Energy-saving servo control hydraulic system for hydraulic excavator

Abstract

This invention discloses an energy-saving servo control hydraulic system for hydraulic excavators, relating to the field of hydraulic excavators. It includes an oil tank for storing hydraulic oil and an on-board power supply unit for supplying power to the servo motor and control system. This energy-saving servo control hydraulic system for hydraulic excavators effectively reduces overall machine energy consumption by combining on-demand oil supply with potential energy recovery, thereby significantly reducing system heat generation. This helps slow down the aging of hydraulic components, maintain good oil performance, extend the service life of hydraulic components and oil, and reduce maintenance costs. The high-pressure oil supply circuit unit is equipped with components such as a check valve, an overflow safety valve, and a filter to ensure stable oil supply direction. The overflow safety valve is set at 1.1-1.2 times the system's rated pressure, allowing for timely overflow when the system pressure is too high, ensuring system safety. The filter has a filtration accuracy of 5-10 μm, effectively filtering impurities in the oil and ensuring oil cleanliness.

Description

Technical Field

[0001] This invention relates to hydraulic excavator technology, and more specifically to an energy-saving servo control hydraulic system for hydraulic excavators. Background Technology

[0002] Hydraulic excavators, as core equipment in the field of engineering construction, have been widely used in various engineering projects due to their powerful digging, loading and leveling capabilities. Their working conditions are extremely complex, covering multiple modes such as digging, loading and leveling, and the load fluctuates greatly, frequently switching from light load to heavy load. At the same time, the intermittent operation time is long, and frequent start-stop and switching actions are required during operation.

[0003] Traditional hydraulic excavators mostly use an engine to directly drive the hydraulic pump, combined with throttling speed regulation and overflow pressure stabilization. Even under light load, no-load, and standby conditions, the engine maintains high power output, and the hydraulic pump continues to supply oil, resulting in a significant waste of energy. For example, when waiting for material to be loaded, the engine and hydraulic pump continue to run, consuming fuel without producing effective work output. Due to the large energy loss, a large amount of energy is converted into heat, causing a sharp increase in system heat generation. Prolonged operation at high temperatures accelerates the aging of hydraulic components; for example, seals are prone to deformation due to high temperatures, losing their sealing performance and leading to hydraulic oil leakage. Simultaneously, oil performance deteriorates, oxidation and deterioration accelerate, lubrication performance decreases, and the normal operation of the entire hydraulic system is affected. Therefore, an energy-saving servo-controlled hydraulic system for hydraulic excavators is proposed. Summary of the Invention

[0004] The purpose of this invention is to provide an energy-saving servo control hydraulic system for hydraulic excavators, in order to solve the problem that most traditional hydraulic excavators use the method of directly driving the hydraulic pump by the engine, and operate with throttling speed regulation and overflow pressure stabilization. In light load, no load and standby states, the engine still maintains a high power output and the hydraulic pump continues to supply oil, resulting in a large amount of energy being wasted.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an energy-saving servo control hydraulic system for hydraulic excavators, comprising:

[0006] Oil tank, used to store hydraulic oil;

[0007] Onboard power supply unit, used to power servo motors and control systems;

[0008] The servo power unit, consisting of a servo motor and a high-pressure variable displacement piston pump, is used to convert electrical energy into hydraulic energy.

[0009] The high-pressure oil supply circuit unit is equipped with a check valve, an overflow safety valve, a pressure sensor, a flow sensor, and a filter to ensure stable oil supply, system safety, and clean oil.

[0010] The electro-hydraulic proportional multi-way valve group unit is used to distribute flow to each actuator according to control commands, so as to realize the coordinated control of multiple actuators.

[0011] An actuator assembly unit, comprising a boom, a stick, and a bucket, is used to perform digging operations.

[0012] The signal acquisition unit is used to acquire system pressure, flow rate, actuator displacement and oil temperature signals in real time and transmit them to the central controller of the whole machine.

[0013] The boom potential energy regeneration circuit unit is used to directly realize potential energy recovery and energy feedback using a servo motor during the boom descent process;

[0014] The central controller unit of the whole machine is used to adjust the speed of the servo motor and the pump displacement according to the working conditions and load status, realize pressure-flow dual closed-loop control, and control the start and stop of the boom potential energy regeneration circuit.

