Multi-accumulator automatic oil replenishing system based on pressure deviation comparison and bus competition

Abstract

The application discloses a kind of based on deviation comparison and bus competition's multi-accumulator automatic oiling system, comprising: multistage main accumulator, pressure deviation measuring unit, tournament unit;Pressure deviation measuring unit is used to measure the pressure deviation signal of main accumulator;Tournament unit is used to filter out the maximum pressure deviation signal from the pressure deviation signal of multiple main accumulators;Each main accumulator is provided with corresponding oiling control valve, the position of the maximum pressure deviation signal and the pressure deviation signal of main accumulator controls the position of the oiling control valve spool, to control the on-off of oiling path.

Description

Technical Field

[0001] This invention relates to the field of hydraulic technology, and in particular to an automatic oil replenishment system for multiple accumulators based on pressure deviation comparison and bus competition. Background Technology

[0002] In multi-stage accumulator hydraulic systems, multiple main accumulators with different pressure levels typically share a single replenishing pump to provide a stable and tiered pressure source for downstream actuators. Such systems are widely used in heavy-duty cranes, large hydraulic test benches, mining hoisting equipment, and industrial hydraulic power units requiring multiple pressure levels.

[0003] In existing technologies, oil replenishment control for multi-accumulator systems mainly employs timed cycles, independent pressure switches, or centralized electronic control. Timed cycle control replenishes oil to each accumulator sequentially at fixed intervals, failing to reflect the actual pressure status of the accumulators, resulting in high ineffective energy consumption of the pump source and large system pressure fluctuations. While independent pressure switch control can respond to actual pressure, the complete independence and lack of coordination between accumulators easily leads to a "oil-grabbing" phenomenon when multiple accumulators experience simultaneous pressure drops, causing severe system pressure oscillations. Centralized electronic control achieves scheduling through pressure sensors and program calculations, but it relies on electronic components, requiring additional explosion-proof encapsulation in flammable, explosive, or strong electromagnetic interference environments, and carries risks such as electromagnetic interference failure, program crashes, and component aging, resulting in high life-cycle costs.

[0004] Furthermore, in existing technologies, if pressure deviation is measured using purely mechanical methods, it is difficult to directly output a pressure deviation signal with a uniform slope due to the discrete nature of the piston area of ​​the standard hydraulic cylinder, leading to difficulties in large-scale application. At the same time, existing hydraulic logic control schemes can mostly only achieve oil replenishment with fixed priority or fixed sequence, and cannot dynamically compete and arbitrate based on the "actual pressure deviation degree" of each accumulator, making it difficult to adapt to complex working conditions.

[0005] Therefore, there is an urgent need in this field for a fully hydraulic mechanical multi-accumulator automatic oil replenishment scheme that can automatically identify the degree of pressure deviation of each accumulator, prioritize replenishment of the most urgently needed accumulators through competitive arbitration, and has engineering robustness to the discreteness of standard parts. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing a multi-accumulator automatic oil replenishment system based on deviation comparison and bus competition.

[0007] The objective of this invention is achieved through the following technical solution: a multi-accumulator automatic oil replenishment system based on deviation comparison and bus competition, comprising: a multi-stage main accumulator, a pressure deviation unit, and a competition unit;

[0008] Pressure deviation measurement unit is used to measure the pressure deviation signal of the main accumulator;

[0009] The tournament unit is used to filter out the maximum pressure deviation signal from the pressure deviation signals of multiple main accumulators;

[0010] Each main accumulator is equipped with a corresponding oil replenishment control valve. The maximum pressure deviation signal and the pressure deviation signal of the main accumulator control the position of the valve core of the corresponding oil replenishment control valve, thereby controlling the opening and closing of the oil replenishment circuit.

[0011] Furthermore, the pressure deviation measurement unit includes a cylinder, and a first piston and a second piston built into the cylinder;

[0012] The left annular surface of the first piston forms a reference cavity with the cylinder body, and a reference pressure P2 is applied; the right annular surface of the first piston forms a target cavity with the cylinder body, and a pressure to be measured P1 (i.e., the output pressure of the main accumulator) is applied; the right rod end face of the first piston forms a signal cavity with the cylinder body, and an output signal pressure P3 (i.e., the pressure deviation signal) is applied.

[0013] Springs are provided on both sides of the second piston; the left side of the second piston forms a balance chamber with the cylinder, and the balance chamber is connected to the signal chamber; the right side of the second piston forms an air chamber with the cylinder, and the air chamber is connected to the atmosphere.

[0014] Furthermore, the pressure deviation measurement unit includes a first centering spring mechanism, a second centering spring mechanism, a first single-acting cylinder, a double-acting cylinder with double rod extension, a second single-acting cylinder, and a third single-acting cylinder. All three cylinders are fixedly mounted on the overall platform. Before use, the pressure deviation measurement unit needs to be debugged until the signal pressure P3 is 0, at which point the interaction between the piston rod of the third single-acting cylinder and the output rod on the right side of the second centering spring mechanism is zero. After debugging, the first and second centering spring mechanisms are fixedly mounted on the overall platform.

[0015] Both the first and second centering spring mechanisms include a closed frame and an intermediate spring support; the intermediate spring support is slidably installed inside the closed frame, and both ends of it are provided with force rods.

[0016] The first single-acting cylinder has its piston rod located on the right side, and its rodless chamber is connected to the reference pressure P2.

[0017] The double-acting hydraulic cylinder has its left piston rod connected to the piston rod of the first single-acting hydraulic cylinder, and its right piston rod connected to the output rod on the left side of the first centering spring mechanism. Its left chamber is open to the atmosphere, and its right chamber outputs signal pressure P3.

[0018] The second single-acting cylinder has its piston rod located on the left side and connected to the output rod on the right side of the first centering spring mechanism; its rodless chamber is connected to the pressure to be measured, P1.

[0019] The third single-acting hydraulic cylinder has its piston rod located on the left side, connected to the output rod on the right side of the second centering spring mechanism, and its rodless chamber is connected to the signal pressure P3.

[0020] Furthermore, the tournament unit is a binary tree or hierarchical clustering tree structure composed of shuttle valves, used to compare the pressure deviation signal step by step to output the maximum pressure deviation signal.

[0021] Furthermore, the hydraulic pressure output by the hydraulic pump is filtered by a filter and then output as a reference pressure by a fixed-value pressure reducing valve, which is then sent to the reference accumulator to provide a stable reference pressure for the pressure deviation measurement unit.

