Closed pump-controlled hydraulic circuit, adaptive flow compensation system and control method thereof

Abstract

The present application relates to closed pump control hydraulic technology field, especially to a kind of closed pump control hydraulic circuit, adaptive flow compensation system and control method thereof.The closed pump control hydraulic circuit includes the piston assembly of two synchronously movable piston rods, which is installed in main hydraulic cylinder and adaptive flow compensator to form an integrated unit, and the main hydraulic cylinder and adaptive flow compensator are connected by the third electromagnetic switch switching valve, which can form a compensation hydraulic circuit for closed pump control main hydraulic cylinder, and when working in four-quadrant operating condition, it forms the absorption and compensation of asymmetric flow in the main hydraulic cylinder.The present application solves the structural problem of asymmetric flow of single-outlet-rod hydraulic cylinder in closed pump control hydraulic system from the root, without relying on complex auxiliary devices or high-difficulty special pump body design, thus having important significance in improving system reliability, reducing cost and optimizing control performance.

Description

Technical Field

[0001] This invention relates to the field of closed-loop pump-controlled hydraulic technology, and in particular to a closed-loop pump-controlled hydraulic circuit, an adaptive flow compensation system, and a control method thereof. Background Technology

[0002] Electro-hydraulic control systems are mainly divided into two technical routes: pump control and valve control. Valve control systems, with their rapid response and high-precision control capabilities, are widely used in scenarios with stringent dynamic performance requirements. However, their core control component—the multi-way valve—inevitably experiences a throttling effect during operation, leading to a significant increase in system energy loss and low energy utilization efficiency. This inherent defect limits its application in fields with high energy efficiency requirements. In contrast, pump control systems employ a topology of direct coupling between the hydraulic pump and the hydraulic cylinder. By regulating core parameters such as the pump's displacement and speed, they achieve direct control of the hydraulic cylinder's output characteristics, fundamentally eliminating the energy loss caused by throttling in valve control systems and significantly improving system energy utilization.

[0003] However, when a traditional closed-loop pump control system is equipped with a single-rod hydraulic cylinder, there is an inherent and unavoidable difference in the effective working area between the rod chamber and the rodless chamber, and this difference remains constant. This asymmetry in area can lead to a serious flow imbalance problem: under the same working conditions, the theoretical discharge flow of the rodless chamber and the theoretical intake flow of the rod chamber cannot be balanced, resulting in a significant deviation in the inlet and outlet flow of the entire hydraulic circuit. This problem has become a key bottleneck restricting the improvement of system performance.

[0004] In addressing this issue, existing closed-loop pump-controlled hydraulic systems have the following shortcomings:

[0005] 1. Patent No. [202210816720.X] discloses a [Distributed Independent Variable Speed ​​Closed-Loop Pump-Controlled Hydraulic System for Excavators]. This system consists of four pump-controlled hydraulic subsystems. The first and second hydraulic pumps are four-quadrant asymmetric fixed-displacement hydraulic pumps to achieve inlet and outlet flow balance. The third and fourth hydraulic pumps are four-quadrant symmetric fixed-displacement hydraulic pumps, requiring an oil replenishment system composed of an accumulator and a check valve to address the flow asymmetry between the inlet and outlet chambers. On one hand, the asymmetric three-port pump compensates for the flow difference through a special flow distribution design. However, this pump body faces significant technical challenges in areas such as curved distribution plate machining, three-port pressure matching, and dynamic sealing. Not only are the design and manufacturing costs high, but the volumetric efficiency also drops significantly under high pressure, making it difficult to meet the needs of large-scale applications. On the other hand, adding an auxiliary oil replenishment circuit consisting of a low-pressure accumulator, a hydraulic check valve, and an oil replenishment / relief valve group to adjust the flow difference can alleviate the contradiction to a certain extent. However, the additional hydraulic components and control logic not only increase the integration difficulty of the system, but may also cause pressure instability due to untimely oil replenishment, affecting the control accuracy of the system.

[0006] 2. Patent No. [202310324055.7] discloses [a discrete four-chamber hydraulic cylinder system controlled by multiple solenoid valves]. This solution is a multi-cylinder split combination four-chamber cylinder system, which relies on the coordinated combination of multiple independent two-chamber cylinders to regulate the flow. Although it can try to solve the problem of flow asymmetry by designing the effective working area of ​​each chamber / cylinder, it generally has common defects: the multi-cylinder split structure has a loose layout and low space utilization, which lacks both compactness and economy.

[0007] 3. Patent No. [202411110052.4] discloses [Potential Energy Recovery System and Control Method for Heavy-Duty Pressing Device]. This solution uses an integrated four-cavity hydraulic cylinder. Although it reduces the actuator volume to a certain extent and improves the space occupation problem, the multi-cavity integrated hydraulic cylinder is difficult to process and manufacture, and the assembly accuracy and quality are not easy to guarantee. Summary of the Invention

[0008] The present invention aims to at least improve one of the technical problems existing in the prior art. To this end, the present invention proposes a closed-loop pump-controlled hydraulic circuit, an adaptive flow compensation system, and a control method thereof.

[0009] The technical solution of the present invention is as follows:

[0010] A closed-loop pump-controlled hydraulic circuit, comprising:

[0011] The main hydraulic cylinder body has a first cavity;

[0012] An adaptive flow compensator is installed on the surface of the main hydraulic cylinder. The adaptive flow compensator has a second cavity. The first cavity and the second cavity are not connected to each other and have different volumes.