[0015] Furthermore, in the servo power unit, the servo motor and the high-pressure variable displacement piston pump are directly connected via a coupling. The speed adjustment range of the servo motor is 0-3000 rpm, and the displacement adjustment range of the high-pressure variable displacement piston pump is 0-100% of the rated displacement.

[0016] In the high-pressure oil supply circuit unit, the opening pressure of the one-way valve is 0.5-1.5MPa, the set pressure of the overflow safety valve is 1.1-1.2 times the rated pressure of the system, and the filtration accuracy of the filter is 5-10μm.

[0017] Furthermore, the electro-hydraulic proportional multi-way valve group unit is controlled by a proportional electromagnet, the valve opening degree of the electro-hydraulic proportional multi-way valve group unit is linearly related to the input current, and the flow distribution accuracy error of the electro-hydraulic proportional multi-way valve group unit is ≤3%;

[0018] The electro-hydraulic proportional multi-way valve group unit integrates load-sensing function, automatically adjusting the output flow according to the load pressure of the actuator to achieve on-demand flow distribution.

[0019] Furthermore, the signal acquisition unit includes a pressure sensor, a flow sensor, a displacement sensor, and an oil temperature sensor:

[0020] The pressure sensor is located at the outlet of the high-pressure oil supply circuit unit and the inlet of each actuator. The pressure sensor has a measurement range of 0-40 MPa and an accuracy of ±0.5%.

[0021] The flow sensor is arranged in the high-pressure oil supply circuit unit. The flow sensor has a measurement range of 0-500 L / min and an accuracy of ±1%.

[0022] The displacement sensors are arranged inside the hydraulic cylinders of each actuator. The measurement range of the displacement sensors is 0-2m, and the accuracy of the displacement sensors is ±1mm.

[0023] The oil temperature sensor is arranged inside the oil tank. The oil temperature sensor has a measurement range of -20 to 120℃ and an accuracy of ±1℃.

[0024] Furthermore, the boom potential energy regeneration circuit includes a bidirectional hydraulic motor, a rectifier, a battery pack, and an energy management module.

[0025] The bidirectional hydraulic motor is connected to the rodless chamber of the boom hydraulic cylinder and operates as a generator when the boom is lowered.

[0026] The rectifier converts the three-phase AC power output from the bidirectional hydraulic motor into DC power.

[0027] The battery pack is used to store the recovered electrical energy and to supply power to the servo motor when the system needs it.

[0028] The energy management module dynamically adjusts the power allocation for potential energy recovery and release based on the system load status.

[0029] Furthermore, the central controller of the entire machine adopts PID control algorithm and fuzzy control algorithm, and dynamically adjusts the servo motor speed and pump displacement based on real-time data fed back by the signal acquisition unit, to achieve at least one of the following control strategies:

[0030] Under light load conditions, the servo motor speed is reduced to 500-1000 rpm to reduce no-load energy consumption;

[0031] Under heavy load conditions, the servo motor speed is increased to 2000-3000 rpm, and the pump displacement is increased to 80%-100% of the rated displacement.

[0032] Under combined operating conditions, coordinate the flow distribution of the electro-hydraulic proportional multi-way valve group to avoid operational interference;

[0033] In standby mode, the servo motor is turned off or put into low power mode, with standby power consumption ≤50W.

[0034] Furthermore, the high-pressure oil supply circuit unit also includes an accumulator, a pressure compensation valve, and a cooling bypass:

[0035] The accumulator is connected in parallel to the high-pressure oil supply circuit unit to absorb system pressure pulsations and store instantaneous excess energy.

[0036] The pressure compensation valve is linked with the electro-hydraulic proportional multi-way valve group unit to maintain stable pressure in each branch when multiple actuators perform compound actions, thus avoiding sluggish action due to load differences.

[0037] When the oil temperature exceeds a set threshold, the cooling bypass automatically diverts a portion of the hydraulic oil to the cooling circuit, where it is cooled and then returned to the main circuit.

[0038] Furthermore, the central controller unit also includes a working condition identification module, a fault prediction module, and a wireless communication module:

[0039] The working condition identification module automatically classifies the working mode (such as excavation, loading, and leveling) based on the data from the pressure sensor and displacement sensor, and calls the corresponding control strategy.

[0040] The fault prediction module analyzes historical operating data and real-time sensor signals to predict the remaining lifespan of key components such as hydraulic pumps and servo motors, and triggers maintenance warnings in advance.