[0022] Furthermore, the oil replenishment control valve adopts a combination of a pilot valve and a main valve;

[0023] The pilot valve is a two-position three-way pilot valve. Its normal position is the left position, with port P closed and ports T and A connected. In the right position, port P is connected to the pilot oil source, port T is connected to the oil tank, and port A is connected to the right position pilot control port of the main valve. The left position pilot control port of the pilot valve is connected to the pressure deviation signal of the corresponding main accumulator, the right position pilot control port is connected to the maximum pressure deviation signal, and port A is connected to the right position pilot control port of the main valve.

[0024] The main valve is a two-way hydraulic control valve. Its normal position is the left position, with ports P and A closed; when in the right position, ports P and A are connected.

[0025] Furthermore, the maximum pressure deviation signal output by the tournament unit is connected to the signal bus, and the right-position pilot control port of the pilot valve is connected to the signal bus; a check valve is set between the tournament unit and the signal bus, or a valve group consisting of a forward-mounted check valve and a reverse-mounted spring-loaded check valve (spring biased) connected in parallel is set between the tournament unit and the signal bus; and the minimum pressure preset by the signal bus is maintained through an independent pressure-holding branch, with a check valve set between the pressure-holding branch and the signal bus;

[0026] The pressure-holding branch includes a small accumulator, a micro accumulator, and a pressure-reducing valve;

[0027] The pressure output by the pressure reducing valve is the minimum pressure preset by the signal bus. It draws oil from the small accumulator to maintain the minimum pressure preset by the signal bus.

[0028] The pressure output by the micro accumulator is the minimum pressure preset by the signal bus, which is used to absorb fluctuations in the opening and closing of the pressure reducing valve and compensate for instantaneous leakage.

[0029] Furthermore, the hydraulic pressure output by the hydraulic pump is supplied to the corresponding main accumulator via the replenishment control valve. The hydraulic pressure output by the hydraulic pump is connected to the replenishment main pipe, and the replenishment main pipe is connected to each replenishment control valve. Each of the connected oil circuits is equipped with a check valve.

[0030] Furthermore, it also includes an unloading valve, whose inlet is connected to the hydraulic pump outlet and whose outlet is connected to the oil tank; when all accumulators finish replenishing oil and reach the exit standard, the replenishment control is turned off, the outlet pressure of the hydraulic pump rises and reaches the trigger value of the unloading valve, and then the unloading valve opens to unload.

[0031] The main oil supply line provides a clean control signal pressure to the unloading valve through a filter, and a check valve is installed between the hydraulic pressure output from the hydraulic pump and the main oil supply line.

[0032] Furthermore, it also includes: adding a return oil accumulator between each main accumulator and the downstream actuator, with a check valve is used to isolate the main accumulator and the return oil accumulator;

[0033] From the high-pressure stage to the low-pressure stage, the return oil accumulators at each stage are connected by pilot relief valves, and the set pressure of the pilot relief valves is equal to the rated pressure of the main accumulator at this stage.

[0034] This invention also provides an automatic refueling method for multiple accumulators based on deviation comparison and bus competition, comprising:

[0035] Acquire the pressure deviation signal for each accumulator;

[0036] The maximum pressure deviation signal is selected from the pressure deviation signals of multiple main accumulators;

[0037] Each main accumulator is equipped with a corresponding oil replenishment control valve. The maximum pressure deviation signal and the pressure deviation signal of the main accumulator control the position of the valve core of the corresponding oil replenishment control valve, thereby controlling the opening and closing of the oil replenishment circuit.

[0038] Compared with the prior art, the beneficial effects of the present invention are:

[0039] This invention implements a dynamic tournament-style refueling mechanism based on the degree of deviation, solving the problems of blind refueling and insufficient coordination in existing technologies. The invention compares the actual pressure of each main accumulator with the reference pressure through a pressure deviation measurement unit, outputting a continuous pressure signal reflecting the degree of deviation. Then, a tournament unit composed of shuttle valves performs pairwise comparisons at each stage to filter out the signal with the largest deviation. Finally, a second arbitration is conducted through dual pressure comparison pilot valves, allowing only the accumulator with the largest current deviation to qualify for refueling. Compared with existing timed cycle or independent switch control, the system always prioritizes the accumulator that most needs refueling, avoiding ineffective refueling and multi-channel refueling competition, and significantly reducing the ineffective operation time of the pump source.

[0040] Employing a fully hydraulic mechanical control system solves the applicability issue of electronic control schemes in special environments. The entire process of signal generation, comparison, arbitration, and execution in this invention is completed by hydraulic components, eliminating the need for electronic sensors, PLCs, electromagnets, or software programs. Compared to existing centralized electronic control management schemes, it eliminates failure modes such as electromagnetic interference, program crashes, and component aging. It can operate reliably for extended periods in extreme environments such as flammable and explosive materials, strong electromagnetic interference, and nuclear radiation, reducing explosion-proof certification costs and maintenance workload.

[0041] By employing a high-signal-gain design, the sensitivity of purely mechanical measurements to manufacturing tolerances is resolved. Through a rational configuration of the piston area ratio and spring stiffness of the pressure deviation measurement unit, the minute accumulator pressure drop is amplified into a megapascal-level pressure signal. This makes interference factors such as component friction, spring dispersion, and oil viscosity changes negligible relative to the signal amplitude during the comparison and switching processes of the subsequent control unit and pilot valve. Compared to existing simple hydraulic logic control, this improves the consistency of batch manufacturing and adaptability to field conditions.

[0042] By adjusting the centering spring mechanism to compensate for the discreteness of standard parts, the problem of the shelf products being difficult to use directly for precision pressure measurement was solved. Solution two uses standard hydraulic cylinders and springs, and by adjusting the preload of the first centering spring mechanism, the unbalanced force caused by the mismatch in cylinder area is compensated, enabling the standard parts to output deviation signals with a uniform slope. Compared with existing customized hydraulic cylinder solutions, this reduces processing costs and facilitates mass production.

[0043] The combination of a rigid signal bus and independent pressure-holding branches ensures both dynamic response and static reliability. The signal bus does not have an accumulator, ensuring that the maximum deviation signal from the competition output is transmitted to the pilot valves of each branch without lag. The independent pressure-holding branches maintain the minimum pressure of the bus in standby mode, preventing pilot valve malfunction due to leakage. Compared with existing technologies, this approach guarantees both the speed and determinism of the competition while avoiding the risk of accidental opening in a static state.

