Automobile hydraulic power generation system and control method

Abstract

The present application relates to the technical field of vehicle power output and electric energy conversion, and particularly relates to a kind of automobile hydraulic power generation system and control method, system includes power take-off module, hydraulic power module, power generation module, energy storage module, control module.The present application introduces adjustable energy conversion link consisting of hydraulic pump and hydraulic motor between vehicle power take-off interface and generator, realizes flexible decoupling and reconstruction of mechanical power, reduces the direct influence of engine operating condition fluctuation on generator speed, thereby significantly improves output frequency and voltage stability, on this basis, constructs double-loop control mechanism with generator speed stability as target and hydraulic circuit pressure as constraint, and adopts hierarchical control strategy of preferentially regulating hydraulic motor displacement, regulating hydraulic pump flow after displacement is limited, effectively shortens speed recovery time, suppresses pressure surge, reduces energy loss, improves overall control efficiency and operating stability of system.

Description

Technical Field

[0001] This invention relates to the field of vehicle power output and electrical energy conversion technology, specifically to an automotive hydraulic power generation system and control method. Background Technology

[0002] With the rapid development of automotive technology, vehicle power output and electric energy conversion systems play a crucial role in improving energy efficiency and achieving energy recovery. In existing technologies, hybrid power systems achieve power output and electric energy conversion through the coordinated operation of the engine and electric motor. However, they still have shortcomings in system integration, energy conversion efficiency, and adaptability to operating conditions, making it difficult to meet the growing demands for energy conservation and environmental protection.

[0003] CN101249830B discloses a system and method for adjusting the lock-up state of a torque converter using an electric energy conversion device. More specifically, it relates to a hybrid vehicle propulsion system, including an internal combustion engine, a torque converter, an electric energy conversion device, and a control system. The system improves the smoothness of power delivery during the engagement and disengagement of the torque converter's lock-up clutch by adjusting the torque output of the electric energy conversion device. However, this solution still has the following shortcomings: First, the system mainly focuses on the lock-up control of the torque converter, and the management of energy flow between the engine and the electric motor is not precise enough, resulting in limited improvement in energy conversion efficiency. Second, it lacks a dynamic energy distribution strategy for different driving conditions, making it difficult to achieve optimal energy recovery under complex road conditions. Third, the system structure is relatively complex, requiring high control precision, which increases manufacturing costs and maintenance difficulty.

[0004] CN113415159A discloses an on-board system for converting vehicle mechanical power into electricity, which achieves the conversion of mechanical energy into electrical energy through a power take-off (PTO) connected to a generator. The system includes a PTO, a generator, and a switch control device. This technical solution can convert the mechanical energy of a vehicle's power system into electrical energy output. However, this solution has the following drawbacks: First, the rigid mechanical connection method makes it susceptible to fluctuations in engine speed during vehicle operation, leading to unstable output voltage and frequency. Second, the system lacks an effective energy buffering and regulation mechanism, easily causing energy waste under transient conditions such as rapid acceleration and braking. Third, it does not consider multi-energy collaborative working modes, making it difficult to optimize the engine operating point and affecting the overall vehicle fuel economy.

[0005] The aforementioned problems indicate that existing vehicle power output and energy conversion technologies still have significant shortcomings in terms of system integration, energy conversion efficiency, and adaptability to operating conditions. Therefore, this invention provides an automotive hydraulic power generation system and control method, aiming to achieve more efficient and stable energy conversion and control through the organic combination of hydraulic transmission and power generation systems. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides an automotive hydraulic power generation system and its control method.

[0007] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides an automotive hydraulic power generation system, the system comprising a power take-off module, a hydraulic power module, a power generation module, an energy storage module, and a control module; The power take-off module is used to connect to the power take-off interface of the vehicle engine or transmission to extract the mechanical power output from the power system when the vehicle is not in motion, and to engage or disconnect the power transmission path in response to the control signal of the control module. The hydraulic power module includes a hydraulic pump, a hydraulic motor, and a hydraulic circuit connected to the hydraulic pump and the hydraulic motor. The hydraulic pump is used to convert the mechanical power into hydraulic energy, and the hydraulic motor is used to convert the hydraulic energy into rotational mechanical energy. The power generation module includes a generator, which is used to output electrical energy under the drive of the hydraulic motor; The energy storage module consists of a lithium iron phosphate energy storage battery, a protection board, a charging and discharging system, and a battery pack package. It is used to store excess power from the generator and form a mixed discharge of the generator and the energy storage battery to the load.

[0008] The control module is used to acquire the rotational speed of the generator and the pressure of the hydraulic circuit, and control the power take-off module to be in an engaged or disengaged state based on the rotational speed and the pressure. When the power take-off module is in an engaged state, the module controls the output flow rate of the hydraulic pump and the displacement of the hydraulic motor to maintain the rotational speed of the generator within a preset speed range corresponding to the target output frequency.

[0009] Furthermore, the power take-off module includes a power take-off unit, an elastic coupling disposed between the power take-off unit and the hydraulic pump, and a power on / off mechanism. The elastic coupling is used to compensate for axial deviation, angular deviation, and radial deviation between the output shaft of the power take-off unit and the input shaft of the hydraulic pump, and to reduce the impact and vibration during power transmission. The power on / off mechanism is disposed inside the power take-off unit and is used to engage or disconnect the power transmission path under the control of the control module.

[0010] Furthermore, the hydraulic circuit is a closed hydraulic circuit, and the hydraulic power module also includes a hydraulic oil tank, a replenishment branch, and a flushing and cooling branch. The replenishment branch is used to replenish hydraulic oil to the low-pressure side of the closed hydraulic circuit, and the flushing and cooling branch is used to export part of the hydraulic oil from the low-pressure side of the closed hydraulic circuit, which is then filtered by the return oil filter module and cooled by the cooling module before flowing back to the hydraulic oil tank.

[0011] Furthermore, the oil replenishment branch includes an oil replenishment check valve group that is connected to the main oil circuits on both sides of the closed hydraulic circuit respectively, and the flushing and cooling branch includes a flushing shuttle valve that is connected to the oil ports on both sides of the hydraulic motor and a flushing overflow valve that is connected downstream of the flushing shuttle valve. The flushing shuttle valve is used to introduce the hydraulic oil on the side with lower pressure in the oil ports on both sides of the hydraulic motor into the flushing and cooling branch.

[0012] Furthermore, the control module includes a speed sensor, a pressure sensor, a flow regulation actuator, a displacement regulation actuator, and an electronic controller. The electronic controller establishes a main control loop based on the speed with the goal of stabilizing the generator output, and establishes a constraint control loop based on the pressure. When the rotational speed deviates from the preset rotational speed range and the pressure does not reach the preset pressure threshold, the hydraulic motor displacement is preferentially adjusted by the displacement adjustment actuator. If adjusting the hydraulic motor displacement to the preset displacement limit still fails to restore the rotational speed to the preset rotational speed range, the hydraulic pump output flow is then adjusted through the flow regulation actuator.