[0041] The wireless communication module supports remote monitoring and firmware upgrades, allowing control algorithm parameters to be updated via a cloud server.

[0042] Compared with existing technologies, this invention provides an energy-saving servo control hydraulic system for hydraulic excavators. By combining on-demand oil supply with potential energy recovery, this invention effectively reduces the overall machine energy consumption, thereby significantly reducing system heat generation. This helps slow down the aging of hydraulic components, maintains good oil performance, extends the service life of hydraulic components and oil, and reduces maintenance costs. The high-pressure oil supply circuit unit is equipped with components such as a check valve, an overflow safety valve, and a filter. The check valve has an opening pressure of 0.5-1.5 MPa, ensuring stable oil supply direction. The overflow safety valve is set to a pressure of 1.1-1.2 times the system's rated pressure, enabling timely overflow when the system pressure is too high, ensuring system safety. The filter has a filtration accuracy of 5-10 μm, effectively filtering impurities in the oil and ensuring oil cleanliness. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0044] Figure 1 This is a schematic diagram of the system structure provided in an embodiment of the present invention. Detailed Implementation

[0045] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0046] As attached Figure 1 As shown:

[0047] This invention provides an energy-saving servo control hydraulic system for hydraulic excavators, including an oil tank for storing hydraulic oil;

[0048] Onboard power supply unit, used to power servo motors and control systems;

[0049] The servo power unit, consisting of a servo motor and a high-pressure variable displacement piston pump, is used to convert electrical energy into hydraulic energy.

[0050] The high-pressure oil supply circuit unit is equipped with a check valve, an overflow safety valve, a pressure sensor, a flow sensor, and a filter to ensure stable oil supply, system safety, and clean oil.

[0051] The electro-hydraulic proportional multi-way valve group unit is used to distribute flow to each actuator according to control commands, so as to realize the coordinated control of multiple actuators.

[0052] An actuator assembly unit, comprising a boom, a stick, and a bucket, is used to perform digging operations.

[0053] The signal acquisition unit is used to acquire system pressure, flow rate, actuator displacement and oil temperature signals in real time and transmit them to the central controller of the whole machine.

[0054] The boom potential energy regeneration circuit unit is used to directly realize potential energy recovery and energy feedback using a servo motor during the boom descent process;

[0055] The central controller unit of the whole machine is used to adjust the speed of the servo motor and the pump displacement according to the working conditions and load status, realize pressure-flow dual closed-loop control, and control the start and stop of the boom potential energy regeneration circuit.

[0056] The present invention is further described in detail as follows: in the servo power unit, the servo motor and the high-pressure variable displacement piston pump are directly connected through a coupling; the speed adjustment range of the servo motor is 0-3000 rpm; and the displacement adjustment range of the high-pressure variable displacement piston pump is 0-100% of the rated displacement.

[0057] In the high-pressure oil supply circuit unit, the opening pressure of the one-way valve is 0.5-1.5 MPa, the set pressure of the overflow safety valve is 1.1-1.2 times the rated pressure of the system, and the filtration accuracy of the filter is 5-10 μm; the electro-hydraulic proportional multi-way valve group unit is controlled by a proportional electromagnet, the valve opening degree of the electro-hydraulic proportional multi-way valve group unit is linearly related to the input current, and the flow distribution accuracy error of the electro-hydraulic proportional multi-way valve group unit is ≤3%;

[0058] The electro-hydraulic proportional multi-way valve group unit integrates a load-sensing function, which automatically adjusts the output flow according to the load pressure of the actuator to achieve on-demand flow distribution.

[0059] The present invention is further described in detail below, wherein the signal acquisition unit includes a pressure sensor, a flow sensor, a displacement sensor, and an oil temperature sensor:

[0060] The pressure sensor is located at the outlet of the high-pressure oil supply circuit unit and the inlet of each actuator. The pressure sensor has a measurement range of 0-40 MPa and an accuracy of ±0.5%.

[0061] The flow sensor is arranged in the high-pressure oil supply circuit unit. The flow sensor has a measurement range of 0-500 L / min and an accuracy of ±1%.

[0062] The displacement sensors are arranged inside the hydraulic cylinders of each actuator. The measurement range of the displacement sensors is 0-2m, and the accuracy of the displacement sensors is ±1mm.

[0063] The oil temperature sensor is arranged inside the oil tank. The oil temperature sensor has a measurement range of -20 to 120℃ and an accuracy of ±1℃.