[0044] The positive logic replenishment valve assembly achieves low standby power consumption. The main replenishment valve is a normally closed two-way hydraulic control valve, and the pilot valve employs a dual-pressure sensing structure with a compensating spring, opening the pilot oil circuit only when replenishment is needed. Once all accumulator pressures reach the target, the system enters a static state, the main valve consumes no control oil, and the replenishment pump can be unloaded via the unloading valve. Compared to existing normally open or continuously consuming pilot oil solutions, long-term standby power consumption is significantly reduced.

[0045] Each replenishment branch has a check valve that provides a third arbitration based on low pressure priority, preventing system oscillation. A check valve is installed between the replenishment control valve of each branch and the main replenishment pipe. When multiple replenishment conditions are met simultaneously, the branch with the lower actual pressure receives oil first due to the reverse shut-off action of the check valve, while the branch with the higher pressure is automatically isolated. Compared to existing schemes lacking isolation mechanisms, this avoids pump overload and system pressure oscillations caused by simultaneous replenishment from multiple branches.

[0046] An optional oil return accumulator subsystem can be added to achieve the dual benefits of energy saving and oil cleanliness. By adding an oil return accumulator and a pilot relief valve network, the return oil pressure from the actuator is recovered to replenish the main accumulator, reducing the frequency of the make-up pump start-up. At the same time, the downstream oil containing impurities mainly circulates between the oil return accumulator and the actuator, keeping the main system oil clean. Compared with a system without oil return accumulator, this extends the life of the main accumulator and pump source, and improves energy utilization efficiency. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of 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.

[0048] Figure 1 A schematic diagram of a multi-accumulator automatic oil replenishment system based on deviation comparison and bus competition is provided in an embodiment of the present invention;

[0049] Figure 2 This is a schematic diagram of a pressure deviation measurement unit provided in this specification;

[0050] Figure 3 This is a schematic diagram of an oil replenishment control valve provided in this manual;

[0051] Figure 4 This is a schematic diagram of another pressure deviation measurement unit provided in this manual. Detailed Implementation

[0052] The present invention will now be described in detail with reference to the accompanying drawings. Unless otherwise specified, the features of the following embodiments and implementations can be combined with each other.

[0053] Explanation of technical terms:

[0054] Tournament Unit: This refers to the process of comparing multiple input signals one by one through a comparison network composed of hydraulic components such as shuttle valves, and finally outputting the maximum value, similar to the tournament system in sports competitions.

[0055] Arbitration: This refers to the process of making decisions based on comparison results. The first level of arbitration is completed by the shuttle valve comparison network, selecting the accumulator with the largest deviation from all main accumulators. The second level of arbitration is completed independently by the replenishment valve assemblies of each branch main accumulator, deciding whether to perform replenishment based on the comparison result of its own deviation signal and the bus signal. The third level of arbitration is completed by the check valves of each branch, prioritizing replenishment to the accumulator with the absolute lowest pressure in the event of multi-path competition.

[0056] This invention provides an automatic oil replenishment system for multiple accumulators based on deviation comparison and bus competition. (See also...) Figures 1-4 ,include:

[0057] 1. Reference pressure source

[0058] The reference pressure of the system is determined by the fixed-value pressure reducing valve 102: the hydraulic pressure output by the hydraulic pump is filtered by the first filter 101, and then the reference pressure is output by the fixed-value pressure reducing valve 102 and sent to the medium-sized accumulator 103 (i.e., the reference accumulator) and stabilized at the set value (e.g., 16 MPa). This reference pressure serves as the reference end for all pressure deviation measurement units and is not involved in external output.

[0059] 2. Pilot System

[0060] Pilot oil is output from the medium-sized accumulator 103 of the reference pressure source by the set pressure reducing valve 201. The pilot oil is stored in the small accumulator 202 to provide stable pilot hydraulic pressure to the downstream working valves.

[0061] 3. First pressure deviation measurement unit 3: Each main accumulator 1101 is independently equipped with a pressure deviation measurement unit.

[0062] 3.1 Customized products are used; see [link / reference]. Figure 2 The pressure deviation measuring unit provided in this embodiment of the invention includes a first piston 301, a second piston 302, a spring centering structure 303, and a cylinder 304.

[0063] The first piston 301 has a diameter of d1 and protruding rods at both ends. The left rod has a diameter of d2, and the right rod has a diameter of d3. The left rod protrudes beyond the cylinder body 304 and can be used for on-site observation (when the seals age, hydraulic pressure in the target chamber may leak into the signal chamber, causing an increase in oil in the signal circuit, and the left rod will deviate from its initial position and move to the left. At this time, a pressure relief valve (preferably a mechanical push rod type jog pressure relief valve) can be installed on the left side of the left rod. When the rod deviates, it touches the pressure relief valve to discharge excess oil. After installing the pressure relief valve, a second one-way valve 602 cannot be installed in parallel with the first one-way valve 601). The right rod is inside the cylinder body 304. The left annular surface A2 of the first piston 301 and the cylinder body 304 form a hydraulic cavity (named the reference cavity), which is connected to the reference pressure P2. The right annular surface A1 of the first piston 301 and the cylinder body 304 form a hydraulic cavity (named the target cavity), which is connected to the pressure to be measured P1. The right end face A3 of the first piston 301 forms a hydraulic cavity (named the signal cavity) with the cylinder 304, and outputs signal pressure P3.

[0064] The second piston 302 has a diameter of d4 and protruding rods at both ends. Preferably, the length of the protrusions is greater than the spring's maximum compression (protective spring). The entire left end face A4 of the second piston 302 forms a hydraulic cavity (named the balance cavity) with the cylinder body 304, and the balance cavity is connected to the signal cavity channel. The right side of the second piston 302 forms an air cavity with the cylinder body 304, and this cavity is open to the atmosphere.

[0065] Two springs of equal stiffness are installed on both sides of the second piston 302, forming a spring centering structure 303. The total stiffness of the centering springs is K1 (the total stiffness of the centering springs is twice that of a single spring).

[0066] Working principle:

[0067] Requirements to be met during customization:

[0068] Right now: or

[0069] The set pressure of the main accumulator (e.g., standard pressure: 4, 6.3, 10, 16, 20, 25, 31.5, 40 MPa); The selected reference pressure (e.g., 16 MPa).

[0070] The above formula requires the test P1 to be equal to At that time, the first piston 301 self-balances (reference pressure). (Maintain stability).

[0071] Based on the aforementioned physical structure, the following equations are derived, and the analytical expression for the pressure signal P3 is obtained:

[0072] (Direction setting: When the pressure P1 to be measured in the main accumulator decreases, the first piston 301 moves to the right by L1 and the second piston 302 moves to the right by L2.)