[0013] Furthermore, the electronic controller is configured to switch between standby mode, idle power generation mode, full-speed power generation mode and shutdown protection mode when the vehicle is not in motion, based on power demand signals and vehicle operating condition signals. In standby mode, the power on / off mechanism is disconnected and the hydraulic pump is in an unloaded state. In idle power generation mode, the power on / off mechanism is engaged, and the hydraulic pump output flow is within a first preset range; In full-speed power generation mode, the power on / off mechanism is engaged, and the output flow of the hydraulic pump is within a second preset range, which is higher than the first preset range. In the shutdown protection mode, the power on / off mechanism is disconnected, and the displacement of the hydraulic pump is reduced to zero.

[0014] Furthermore, the electronic controller sets a hysteresis threshold on at least one vehicle operating condition determination parameter, which includes at least one of engine speed, load power, and energy storage status parameters, to suppress frequent switching of the system between the idle power generation mode and the full-speed power generation mode near the critical operating condition.

[0015] Furthermore, the hydraulic power module also includes a return oil filter module, a cooling module, and a high-pressure protection component. The return oil filter module is located on the return oil passage, the cooling module is used to reduce the hydraulic oil temperature, and the high-pressure protection component includes a pressure shut-off valve to reduce the displacement of the hydraulic pump to a preset safe displacement when the hydraulic circuit pressure exceeds a preset pressure threshold.

[0016] Furthermore, the power generation module also includes a power conversion module electrically connected to the generator. The power conversion module is used to rectify, invert, and convert the voltage level of the electrical energy output by the generator to output AC power at a preset voltage level suitable for energy storage batteries, vehicle loads, or external AC loads. The power take-off is a gearbox-type power take-off, the flexible coupling is a diaphragm-type flexible coupling, and the cooling module is an air-cooled cooler.

[0017] Secondly, the present invention also provides a control method for an automotive hydraulic power generation system, comprising the following steps: S1: Acquire power demand signals, vehicle operating condition signals, generator speed, and hydraulic circuit pressure; S2: Based on the power demand signal and the vehicle operating condition signal, determine whether the automotive hydraulic power generation system has entered the power generation operation state, and control the power take-off module to enter the engaged state or the disengaged state. S3: After the power take-off module enters the engagement state, control the hydraulic pump to output hydraulic energy and drive the hydraulic motor to drive the generator to generate electricity; S4: Based on the generator speed, determine whether the generator speed is within the corresponding preset range, and if it deviates from the corresponding preset range, prioritize adjusting the hydraulic motor displacement; if adjusting the hydraulic motor displacement to the preset displacement limit still cannot restore the generator output frequency to the corresponding preset range, then adjust the hydraulic pump output flow rate. S5: During the adjustment of the hydraulic motor displacement and the hydraulic pump output flow, the adjustment process is constrained based on the hydraulic circuit pressure. S6: When abnormal hydraulic circuit pressure, abnormal hydraulic oil temperature, abnormal generator output, or abnormal power on / off mechanism status is detected, the power take-off module is disconnected and the hydraulic pump displacement is reduced to zero displacement.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention introduces an adjustable energy conversion link consisting of a hydraulic pump and a hydraulic motor between the vehicle's power take-off interface and the generator. This prevents the mechanical power output from the engine or transmission from rigidly and directly acting on the generator. Instead, it decouples and reconfigures the power through a hydraulic intermediate link. This reduces the direct impact of vehicle idling, engine acceleration / deceleration, and sudden load changes on the generator's input speed, thereby improving the stability of the generator's output frequency and voltage. Compared to a simple connection between the power take-off and the generator, this invention establishes a dual-loop control mechanism with generator speed stability as the goal and hydraulic circuit pressure as the constraint. It also adopts a layered control strategy that prioritizes adjusting the hydraulic motor displacement and then adjusts the hydraulic pump output flow rate only after the displacement reaches its limit. This shortens the speed recovery time and reduces pressure surges and power waste caused by directly increasing the hydraulic pump flow rate, thus improving system control efficiency and stability.

[0019] By installing a flexible coupling between the power take-off (PTO) and the hydraulic pump, this invention can compensate for installation deviations and reduce the impact and vibration during power transmission, thereby reducing the additional load on the PTO, hydraulic pump, and related bearing components, and improving the system's installation adaptability and long-term operational reliability.

[0020] By adopting a closed hydraulic circuit and configuring a replenishment branch and a flushing and cooling branch, this invention can maintain high-efficiency hydraulic transmission while compensating for leakage in the circuit, controlling the fluid filling state on the low-pressure side of the main circuit, and continuously drawing out high-temperature oil for filtration and cooling, thereby improving the thermal balance and cleanliness of the oil and reducing the wear of hydraulic components.

[0021] By setting standby mode, idle power generation mode, full-speed power generation mode and shutdown protection mode, and setting a hysteresis threshold on the mode determination parameters, this invention can reduce frequent mode switching under critical operating conditions while ensuring power supply demand, thereby improving the stability of control logic and the lifespan of the entire machine.

[0022] By setting up high-voltage protection components, abnormal power output detection, and abnormal power on / off mechanism status detection, this invention forms a multi-layer protection link of mechanical, hydraulic, and electrical control. In the event of overvoltage, overheating, abnormal power generation, or abnormal mechanism, the power transmission path can be disconnected in time and the hydraulic pump can be reduced to a safe displacement or zero displacement state, thereby improving system safety. Attached Figure Description

[0023] Figure 1 This is a flowchart of the system modules of the present invention; Figure 2 This is a flowchart of the control method of the present invention. Detailed Implementation

[0024] 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 some embodiments of the present invention, and not all embodiments. 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.

[0025] To avoid the terms in the claims being considered ambiguous in the embodiments, the relevant terms are now explained.

[0026] The preset speed range corresponding to the target output frequency refers to the allowable speed range given to the mechanical input terminal of the generator to achieve the target AC output frequency. This range can be determined by the number of generator pole pairs, the target output frequency, the compensation capability of the power conversion module, and the allowable load deviation. When the generator directly outputs AC at the power frequency, the target output frequency and the mechanical speed are determined according to the number of generator pole pairs. When the generator output is rectified and inverted to form AC output, the preset speed range is preferably set to the mechanical input range corresponding to the high-efficiency and stable operating range of the inverter.

[0027] Vehicle operating condition signals include one or more of the following: engine speed, parking status, throttle opening, braking status, load power, and energy storage status parameters.

[0028] Electricity demand signals include one or more of the following: vehicle load access signal, external AC load access signal, load power estimate, battery energy storage unit charging demand signal, or driver active power generation command.

[0029] Abnormal power generation output includes at least one of the following: output voltage higher than the upper limit, lower than the lower limit, output current exceeding the rated value, output frequency deviating from the allowable range, or inverter failure.

[0030] Abnormal status of the power on / off mechanism includes at least one of the following: inconsistency between the feedback status of the power on / off mechanism and the control command status, failure to reach the time limit, slippage after engagement, or failure to disengage after disconnection.

[0031] The preset displacement limit refers to the minimum or maximum displacement boundary value that the hydraulic motor variable mechanism is allowed to reach under the current system calibration conditions.

[0032] The preset pressure thresholds include a first pressure threshold for process constraints and a second pressure threshold for protective actions, wherein the second pressure threshold is higher than the first pressure threshold.