[0013] A piston assembly having two synchronously movable piston rods is respectively installed in the main hydraulic cylinder and the adaptive flow compensator to form an adaptive flow compensator actuator unit, wherein the first cavity is divided into a rod-side cavity and a rodless cavity of the main hydraulic cylinder based on the piston rods, and the second cavity is divided into a hydraulic cavity and an atmospheric cavity of the adaptive flow compensator.

[0014] The hydraulic pump motor has a first oil port and a second oil port;

[0015] The first electromagnetic switch switching valve connects the first oil port to the rodless chamber of the main hydraulic cylinder;

[0016] The second electromagnetic switch switching valve connects the second oil port to the rod chamber of the main hydraulic cylinder to form a closed pump-controlled main hydraulic circuit.

[0017] The third electromagnetic switch valve has its return port connected to the rodless chamber of the main hydraulic cylinder, its working port connected to the hydraulic chamber of the adaptive flow compensator, and its supply port connected to the second port to form a closed-loop pump-controlled compensation hydraulic circuit. When operating in a four-quadrant condition, the difference between the area of ​​the rodless chamber and the area of ​​the rod chamber of the main hydraulic cylinder is equal to the area of ​​the hydraulic chamber of the adaptive flow compensator, thereby absorbing and compensating for the asymmetrical flow in the main hydraulic cylinder.

[0018] In one possible technical solution, the main hydraulic cylinder is a single-rod hydraulic cylinder, the adaptive flow compensator has a crescent-shaped cross-section and is closely attached to the main hydraulic cylinder body, the two components are integrated into one, and the piston assembly is mechanically coupled to share the same displacement variable.

[0019] In one possible technical solution, the bottom of the adaptive flow compensator's atmospheric cavity is provided with a notch, allowing the atmospheric cavity to communicate with the atmosphere. A filter screen is provided at the notch to block impurities from entering and keep the cavity clean.

[0020] In one possible technical solution, a further component is included: an oil replenishment assembly for replenishing leaked oil to maintain absolute stability of the closed-loop system's replenishment pressure. This protects the hydraulic pump motor, ensures control accuracy, improves system response speed, and achieves system miniaturization and energy saving. The oil replenishment assembly includes:

[0021] A first pressure sensor is installed between the rodless chamber of the main hydraulic cylinder and the first electromagnetic switch valve to monitor the pressure in the rodless chamber of the main hydraulic cylinder.

[0022] The second pressure sensor is installed between the rod chamber of the main hydraulic cylinder and the second electromagnetic switch valve to monitor the pressure in the rod chamber of the main hydraulic cylinder.

[0023] A low-pressure accumulator is connected to the first electromagnetic switch valve to form a first oil replenishment channel, and the low-pressure accumulator is connected to the second electromagnetic switch valve to form a second oil replenishment channel.

[0024] In one possible technical solution, a first check valve and a second check valve are respectively provided on the first oil replenishment channel and the second oil replenishment channel.

[0025] An adaptive flow compensation system, comprising:

[0026] The aforementioned closed-loop pump-controlled hydraulic circuit;

[0027] An electric generator is coaxially connected to the hydraulic pump motor;

[0028] A hybrid energy recovery system is connected to the electric generator to supply energy to the closed-loop pump-controlled hydraulic circuit or to recover and store the electrical energy of the electric generator.

[0029] An adaptive flow compensation system control method, wherein the adaptive flow compensation system is used to control the load using a hydraulic cylinder, includes the following steps:

[0030] Obtain the displacement direction of the load and the piston assembly, and determine the command speed of the piston assembly based on the displacement direction;

[0031] The pressure P1 in the rodless chamber of the main hydraulic cylinder and the pressure P2 in the rod chamber of the main hydraulic cylinder are obtained. Based on the pressure P1 and the pressure P2 and the piston assembly command speed, the operating condition of the system is determined, wherein the operating condition includes the resistance extension condition, the resistance retraction condition, the over-extension condition, and the over-retraction condition.

[0032] Based on the aforementioned operating conditions, corresponding control strategies are implemented to achieve external work or energy recovery.

[0033] In one possible technical solution, further, the execution of the corresponding control strategy based on the operating condition includes:

[0034] If the hydraulic pump motor is in the resistance extension condition, it switches to the pumping mode, the first solenoid switch valve is in the right position, the second solenoid switch valve is in the left position, the third solenoid switch valve is in the right position, and the electric generator drives the hydraulic pump to operate.

[0035] If it is in the resistance retraction working condition, the hydraulic pump motor switches to the pumping mode, the first solenoid switch valve is in the right position, the second solenoid switch valve is in the left position, the third solenoid switch valve is in the left position, and the electric generator drives the hydraulic pump to operate.

[0036] In one possible technical solution, further, the step of executing the corresponding control strategy based on the operating condition also includes:

[0037] If the hydraulic pump motor is in over-extension working condition, it switches to motor mode. The first solenoid switch valve is in the right position, the second solenoid switch valve is in the left position, and the third solenoid switch valve is in the right position. The electric generator recovers the rotational energy of the hydraulic pump motor and converts the rotational energy into electrical energy, which is stored in the battery and supercapacitor.