[0064] The present invention is further described in detail as follows: the boom potential energy regeneration circuit includes a bidirectional hydraulic motor, a rectifier, a battery pack, and an energy management module.

[0065] The bidirectional hydraulic motor is connected to the rodless chamber of the boom hydraulic cylinder and operates as a generator when the boom is lowered.

[0066] The rectifier converts the three-phase AC power output from the bidirectional hydraulic motor into DC power.

[0067] The battery pack is used to store the recovered electrical energy and to supply power to the servo motor when the system needs it.

[0068] The energy management module dynamically adjusts the power allocation for potential energy recovery and release based on the system load status.

[0069] The present invention further details that the central controller of the whole machine adopts PID control algorithm and fuzzy control algorithm, and dynamically adjusts the servo motor speed and pump displacement based on real-time data fed back by the signal acquisition unit, so as to realize at least one of the following control strategies:

[0070] Under light load conditions, the servo motor speed is reduced to 500-1000 rpm to reduce no-load energy consumption;

[0071] Under heavy load conditions, the servo motor speed is increased to 2000-3000 rpm, and the pump displacement is increased to 80%-100% of the rated displacement.

[0072] Under combined operating conditions, coordinate the flow distribution of the electro-hydraulic proportional multi-way valve group to avoid operational interference;

[0073] In standby mode, the servo motor is turned off or put into low power mode, with standby power consumption ≤50W;

[0074] The present invention further details that the high-pressure oil supply circuit unit also includes an accumulator, a pressure compensation valve, and a cooling bypass:

[0075] The accumulator is connected in parallel to the high-pressure oil supply circuit unit to absorb system pressure pulsations and store instantaneous excess energy.

[0076] The pressure compensation valve is linked with the electro-hydraulic proportional multi-way valve group unit to maintain stable pressure in each branch when multiple actuators perform compound actions, thus avoiding sluggish action due to load differences.

[0077] When the oil temperature exceeds a set threshold, the cooling bypass automatically diverts a portion of the hydraulic oil to the cooling circuit, and after cooling, it flows back into the main circuit.

[0078] The present invention further details that the central controller unit of the whole machine also includes an operating condition identification module, a fault prediction module, and a wireless communication module:

[0079] The working condition identification module automatically classifies the working mode (such as excavation, loading, and leveling) based on the data from the pressure sensor and displacement sensor, and calls the corresponding control strategy.

[0080] The fault prediction module analyzes historical operating data and real-time sensor signals to predict the remaining lifespan of key components such as hydraulic pumps and servo motors, and triggers maintenance warnings in advance.

[0081] The wireless communication module supports remote monitoring and firmware upgrades, and allows the control algorithm parameters to be updated via a cloud server.

[0082] Working principle: The oil tank serves as the hydraulic oil storage container for the entire hydraulic system, providing a stable source of hydraulic oil for the system. It not only stores hydraulic oil but also plays a role in heat dissipation and sedimentation of impurities, ensuring that the hydraulic oil entering the system is clean and at a suitable temperature, thus providing a basic guarantee for the stable operation of the system.

[0083] The on-board power supply unit is responsible for providing power to the servo motor and control system; in hybrid or pure electric excavators, it may be a battery pack; after the traditional diesel excavator is upgraded, it can be combined with generators and other equipment to power the system; a stable power supply is a prerequisite for the normal operation of the servo motor and the conversion of electrical energy into hydraulic energy.

[0084] The servo power unit consists of a servo motor and a high-pressure variable displacement piston pump directly connected by a coupling. The servo motor operates under the power supply of the vehicle power unit, and its speed adjustment range is 0-3000 rpm. The displacement adjustment range of the high-pressure variable displacement piston pump is 0-100% of its rated displacement. When the servo motor rotates, it drives the high-pressure variable displacement piston pump to work, converting electrical energy into hydraulic energy. According to different combinations of servo motor speed and pump displacement, the output hydraulic oil flow and pressure can be precisely controlled to achieve on-demand oil supply and avoid energy waste caused by continuous oil supply in traditional systems.

[0085] The high-pressure oil supply circuit unit is equipped with a check valve, a relief safety valve, a pressure sensor, a flow sensor, and a filter. It may also include an accumulator, a pressure compensation valve, and a cooling bypass.

[0086] One-way valve: The opening pressure is set at 0.5-1.5MPa. Its function is to prevent hydraulic oil backflow, ensure the single direction of oil supply, and maintain stable system pressure.

