, a steering drive subsystem, and an electro-hydraulic composite working subsystem. The electro-hydraulic composite working subsystem includes a hydraulic oil supply component, a working execution component, and an oil tank. The steering drive subsystem and the electro-hydraulic composite working subsystem are respectively connected to the power system through a power distribution unit, and the steering drive subsystem and the electro-hydraulic composite working subsystem are decoupled. The working execution component is connected to the oil tank through the hydraulic oil supply component. The work execution components include a bucket cylinder and a boom cylinder; The hydraulic oil supply assembly includes a high-flow working motor pump group, a low-flow working motor pump group, a first relief valve, a second relief valve, a distribution valve group, and an accumulator. The oil inlets of the high-flow-rate pump set and the low-flow-rate pump set are respectively connected to the oil tank; the oil outlets of the high-flow-rate pump set and the low-flow-rate pump set are both connected to the oil inlet of the distribution valve set, and the oil outlet of the high-flow-rate pump set is connected to the oil inlet of the first relief valve, while the oil outlet of the low-flow-rate pump set is connected to the oil inlet of the second relief valve; the return ports of the first and second relief valves are both connected to the oil tank. The working oil port of the distribution valve group is connected to the control oil port of the boom cylinder and the bucket cylinder respectively, and the return oil port of the distribution valve group is connected to the oil tank. It also includes a vehicle controller, which is configured to acquire the vehicle's operating signals and status parameters, identify the vehicle's operating conditions, and coordinate the power output of the hydraulic oil supply components and the operation of the steering drive subsystem based on the operating conditions.

2. The distributed electro-hydraulic hybrid drive hydraulic system for a loader according to claim 1, characterized in that... , The flow distribution valve group includes a boom flow distribution valve, a boom potential energy recovery control valve, a bucket potential energy recovery control valve, and a bucket flow distribution valve. The inlet of the boom flow distribution valve is connected to the outlet of the high-flow working motor pump group and the low-flow working motor pump group respectively, and the working port of the boom flow distribution valve is connected to the boom cylinder. The inlet of the bucket flow distribution valve is connected to the outlet of the high-flow working motor pump group and the low-flow working motor pump group respectively, and the working port of the bucket flow distribution valve is connected to the bucket cylinder. The boom potential energy recovery control valve is equipped with a floating working position; The accumulator is used to recover and store the hydraulic energy returned from the boom cylinder and bucket cylinder during boom lowering and bucket lowering operations. The rodless chamber oil port of the bucket cylinder is connected to the oil inlet of the bucket potential energy recovery control valve, and the oil outlet of the bucket potential energy recovery control valve is connected to the accumulator. The rodless chamber port of the boom cylinder is connected to the inlet of the boom potential energy recovery control valve, and the outlet of the boom potential energy recovery control valve is connected to the accumulator.

3. The distributed electro-hydraulic hybrid drive hydraulic system for a loader according to claim 1, characterized in that... , The power system includes a power management subsystem, a power distribution unit, a battery pack, a charging socket, and a battery thermal management system. The power management subsystem is connected to the power distribution unit, the battery pack, the charging socket, and the battery thermal management system, respectively.

4. The distributed electro-hydraulic hybrid drive hydraulic system for a loader according to claim 3, characterized in that... , The steering drive subsystem includes a steering motor and a steering cylinder. The steering motor is electrically connected to the power distribution unit of the power system, and the steering cylinder is driven by the steering motor.

5. A distributed electro-hydraulic hybrid drive hydraulic system for a loader according to claim 4, characterized in that... , The vehicle controller is equipped with a data acquisition unit, which is used to acquire: handle signal, steering wheel signal, accelerator pedal signal, brake pedal signal, pressure of the large and small chambers of the boom cylinder and bucket cylinder, outlet pressure of the high-flow working motor pump group, outlet pressure of the low-flow working motor pump group, motor speed and torque of the high-flow working motor pump group, motor speed and torque of the low-flow working motor pump group, steering motor speed of the steering drive subsystem, and outlet pressure of the accumulator. The vehicle controller is also configured to: calculate the target working speed of the boom cylinder, bucket cylinder, and steering drive subsystem based on the signals and status parameters acquired by the acquisition unit, and identify the working conditions of the entire vehicle; The vehicle controller is also configured to: calculate the required flow rate of the hydraulic oil supply components based on the target operating speed of the boom cylinder and bucket cylinder; and calculate the target speed of the steering motor based on the target operating speed of the steering drive subsystem.