[0033] Example 1 Please see Figure 1 The present invention provides an automotive hydraulic power generation system, the system comprising a power take-off module, a hydraulic power module, a power generation module, an energy storage module, and a control module; The power take-off module is used to connect to the power take-off interface of the car engine or transmission to extract the mechanical power output from the car's power system and to engage or disconnect the power transmission path in response to the control signal of the control module.

[0034] In this embodiment, the power take-off module adopts a transmission power take-off unit. The reason for adopting a transmission power take-off unit is that commercial vehicles usually have relatively stable installation space on the side of the transmission, and the transmission structure is conducive to the hydraulic pump being arranged along a shorter path, thereby reducing intermediate transition parts and installation errors. The power take-off unit can be connected to the transmission power take-off port by a flange, or it can be connected to the engine power take-off interface by a special connecting seat. The output shaft of the power take-off unit is connected to the hydraulic pump input shaft through a flexible coupling.

[0035] The flexible coupling adopts a diaphragm type flexible coupling, which includes a driving half-coupling, a driven half-coupling, an intermediate connecting body, and at least one set of metal diaphragms. The diaphragm sets are connected between the half-couplings and the intermediate connecting body by high-strength bolts in an alternating manner, so as to compensate for the axial deviation, angular deviation, and radial deviation between the driving shaft and the driven shaft through the elastic deformation of the diaphragms. By setting the diaphragm type flexible coupling, assembly errors and operating shocks can be absorbed while maintaining high transmission stiffness.

[0036] Preferably, the axial compensation capability can be ±2.0mm, the angular compensation capability can be ±1.5°, and the radial compensation capability can be ±0.8mm. The above compensation parameters can be determined based on the vehicle installation tolerance, the bracket thermal deformation, the vibration displacement amplitude, and the allowable front-end load of the hydraulic pump.

[0037] The power on / off mechanism is located inside the power take-off unit and is used to engage or disconnect the power transmission path under the control of the control module.

[0038] Preferably, the power on / off mechanism is a pneumatic shift fork mechanism or an electric push-pull shift fork mechanism, including a cylinder, a shift fork, a sliding engagement sleeve, a meshing gear, and a position feedback sensor. The control module controls the solenoid valve to allow compressed air to enter the cylinder, pushing the shift fork to engage or disengage the sliding engagement sleeve with the power take-off gear, thereby realizing power engagement or disengagement.

[0039] The hydraulic power module includes a hydraulic pump, a hydraulic motor, and a hydraulic circuit connected to the hydraulic pump and the hydraulic motor. The hydraulic pump is used to convert mechanical power into hydraulic energy, and the hydraulic motor is used to convert hydraulic energy into rotational mechanical energy.

[0040] In this embodiment, the hydraulic pump is preferably a swashplate axial piston variable pump with a rated pressure of 35MPa and a rated flow rate of 120L / min. The reason for using a variable pump is that this invention does not generate electricity under constant operating conditions. The vehicle's operating conditions vary significantly between idling, low load, high load, and abnormal conditions. It is necessary to actively adjust the output flow rate by changing the pump displacement in order to achieve power matching and pressure control. If a fixed displacement pump is used, it is necessary to rely on a lot of throttling adjustment, which is not only inefficient but also generates significant heat, which is not conducive to the long-term operation of the vehicle system.

[0041] The hydraulic motor is a swashplate axial piston variable displacement motor or a gear motor, with a displacement adjustment range of 25 mL / r to 100 mL / r. The reason for setting a variable displacement motor is that, under certain flow conditions, the speed of the hydraulic motor is inversely proportional to its displacement. By changing the motor displacement, the output shaft speed can be quickly changed without immediately increasing the output power of the hydraulic pump. Therefore, the hydraulic motor variable displacement mechanism is the key execution basis for the present invention to realize the strategy of prioritizing displacement adjustment and then adjusting flow. The lower and upper limits of displacement can be determined based on the hydraulic motor body structure, volumetric efficiency, starting torque requirements, and high-speed stability.

[0042] The hydraulic circuit is preferably a closed-loop hydraulic circuit. The reason for setting a closed-loop circuit is that the main circulation is formed between the hydraulic pump and the hydraulic motor in the closed-loop circuit. The main flow path is short, the throttling loss is small, and the dynamic response is fast. It is more suitable for establishing a high-response speed regulation closed loop around the generator output speed. Compared with the open-loop circuit, the closed-loop circuit can reduce the energy loss caused by the large flow circulation through the oil tank. It is particularly suitable for medium and high power vehicle-mounted power generation scenarios that require continuous and stable output.

[0043] The hydraulic power module also includes a hydraulic oil tank, a replenishment branch, and a flushing and cooling branch. The hydraulic oil tank is used to store hydraulic oil, separate air bubbles, settle contaminant particles, and provide heat capacity buffer. The tank volume can be determined according to the system's rated flow rate, continuous working time, allowable temperature rise, and vehicle installation space. For example, for a 15kW system, 60L to 80L is preferred. The tank can be equipped with a level gauge, temperature sensor, and air filter to detect the liquid level and oil temperature and prevent airborne contaminants from entering.

[0044] The replenishment branch is used to replenish hydraulic oil to the low-pressure side of the closed hydraulic circuit. In the closed hydraulic circuit, due to the inevitable leakage inside the hydraulic pump and hydraulic motor, and the continuous removal of some oil by the flushing and cooling branch, if oil is not replenished, the low-pressure side will experience cavitation, insufficient lubrication, and suction problems due to insufficient oil. Therefore, this embodiment uses a replenishment pump and a replenishment check valve assembly to achieve oil replenishment. The replenishment pump draws oil from the hydraulic oil tank, filters it, and sends it to the replenishment check valve assembly. The replenishment check valve assembly is connected to the main oil circuits on both sides of the closed circuit. When one side becomes the low-pressure side, the corresponding check valve is opened by the replenishment pressure, replenishing hydraulic oil to the low-pressure side, while the corresponding check valve on the high-pressure side remains closed. This allows for automatic replenishment of oil to the low-pressure side without complex switching control. The replenishment pressure is preferably higher than the minimum filling pressure of the closed circuit and lower than the working pressure of the main circuit, and can be determined based on the pump suction conditions, cavitation margin, and stability of the variable mechanism.

[0045] The flushing and cooling branch is used to export a portion of the hydraulic oil from the low-pressure side of the closed hydraulic circuit. After being filtered by the return oil filter module and cooled by the cooling module, it flows back to the hydraulic oil tank. The reason for setting up the flushing and cooling branch is that although the closed circuit is highly efficient, the oil in its main circuit circulates repeatedly between the pump and the motor. If there is no hot oil replacement path, the local oil temperature will continue to rise, the oil viscosity will decrease, and internal leakage will increase, which will further reduce efficiency. Therefore, in this embodiment, flushing shuttle valves are set on the oil ports on both sides of the hydraulic motor. The flushing shuttle valve automatically identifies the side with lower pressure and introduces a portion of the hydraulic oil from the low-pressure side into the flushing and cooling branch. A flushing overflow valve is set downstream of the flushing shuttle valve to control the pressure and flow rate of the flushing branch, preventing excessive oil from being drawn from the low-pressure side and disrupting the main circuit filling conditions. The setting value of the flushing overflow valve can be determined according to the minimum allowable pressure on the low-pressure side of the system, the oil replenishment capacity, and the heat load. For example, it can be preferably around 1.5 MPa, but is not limited to this value.