[0038] If the system is in the over-retraction condition, the hydraulic pump motor switches to motor mode, the first solenoid switch valve is in the right position, the second solenoid switch valve is in the left position, and the third solenoid switch valve is in the right position. The electric generator recovers the rotational energy of the hydraulic pump motor and converts the rotational energy into electrical energy, which is then stored in the battery and supercapacitor.

[0039] The closed-loop pump-controlled hydraulic circuit, adaptive flow compensation system, and control method of the present invention have the following beneficial effects:

[0040] 1. Compared to traditional closed-loop pump control systems, this system does not rely on complex oil replenishment circuits or special pump designs to alleviate flow asymmetry problems. By optimizing the effective working area parameters of each hydraulic cavity in the system, the adaptive flow compensator absorbs and compensates for the asymmetrical flow of the main hydraulic cylinder under all operating conditions. This fundamentally solves the structural problem of flow asymmetry in the single-rod hydraulic cylinder in closed-loop pump control hydraulic systems, simplifying control, improving operational reliability, and significantly reducing costs.

[0041] 2. Compared with centralized valve-controlled hydraulic systems, the proposed system adopts a closed-loop pump-controlled hydraulic transmission architecture. By controlling the speed of the hydraulic pump, the movement state of the hydraulic cylinder is directly controlled, effectively avoiding the energy loss caused by throttling in traditional valve-controlled systems. At the same time, it significantly reduces the pressure loss along the pipeline caused by fluid viscous friction during long-distance pipeline transmission, and significantly improves the system's energy utilization efficiency.

[0042] 3. Compared with discrete or integrated multi-cavity hydraulic cylinder systems, this system innovatively adopts an adaptive flow compensator to solve the problem of flow asymmetry. It not only accurately achieves flow balance, but also fundamentally avoids the inherent drawbacks of multi-cavity design, such as loose structure, low space utilization and high processing and manufacturing difficulty.

[0043] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0044] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is a schematic diagram of the structure of an adaptive flow compensation actuator unit according to an embodiment of the present invention;

[0046] Figure 2 This is a schematic diagram of the adaptive flow compensation actuator unit from another perspective according to an embodiment of the present invention;

[0047] Figure 3 This is a cross-sectional view of an adaptive flow compensation actuator unit according to an embodiment of the present invention;

[0048] Figure 4 This is a side view of the adaptive flow compensation actuator unit according to an embodiment of the present invention;

[0049] Figure 5 This is a schematic diagram of the structure of an adaptive flow compensation system according to an embodiment of the present invention;

[0050] Figure 6 This is a flowchart of an adaptive flow compensation system control method according to an embodiment of the present invention.

[0051] Figure label:

[0052] Adaptive flow compensation actuator unit 1, main hydraulic cylinder body 101, adaptive flow compensator 102, piston assembly 103, rodless chamber inlet / outlet port C of main hydraulic cylinder, rod chamber inlet / outlet port D of main hydraulic cylinder, hydraulic chamber inlet / outlet port E of adaptive flow compensator, notch F;

[0053] Hydraulic pump motor 2, first oil port A, second oil port B;

[0054] First electromagnetic switch switching valve 3, second electromagnetic switch switching valve 4, third electromagnetic switch switching valve 5, return port T, working port A, supply port P;

[0055] First pressure sensor 6, second pressure sensor 7, low-pressure accumulator 8, first check valve 9, second check valve 10, overflow valve 11, third check valve 12, fourth check valve 13;

[0056] 14. Electric generator; 15. Hybrid energy recovery system;

[0057] DC-AC converter 16, DC-DC converter 17, supercapacitor 18, storage battery 19;

[0058] 20. Closed-loop pump-controlled hydraulic circuit. Detailed Implementation

[0059] The embodiments of the present invention are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0060] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component.

[0061] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0062] The terms "first," "second," "third," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects and not to describe a particular order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, it may include a series of steps or units, or optionally, steps or units not listed, or other steps or units inherent to these processes, methods, products, or devices.

[0063] The accompanying drawings show only the portions relevant to this application, not all of them. Before discussing exemplary embodiments in more detail, it should be noted that some exemplary embodiments are described as processes or methods depicted as flowcharts. Although the flowcharts describe operations (or steps) as sequential processes, many of these operations may be performed in parallel, concurrently, or simultaneously. Furthermore, the order of the operations may be rearranged. The process may be terminated when its operation is completed, but may also have additional steps not included in the drawings. The process may correspond to a method, function, procedure, subroutine, subprogram, etc.

[0064] Example 1

[0065] like Figures 1 to 5As shown, this embodiment provides a closed-loop pump-controlled hydraulic circuit 20, which includes:

[0066] The main hydraulic cylinder body 101 has a first cavity;

[0067] An adaptive flow compensator 102 is installed on the surface of the main hydraulic cylinder 101. The adaptive flow compensator 102 has a second cavity. The first cavity and the second cavity are not connected to each other and have different volumes.