[0087] Relief safety valve: The set pressure is 1.1-1.2 times the rated pressure of the system. When the system pressure exceeds the set value, the relief safety valve opens to overflow the excess hydraulic oil back to the oil tank, preventing the hydraulic components from being damaged by excessive system pressure and ensuring system safety.

[0088] Pressure and flow sensors are respectively located at the outlet of the high-pressure oil supply circuit unit and the inlet of each actuator, as well as within the high-pressure oil supply circuit unit. The pressure sensor has a measurement range of 0-40MPa and an accuracy of ±0.5%. The flow sensor has a measurement range of 0-500L / min and an accuracy of ±1%. They collect system pressure and flow signals in real time and transmit them to the central controller of the whole machine, providing a basis for the controller to adjust the servo motor speed and pump displacement.

[0089] Filter: With a filtration accuracy of 5-10μm, it is used to filter impurities in hydraulic oil, ensuring oil cleanliness, reducing wear on hydraulic components caused by impurities, and extending the service life of components;

[0090] Energy accumulator: Connected in parallel to the high-pressure oil supply circuit unit, it can absorb system pressure pulsations, making the system pressure more stable; at the same time, it stores instantaneous excess energy and releases energy when the system needs it, improving the system's energy utilization efficiency.

[0091] Pressure compensation valve: It is linked with the electro-hydraulic proportional multi-way valve group unit. When multiple actuators perform compound actions, it automatically adjusts the output flow according to the load pressure of each actuator to maintain the pressure stability of each branch, avoid the action delay caused by load difference, and ensure the smooth and coordinated compound action.

[0092] Cooling bypass: When the oil temperature exceeds the set threshold, a portion of the hydraulic oil is automatically diverted to the cooling circuit. The cooled hydraulic oil then flows back into the main circuit, effectively reducing the system oil temperature and preventing the aging of hydraulic components and the degradation of oil performance due to high temperature.

[0093] The electro-hydraulic proportional multi-way valve unit is controlled by a proportional electromagnet, and the valve opening degree is linearly related to the input current, with a flow distribution accuracy error of ≤3%. It integrates a load-sensing function, automatically adjusting the output flow according to the load pressure of the actuator. When the central controller of the whole machine issues a control command, the electro-hydraulic proportional multi-way valve unit distributes the corresponding flow to the actuators such as the boom, stick, and bucket according to the command, realizing the coordinated control of multiple actuators, accurately controlling the action speed and force of each actuator, and meeting the needs of different digging operations.

[0094] The actuator unit includes the boom, stick, and bucket, which are the direct actuators for completing the digging operation. Under the action of the hydraulic oil distributed by the electro-hydraulic proportional multi-way valve unit, the hydraulic cylinders of each actuator extend and retract, driving the boom, stick, and bucket to perform various actions such as raising, lowering, digging, and loading, thus completing the digging operation task.

[0095] Signal acquisition unit

[0096] The signal acquisition unit includes a pressure sensor, a flow sensor, a displacement sensor, and an oil temperature sensor;

[0097] Pressure and flow sensors: As mentioned above, they acquire system pressure and flow signals in real time;

[0098] Displacement sensor: Arranged inside the hydraulic cylinder of each actuator, with a measurement range of 0-2m and an accuracy of ±1mm; it is used to collect displacement signals of the hydraulic cylinder of the actuator, reflecting the actual position and stroke of each actuator, and providing data support for the central controller of the whole machine to accurately control the action of the actuator;

[0099] Oil temperature sensor: Located inside the oil tank, with a measurement range of -20-120℃ and an accuracy of ±1℃; it monitors the temperature of the hydraulic oil in the tank in real time and transmits the oil temperature signal to the central controller of the whole machine so that the controller can take corresponding measures according to the oil temperature, such as starting the cooling bypass, to ensure that the system operates at a suitable temperature.

[0100] The boom potential energy regeneration circuit unit includes a bidirectional hydraulic motor, a rectifier, a battery pack, and an energy management module. During boom descent, the hydraulic oil in the rodless chamber of the boom hydraulic cylinder drives the bidirectional hydraulic motor to rotate. At this time, the bidirectional hydraulic motor operates as a generator, converting the boom's potential energy into mechanical energy. The rectifier then converts the three-phase AC power output from the bidirectional hydraulic motor into DC power, which is stored in the battery pack. When the system needs energy, the battery pack supplies power to the servo motor, realizing energy feedback. The energy management module dynamically adjusts the power distribution for potential energy recovery and release according to the system load status, ensuring the efficiency and rationality of energy recovery and utilization.