[0046] The return oil filtration module is installed on the flushing and cooling branch or the return oil passage to filter out particulate impurities in the hydraulic oil. The filtration accuracy can be determined according to the cleanliness requirements of the hydraulic pump, hydraulic motor and variable valve core, for example, 10μm is preferred. The cooling module can be an air-cooled cooler or an oil-cooled cooler. If an air-cooled cooler is used, the fan can be started and stopped in stages according to the oil temperature. For example, it can run at low speed when the oil temperature exceeds the first temperature threshold and at high speed when the oil temperature exceeds the second temperature threshold. The first temperature threshold and the second temperature threshold can be determined based on the viscosity-temperature characteristics of the hydraulic oil, the results of the system thermal balance test and the allowable operating temperature of the components. For example, the first temperature threshold can be calibrated between 60℃ and 70℃ and the second temperature threshold can be calibrated between 75℃ and 85℃.

[0047] The hydraulic power module also includes a high-pressure protection component, which includes a pressure shut-off valve. The pressure shut-off valve can be integrated into the hydraulic pump variable mechanism. When the hydraulic circuit pressure exceeds the second pressure threshold, the pressure shut-off valve directly causes the hydraulic pump swashplate to move towards a smaller displacement, reducing the hydraulic pump displacement to a preset safe displacement. The preset safe displacement can be a small displacement close to zero to take into account both the basic lubrication and rapid unloading needs of the hydraulic pump. The second pressure threshold should be higher than the first pressure threshold and can be determined based on the rated working pressure of the hydraulic pump, the pressure resistance rating of the pipeline, the continuous allowable pressure of the motor, and the safety margin. For example, when the rated working pressure of the system is 35MPa, the first pressure threshold can be calibrated between 35MPa and 37MPa, and the second pressure threshold can be calibrated between 38MPa and 40MPa.

[0048] The power generation module includes a generator, which is used to output electrical energy driven by a hydraulic motor; Preferably, the power generation module further includes a power conversion module electrically connected to the generator. The power conversion module includes a rectifier unit, a DC bus, an inverter unit, and an output voltage level conversion unit. Its function is to rectify, invert, and convert the electrical energy output by the generator to output AC power at a preset voltage level suitable for the vehicle load or external AC load. The reason for using the power conversion module is that even if the control module has controlled the generator speed near the target range, changes in vehicle operating conditions and load may still cause a certain degree of mechanical fluctuation. By setting up the power conversion module, the stability of the electrical output can be further improved, and the system can have the output capability of 220V single-phase AC, 380V three-phase AC, or other preset voltage levels. In addition, the power conversion module also includes overvoltage, overcurrent, overload, and short-circuit protection functions to protect the power generation unit and hydraulic power module when there is an abnormality on the load side.

[0049] This embodiment provides a specific explanation regarding the determination of the preset speed range corresponding to the target output frequency: When the generator directly outputs AC power frequency, the relationship between the generator's mechanical speed and electrical output frequency is determined by the number of pole pairs of the generator. For example, in the case of a four-pole generator, a 50Hz AC output typically corresponds to a mechanical speed of approximately 1500 r / min; in the case of a six-pole generator, a 50Hz AC output typically corresponds to a mechanical speed of approximately 1000 r / min. If the generator output is rectified and inverted to form AC power frequency, the preset speed range in the control module does not necessarily need to be equal to a single point of the theoretical power frequency mechanical point. Instead, it is preferable to determine the mechanical input range corresponding to the high-efficiency stable operating range of the inverter. This range can be determined by the following method: First, select the center value of the mechanical input speed with high overall efficiency based on the generator efficiency curve, the rectifier-inverter efficiency curve, and the target output power range. Then, determine the allowable fluctuation range on both sides of this center value based on the allowable fluctuation range of the inverter input, the load's sensitivity to frequency and voltage, and the control response speed. Finally, correct this range through prototype testing so that the system can meet the requirements of stable electrical output under typical operating conditions without excessively increasing the hydraulic regulation burden. For example, in a 15kW, 50Hz output scenario, it is preferable to set the mechanical input target at around 1500r / min, and calibrate the preset speed range as 1500±10r / min, 1500±20r / min, or other ranges determined by testing.

[0050] The energy storage module consists of a lithium iron phosphate energy storage battery, a protection board, a charging and discharging system, and a battery pack package. It is used to store excess power from the generator and form a mixed discharge from the generator and the energy storage battery to the load.

[0051] Preferably, the energy storage module is used to store excess power output from the generator to achieve a hybrid discharge mode of the generator and the energy storage battery, thereby providing continuous power to the load. This module mainly consists of the following parts: Lithium iron phosphate energy storage battery: Lithium iron phosphate batteries are widely used in energy storage systems due to their high energy density, long service life and high safety. In this embodiment, the energy storage module uses a lithium iron phosphate energy storage battery to store excess power obtained from the generator, ensuring a stable power supply.

[0052] Protection board: The protection board is used to monitor key parameters of the battery such as voltage, current and temperature, and prevent the battery from being overcharged, over-discharged or overheated. The protection board can effectively ensure the safety of the battery and improve the reliability and stability of the system.

[0053] Charging and discharging system: The charging and discharging system is responsible for managing the charging and discharging process of the battery, including adjusting the charging current and voltage according to the battery status to ensure the safety and efficiency of the charging process. At the same time, the system also supports discharging from the battery to the load, so that the battery can provide power to the load when the generator cannot provide enough power.

[0054] Battery pack packaging: Battery pack packaging is the process of assembling multiple lithium iron phosphate battery cells into a whole and encapsulating them into a stable battery pack through mechanical structure. The battery pack not only has a protective function, but also effectively manages thermally, ensuring that the battery is maintained within a safe temperature range during operation.

[0055] Specifically, during system operation, when the power output of the generator exceeds the load demand, the excess power will be stored in the lithium iron phosphate energy storage battery through the charging and discharging system. The stored power will be automatically released when the load demand increases or the generator output is insufficient, and the load will be powered by the hybrid discharge mode of the energy storage battery and the generator. This mode effectively balances the fluctuations in power supply and demand, and improves the stability and reliability of the system.

[0056] Based on the above structure and working principle, the energy storage module can store electrical energy when the generator outputs excess power and provide support when the generator output is insufficient, ensuring that the load's power demand is always met.

[0057] The control module is used to acquire the generator speed and the hydraulic circuit pressure, and control the power take-off module to be in an engaged or disengaged state based on the speed and pressure. When the power take-off module is in an engaged state, it controls the output flow of the hydraulic pump and the displacement of the hydraulic motor to maintain the generator speed within a preset speed range corresponding to the target output frequency.

[0058] The control module includes a speed sensor, a pressure sensor, a flow regulation actuator, a displacement regulation actuator, and an electronic controller. The control module is used to acquire the generator speed and hydraulic circuit pressure, and to control the engagement or disengagement of the power take-off module based on the speed and pressure, as well as to control the output flow of the hydraulic pump and the displacement of the hydraulic motor in the engaged state.

[0059] A speed sensor is used to detect the generator speed.