[0068] The piston assembly 103 has two synchronously movable piston rods, which are respectively installed in the main hydraulic cylinder body 101 and the adaptive flow compensator 102 to form an adaptive flow compensator actuator unit 1. The piston rods are used to divide the first cavity into a main hydraulic cylinder rod chamber and a main hydraulic cylinder rodless chamber, and to divide the second cavity into an adaptive flow compensator hydraulic chamber and an adaptive flow compensator atmospheric chamber. It should be noted that, in this embodiment, the main hydraulic cylinder rod chamber has a main hydraulic cylinder rod chamber inlet / outlet port D, the main hydraulic cylinder rodless chamber has a main hydraulic cylinder rodless chamber inlet / outlet port C, and the adaptive flow compensator hydraulic chamber has an adaptive flow compensator hydraulic chamber inlet / outlet port E.

[0069] Hydraulic pump motor 2 has a first oil port A and a second oil port B;

[0070] The first electromagnetic switch switching valve 3 is connected to the first oil port A and the rodless chamber of the main hydraulic cylinder;

[0071] The second electromagnetic switch valve 4 is connected to the second oil port B and the rod chamber of the main hydraulic cylinder to form a closed pump-controlled main hydraulic circuit. The first electromagnetic switch valve 3 and the second electromagnetic switch valve 4 are both two-position two-way electromagnetic switch valves.

[0072] The third electromagnetic switch valve 5 has its return port T connected to the rodless chamber of the main hydraulic cylinder, its working port A connected to the hydraulic chamber of the adaptive flow compensator, and its supply port P connected to the second port B to form a closed-loop pump-controlled compensation hydraulic circuit. When operating in a four-quadrant condition, the difference between the area A1 of the rodless chamber of the main hydraulic cylinder and the area A2 of the rod chamber of the main hydraulic cylinder is equal to the area A3 of the hydraulic chamber of the adaptive flow compensator, i.e., A1-A2=A3, to absorb and compensate for the asymmetrical flow in the main hydraulic cylinder body 101. In this embodiment, the third electromagnetic switch valve 5 is a two-position three-way electromagnetic switch valve.

[0073] In this embodiment, through the synchronous operation mechanism of the main hydraulic cylinder and the adaptive flow compensator, even if the closed-loop pump-controlled hydraulic system is in any of the four-quadrant operating conditions, the adaptive flow compensator can absorb and compensate for the asymmetrical flow of the main hydraulic cylinder, thus fundamentally solving the structural problem of asymmetrical flow of the single-rod hydraulic cylinder in the closed-loop pump-controlled hydraulic system.

[0074] It should be noted that in this embodiment, the main hydraulic cylinder is a single-rod hydraulic cylinder, and the adaptive flow compensator has a crescent-shaped cross-section and is closely attached to the main hydraulic cylinder body. The two components are integrated into one unit, and the piston assembly is mechanically coupled to share the same displacement variable.

[0075] It should be noted that, in this embodiment, the bottom of the atmospheric cavity of the adaptive flow compensator is provided with a notch F, so that the atmospheric cavity of the adaptive flow compensator is connected to the atmosphere. A filter screen is provided at the notch F to block impurities from entering and keep the cavity clean.

[0076] It should be noted that, in this embodiment, the closed-loop pump-controlled hydraulic circuit 20 further includes an oil replenishment component for replenishing leaked oil to maintain the absolute stability of the closed-loop system's replenishment pressure, thereby protecting the hydraulic pump motor, ensuring control accuracy, improving system response speed, and achieving system miniaturization and energy saving. The oil replenishment component includes:

[0077] The first pressure sensor 6 is installed between the rodless chamber of the main hydraulic cylinder and the first electromagnetic switch valve 3 to monitor the pressure in the rodless chamber of the main hydraulic cylinder.

[0078] The second pressure sensor 7 is installed between the rod chamber of the main hydraulic cylinder and the second electromagnetic switch valve 4 to monitor the pressure in the rod chamber of the main hydraulic cylinder.

[0079] The low-pressure accumulator 8 is connected to the first electromagnetic switch valve 3 to form a first oil replenishment channel, and the low-pressure accumulator 8 is connected to the second electromagnetic switch valve 4 to form a second oil replenishment channel.

[0080] It should be noted that, in this embodiment, a first check valve 9 and a second check valve 10 are respectively provided on the first oil replenishment channel and the second oil replenishment channel.

[0081] It should be noted that, in this embodiment, the closed-loop pump-controlled hydraulic circuit 20 further includes:

[0082] The overflow valve 11 has two oil inlets and one oil outlet. The two oil inlets are respectively connected between the first oil inlet A and the first electromagnetic switch valve 3, and between the second oil inlet B and the second electromagnetic switch valve 4. The oil outlet is connected to the low-pressure accumulator 8.

[0083] It should be noted that, in this embodiment, a third check valve 12 is installed between one of the oil inlets of the overflow valve 11 and the first oil port A, and a fourth check valve 13 is installed between the other oil inlet and the second oil port B, for overload protection, so as to keep the pressure in the closed pump-controlled hydraulic circuit 20 within the set range.

[0084] Example 2

[0085] like Figure 5 As shown, this embodiment provides an adaptive traffic compensation system, which includes:

[0086] The aforementioned closed-loop pump-controlled hydraulic circuit 20;

[0087] Electric generator 14 is coaxially connected to the hydraulic pump motor 2;

[0088] The hybrid energy recovery system 15 is connected to the electric generator 14 to supply energy to the closed-loop pump-controlled hydraulic circuit 20 or to recover and store the electrical energy of the electric generator 14.