[0073] Static balance of first piston 301:

[0074] have to: as well as:

[0075] The pressure relative deviation of the main accumulator is uniformly set to δ;

[0076]

[0077] Set signal gain G:

[0078]

[0079] We can obtain:

[0080]

[0081] (The signal is zero when the decrease is zero).

[0082] And because:

[0083] Static balance of the second piston 302:

[0084] Solving for:

[0085] The oil circuit volume remains unchanged:

[0086] Solving for:

[0087] And when At that time, L1 and L2 are equal to 0 (that is, the main accumulator has reached the target pressure).

[0088] 3.2 Self-assembly using shelving products (Option 2, parameter settings see Table 2), see [link / reference]. Figure 4 The second pressure deviation measuring unit 4 provided in this embodiment of the invention addresses the issue that, due to the discreteness of the cylinder area in the shelf product (standard part), a new set of centering springs must be added to balance the area difference. This pressure deviation measuring unit includes:

[0089] The overall platform 401 is used to mount components. For consistency, this bracket will be used as the fixed reference frame in the following text, and the orientation of each component will be described as "left" or "right".

[0090] The first single-acting cylinder 402 (named the reference cylinder): its outer casing is fixed to the left side of the integral platform 401, and its piston rod points to the right. Its rodless chamber (piston area A6) is connected to the reference pressure P2.

[0091] Double-acting hydraulic cylinder 403 (named signal cylinder): The outer casing is fixed in the middle of the overall platform 401, and the two piston rods point to the left and right respectively. Its right chamber (piston area A7) outputs a pressure signal P3; the left chamber is not used (vented to the atmosphere, pressure maintained at 0).

[0092] The first centering spring mechanism 404 consists of a closed frame 40401 (slidably mounted on the overall platform 401 and fixed after debugging), a left spring 40402, a middle spring support 40403 (with an output rod fixed to its axis), a right spring 40404, a sealing support 40405, a sealing nut 40406, and an output rod limiting nut 40407. The left spring 40402 and right spring 40404 are respectively installed on both sides of the middle spring support 40403, and the output rod passes through and extends out of the sealing support 40405. Before debugging, the spring is preloaded by tightening the sealing nut 40406, generating an internal preload force in the centering spring (this internal preload force is not involved in subsequent static balance calculations, but only ensures that the spring does not loosen throughout the entire working process); the limiting nuts 40407 at both ends of the output rod act as mechanical limits at the stroke limits to prevent overload. The left spring 40402 and the right spring 40404, through pre-tensioning, form the first centering spring structure 404, named K2. During subsequent debugging, the first centering spring structure 404 will generate a debugging force. and displacement After debugging, fix the entire mechanism to the bracket. and That is, locking. During operation, the total stiffness of the first centering spring structure 404 is K2, and the output rod is in the initial position. The relative displacement (i.e., the displacement after debugging) is L3 (i.e., the displacement superimposed during operation), and the output force F2 of the output rod is... ( (See below for details).

[0093] The second single-acting cylinder 405 (named the target cylinder): its outer casing is fixed to the right side of the overall platform 401, and its piston rod points to the left. Its rodless chamber (piston area A5) is connected to pressure P1 from the target main accumulator.

[0094] The reference cylinder 402, signal cylinder 403, first centering spring mechanism 404, and target cylinder 405 are installed onto the overall platform 401 from left to right. The piston rods and output rods are then fixedly connected in pairs to form a whole. The overall platform 401 is movable during the debugging phase and fixed after debugging is completed.

[0095] The third single-acting hydraulic cylinder 406 (named the balance cylinder) is independently fixed on the overall platform 401. Its rodless chamber (piston area A8) oil port is connected in parallel with the left oil port of the double-acting double-rod hydraulic cylinder 403 (specifically, through a three-way pipe; one end of the three-way pipe connects to the left oil port of the double-acting double-rod hydraulic cylinder 403, one end connects to the right oil port of the third single-acting hydraulic cylinder 406, and one end connects to the championship unit) on the pressure signal P3 output oil circuit. There is also a second centering spring mechanism 407 (its structure is the same as the first centering spring mechanism 404, and will not be described again here). The output rod of the second centering spring mechanism 407 is fixedly connected to the piston rod of the balance cylinder. The total stiffness of the second centering spring mechanism 407 is K3, the relative displacement of the output rod from the initial position (the position after debugging) is L4, and the output force F3 of the output rod is... ( (See below for details). After adjusting the relative distance between the second centering spring mechanism 407 and the balance cylinder to ensure that the available piston stroke is greater than L4 during operation, fix the second centering spring mechanism 407 onto the overall platform 401.

[0096] Working principle:

[0097] Based on the configuration of Scheme 2, the following equations can be listed, and the analytical expression for pressure signal P3 can be obtained:

[0098] (Direction setting: When the actual pressure P1 of the main accumulator decreases, the piston rod moves to the right)

[0099] set up: ,

[0100] Piston rod spring K2 is in static equilibrium:

[0101] Volume invariance of signal oil circuit

[0102] Static balancing of hydraulic cylinder and spring K3

[0103] The above three equations, after being rearranged, yield:

[0104] (1)

[0105] Debugging method 1 of scheme 2

[0106] At reference pressure Under stable conditions, when the main accumulator reaches its rated value (or other set value), the signal pressure set value is required. It is 0, that is:

[0107] hour

[0108] At the same time, when signal pressure At that time, the interaction force between the piston rod of the balance cylinder and the second centering spring mechanism 407 It is 0, that is:

[0109]

[0110] The adjustment value of F2 can be obtained from equation (1). :

[0111] (2)

[0112] (2) means that the first centering spring mechanism 404 bears the unbalanced force caused by the mismatch in area when the oil cylinder is selected.

[0113] Once debugging is complete, fix it. Then, substituting equation (2) back into equation (1), we get:

[0114] ( )

[0115] Right now:

[0116] set up:

[0117] G is the signal gain coefficient:

[0118] have to:

[0119]

[0120] Right now:

[0121] On the test bench, input the rated pressure and reference pressure of the main accumulator respectively, and close the pressure gauge after connecting it to P3 using a throttle valve. Adjust the spring compression through the second centering spring mechanism 407 until the pressure gauge displays P3 as 0. The second centering spring mechanism 407 is fixed on the overall platform 401 (that is, the fixing bolts on the back of the second centering spring mechanism 407 pass through the pre-set oblong holes of the overall platform 401 and are then fixed together with nuts), thus completing the debugging. After debugging, temporarily tighten the double nuts 40407.