6. A distributed electro-hydraulic hybrid drive hydraulic system for a loader according to claim 5, characterized in that... , The vehicle controller is also configured to calculate the target speed and target displacement of the high-flow-rate motor pump group and the target speed and displacement of the low-flow-rate motor pump group based on the required flow rate of the hydraulic oil supply components and the identified vehicle operating conditions. Specifically, under low flow conditions, the low flow working motor pump set is controlled to work independently to supply oil to the hydraulic oil supply component; under high flow conditions, the high flow working motor pump set is controlled to work independently to supply oil to the hydraulic oil supply component. The signal output terminal of the vehicle controller is electrically connected to the high-flow working motor pump group, the low-flow working motor pump group and the steering motor of the steering drive subsystem, respectively. The vehicle controller is also configured to: send the calculated target speed and target displacement to the corresponding high-flow working motor pump group and low-flow working motor pump group; and send the calculated target speed of the steering drive subsystem to the steering motor so that the boom cylinder, bucket cylinder and steering electric cylinder can reach the target working speed.

7. A distributed electro-hydraulic hybrid drive hydraulic system for a loader according to claim 3, characterized in that... , Both the high-flow-rate working motor pump set and the low-flow-rate working motor pump set are equipped with motor pumps that can operate in four quadrants, so as to convert the hydraulic energy of the return oil from the boom cylinder and bucket cylinder into electrical energy and store it in the battery pack during boom lowering and bucket lowering operations.

8. A distributed electro-hydraulic hybrid drive hydraulic system for a loader according to claim 2, characterized in that... , Both the bucket potential energy recovery control valve and the boom potential energy recovery control valve are two-position two-way proportional control valves, so that the control flow of each hydraulic circuit can be linearly adjusted through the two-position two-way proportional control valve.

9. A control method for a loader's distributed electro-hydraulic hybrid drive hydraulic system as described in any one of claims 1-8, characterized in that... This includes the following steps: S1. Signal Acquisition: The control signals and status parameters of the entire vehicle are acquired through the acquisition unit. The control signals include handle signals, steering wheel signals, accelerator pedal signals, and brake pedal signals. The status parameters include the pressure of the large and small chambers of the boom cylinder and bucket cylinder, the outlet pressure of the high-flow working motor pump group, the outlet pressure of the low-flow working motor pump group, the motor speed and torque of the high-flow working motor pump group, the motor speed and torque of the low-flow working motor pump group, the steering motor speed of the steering drive subsystem, and the outlet pressure of the accumulator. S2. Working Condition Identification and Target Calculation: Based on the control signals and state parameters obtained in step S1, calculate the target working speed of the boom cylinder, bucket cylinder, and steering drive subsystem, and identify the working condition of the entire vehicle. S3. Demand Calculation: Calculate the required flow rate of the hydraulic oil supply components based on the target working speed of the boom cylinder and bucket cylinder. Calculate the target speed of the steering motor based on the target operating speed of the steering drive subsystem; S4. Power Parameter Matching: Based on the required flow rate of the hydraulic oil supply components and the identified vehicle operating conditions, calculate the target speed and target displacement of the high-flow working motor pump set and the target speed and target displacement of the low-flow working motor pump set; in the low-flow condition, match the parameters of the low-flow working motor pump set working alone; in the high-flow condition, match the parameters of the high-flow working motor pump set working alone. S5. Closed-loop execution: The target speed and target displacement obtained in step S4 are sent to the corresponding high-flow working motor pump group and low-flow working motor pump group. The target speed of the steering motor obtained in step S3 is sent to the steering motor of the steering drive subsystem to control the boom cylinder, bucket cylinder and steering electric cylinder to run to the target working speed respectively.

10. The control method for the distributed electro-hydraulic hybrid drive hydraulic system of a loader according to claim 9, characterized in that... , The high-flow working motor pump set and the low-flow working motor pump set can operate in four quadrants. During the boom lowering and bucket lowering conditions, they can recover energy from the high-pressure hydraulic oil returning from the cylinder to convert hydraulic energy into electrical energy and store it in the battery pack. The accumulator can recover energy from the high-pressure hydraulic oil returning from the cylinder during boom lowering and bucket lowering operations, so as to store the hydraulic energy. The energy recovery of the accumulator and the energy recovery of the high-flow-rate working motor pump group and the low-flow-rate working motor pump group can be carried out simultaneously.

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