[0089] It should be noted that, in this embodiment, the hybrid energy supply and recovery system 15 includes:

[0090] DC-AC converter 16 is connected to the electric generator 14 to realize bidirectional conversion between direct current and alternating current;

[0091] DC-DC converter 17 is connected to DC-AC converter 16 to realize DC-DC conversion and to regulate voltage and current;

[0092] The supercapacitor 18 is connected to the DC-DC converter 17;

[0093] A storage battery 19 is connected in parallel with the supercapacitor 18. The system can distribute the energy between the storage battery 19 and the supercapacitor 18 according to its energy management strategy. When the closed-loop pump-controlled hydraulic circuit 20 requires electrical energy for subsequent operations, the storage battery 19 and the supercapacitor 18 will work together to supply power; when the closed-loop pump-controlled hydraulic circuit 20 has no subsequent operations and does not require electrical energy, the supercapacitor 18 will use its stored electrical energy to charge the storage battery 19.

[0094] The adaptive flow compensation system based on the above embodiments has four quadrant operating conditions, including impedance extension, impedance retraction, overshoot extension, and overshoot retraction. When the system is in the overshoot condition, it can recover energy. The system can also maintain the load by coordinating the on / off states of the various electromagnetic switch valves. These will be explained in detail below.

[0095] When the adaptive flow compensation system needs to maintain its load, the third solenoid switch valve 5 is fully positioned to the right, the first solenoid switch valve 3 is fully positioned to the left, and the second solenoid switch valve 4 is fully positioned to the right. This load-maintaining function not only improves system stability and safety but also reduces energy consumption and extends equipment lifespan.

[0096] 1. Impedance Extension Condition: When the piston assembly 103 of the adaptive flow compensation actuator unit 1 extends outward, and the direction of the external load force is opposite to the extension direction of the piston assembly 103, that is:

[0097] The commanded velocity v of piston assembly 103 satisfies: v > 0.

[0098] The pressures in the rodless and rod chambers of the main hydraulic cylinder satisfy: P1 > P2. At this time, the entire system is in the resistance extension condition.

[0099] At this time, the hydraulic pump motor 2 is in pumping mode: hydraulic oil flows out from the first oil port A of the hydraulic pump motor 2, flows through the first electromagnetic switch switching valve 3 which is fully in the right position, and then flows into the rodless chamber of the main hydraulic cylinder through the oil port C of the rodless chamber.

[0100] The returned hydraulic oil is divided into two parts:

[0101] In the first part, hydraulic oil flows out from the rod chamber of the main hydraulic cylinder through the oil inlet / outlet port D, passes through the second electromagnetic switch valve 4 which is fully in the left position, and is then drawn in by the hydraulic pump motor 2 from the second oil port B.

[0102] In the second part, hydraulic oil flows out from the inlet / outlet port E of the hydraulic chamber of the adaptive flow compensator, flows through the third electromagnetic switch valve 5 which is fully in the right position, and is then drawn in by the hydraulic pump motor 2 from the second port B, thus completing the unbalanced flow compensation for the main hydraulic cylinder 101.

[0103] 2. Impedance Retraction Condition: When the piston assembly 103 of the adaptive flow compensation actuator unit 1 retracts inward, and the direction of the external load force is opposite to the retraction direction of the piston assembly 103, that is:

[0104] The commanded velocity v of piston assembly 103 satisfies: v < 0.

[0105] The pressures in the rodless and rod chambers of the main hydraulic cylinder satisfy: P1 < P2, at which point the entire system is in the resistance retraction condition.

[0106] At this time, the hydraulic pump motor 2 is in pumping mode. The hydraulic oil flows out from the second oil port B of the hydraulic pump motor 2, flows through the second electromagnetic switch valve 4 which is completely in the left position, and then flows into the rod chamber of the main hydraulic cylinder through the oil inlet / outlet D of the rod chamber.

[0107] The returned hydraulic oil is divided into two parts:

[0108] In the first part, hydraulic oil flows out from the rodless chamber of the main hydraulic cylinder through the oil inlet / outlet port C, passes through the first electromagnetic switch valve 3 which is fully in the right position, and is then drawn in by the hydraulic pump motor 2 from the first oil port A.

[0109] In the second part, the hydraulic oil flows out from the rodless chamber inlet / outlet C of the main hydraulic cylinder, flows through the third electromagnetic switch valve 5 which is fully in the left position, and then flows into the hydraulic chamber of the adaptive flow compensator through the inlet / outlet E of the hydraulic chamber of the adaptive flow compensator, thus completing the absorption of the unbalanced flow of the main hydraulic cylinder body 101.

[0110] 3. Overextended operating condition: When the piston assembly 103 of the adaptive flow compensation actuator unit 1 extends outward, and the direction of the external load force is the same as the extension direction of the piston assembly 103, that is:

[0111] The commanded velocity v of piston assembly 103 satisfies v > 0.

[0112] The pressures in the rodless and rod chambers of the main hydraulic cylinder satisfy the condition that P1 < P2, at which point the entire system is in overextended operation.

[0113] At this time, the hydraulic pump motor 2 is in motor mode and the electric generator 14 is in generator mode, recovering energy from the system and storing electrical energy in the battery 19 and the supercapacitor 18.