[0122] When the leakage and When the pressure measuring unit, after commissioning, is disassembled from the test bench for assembly, the double nuts 40407 on the two output rods act as limiters, sealing the hydraulic oil inside the measuring unit. This adjustment method does not require a spring force measuring device; it only requires… Once the signal is zeroed, the debugging is complete. Note that the amount of oil inside the unit will affect the final position of the second centering spring mechanism 407; oil can be added or drained to adjust the position.

[0123] Debugging method two of scheme two

[0124] The constant term in equation (1) This is the intercept of the P3 linear function. After selecting the parameters of all components (cylinder specifications and spring stiffness), it is adjusted... The actual output value of P3 can still be fine-tuned (during debugging). < 0.7 MPa (considering the equivalent frictional force of approximately 0.1 MPa in the downstream pilot valve spool, the actual opening threshold is 0.1 MPa higher than the theoretical calculation, thus providing a safety margin). Otherwise, when other main accumulators reach their rated pressure, the signal bus pressure drops to 1 MPa, while P3 + 0.3 > 1 MPa in this branch, leading to unexpected oil replenishment. The oil replenishment threshold of each main accumulator can be changed by adjusting the position of the first centering spring mechanism 404. This method is used when precise pressure regulation is required.

[0125] Component parameter design

[0126] because To ensure a unified standard for subsequent tournament algorithms, each branch... They must be identical. In engineering practice, the actual pressure deviation of accumulators in general industrial systems is typically controlled within 8% to 12% of the rated pressure, balancing regulation performance and energy efficiency. Therefore, the implementation example (Scheme 1, see Table 1) uniformly sets... The design benchmark is MPa, and the bus pressure is set at 1 MPa. This means that when the accumulator pressure drop is above 5%, it is allowed to participate in the oil replenishment competition. However, oil replenishment takes time, so as to control the final deviation of multiple accumulators to be less than 10%.

[0127] Example 2 (see Table 2) uses simultaneous output of 8 pressure levels as verification, with uniform settings. Using megapascals as the design benchmark, theoretical calculations show that all parameters are well-compliant, and the design offers greater cost advantages after scaling up. Option two uses rack-type cylinders and springs, and some compromises were made in the matching process to accommodate the diameter variation of standard cylinders; the results are still quite satisfactory (maximum competitive error less than 3%).

[0128] Note: Because the dual pressure comparison pilot valve in this scheme (detailed below) requires a second arbitration, and the hydraulic schematic diagram drawing standard follows the "master-slave control" principle, it cannot express the "comparison arbitration" logic of this scheme. Therefore, the dual pressure pilot valve in the attached diagram of this scheme is expressed in its actual physical position (not functional position).

[0129] Option 2: Using a hydraulic cylinder as a pressure conversion tool has the advantage of isolating the hydraulic cylinder from oil contamination from the actuator and main accumulator, which is a unique advantage.

[0130] 4. Tournament Unit 5 (First Arbitration)

[0131] The P3 signal from all pressure deviation measurement units is connected to a binary tree (race tree) or hierarchical clustering tree structure composed of shuttle valves. The pressure signals are compared pairwise at each level, and the maximum value is output. The binary tree structure is suitable for scenarios where the working intensity of all main accumulators is balanced and the oil replenishment requirements are equal. The hierarchical clustering tree structure (asymmetric topology) is suitable for scenarios where the working intensity of individual main accumulators is particularly high and the oil replenishment response must be prioritized.

[0132] The output signal P3 of all pressure deviation measurement units must have a uniform slope. : When the percentage decrease in main accumulator pressure At the same time, the outputs of each pressure deviation measurement unit Same. (Slope in the example) In Scheme 1, the pressure is 20 MPa, and in Scheme 2, it is 27.72 MPa.

[0133] When P3 reaches the minimum bus pressure (1 MPa in Scheme 1), it is qualified for the competition and has a chance to win. The corresponding trigger criterion δ` is: 1 / 20 = 5%. For Scheme 2, if the minimum bus pressure is set to 2 MPa, δ` = 2 / 27.72 = 7.2%. The specific value can be changed by adjusting the bus pressure holding branch (see below).

[0134] This unit obtains the maximum value among all pressure signals P3. , input signal bus. This represents the primary accumulator that most urgently needs refueling among all current target accumulators. This is the result of the first arbitration.

[0135] Table 1

[0136] Table 2

[0137] Table 2 Notes: The reference pressure is 16 MPa; the cylinder is a GB / T 2348 standard part, and the spring is a GB / T 2089 standard part; the direction of the hydraulic pressure in the reference cylinder points to the right, therefore, the direction of the force pointing to the right is set as positive, and the rightward movement of the piston rod is set as positive. When the spring force in the table is negative, it indicates that the force is pointing to the left and is resisting the reference cylinder. At this time, the piston rod is to the right of the zero point of the centering spring.

[0138] 5. Signal bus

[0139] A first check valve 601 is installed between the tournament unit and the signal bus to allow signals to enter the signal bus from the tournament unit and prevent reverse flow (forward installation); at the same time, a minimum bus pressure of 1MPa is maintained through an independent pressure-holding branch, and signals below this value cannot interfere with the bus.

[0140] In another embodiment, when the second pressure deviation measuring unit 4 is used, a second one-way valve 602 is also provided in parallel with the first one-way valve 601. The second one-way valve 602 is spring-biased, and the equivalent pressure of the spring is adjustable (e.g., 0.5 MPa). It is installed in reverse: when When the pressure is less than 0.5 MPa, the valve opens, allowing the signal bus to hydraulically enter the test unit, and replenishing the upstream measurement unit for possible leakage losses through the reverse penetration action of the shuttle valve tree.

[0141] The signal bus connects to the downstream dual pressure comparison pilot valve (i.e., dual pilot control) to prepare for the second arbitration.

[0142] 6. Oil replenishment control valve 7 (second arbitration) (independent configuration for each main accumulator branch)

[0143] The main accumulator's replenishment control valve 7 adopts a combination of pilot valve and main valve, with the following control logic:

[0144] Pilot valve: Normally open 2-position 3-way pilot valve, mounted on the main valve control cover, with two pressure sensing chambers. The left chamber is connected to the group's pressure signal P3, and the right chamber is connected to the signal bus pressure. The pressure in the left chamber pushes the valve spool to the right, and the pressure in the right chamber pushes it to the left. The spring is physically located on the left side, and the equivalent pressure pushing it to the right is 0.3 MPa (greater than the valve spool's static friction), keeping the valve spool in the right position (opening pilot) when there is no control pressure. See [link to relevant documentation]. Figure 3 The topmost part. During operation, the valve core closes the pilot when it is in the physical left position and opens the pilot when it is in the physical right position.