[0060] Preferably, the speed sensor is a Hall sensor or a magnetoelectric sensor, installed at the generator shaft end, near the encoder wheel, or at the hydraulic motor output shaft. Because the Hall sensor has a simple structure, strong anti-pollution ability, and is suitable for oil and vibration conditions in the vehicle environment, the Hall sensor is adopted. The control module can calculate the real-time speed based on the pulse period or the number of pulses per unit time. To improve the measurement accuracy at low and high speeds, the electronic controller can adopt an adaptive speed measurement algorithm, using a periodic measurement method at low speeds and a counting method at high speeds.

[0061] Pressure sensors are used to detect pressure in hydraulic circuits.

[0062] Preferably, at least one pressure sensor is installed at the main high-pressure oil circuit outlet of the hydraulic pump; more preferably, an auxiliary pressure sensor can also be installed at the inlet of the hydraulic motor. The main high-pressure side pressure sensor is used to reflect the current pressure level of the main circuit of the system and serves as an important basis for process constraints and protection actions. The auxiliary pressure sensor is used to evaluate pipeline pressure drop, the health status of hydraulic components, and the control execution effect.

[0063] Flow regulating actuators are used to regulate the output flow of hydraulic pumps, while displacement regulating actuators are used to regulate the displacement of hydraulic motors.

[0064] Specifically, the flow rate regulating actuator can be an electro-hydraulic proportional actuator, servo actuator, or other actuator capable of controlling the hydraulic pump displacement corresponding to the hydraulic pump variable mechanism; the displacement regulating actuator can be a proportional actuator, servo actuator, or other actuator capable of controlling the hydraulic motor displacement corresponding to the hydraulic motor variable mechanism. Since the hydraulic pump output flow rate is related to the hydraulic pump displacement and input speed, under the condition that the engine or gearbox input speed is constant, adjusting the hydraulic pump displacement can achieve the control of the output flow rate.

[0065] The electronic controller is used to form a main control loop and a constraint control loop. The main control loop aims to stabilize the generator speed, while the constraint control loop uses the hydraulic circuit pressure as a constraint to prevent the hydraulic circuit from entering the overpressure or high-risk operating area during speed regulation. The reason for adopting a dual-loop control structure of speed main loop plus pressure constraint loop is that the ultimate goal of this invention is to obtain stable electrical output. Hydraulic pressure reflects both the system load and hydraulic power status, and is directly related to the safety boundary of hydraulic components. If only speed is controlled in a closed loop, there is a risk of continuously increasing the hydraulic pressure in pursuit of speed stability; if only pressure is controlled, the generator output quality cannot be guaranteed. Therefore, dual-loop control is necessary.

[0066] In this embodiment, the electronic controller preferably executes the following control logic: Speed ​​deviation judgment logic: The electronic controller collects the generator speed n in real time and compares it with the preset speed range. When n is within the preset speed range, the current control value is maintained or a small correction is made. When n is lower than the lower limit of the preset speed range, it is judged as underspeed. When n is higher than the upper limit of the preset speed range, it is judged as overspeed. In order to prevent measurement noise from causing misjudgment, the speed signal can be low-pass filtered or moving average filtered, and a minimum duration threshold can be set. For example, the speed can be continuously exceeded by the boundary for more than a certain number of sampling periods before it is considered as a valid deviation.

[0067] Priority adjustment of displacement logic: When underspeed or overspeed occurs, and the hydraulic circuit pressure P is lower than the first pressure threshold P1, the electronic controller prioritizes controlling the displacement adjustment actuator to adjust the hydraulic motor displacement Dm. For underspeed conditions, the electronic controller controls the hydraulic motor displacement to change in a direction that is conducive to increasing the speed; for overspeed conditions, the electronic controller controls the hydraulic motor displacement to change in a direction that is conducive to reducing the speed. The reason for prioritizing displacement adjustment is that the hydraulic motor displacement directly determines the output speed at a given flow rate. The adjustment path is short, the response is fast, and the disturbance to the input power and main circuit pressure of the entire hydraulic system is small. Therefore, it is more suitable as the first means of adjusting speed deviation.

[0068] Limit-adjusted flow logic: When the hydraulic motor displacement is adjusted to the preset displacement limit, but the generator speed still cannot be restored to the preset speed range, the electronic controller controls the flow adjustment actuator to adjust the hydraulic pump output flow. For underspeed conditions, if the hydraulic motor displacement is adjusted to the limit most conducive to speed increase but is still insufficient, it indicates that the system hydraulic power input is insufficient. At this time, the hydraulic pump is controlled to increase the displacement to increase the output flow. For overspeed conditions, if the hydraulic motor displacement is adjusted to the limit most conducive to speed decrease but is still overspeed, it indicates that the system hydraulic power input is relatively excessive. At this time, the hydraulic pump is controlled to decrease the displacement to reduce the output flow.

[0069] Pressure constraint logic: The electronic controller collects the hydraulic circuit pressure P in real time. When P is less than the first pressure threshold P1, active speed adjustment is allowed according to the above logic of prioritizing displacement adjustment followed by flow adjustment. When P approaches P1, the electronic controller preferentially limits the adjustment range or rate of the hydraulic pump output flow to avoid rapid pressure surge. When P reaches or exceeds the second pressure threshold P2, the electronic controller immediately puts the system into protection derating or shutdown protection logic, controls the hydraulic pump displacement to decrease to the preset safe displacement or zero displacement, and controls the power on / off mechanism to disconnect. The settings of P1 and P2 should satisfy P2 > P1. P1 is used for process control constraints, and P2 is used for protection actions. By setting two pressure thresholds, the system can enter a restricted control state before actual overpressure, avoiding frequent triggering of hardware-level overpressure protection.

[0070] Mode switching logic: The electronic controller switches between standby mode, idle power generation mode, full-speed power generation mode and shutdown protection mode according to the power demand signal and vehicle operating condition signal.

[0071] The conditions for entering standby mode can be: no effective power demand, or the driver turns off the generator function, or the system does not meet the safety access conditions for entering the generator state. In standby mode, the power on / off mechanism is disconnected, the hydraulic pump is in an unloaded state or near-zero displacement state, and the generator does not work. This mode is used to reduce no-load energy consumption and unnecessary wear.

[0072] The conditions for entering the idle power generation mode are: the engine speed is within the idle speed determination range, there is a basic power demand, and the system meets the safety access conditions for entering the power generation state. The idle speed determination range can be set according to the engine calibration characteristics, such as 650rpm to 900rpm. The basic power demand can be determined by the estimated total load power, the external AC load connection status, or the charge status of the energy storage unit. In the idle power generation mode, the power on / off mechanism is engaged, and the hydraulic pump output flow is within the first preset range. The first preset range can be determined based on the engine's continuous idle output torque, the hydraulic pump efficiency, and the target basic load power, for example, it can be 30% to 50% of the rated flow.

[0073] The conditions for entering the full-speed power generation mode can be: the engine speed is higher than the idle speed range and reaches the speed range suitable for higher power output, and there is a high power demand, or the driver actively selects the forced power generation mode. In the full-speed power generation mode, the power on / off mechanism is engaged, and the hydraulic pump output flow is in the second preset range. The second preset range is higher than the first preset range, for example, it can be 60% to 100% of the rated flow. This setting is because high power output requires higher hydraulic power input, and high speed conditions are more conducive to providing this input capability.