[0114] Hydraulic oil is divided into two parts:

[0115] The first part flows out from the oil inlet / outlet port D of the rod chamber of the main hydraulic cylinder, flows through the second electromagnetic switch switching valve 4 which is completely in the left position, and then flows in through the second oil port B of the hydraulic pump motor 2, driving the motor of the hydraulic pump motor 2 to rotate, thereby generating electrical energy from the generator.

[0116] The second part flows out from the inlet / outlet port E of the hydraulic chamber of the adaptive flow compensator, flows through the third electromagnetic switch valve 5 which is fully in the right position, and then flows in through the second port B of the hydraulic pump motor 2, completing the unbalanced flow compensation for the main hydraulic cylinder 101 and driving the motor to rotate so that the generator generates electrical energy.

[0117] The returning hydraulic oil flows out through the first oil port A of the hydraulic pump motor 2, flows through the first electromagnetic switch switching valve 3 which is fully in the right position, and then flows into the rodless chamber of the main hydraulic cylinder through the oil port C of the rodless chamber.

[0118] 4. Overrun Retraction Condition: When the piston assembly 103 of the adaptive flow compensation actuator unit 1 retracts inward, and the direction of the external load force is the same as the retraction direction of the piston assembly 103, that is:

[0119] The commanded velocity v of piston assembly 103 satisfies: v < 0.

[0120] The pressures in the rodless and rod chambers of the main hydraulic cylinder satisfy the condition that P1 > P2, at which point the entire system is in the overrun and retraction condition.

[0121] At this time, the hydraulic pump motor 2 is in motor mode and the electric generator 14 is in generator mode, recovering energy from the system and storing electrical energy in the battery 19 and the supercapacitor 18.

[0122] Hydraulic oil flows out from the rodless chamber of the main hydraulic cylinder through the inlet / outlet port C, passes through the first electromagnetic switch valve 3 which is fully in the right position, and then flows in through the first port A of the hydraulic pump motor 2, driving the motor of the hydraulic pump motor 2 to rotate, thereby generating electrical energy from the generator.

[0123] The returned hydraulic oil is divided into two parts:

[0124] In the first part, hydraulic oil flows out from the second oil port B of the hydraulic pump motor 2, flows through the second electromagnetic switch switching valve 4 which is fully in the left position, and then flows into the rod chamber of the main hydraulic cylinder through the oil port D of the rod chamber of the main hydraulic cylinder.

[0125] In the second part, hydraulic oil flows out from the second oil port B of the hydraulic pump motor 2, flows through the third electromagnetic switch valve 5 which is fully in the right position, and then flows into the hydraulic chamber of the adaptive flow compensator through the oil inlet and outlet E of the hydraulic chamber of the adaptive flow compensator, thus completing the absorption of the unbalanced flow of the main hydraulic cylinder 101.

[0126] Under the above operating conditions, the low-pressure accumulator 8 only needs to compensate for a small amount of hydraulic oil leakage in the system, and the overflow valve 11 plays an overload protection role, keeping the pressure of the hydraulic oil in the system within the set range.

[0127] Example 3

[0128] like Figure 6 As shown, this embodiment provides an adaptive flow compensation system control method, wherein the adaptive flow compensation system is used to control the load using a hydraulic cylinder, including the following steps:

[0129] S1: Obtain the displacement direction of the load and the piston assembly, and determine the command speed of the piston assembly based on the displacement direction;

[0130] S2: Obtain the pressure P1 in the rodless chamber of the main hydraulic cylinder and the pressure P2 in the rod chamber of the main hydraulic cylinder. Based on the pressure P1 and the pressure P2 and the piston assembly command speed, determine the operating condition of the system. The operating condition includes the resistance extension condition, the resistance retraction condition, the over-extension condition, and the over-retraction condition.

[0131] S3: Based on the operating conditions, execute the corresponding control strategy to achieve external work or energy recovery.

[0132] It should be noted that, in this embodiment, S1 specifically includes:

[0133] When the piston assembly extends outward, the piston assembly is commanded to have a velocity v > 0;

[0134] When the piston assembly retracts inward, the piston assembly command speed v < 0.

[0135] It should be noted that in this embodiment, in S2, the pressure P1 of the rodless chamber and the pressure P2 of the rod chamber of the main hydraulic cylinder can be collected by the first pressure sensor 6 and the second pressure sensor 7. Combined with the piston assembly command speed v and the direction of action of the external load force F, the working mode of the system at this time can be determined, thereby realizing control in the four-quadrant working mode.

[0136] It should be noted that, in this embodiment, S3 specifically includes:

[0137] If the hydraulic pump motor is in the resistance extension condition, it switches to the pumping mode, the first solenoid switch valve is in the right position, the second solenoid switch valve is in the left position, the third solenoid switch valve is in the right position, and the electric generator drives the hydraulic pump to operate.

[0138] If it is in the resistance retraction working condition, the hydraulic pump motor switches to the pumping mode, the first solenoid switch valve is in the right position, the second solenoid switch valve is in the left position, the third solenoid switch valve is in the left position, and the electric generator drives the hydraulic pump to operate.

[0139] If the hydraulic pump motor is in over-extension working condition, it switches to motor mode. The first solenoid switch valve is in the right position, the second solenoid switch valve is in the left position, and the third solenoid switch valve is in the right position. The electric generator recovers the rotational energy of the hydraulic pump motor and converts the rotational energy into electrical energy, which is stored in the battery and supercapacitor.