[0145] Main valve: Normally closed two-way hydraulic control valve (balanced piston type). When there is no pilot pressure, the main valve core is in the closed position under the action of spring force, blocking the main oil circuit.

[0146] Second Arbitration Principle

[0147] When P3 = (When this path represents the path with the greatest deviation), P3 + 0.3 > The valve core is pushed to the right, triggering a pilot output that opens the main valve, initiating oil replenishment to the main accumulator. This is the result of the second arbitration; see [link / reference]. Figure 3 The bottom part.

[0148] When P3 + 0.3 < (When this route is not at its maximum deviation), the pilot valve closes, there is no pilot pressure output, the main valve closes under spring force, and oil replenishment stops. See [link / reference]. Figure 3 The middle part.

[0149] When P3 ≈ 0, the right chamber of the pilot valve still has the bus base pressure (1 MPa), which is greater than the spring equivalent pressure. The valve core is pushed to the left, closing the pilot output, and the main valve closes under the action of the spring force.

[0150] See Figure 3 The upper, middle, and lower parts correspond to the three states of the pilot valve core in the oil replenishment control valve 7. The upper part indicates that when the control pressure on both sides of the pilot valve is zero, the spring pushes the valve core to the right end, the pilot valve opens, and the main valve opens. The middle part indicates that when... When the valve core is pushed to the left end, the pilot valve closes, the residual pilot valve in the main valve is released, and the main valve closes; the lower part indicates: when When the valve core is pushed to the right end, the pilot valve opens, which in turn pushes the main valve to open; where 0.3 is the spring equivalent pressure set in this embodiment, i.e., 0.3 MPa.

[0151] Automatic shut-off principle

[0152] When this branch is in a separate oil replenishment state, and the oil replenishment reaches the exit standard, for example, if the reduction is set to 5% in Scheme 1, the P3 output pressure will be less than the system bus pressure (1 MPa). Due to the combined effect of the pilot valve spring equivalent pressure of 0.3 MPa and the valve core equivalent friction force of 0.1 MPa, the actual P3 pressure corresponding to the main valve closing is 1 - 0.1 - 0.3 = 0.6 MPa, that is, the accumulator reduction is: 0.6 / 20 = 3%. In other words, after the accumulator reaches 97% of the target value through oil replenishment, the oil replenishment main valve automatically closes.

[0153] 7. Branch road isolation

[0154] A third check valve 8 is installed on each branch of the main oil supply pipe and each oil supply control valve 7. The third check valve 8 allows oil to flow from the main oil supply pipe to the main accumulator and cuts off the flow in the reverse direction to prevent the main accumulator from pumping hydraulic pressure back into the main oil supply pipe.

[0155] 8. Bus pressure holding branch 9 (independent pressure holding module)

[0156] To address the issues of unexpected main valve opening during system standby, potential signal circuit leakage, and preset (or later adjusted) pressure compensation deviation. Therefore, an independent pressure-maintaining branch is added:

[0157] The preferred method is to use an adjustable pressure reducing valve 901: Option 1 sets the pressure to 1MPa, draws oil from the small accumulator 202, and maintains the static pressure of the bus.

[0158] Miniature accumulator 902: capacity 0.1~0.5 L, used to absorb fluctuations in the opening and closing of pressure reducing valve 901 and compensate for instantaneous leakage.

[0159] The third check valve 903: only performs reverse shut-off, the forward opening pressure is negligible, it is connected in parallel on the signal bus, the downstream is connected to the bus, and the upstream is connected to the micro accumulator and pressure reducing valve 901.

[0160] Work logic:

[0161] During operation: When the P bus pressure is greater than 1 MPa, the third check valve 903 is closed, the pressure holding branch does not participate in the operation, and the bus pressure is determined by the rigidity of the championship unit 5.

[0162] In standby mode (all comparison signals tend to zero): no signal pressure is output. If the signal bus leaks oil and the pressure is less than 1MPa, the third check valve 903 opens and the pressure reducing valve 901 maintains the bus pressure at 1MPa, ensuring that the right chamber of the pilot valve always has a stable base pressure and avoiding malfunction.

[0163] 9. Oil pump unloading valve module

[0164] When all accumulators (main accumulator, or return accumulator if the system has one) finish replenishing oil and reach the exit criteria, the replenishment control valve 7 of each branch closes. After the hydraulic pump's outlet pressure rises and reaches the trigger value, the unloading valve 1001 opens to unload, and the pump's prime mover (e.g., motor) rotates without load.

[0165] The main oil supply line provides a clean control signal pressure to the unloading valve through filter 1002. The fifth check valve 1003 prevents pressure leakage from the main oil supply line.

[0166] 10. Oil return energy storage subsystem (optional)

[0167] If oil return and energy storage are required in the working scenario, an oil return and energy storage subsystem can be built on the basis of the main system. This subsystem has three advantages: assisting in stabilizing the main system, isolating downstream actuators from hydraulic oil containing impurities, and saving energy.

[0168] Oil return energy storage subsystem configuration:

[0169] A return oil accumulator 1103 is added between each main accumulator 1101 and the downstream actuator. The main accumulator and the return oil accumulator are isolated by a sixth check valve 1102 (the sixth check valve 1102 prevents the return oil accumulator 1103 from feeding back to the main accumulator 1101). The return oil accumulator 1103 directly faces the downstream actuator.

[0170] From the high-pressure stage to the low-pressure stage, the return oil accumulators at each stage are connected by a pilot relief valve 1104. The set pressure of the pilot relief valve 1104 is equal to the rated pressure of the main accumulator at this stage.

[0171] Working principle:

[0172] When the return oil pressure of a certain actuator has been set during the design phase, the return oil can be connected to the corresponding return oil accumulator. The pressure fluctuation range of this return oil accumulator has been limited by the upstream main accumulator, and it can be used as the output target.

[0173] When the pressure of the return oil accumulator is higher than the rated pressure of this circuit, it overflows to the lower-level return oil accumulator through the pilot relief valve. When the pressure of the lower level also reaches the rated pressure, it continues to overflow to the lower level.

[0174] Because the return oil pressure replenishes the main accumulator, the main accumulator loses pressure less, so the oil pump does not need to be started to replenish oil more often, making the main system work more stably.

[0175] The presence of the return oil accumulator and the one-way valve 1102 allows the hydraulic oil involved in the operation to circulate more between the return oil accumulator and the actuator, making it easier to keep the hydraulic oil in the main system clean.