[0074] The shutdown protection mode can be entered under any of the following conditions: abnormal hydraulic circuit pressure, abnormal hydraulic oil temperature, abnormal generator output, or abnormal power switching mechanism status. In shutdown protection mode, the power switching mechanism is disconnected, the hydraulic pump displacement is reduced to zero displacement, and audible and visual alarms and fault latching can be triggered as needed. This mode is used to quickly cut off power input and hydraulic power input under abnormal conditions to prevent the fault from escalating.

[0075] Hysteresis logic: To avoid frequent switching between idle and full-speed power generation modes near critical operating conditions, the electronic controller sets a hysteresis threshold for at least one vehicle operating condition judgment parameter. Taking engine speed as an example, the upper cut-off threshold for switching from idle to full-speed power generation can be set to 1000 rpm, while the lower cut-off threshold for returning from full-speed to idle power generation can be set to 900 rpm. Duration requirements can also be set simultaneously. For example, the upper cut-off condition can be met continuously for more than 3 seconds before entering full-speed power generation, and the lower cut-off condition can be met continuously for more than 5 seconds before returning to idle power generation. A similar hysteresis method can also be used for load power and energy storage status parameters. For example, when entering full-speed power generation, the load power is required to exceed 4.5 kW, while when exiting full-speed power generation, the load power is required to be below 3.5 kW for a certain period of time. The size of the hysteresis threshold can be calibrated according to the natural fluctuation amplitude of the operating condition signal, the system switching cost, and the response requirements. Generally, it can be taken as 5% to 10% of the typical fluctuation amplitude of the corresponding judgment quantity.

[0076] The center value of the generator's preset speed range is determined by the target output frequency and the number of generator pole pairs, or by the inverter's high-efficiency input range. Its bandwidth is jointly determined by the load's allowable frequency fluctuation, voltage fluctuation, controller response speed, generator inertia, and inverter compensation capability.

[0077] The first pressure threshold P1 should not be higher than the upper limit of the long-term reliable working pressure of the system, preferably lower than the upper limit of the continuous working pressure of the hydraulic pump and hydraulic motor, and a control adjustment margin should be reserved. The second pressure threshold P2 should be higher than P1, but lower than the system structure pressure resistance limit and the upper limit of the allowable instantaneous pressure of the hydraulic components.

[0078] The oil temperature protection threshold can be determined based on the recommended operating temperature range of hydraulic oil, the heat resistance rating of seals, the efficiency degradation of pumps and motors, and cooling capacity. The normal heat dissipation control threshold should be lower than the shutdown protection threshold.

[0079] The abnormal power generation output threshold can be determined based on the generator's rated voltage and current, the inverter's allowable output deviation, and the load's tolerance. For example, for a 380V AC output scenario, the voltage abnormality criterion can be set around the rated value with an allowable deviation range; the current abnormality threshold can be determined based on the rated output current plus a safety margin.

[0080] The timeout determination time of the power on / off mechanism can be determined based on the theoretical operating time of the drive mechanism, the fluctuation range caused by temperature and air pressure changes, and safety requirements. This time should not be too short to avoid false alarms, nor too long to avoid missing the protection opportunity.

[0081] The electronic controller continuously monitors the hydraulic circuit pressure, hydraulic oil temperature, generator output voltage, current and frequency, power on / off mechanism feedback status, and speed sensor signal integrity. When any of the following abnormalities are detected, the system enters shutdown protection mode: The hydraulic circuit pressure exceeds the second pressure threshold and remains above the preset confirmation time; The hydraulic oil temperature exceeds the preset upper limit. The following are examples of power generation issues: output voltage exceeding the upper limit or falling below the lower limit; output current exceeding the rated value and continuing for an extended period; output frequency continuously deviating from the allowable range; feedback status of the power switching mechanism being inconsistent with control command status and continuing for an extended period; loss or obvious abnormality of speed sensor signal; hydraulic oil tank level falling below the safe level; and internal protection activation of the power conversion module.

[0082] After entering the shutdown protection mode, the electronic controller preferably performs the following actions in sequence: First, it directs the flow regulation actuator to unload or reduce the displacement direction; second, it directs the displacement regulation actuator to a safe position; third, it controls the power on / off mechanism to disconnect; fourth, it keeps the cooling module running for a delay as needed to remove residual heat; fifth, it records the fault code and activates the audible and visual alarm; sixth, it determines whether to allow automatic reset or manual reset only based on the fault level.

[0083] Specifically, after the vehicle starts and meets the system safety access conditions, if the control module detects no power demand, it will remain in standby mode, the power on / off mechanism will be disconnected, and the hydraulic pump will be unloaded.

[0084] When a valid power demand signal is detected and the vehicle operating condition signal indicates that the current operating condition allows for power generation, the control module determines that the system has entered the power generation operation state. If the engine speed is in the idle range, it enters the idle power generation mode. The control module controls the power on / off mechanism to engage the power take-off, so that the mechanical power output by the engine or transmission is transmitted to the hydraulic pump through the power take-off and the flexible coupling. The hydraulic pump converts the mechanical power into hydraulic energy, which drives the hydraulic motor to rotate through the closed hydraulic circuit. The hydraulic motor further drives the generator to generate electricity. The control module collects the generator speed and hydraulic circuit pressure in real time, and adjusts the hydraulic motor displacement first according to the speed deviation. When the hydraulic motor displacement reaches the preset displacement limit and still cannot restore the generator speed to the preset range, the hydraulic pump output flow is adjusted. During the control process, if the hydraulic circuit pressure approaches the first pressure threshold, the control module restricts the continued increase in flow to ensure that the system does not enter the dangerous pressure zone in pursuit of stable speed.

[0085] When the vehicle is operating under conditions suitable for higher power output and has a large power demand, the control module switches the system to full-speed power generation mode. At this time, the hydraulic pump output flow enters the second preset range, and the hydraulic motor displacement is dynamically adjusted within the allowable range to maintain the generator speed within the target range. Since the hydraulic power is higher in full-speed power generation mode, the control module will more strictly monitor the circuit pressure and oil temperature, and limit the increase rate of hydraulic pump displacement in advance when necessary to prevent pressure surge due to sudden load changes.

[0086] During operation, the low-pressure side of the closed hydraulic circuit is continuously replenished with oil by the replenishment branch; the flushing shuttle valve automatically selects the side with lower pressure on both sides of the hydraulic motor, draws out some high-temperature oil, filters it through the return oil filter module, cools it through the cooling module, and then returns it to the hydraulic oil tank, and is then replenished to the low-pressure side by the replenishment branch. In this way, the oil temperature, cleanliness and low-pressure side filling status can be continuously controlled.

[0087] When the control module detects abnormal hydraulic circuit pressure, abnormal hydraulic oil temperature, abnormal generator output, or abnormal power on / off mechanism status, it immediately controls the system to enter the shutdown protection mode, disconnects the power on / off mechanism, and reduces the hydraulic pump displacement to zero. At the same time, it triggers alarms and fault latches until the fault is cleared or manually reset.