[0101] The central controller unit is the core control component of the entire system, employing PID control and fuzzy control algorithms. It receives real-time data from the signal acquisition unit, including system pressure, flow rate, actuator displacement, and oil temperature. Based on this data and different operating conditions and load states, it dynamically adjusts the servo motor speed and pump displacement to achieve pressure-flow dual closed-loop control. The specific control strategy is as follows:

[0102] Light load conditions: Reduce the servo motor speed to 500-1000rpm to reduce no-load energy consumption and improve energy utilization efficiency;

[0103] Heavy-duty working conditions: Increase the servo motor speed to 2000-3000 rpm, and increase the pump displacement to 80%-100% of the rated displacement to meet the hydraulic oil flow and pressure requirements of heavy-duty operations and ensure the smooth progress of excavation operations;

[0104] Composite action mode: Coordinate the flow distribution of the electro-hydraulic proportional multi-way valve group, avoid interference between the actions of each actuator, ensure smooth and coordinated composite action, and improve operation accuracy and operating comfort;

[0105] Standby mode: Turn off the servo motor or put it into low power mode, with standby power consumption ≤50W, further reducing energy consumption;

[0106] In addition, the central controller unit of the whole machine also includes a working condition identification module, a fault prediction module, and a wireless communication module. The working condition identification module automatically classifies the operation mode (such as digging, loading, and leveling) based on the data of pressure sensors and displacement sensors through machine learning algorithms, and calls the corresponding control strategy to achieve adaptive control of working conditions. The fault prediction module predicts the remaining life of key components such as hydraulic pumps and servo motors by analyzing historical operating data and real-time sensor signals, triggering maintenance warnings in advance, facilitating timely equipment maintenance, reducing the occurrence of failures, and improving system reliability. The wireless communication module supports remote monitoring and firmware upgrades, allowing the control algorithm parameters to be updated through a cloud server, enabling the system to continuously optimize performance and adapt to different working environments and operation requirements.

[0107] Through the above technical solution, the central controller of the machine dynamically adjusts the servo motor speed and pump displacement according to the working conditions and load status. Under light load conditions, the servo motor speed is reduced to 500-1000 rpm to reduce no-load energy consumption. Under heavy load conditions, the servo motor speed is increased to 2000-3000 rpm, while the pump displacement is increased to 80%-100% of the rated displacement, achieving precise oil supply. This avoids the energy loss caused by the engine directly driving the hydraulic pump and using throttling speed regulation and overflow pressure stabilization in traditional hydraulic excavators under light load and no-load conditions. The system effectively reduces overall machine energy consumption and minimizes energy waste. During boom descent, the boom potential energy regeneration circuit unit utilizes a bidirectional hydraulic motor connected to the rodless chamber of the boom hydraulic cylinder to function as a generator, converting the potential energy generated during boom descent into electrical energy. The rectifier converts the three-phase AC power output from the bidirectional hydraulic motor into DC power, stores it in the battery pack, and supplies power to the servo motor when needed. The energy management module dynamically adjusts the power distribution for potential energy recovery and release based on the system load status, achieving efficient recovery and reuse of potential energy and further reducing energy consumption.

[0108] Traditional hydraulic excavators suffer from high energy consumption and system heat generation, leading to problems such as aging of hydraulic components and deterioration of hydraulic fluid performance over long-term operation. This invention effectively reduces overall machine energy consumption by combining on-demand oil supply with potential energy recovery, thereby significantly reducing system heat generation. This helps slow down the aging of hydraulic components, maintain good hydraulic fluid performance, extend the service life of hydraulic components and fluid, and reduce maintenance costs. The high-pressure oil supply circuit unit is equipped with components such as a check valve, a relief safety valve, and a filter. The check valve opening pressure is 0.5-1.5 MPa, ensuring stable oil supply direction. The relief safety valve is set at 1.1-1.2 times the system's rated pressure, ensuring stable oil supply. The system features timely overflow when the pressure is too high, ensuring system safety. The filter has a filtration accuracy of 5-10μm, effectively filtering impurities in the oil and ensuring its cleanliness. Furthermore, the high-pressure oil supply circuit unit includes an accumulator, a pressure compensation valve, and a cooling bypass. The accumulator absorbs system pressure pulsations and stores excess instantaneous energy. The pressure compensation valve maintains stable pressure in each branch during multi-actuator compound operations, preventing sluggish action due to load differences. The cooling bypass automatically diverts a portion of the hydraulic oil to the cooling circuit when the oil temperature exceeds a set threshold, and then rejoins the main circuit after cooling. These comprehensive protection functions enable the system to adapt to complex operating environments, reduce malfunctions, and further extend the equipment's service life.