[0140] If the system is in the over-retraction condition, the hydraulic pump motor switches to motor mode, the first solenoid switch valve is in the right position, the second solenoid switch valve is in the left position, and the third solenoid switch valve is in the right position. The electric generator recovers the rotational energy of the hydraulic pump motor and converts the rotational energy into electrical energy, which is then stored in the battery and supercapacitor.

[0141] The specific working principle of this adaptive flow compensation system control method is as follows:

[0142] The piston assembly command speed v is set with the piston assembly extending outward as the positive direction, the load force F is set with the piston assembly retracting inward as the positive direction, and the rotational speed is set with the hydraulic pump motor 2 rotating clockwise as the positive direction.

[0143] The control signals for the adaptive flow compensation system are as follows:

[0144] When the piston assembly 103 of the adaptive flow compensation actuator unit 1 extends outward and the entire system is in the resistive extension condition, the hydraulic pump motor 2 is in pumping mode, and the electric generator 14 is in motor mode to drive the hydraulic pump. At this time, the motor speed signal of the electric generator 14 is:

[0145]

[0146] Where v is the commanded speed of the piston assembly. This indicates the area of ​​the rodless chamber of the main hydraulic cylinder. This represents the leakage coefficient of the main hydraulic cylinder. This indicates the pressure difference between the rodless chamber and the rod chamber of the main hydraulic cylinder: = - , This represents the hydraulic pump leakage coefficient of hydraulic pump motor 2. This indicates the pressure difference between the two chambers of the hydraulic pump. = - , This indicates the displacement of the hydraulic pump.

[0147] When the piston assembly 103 of the adaptive flow compensation actuator unit 1 retracts inward and the entire system is in the impedance retraction condition, the hydraulic pump motor 2 is in pumping mode, and the electric generator 14 is in motor mode to drive the hydraulic pump. At this time, the motor speed signal of the electric generator 14 is:

[0148]

[0149] in, This indicates the area of ​​the rod chamber of the main hydraulic cylinder.

[0150] When the piston assembly 103 of the adaptive flow compensation actuator unit 1 extends outward, and the entire system is in the over-extension condition, the hydraulic pump motor 2 is in motor mode, and the electric generator 14 is in generator mode, used to recover the system's energy (i.e., the rotational energy of the hydraulic pump motor). The electrical energy is stored in the battery and supercapacitor. The motor speed signal at this time is:

[0151]

[0152] in, This indicates the area of ​​the hydraulic chamber of the adaptive flow compensator.

[0153] When the piston assembly 103 of the adaptive flow compensation actuator unit 1 extends outward and the entire system is in the over-retraction condition, the hydraulic pump motor 2 is in motor mode and the electric generator 14 is in generator mode, used to recover energy from the system. The electrical energy is stored in the battery and supercapacitor. The motor speed signal at this time is:

[0154] .

[0155] Based on the aforementioned motor speed signal, which can be used as a control signal, the motor speed is controlled according to the motor speed signal under different operating conditions, thereby controlling the flow rate and allowing the hydraulic cylinder to move at the expected speed. For example, when in an impedance condition, the adaptive flow compensation system can control the piston extension speed to perform work by controlling the flow rate; when in an overload condition, the adaptive flow compensation system can recover energy based on the motor speed signal.

[0156] The adaptive flow compensation system control system according to embodiments of the present invention can directly control the motion state of the hydraulic cylinder by controlling the speed of the hydraulic pump, eliminating throttling losses and pressure losses along the pipeline caused by excessively long pipelines. The system has high energy efficiency and better energy-saving effect. This invention designs the effective working area of ​​each cavity so that the difference between the area of ​​the rodless cavity and the area of ​​the rod cavity of the main hydraulic cylinder is equal to the area of ​​the hydraulic cavity of the adaptive flow compensator. Through the synchronous operation mechanism of the two components, when the system is in any of the four quadrant operating conditions, the adaptive flow compensator can absorb and compensate for the asymmetrical flow of the main hydraulic cylinder, fundamentally solving the structural problem of asymmetrical flow of the single-rod hydraulic cylinder in a closed-loop pump-controlled hydraulic system. It does not require complex auxiliary devices or highly complex special pump designs, thereby improving system reliability, reducing costs, and optimizing control performance. This system utilizes batteries and supercapacitors to convert the energy of the system under overload conditions into electrical energy for storage and subsequent use. This results in high energy density, good energy-saving effect, and improved system stability.

[0157] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention.

[0158] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0159] Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. The reference to "embodiment" herein means that a specific feature, structure, or characteristic described in connection with an embodiment can be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily indicate the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0160] Although embodiments of the invention have been shown and described, those skilled in the art will understand 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 claims and their equivalents.