[0176] Increase the minimum pressure on the signal bus:

[0177] In applications requiring energy recovery and storage, the signal bus pressure should be increased as needed. The threshold for participating in replenishment competition should be raised to reserve sufficient accumulator space for the recovered hydraulic flow, thus minimizing the activation frequency of the pilot relief valve 1104.

[0178] Advantages analysis:

[0179] The return oil pressure replenishment means that the main accumulator does not need more oil replenishment, making the main system work more stably.

[0180] The presence of the return oil accumulator allows the downstream hydraulic oil to circulate more frequently between the return oil accumulator and the actuator, making it easier to keep the hydraulic oil in the main system clean.

[0181] Reduce the contact between the main accumulator and high-temperature oil.

[0182] More energy efficient.

[0183] This invention further analyzes specific working conditions:

[0184] 1. System cold start

[0185] Before the system's initial startup, all main accumulators are at zero pressure, and all main valves are normally closed. After startup, the reference pressure and pilot pressure begin to build up. The reference pressure pushes the reference cylinder piston out (at this time, the main accumulator pressure is still 0), and the output pressure signals P3 from each group are filtered by a comparison tree (with randomness), after which a certain main accumulator begins to replenish oil. Initially, there is some randomness and jumps in oil replenishment, but after all main accumulators have established initial pressure, the system will stably select the one with the largest deviation for oil replenishment. Subsequent oil replenishment proceeds in descending order of pressure until all are finished.

[0186] When the system restarts, due to residual pressure, the oil replenishment process will proceed sequentially according to the principle of prioritizing those with the largest deviation. The disordered replenishment that occurred during the initial startup will not occur.

[0187] 2. Low pressure priority case (one-way valve isolation, third arbitration)

[0188] For any target main accumulator, its replenishment valve's dual pressure sensing pilot valve compares the local signal P3 with the bus signal in real time. :

[0189] While one main accumulator is being refueled, the P3+0.3 of another main accumulator is greater than or equal to... ( (If there is a pressure drop in the shuttle valve tree), open its main valve.

[0190] If the pressure of the activated main accumulator is lower than that of the main accumulator currently being replenished, the system will switch to replenishing oil to the newly activated main accumulator. At the same time, due to the presence of the third check valve 8 in the branch, the main accumulator with the relatively higher original pressure will be isolated, and oil replenishment will be suspended.

[0191] If the pressure of the main accumulator that is opened is higher than that of the main accumulator that is replenishing oil, the relatively high-pressure main accumulator will be isolated due to the presence of the third check valve 8 in the branch, and the oil replenishment control valve 7 will be ineffective.

[0192] This phenomenon aligns with actual work needs.

[0193] 3. Multiple main accumulators competing for fuel caused system "oscillations".

[0194] If, under typical operating conditions, multiple main accumulators simultaneously request replenishment oil, or even if "oscillating" oil competition occurs and the pressure of each main accumulator still fails to reach the required level, it indicates that the current pump's displacement or power is insufficient to meet the replenishment oil needs of the main accumulator group. Therefore, the hydraulic pump selection should ensure that, under the "worst operating conditions," during the replenishment period of the main accumulator with the largest deviation, the other two or more main accumulators will not enter into "competition" due to starvation. Under certain extreme operating conditions (such as multiple actuators operating at high flow rates simultaneously, or instantaneous insufficient oil supply from the pump source), brief oscillations are a normal manifestation of system self-regulation and should not be considered a fault, as long as the oscillations converge as the load decreases. In actual operation and maintenance, oscillation phenomena can be used as a basis for judging the health of the system.

[0195] 4. Repeated oil replenishment to a single main accumulator causes single-channel "oscillation".

[0196] This clearly indicates that the capacity of the main energy storage device is insufficient to meet current operational needs, and the capacity should be increased.

[0197] 5. Static pressure maintenance

[0198] When all main accumulator pressures reach the target, all comparison signals P3 decrease, and the bus pressure begins to drop. When the bus pressure falls below 1 MPa, the third check valve 903 in the bus pressure holding circuit opens, and the pressure reducing valve 901 replenishes oil to the signal bus through the miniature main accumulator 902, maintaining the bus pressure at 1 MPa. At this time, all dual-pressure sensing pilot valves are closed in the left position, and the main valve is closed. The main valve consumes no pilot oil.

[0199] Applicable scenarios:

[0200] This hydraulic system requires high reliability and optimized life-cycle cost. It features low maintenance, low standby power consumption, and no need for periodic replacement of electronic components, resulting in a lower overall long-term cost compared to electronic control solutions.

[0201] Flammable and explosive environments such as coal mines and petrochemical plants;

[0202] In situations where electronic equipment is restricted, such as those involving strong electromagnetic interference or nuclear radiation;

[0203] For offshore platforms and remote unmanned stations with extremely high reliability requirements and difficult maintenance;

[0204] Special equipment with specific limitations on electronic control;

[0205] Intermittent hydraulic systems that require energy conservation and consumption reduction.

[0206] System advantages description:

[0207] Intrinsically safe: Fully hydraulic mechanical control, no electrical components, no risk of sparks, and low cost of explosion-proof certification;

[0208] Autonomous competition: Automatically identifies the main accumulator with the largest deviation and prioritizes oil replenishment without program intervention;

[0209] High reliability: Avoids failure modes such as electronic component aging and electromagnetic interference; high signal gain makes the system insensitive to component tolerances and external interference;

[0210] Low energy consumption: There is no throttling loss or fixed overflow loss. The pump can be unloaded when in standby and the pilot valve has no consumption. The long-term energy saving effect is significant.

[0211] Modular structure: easy to expand the number of main energy storage units to adapt to different system sizes;

[0212] Good manufacturing stability: The number of components is small, and key components can be produced in batches stably through reasonable tolerance design.

[0213] This system achieves its engineering goals of high stability, low energy consumption, and ease of manufacture through the following key optimizations:

[0214] High-stiffness springs: increase signal amplitude and enhance system robustness to manufacturing tolerances and operating condition disturbances;

[0215] Rigid capacity signal bus: No accumulator, ensuring fast and deterministic contention response;

[0216] Independent pressure-holding branch: solves the problem of static leakage without interfering with dynamic logic;

[0217] Positive logic oil replenishment valve: (normally closed main valve + dual pressure sensing pilot valve with compensation spring, normally closed during operation) ensures no pilot oil source consumption during standby;

[0218] Mature two-way cartridge valve: As a replenishing valve, it ensures large flow capacity and long-term reliability;

[0219] Modular architecture: Facilitates manufacturing, testing, and maintenance.