[0109] The servo power unit consists of a servo motor and a high-pressure variable displacement piston pump. The servo motor's speed adjustment range is 0-3000 rpm, and the high-pressure variable displacement piston pump's displacement adjustment range is 0-100% of its rated displacement. The two are directly connected via a coupling, resulting in high transmission efficiency. This design enables the system to respond quickly to control commands and achieve rapid dynamic adjustments, improving the timeliness and flexibility of operations. The electro-hydraulic proportional multi-way valve group unit uses proportional electromagnet control, with a linear relationship between valve opening and input current. The flow distribution accuracy error is ≤3%, and it integrates load-sensing functionality, automatically adjusting the output flow according to the actuator's load pressure to achieve on-demand flow distribution. Under complex operating conditions, the central controller of the entire machine can coordinate the flow distribution of the electro-hydraulic proportional multi-way valve group, avoiding action interference and making the complex actions of the boom, stick, and bucket actuators smoother and more coordinated, significantly improving operating accuracy and comfort.

[0110] This invention can be used in the design and development of new hybrid and pure electric excavators, providing a highly efficient and energy-saving hydraulic control system solution for new equipment, meeting the market demand for environmentally friendly and energy-saving construction machinery. This invention has good adaptability to modification, enabling energy-saving upgrades without altering the original equipment's main structure. For existing traditional diesel excavators, only the relevant hydraulic system components need to be replaced and installed to achieve functions such as on-demand oil supply, potential energy recovery, adaptive operation, and multi-actuator coordinated control, improving the overall machine's energy efficiency, reliability, and service life. It also reduces the difficulty and cost for users to perform energy-saving modifications to their equipment, and has broad market application prospects.

[0111] The working condition identification module in the central controller unit automatically classifies work modes (such as digging, loading, and leveling) using machine learning algorithms based on data from pressure and displacement sensors, and calls corresponding control strategies. This enables the system to automatically adjust operating parameters according to different working conditions, achieving optimal energy saving and operational performance, and improving the intelligence level of the equipment. The fault prediction module predicts the remaining lifespan of key components such as hydraulic pumps and servo motors by analyzing historical operating data and real-time sensor signals, triggering maintenance warnings in advance. This helps users schedule equipment maintenance in a timely manner, avoiding equipment downtime due to sudden failures of key components, reducing maintenance time and costs, and improving equipment reliability and availability. The wireless communication module supports remote monitoring and firmware upgrades, allowing control algorithm parameters to be updated via a cloud server. Users can monitor the operating status of the equipment in real time, promptly identify and resolve potential problems, and optimize and upgrade the control algorithm according to actual usage and needs, continuously improving the system's performance and functionality, ensuring the equipment always maintains optimal operating conditions.

[0112] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. An energy-saving servo control hydraulic system for a hydraulic excavator, characterized in that, include: Oil tank, used to store hydraulic oil; Onboard power supply unit, used to power servo motors and control systems; The servo power unit, consisting of a servo motor and a high-pressure variable displacement piston pump, is used to convert electrical energy into hydraulic energy. The high-pressure oil supply circuit unit is equipped with a check valve, an overflow safety valve, a pressure sensor, a flow sensor, and a filter to ensure stable oil supply, system safety, and clean oil. An electro-hydraulic proportional multi-way valve unit is used to distribute flow to each actuator according to control commands; An actuator assembly unit, comprising a boom, a stick, and a bucket, is used to perform digging operations. The signal acquisition unit is used to acquire system pressure, flow rate, actuator displacement and oil temperature signals in real time and transmit them to the central controller of the whole machine. The boom potential energy regeneration circuit unit is used to directly realize potential energy recovery and energy feedback using a servo motor during the boom descent process; The central controller unit of the whole machine is used to adjust the speed of the servo motor and the pump displacement according to the working conditions and load status, realize pressure-flow dual closed-loop control, and control the start and stop of the boom potential energy regeneration circuit.