[0088] Example 2 The difference between this embodiment and Embodiment 1 is that the power take-off module adopts a side-mounted power take-off unit to adapt to light commercial vehicles or engineering service vehicles with limited lateral space. The side-mounted power take-off unit is arranged on the side of the gearbox via a bracket, and the hydraulic pump is arranged along the side of the vehicle.

[0089] In this embodiment, the flexible coupling adopts a plum blossom-shaped flexible coupling, which includes two metal half-couplings with protruding claws and a plum blossom-shaped elastic body disposed therebetween. It transmits torque and absorbs vibration through the compression deformation of the elastic body.

[0090] The hydraulic pump and hydraulic motor in the hydraulic power module still adopt a variable structure, but the rated power can be appropriately reduced, for example, to suit 10kW-level external power supply scenarios. The hydraulic oil tank volume can be reduced accordingly, for example, to 50L to 60L. The cooling module can adopt an oil-cooled cooler to utilize the vehicle's original coolant circuit.

[0091] The power generation module can output 220V single-phase AC power or 380V three-phase AC power to adapt to loads such as light-duty work equipment, lighting equipment, and maintenance equipment. The control logic of the control module is the same as that of Embodiment 1, except that the parameters such as target speed range, first preset range, second preset range, pressure threshold and temperature threshold are recalibrated according to the power level and vehicle platform.

[0092] Please see Figure 2 The present invention also provides a control method for an automotive hydraulic power generation system, comprising the following steps: S1: Acquire power demand signals, vehicle operating condition signals, generator speed, and hydraulic circuit pressure.

[0093] Specifically, after power-on, the control module initializes all sensors and actuators, checks whether the speed sensor, pressure sensor, oil temperature sensor, power on / off mechanism feedback sensor, and power conversion module communication status are normal, and then reads the power demand signal, vehicle operating condition signal, generator speed, and hydraulic circuit pressure. In order to reduce the impact of noise, the pressure signal and speed signal can be digitally filtered separately.

[0094] S2: Based on power demand signals and vehicle operating condition signals, determine whether the automotive hydraulic power generation system has entered the power generation operation state, and control the power take-off module to enter the engaged or disengaged state. Specifically, when a valid power demand is detected and the current vehicle operating condition allows for power generation, the control module issues an engagement command to activate the power on / off mechanism and confirm the position feedback is in place; if there is no power demand or the operating condition does not allow for power generation, the system remains in or switches to the off state.

[0095] S3: After the power take-off module enters the engaged state, the hydraulic pump is controlled to output hydraulic energy and drive the hydraulic motor to drive the generator to generate electricity.

[0096] Specifically, the control module first establishes the basic flow and oil replenishment conditions of the main circuit with the hydraulic pump at a small initial displacement to prevent instantaneous large flow shocks. After the hydraulic circuit pressure and generator speed enter the controllable range, the hydraulic pump output is gradually increased to the first preset range or the second preset range according to the mode target. The advantage of doing this is to avoid torque mutation and pressure shock caused by the sudden high displacement output of the hydraulic pump at the moment of engagement.

[0097] S4: Based on the generator speed, determine whether the generator speed is within the corresponding preset range, and adjust the hydraulic motor displacement first when it deviates from the corresponding preset range; when the hydraulic motor displacement is adjusted to the preset displacement limit but still cannot restore the generator output frequency to the corresponding preset range, then adjust the hydraulic pump output flow.

[0098] Specifically, if the generator speed is lower than the lower limit of the preset speed range, the control module prioritizes controlling the hydraulic motor displacement to change in a direction that is conducive to speed increase; if it is higher than the upper limit of the preset speed range, the control module controls the hydraulic motor displacement to change in a direction that is conducive to speed decrease; if the hydraulic motor displacement has reached the corresponding limit but the speed has not recovered, the control module then controls the hydraulic pump displacement to change in order to increase or decrease the hydraulic pump output flow. The reason for adopting this order is that adjusting the displacement first results in a faster response and less disturbance, while adjusting the flow rate later can supplement or reduce the system power input when necessary.

[0099] S5: During the adjustment of hydraulic motor displacement and hydraulic pump output flow, the adjustment process is constrained based on hydraulic circuit pressure.

[0100] Specifically, when the hydraulic circuit pressure is below the first pressure threshold, normal adjustment is allowed; when the hydraulic circuit pressure approaches the first pressure threshold, the range or rate of action of increasing the hydraulic pump displacement is limited; when the hydraulic circuit pressure reaches the second pressure threshold, the power increase adjustment is immediately stopped and the protection logic is executed. This can ensure stable power generation while preventing the hydraulic system from entering the dangerous working area.

[0101] S6: When abnormal hydraulic circuit pressure, abnormal hydraulic oil temperature, abnormal generator output, or abnormal power on / off mechanism status is detected, the power take-off module is disconnected and the hydraulic pump displacement is reduced to zero displacement.

[0102] Specifically, the control module first directs the flow regulation actuator to the unloading direction, then controls the displacement regulation actuator to enter a safe position, and then issues a disconnect command to the power on / off mechanism. At the same time, it records fault information and activates an alarm. If the cooling module still needs to work to reduce residual heat, it can keep the cooling module running for a delay. The technical effect of this step is to quickly cut off the mechanical power and hydraulic power transmission path under abnormal working conditions, reducing the risk of the system continuing to pressurize or overheat.

[0103] Additional numerical notes: The vehicle platform is a general commercial vehicle, the engine idle speed is 700rpm to 850rpm, the power take-off is a gearbox type power take-off, the diaphragm type flexible coupling has an axial compensation capacity of ±2.0mm, an angular compensation capacity of ±1.5°, and a radial compensation capacity of ±0.8mm.

[0104] The hydraulic pump is an axial piston variable pump with a rated pressure of 35MPa and a rated flow of 120L / min. The hydraulic motor is an axial piston variable motor with a displacement range of 25mL / r to 100mL / r. The generator is a 15kW~50kW permanent magnet synchronous generator with a target output of 220V, 380V, and 50Hz AC.

[0105] The control module calibrates the target mechanical input speed at around 1500 r / min and the preset speed range is calibrated to 1480 r / min to 1520 r / min. The first pressure threshold P1 is calibrated to 36 MPa and the second pressure threshold P2 is calibrated to 38 MPa.

[0106] The cooling module starts a low-speed fan when the oil temperature reaches 65°C, starts a high-speed fan when the oil temperature reaches 80°C, and triggers a shutdown protection when the oil temperature reaches 95°C.

[0107] In idle power generation mode, the hydraulic pump output flow is between 30% and 50% of the rated flow; in full-speed power generation mode, the hydraulic pump output flow is between 60% and 100% of the rated flow.

[0108] The above parameters were not arbitrarily selected, but based on the following considerations: 1500 r / min corresponds to a typical mechanical input point with a 50 Hz output; the width of the preset speed range takes into account the generator inertia, inverter compensation capability, and hydraulic speed regulation response time; a safe range between process control and protection actions is maintained between P1 and P2; the three oil temperature nodes of 65℃, 80℃, and 95℃ correspond to normal heat dissipation intervention, enhanced heat dissipation intervention, and shutdown protection intervention, respectively; the two flow ranges of idle speed and full speed correspond to the engine's continuous output capability at idle speed and the hydraulic power requirements under high load conditions, respectively.