[0220] The above embodiments are only used to illustrate the design concept and features of the present invention, and their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. The protection scope of the present invention is not limited to the above embodiments. Therefore, all equivalent changes or modifications made based on the principles and design ideas disclosed in the present invention are within the protection scope of the present invention.

Claims

1. A multi-accumulator automatic refueling system based on deviation comparison and bus competition, characterized in that, include: Multi-stage main accumulator, pressure deviation measurement unit, championship unit; Pressure deviation measurement unit is used to measure the pressure deviation signal of the main accumulator; The tournament unit is used to filter out the maximum pressure deviation signal from the pressure deviation signals of multiple main accumulators; Each main accumulator is equipped with a corresponding oil replenishment control valve. The maximum pressure deviation signal and the pressure deviation signal of the main accumulator control the position of the valve core of the corresponding oil replenishment control valve, thereby controlling the opening and closing of the oil replenishment circuit.

2. The system according to claim 1, characterized in that, The pressure deviation measurement unit includes a cylinder, and a first piston and a second piston built into the cylinder; The left annular surface of the first piston forms a reference cavity with the cylinder body, and the reference pressure P2 is applied; the right annular surface of the first piston forms a target cavity with the cylinder body, and the pressure to be measured P1 is applied; the right rod end face of the first piston forms a signal cavity with the cylinder body, and the signal pressure P3 is output. Springs are provided on both sides of the second piston; the left side of the second piston forms a balance chamber with the cylinder, and the balance chamber is connected to the signal chamber; the right side of the second piston forms an air chamber with the cylinder, and the air chamber is connected to the atmosphere.

3. The system according to claim 1, characterized in that, The pressure deviation measurement unit includes a first centering spring mechanism, a second centering spring mechanism, a first single-acting cylinder, a double-acting cylinder with double rod extension, a second single-acting cylinder, and a third single-acting cylinder. All three cylinders are fixedly mounted on the overall platform. Before use, the pressure deviation measurement unit needs to be debugged until the signal pressure P3 is 0, at which point the interaction between the piston rod of the third single-acting cylinder and the output rod on the right side of the second centering spring mechanism is zero. After debugging, the first and second centering spring mechanisms are fixedly mounted on the overall platform. Both the first and second centering spring mechanisms include a closed frame and an intermediate spring support; the intermediate spring support is slidably installed inside the closed frame, and both ends of it are provided with force rods. The first single-acting cylinder has its piston rod located on the right side, and its rodless chamber is connected to the reference pressure P2. The double-acting hydraulic cylinder has its left piston rod connected to the piston rod of the first single-acting hydraulic cylinder, and its right piston rod connected to the output rod on the left side of the first centering spring mechanism. Its left chamber is open to the atmosphere, and its right chamber outputs signal pressure P3. The second single-acting cylinder has its piston rod located on the left side and connected to the output rod on the right side of the first centering spring mechanism; its rodless chamber is connected to the pressure to be measured, P1. The third single-acting hydraulic cylinder has its piston rod located on the left side, connected to the output rod on the right side of the second centering spring mechanism, and its rodless chamber is connected to the signal pressure P3.

4. The system according to claim 1, characterized in that, The tournament unit is a binary tree or hierarchical clustering tree structure composed of shuttle valves, used to compare pressure deviation signals step by step to output the maximum pressure deviation signal.

5. The system according to claim 3 or 4, characterized in that, The hydraulic pressure output from the hydraulic pump is filtered by a filter and then output as a reference pressure by a fixed-value pressure reducing valve. This pressure is then sent to the reference accumulator to provide a stable reference pressure for the pressure deviation measurement unit.

6. The system according to claim 1, characterized in that, The oil replenishment control valve uses a combination of a pilot valve and a main valve; The pilot valve is a two-position three-way pilot valve. Its normal position is the left position, with port P closed and ports T and A connected. In the right position, port P is connected to the pilot oil source, port T is connected to the oil tank, and port A is connected to the right position pilot control port of the main valve. The left position pilot control port of the pilot valve is connected to the pressure deviation signal of the corresponding main accumulator, the right position pilot control port is connected to the maximum pressure deviation signal, and port A is connected to the right position pilot control port of the main valve. The main valve is a two-way hydraulic control valve. Its normal position is the left position, with ports P and A closed; when in the right position, ports P and A are connected.

7. The system according to claim 6, characterized in that, The maximum pressure deviation signal output by the championship unit is connected to the signal bus, and the right-position pilot control port of the pilot valve is connected to the signal bus; a check valve is set between the championship unit and the signal bus, or a valve group consisting of a forward-mounted check valve and a reverse-mounted spring-loaded check valve connected in parallel is set between the championship unit and the signal bus; and the minimum pressure preset by the signal bus is maintained through an independent pressure-holding branch, and a check valve is set between the pressure-holding branch and the signal bus. The pressure-holding branch includes a small accumulator, a micro accumulator, and a pressure-reducing valve; The pressure output by the pressure reducing valve is the minimum pressure preset by the signal bus. It draws oil from the small accumulator to maintain the minimum pressure preset by the signal bus. The pressure output by the micro accumulator is the minimum pressure preset by the signal bus, which is used to absorb fluctuations in the opening and closing of the pressure reducing valve and compensate for instantaneous leakage.

8. The system according to claim 1, characterized in that, The hydraulic pressure output by the hydraulic pump is supplied to the corresponding main accumulator via the replenishment control valve. The hydraulic pressure output by the hydraulic pump is connected to the replenishment main pipe. The replenishment main pipe is connected to each replenishment control valve, and each connected oil circuit is equipped with a check valve.

9. The system according to claim 5, characterized in that, It also includes an unloading valve, whose inlet is connected to the outlet of the hydraulic pump and whose outlet is connected to the oil tank; when all accumulators finish replenishing oil and reach the exit standard, the replenishment control is turned off, the outlet pressure of the hydraulic pump rises and reaches the trigger value of the unloading valve, and then the unloading valve opens to unload. The main oil supply line provides a clean control signal pressure to the unloading valve through a filter, and a check valve is installed between the hydraulic pressure output from the hydraulic pump and the main oil supply line.

10. The system according to claim 1, characterized in that, Also includes: A return oil accumulator is added between each main accumulator and downstream actuator, and a check valve is used to isolate the main accumulator and the return oil accumulator. From the high-pressure stage to the low-pressure stage, the return oil accumulators at each stage are connected by pilot relief valves, and the set pressure of the pilot relief valves is equal to the rated pressure of the main accumulator at this stage.

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