2. The energy-saving servo control hydraulic system for a hydraulic excavator according to claim 1, characterized in that, In the servo power unit, the servo motor and the high-pressure variable displacement piston pump are directly connected through a coupling. The speed adjustment range of the servo motor is 0-3000 rpm, and the displacement adjustment range of the high-pressure variable displacement piston pump is 0-100% of the rated displacement. In the high-pressure oil supply circuit unit, the opening pressure of the one-way valve is 0.5-1.5MPa, the set pressure of the overflow safety valve is 1.1-1.2 times the rated pressure of the system, and the filtration accuracy of the filter is 5-10μm.

3. The energy-saving servo control hydraulic system for a hydraulic excavator according to claim 1, characterized in that, The electro-hydraulic proportional multi-way valve unit is controlled by a proportional electromagnet. The valve opening degree of the electro-hydraulic proportional multi-way valve unit is linearly related to the input current. The flow distribution accuracy error of the electro-hydraulic proportional multi-way valve unit is ≤3%. The electro-hydraulic proportional multi-way valve group unit integrates load-sensing function, automatically adjusting the output flow according to the load pressure of the actuator to achieve on-demand flow distribution.

4. The energy-saving servo control hydraulic system for a hydraulic excavator according to claim 1, characterized in that, The signal acquisition unit includes a pressure sensor, a flow sensor, a displacement sensor, and an oil temperature sensor. The pressure sensor is located at the outlet of the high-pressure oil supply circuit unit and the inlet of each actuator. The measurement range of the pressure sensor is 0-40 MPa, and the accuracy of the pressure sensor is ±0.5%. The flow sensor is arranged in the high-pressure oil supply circuit unit. The flow sensor has a measurement range of 0-500 L / min and an accuracy of ±1%. The displacement sensors are arranged inside the hydraulic cylinders of each actuator. The measurement range of the displacement sensors is 0-2m, and the accuracy of the displacement sensors is ±1mm. The oil temperature sensor is arranged inside the oil tank. The oil temperature sensor has a measurement range of -20 to 120℃ and an accuracy of ±1℃.

5. The energy-saving servo control hydraulic system for a hydraulic excavator according to claim 1, characterized in that, The boom potential energy regeneration circuit includes a bidirectional hydraulic motor, a rectifier, a battery pack, and an energy management module. The bidirectional hydraulic motor is connected to the rodless chamber of the boom hydraulic cylinder and operates as a generator when the boom is lowered. The rectifier converts the three-phase AC power output from the bidirectional hydraulic motor into DC power. The battery pack is used to store the recovered electrical energy and to supply power to the servo motor when the system needs it. The energy management module dynamically adjusts the power allocation for potential energy recovery and release based on the system load status.

6. The energy-saving servo control hydraulic system for a hydraulic excavator according to claim 1, characterized in that, The central controller of the whole machine adopts PID control algorithm and fuzzy control algorithm, and dynamically adjusts the servo motor speed and pump discharge based on the real-time data fed back by the signal acquisition unit.

7. The energy-saving servo control hydraulic system for a hydraulic excavator according to claim 1, characterized in that, The high-pressure oil supply circuit unit also includes an accumulator, a pressure compensation valve, and a cooling bypass: The accumulator is connected in parallel to the high-pressure oil supply circuit unit to absorb system pressure pulsations and store instantaneous excess energy. The pressure compensation valve is linked with the electro-hydraulic proportional multi-way valve group unit to maintain the pressure stability of each branch when multiple actuators perform compound actions. When the oil temperature exceeds a set threshold, the cooling bypass automatically diverts a portion of the hydraulic oil to the cooling circuit, where it is cooled and then returned to the main circuit.

8. The energy-saving servo control hydraulic system for a hydraulic excavator according to claim 1, characterized in that, The central controller unit of the whole machine also includes an operating condition identification module, a fault prediction module, and a wireless communication module: The working condition identification module automatically classifies the working mode based on the data from the pressure sensor and displacement sensor, and calls the corresponding control strategy. The fault prediction module analyzes historical operating data and real-time sensor signals to predict the remaining lifespan of key components such as hydraulic pumps and servo motors, and triggers maintenance warnings in advance. The wireless communication module supports remote monitoring and firmware upgrades, allowing control algorithm parameters to be updated via a cloud server.

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