[0109] This invention extracts vehicle power through a power take-off module, forms an adjustable hydraulic intermediate energy link through a hydraulic pump and a hydraulic motor, and performs coordinated control based on generator speed and hydraulic circuit pressure through a control module. It also achieves stable power generation under various vehicle operating conditions by prioritizing displacement adjustment, followed by flow rate adjustment, as well as multi-mode switching and abnormal protection logic.

[0110] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0111] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A car hydraulic power generation system, characterized in that, The system includes a power take-off module, a hydraulic power module, a power generation module, an energy storage module, and a control module; The power take-off module is used to connect to the power take-off interface of the vehicle engine or transmission to extract the mechanical power output from the power system when the vehicle is not in motion, and to engage or disconnect the power transmission path in response to the control signal of the control module. The hydraulic power module includes a hydraulic pump, a hydraulic motor, and a hydraulic circuit connected to the hydraulic pump and the hydraulic motor. The hydraulic pump is used to convert the mechanical power into hydraulic energy, and the hydraulic motor is used to convert the hydraulic energy into rotational mechanical energy. The power generation module includes a generator, which is used to output electrical energy under the drive of the hydraulic motor; The energy storage module consists of a lithium iron phosphate energy storage battery, a protection board, a charging and discharging system, and a battery pack package. It is used to store excess power from the generator and form a mixed discharge of the generator and the energy storage battery to the load.

2. The control module is used to acquire the rotational speed of the generator and the pressure of the hydraulic circuit, and control the power take-off module to be in an engaged or disengaged state based on the rotational speed and the pressure. When the power take-off module is in an engaged state, the module controls the output flow rate of the hydraulic pump and the displacement of the hydraulic motor to maintain the rotational speed of the generator within a preset speed range corresponding to the target output frequency.

3. The automotive hydraulic power generation system according to claim 1, characterized in that, The power take-off module includes a power take-off unit, an elastic coupling disposed between the power take-off unit and the hydraulic pump, and a power on / off mechanism. The elastic coupling is used to compensate for axial, angular, and radial deviations between the output shaft of the power take-off unit and the input shaft of the hydraulic pump, and to reduce impacts and vibrations during power transmission. The power on / off mechanism is disposed inside the power take-off unit and is used to engage or disengage the power transmission path under the control of the control module.

4. The automotive hydraulic power generation system according to claim 1, characterized in that, The hydraulic circuit is a closed hydraulic circuit. The hydraulic power module also includes a hydraulic oil tank, a replenishment branch, and a flushing and cooling branch. The replenishment branch is used to replenish hydraulic oil to the low-pressure side of the closed hydraulic circuit. The flushing and cooling branch is used to export part of the hydraulic oil from the low-pressure side of the closed hydraulic circuit, which is then filtered by the return oil filter module and cooled by the cooling module before flowing back to the hydraulic oil tank.

5. The automotive hydraulic power generation system according to claim 3, characterized in that, The oil replenishment branch includes an oil replenishment check valve group that is connected to the main oil circuits on both sides of the closed hydraulic circuit. The flushing and cooling branch includes a flushing shuttle valve that is connected to the oil ports on both sides of the hydraulic motor and a flushing overflow valve that is connected downstream of the flushing shuttle valve. The flushing shuttle valve is used to introduce the hydraulic oil from the lower pressure side of the oil ports on both sides of the hydraulic motor into the flushing and cooling branch.

6. The automotive hydraulic power generation system according to claim 1, characterized in that, The control module includes a speed sensor, a pressure sensor, a flow regulation actuator, a displacement regulation actuator, and an electronic controller. The electronic controller establishes a main control loop based on the speed with the goal of stabilizing the generator output, and establishes a constraint control loop based on the pressure. When the rotational speed deviates from the preset rotational speed range and the pressure does not reach the preset pressure threshold, the hydraulic motor displacement is preferentially adjusted by the displacement adjustment actuator. If adjusting the hydraulic motor displacement to the preset displacement limit still fails to restore the rotational speed to the preset rotational speed range, the hydraulic pump output flow is then adjusted through the flow regulation actuator.

7. The automotive hydraulic power generation system according to claim 5, characterized in that, The electronic controller is configured to switch between standby mode, idle power generation mode, full-speed power generation mode and shutdown protection mode according to power demand signal and vehicle operating condition signal; In standby mode, the power on / off mechanism is disconnected and the hydraulic pump is in an unloaded state. In idle power generation mode, the power on / off mechanism is engaged, and the hydraulic pump output flow is within a first preset range; In full-speed power generation mode, the power on / off mechanism is engaged, and the output flow of the hydraulic pump is within a second preset range, which is higher than the first preset range. In the shutdown protection mode, the power on / off mechanism is disconnected, and the displacement of the hydraulic pump is reduced to zero.

8. The automotive hydraulic power generation system according to claim 6, characterized in that, The electronic controller sets a hysteresis threshold on at least one vehicle operating condition determination parameter, which includes at least one of engine speed, load power, and energy storage status parameters, to suppress frequent switching between the idle power generation mode and the full-speed power generation mode near the critical operating condition.

9. The automotive hydraulic power generation system according to claim 1, characterized in that, The hydraulic power module also includes a return oil filter module, a cooling module, and a high-pressure protection component. The return oil filter module is located on the return oil passage. The cooling module is used to reduce the hydraulic oil temperature. The high-pressure protection component includes a pressure shut-off valve to reduce the displacement of the hydraulic pump to a preset safe displacement when the hydraulic circuit pressure exceeds a preset pressure threshold.

10. A car hydraulic power generation system according to claim 2 or 3, characterized in that, The power generation module also includes a power conversion module electrically connected to the generator. The power conversion module is used to rectify, invert, and convert the voltage level of the electrical energy output by the generator to output AC power at a preset voltage level that is suitable for vehicle loads or external AC loads. The power take-off is a gearbox-type power take-off, the flexible coupling is a diaphragm-type flexible coupling, and the cooling module is an air-cooled cooler.

11. A control method for an automotive hydraulic power generation system, used to implement the automotive hydraulic power generation system according to any one of claims 1-9, characterized in that, Includes the following steps: S1: Acquire power demand signals, vehicle operating condition signals, generator speed, and hydraulic circuit pressure; S2: Based on the power demand signal and the vehicle operating condition signal, determine whether the automotive hydraulic power generation system has entered the power generation operation state, and control the power take-off module to enter the engaged state or the disengaged state. S3: After the power take-off module enters the engagement state, control the hydraulic pump to output hydraulic energy and drive the hydraulic motor to drive the generator to generate electricity; S4: Based on the generator speed, determine whether the generator speed is within the corresponding preset range, and if it deviates from the corresponding preset range, prioritize adjusting the hydraulic motor displacement; if adjusting the hydraulic motor displacement to the preset displacement limit still cannot restore the generator output frequency to the corresponding preset range, then adjust the hydraulic pump output flow rate. S5: During the adjustment of the hydraulic motor displacement and the hydraulic pump output flow, the adjustment process is constrained based on the hydraulic circuit pressure. S6: When abnormal hydraulic circuit pressure, abnormal hydraulic oil temperature, abnormal generator output, or abnormal power on / off mechanism status is detected, the power take-off module is disconnected and the hydraulic pump displacement is reduced to zero displacement.

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