Claims

1. A closed-loop pump-controlled hydraulic circuit, characterized in that, include: The main hydraulic cylinder body (101) has a first cavity; An adaptive flow compensator (102) is installed on the surface of the main hydraulic cylinder (101). The adaptive flow compensator (102) has a second cavity. The first cavity and the second cavity are not connected to each other and have different volumes. The piston assembly (103) has two synchronously movable piston rods, which are respectively installed in the main hydraulic cylinder body (101) and the adaptive flow compensator (102) to form an adaptive flow compensator actuator unit (1), wherein the first cavity is divided into a main hydraulic cylinder rod chamber and a main hydraulic cylinder rodless chamber based on the piston rods, and the second cavity is divided into an adaptive flow compensator hydraulic chamber and an adaptive flow compensator atmospheric chamber. The hydraulic pump motor (2) has a first oil port (A) and a second oil port (B); The first electromagnetic switch switching valve (3) is connected to the first oil port (A) and the rodless chamber of the main hydraulic cylinder; The second electromagnetic switch switching valve (4) is connected to the second oil port (B) and the rod chamber of the main hydraulic cylinder to form a closed pump-controlled main hydraulic circuit; The third electromagnetic switch switching valve (5) has its return port (T) connected to the rodless chamber of the main hydraulic cylinder, its working port (A) connected to the hydraulic chamber of the adaptive flow compensator, and its supply port (P) connected to the second oil port (B) to form a closed pump-controlled compensation hydraulic circuit. When working in the four-quadrant condition, the difference between the area (A1) of the rodless chamber of the main hydraulic cylinder and the area (A2) of the rod chamber of the main hydraulic cylinder is equal to the area (A3) of the hydraulic chamber of the adaptive flow compensator, so as to absorb and compensate for the asymmetrical flow in the main hydraulic cylinder body (101).

2. The closed-loop pump-controlled hydraulic circuit according to claim 1, characterized in that, The main hydraulic cylinder (101) is a single-rod hydraulic cylinder, and the adaptive flow compensator (102) has a crescent-shaped cross-section and is closely attached to the main hydraulic cylinder (101).

3. The closed-loop pump-controlled hydraulic circuit according to claim 1, characterized in that, The adaptive flow compensator has a notch (F) at the bottom of the atmospheric cavity, and a filter screen is installed at the notch (F).

4. The closed-loop pump-controlled hydraulic circuit according to claim 1, characterized in that, It also includes an oil replenishment assembly for replenishing leaked oil to maintain absolute stability of the oil replenishment pressure in the closed system. The oil replenishment assembly includes: The first pressure sensor (6) is installed between the rodless chamber of the main hydraulic cylinder and the first electromagnetic switch valve (3); The second pressure sensor (7) is installed between the rod chamber of the main hydraulic cylinder and the second electromagnetic switch valve (4); The low-pressure accumulator (8) is connected to the first electromagnetic switch valve (3) to form a first oil replenishment channel, and the low-pressure accumulator (8) is connected to the second electromagnetic switch valve (4) to form a second oil replenishment channel.

5. The closed-loop pump-controlled hydraulic circuit according to claim 4, characterized in that, A first check valve (9) and a second check valve (10) are respectively provided on the first oil replenishment channel and the second oil replenishment channel.

6. An adaptive flow compensation system, characterized in that, include: The closed-loop pump-controlled hydraulic circuit according to any one of claims 1 to 5; An electric generator (14) is coaxially connected to the hydraulic pump motor (2); A hybrid energy recovery system (15) is connected to the electric generator (14) to supply energy to the closed-loop pump-controlled hydraulic circuit or to recover and store the electrical energy of the electric generator (14).

7. A control method for an adaptive flow compensation system, characterized in that, The hydraulic cylinder control of the load using the adaptive flow compensation system as described in claim 6 includes the following steps: Obtain the displacement direction of the load and the piston assembly, and determine the command speed of the piston assembly based on the displacement direction; The pressure P1 in the rodless chamber of the main hydraulic cylinder and the pressure P2 in the rod chamber of the main hydraulic cylinder are obtained. Based on the pressure P1 and the pressure P2 and the piston assembly command speed, the operating condition of the system is determined, wherein the operating condition includes the resistance extension condition, the resistance retraction condition, the over-extension condition, and the over-retraction condition. Based on the aforementioned operating conditions, corresponding control strategies are implemented to achieve external work or energy recovery.

8. The adaptive flow compensation system control method according to claim 7, characterized in that, The execution of corresponding control strategies based on the operating conditions includes: If the hydraulic pump motor is in the resistance extension condition, it switches to the pumping mode, the first solenoid switch valve is in the right position, the second solenoid switch valve is in the left position, the third solenoid switch valve is in the right position, and the electric generator drives the hydraulic pump to operate. If the hydraulic pump is in the resistance retraction condition, the hydraulic pump motor switches to the pumping mode, the first solenoid switch valve is in the right position, the second solenoid switch valve is in the left position, the third solenoid switch valve is in the left position, and the electric generator drives the hydraulic pump to operate.

9. The adaptive flow compensation system control method according to claim 8, characterized in that, The step of executing the corresponding control strategy based on the operating condition also includes: If the hydraulic pump motor is in over-extension working condition, the hydraulic pump motor switches to motor mode, the first solenoid switch valve is in the right position, the second solenoid switch valve is in the left position, the third solenoid switch valve is in the right position, and the electric generator recovers the rotational energy of the hydraulic pump motor and converts the rotational energy into electrical energy to be stored in the battery and supercapacitor. If the system is in the over-retraction condition, the hydraulic pump motor switches to motor mode, the first solenoid switch valve is in the right position, the second solenoid switch valve is in the left position, and the third solenoid switch valve is in the right position. The electric generator recovers the rotational energy of the hydraulic pump motor and converts the rotational energy into electrical energy, which is then stored in the battery and supercapacitor.

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