Single-machine multi-pump step-by-step voltage-lifting hydraulic source

Abstract

The application discloses a single-machine multi-pump step-by-step voltage-lifting hydraulic source and belongs to the technical field of hydraulic power units. The application adopts single motor coaxial series connection of at least two hydraulic pumps, forms a step-by-step voltage-lifting structure through liquid path series connection, strictly controls a single-stage hydraulic pump inlet and outlet rated pressure difference to be less than or equal to 7 MPa, simultaneously solves the industry common failure problems of metal pump cavitation and non-metal pump elastic deformation from the root cause, and realizes full-system life synchronization. A single pump set can simultaneously output multi-pressure grade oil, realizes high and low pressure decoupling centralized oil supply, the scheme supports main motor self-oil supply integration, modular parallel expansion power, liquid path series connection pressure expansion, can adapt to all scene demands such as high-power industrial motor, vehicle wheel edge, industrial equipment, laboratory super-high pressure, the whole machine volume is reduced by more than 80% than that of a traditional scheme, the full-condition comprehensive efficiency is greater than or equal to 95%, and the system calendar average trouble-free working time is increased by more than 7 times.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic power unit technology, specifically relating to a single-motor integrated, multi-pump coaxial series, step-by-step balanced pressure increase, and extremely compact hydraulic power source, which can be widely adapted to high-power industrial motor hydrostatic bearing self-supply, new energy vehicle wheel-side EHB, industrial precision equipment, offshore wind power pitch control, aerospace, laboratory ultra-high pressure testing and other full-scenario multi-pressure level hydraulic needs. Background Technology

[0002] Multi-pressure hydraulic systems are core power units in fields such as industrial transmission, military equipment, wind power, precision machine tools, heavy machinery, and new energy vehicles. The core requirement is to simultaneously output multiple independent hydraulic oil sources: one is an intermittent high-pressure, low-displacement oil source for system pressure building, heavy load bearing, and high-precision servo control; another is a continuously operating low-pressure, high-displacement oil source for cooling, lubrication, flushing, and pre-pressurization; some scenarios also require a medium-pressure, medium-displacement oil source for medium-load and auxiliary drive; special scenarios such as laboratory material testing and deep-sea equipment require ultra-high-pressure oil sources of over 100MPa.

[0003] The mainstream technology of existing multi-pressure hydraulic systems has a core defect that cannot be solved:

[0004] 1. Coaxial and speed multi-pump hydraulic system: It cannot simultaneously match the high-efficiency working range of pumps of different pressure levels. The high-pressure pump needs to run at high speed continuously, and the idling loss accounts for more than 60% of the total energy consumption. There is no native pre-pressurization function, and an independent pre-pressurization pump needs to be configured separately. The cooling and lubrication systems are set up independently, with extremely low integration. There are more than 30 leakage points in a single unit, and failures occur frequently.

[0005] 2. Multi-motor independently driven multi-pressure hydraulic power unit: High and low pressure oil circuits require independent pump sets and drive motors, resulting in redundant power components, poor integration, and inability to achieve decoupled oil supply for multiple pressure levels under a single power source. It occupies a large installation space, and multiple independent motors, drivers, and temperature control systems cause serious redundancy and high costs; the high-pressure pump still needs to run continuously to maintain pressure, and the problem of idling losses remains unresolved; there is no modular expansion capability, and synchronization is poor in high-power scenarios.

[0006] 3. Single-motor dual-pump pre-pressurization hydraulic system: This system uses a single motor to drive two pumps, one high-pressure and one low-pressure pump. The low-pressure pump provides pre-pressurization for the high-pressure pump, which improves the integration to some extent. However, the pressure difference between the inlet and outlet of the high-pressure pump is too large, typically exceeding 14MPa. This causes the wear rate of friction pairs such as slippers and distribution plates to be more than 10 times that of the low-pressure pump, limiting the overall lifespan of the system to that of the high-pressure pump. To achieve higher pressure output, more pumps and reducers need to be connected in series, resulting in excessively long shafts, large deflection, severe vibration, and a sharp decline in reliability.

[0007] 4. High-power hydrostatic bearing motor oil supply system: Existing megawatt-level hydrostatic bearing motors generally use independent external hydraulic stations for oil supply. Bearing lubrication and stator cooling require two independent systems: a high-pressure lubrication station and a low-pressure cooling station. This requires additional dedicated hydraulic motors, couplings, valve cabinets, and external pipelines, resulting in a large footprint, numerous leakage points, and high transmission losses. Furthermore, there is a safety hazard due to asynchronous start-stop timing—if the motor starts first and the hydraulic station supplies oil later, it will cause the hydrostatic bearing to dry grind and burn, seriously affecting equipment safety and lifespan.

[0008] 5. Ultra-high pressure hydraulic system: Existing ultra-high pressure hydraulic sources with a pressure of hundreds of megapascals generally adopt a multi-motor, multi-stage booster or booster architecture, which is bulky, complex in structure, and inefficient. The pressure difference between the inlet and outlet of a single stage can generally reach more than 20 MPa, and there are two irreconcilable core failure contradictions:

[0009] Metal pumps: High pressure differential causes the local pressure on the pump suction side to drop sharply below the oil-air separation pressure, triggering severe cavitation, causing erosion and pitting on the surface of the metal friction pair, while generating high-frequency vibration and impact loads. The average lifespan of core components is less than 1,000 hours. Moreover, the greater the single-stage pressure differential, the more exponentially the cavitation intensity increases. Traditional solutions can only alleviate this by thickening the pump body and using high-strength alloy steel, further increasing the size and cost.

[0010] Non-metallic / composite material pumps: In order to achieve lightweighting, the industry has tried to use materials such as carbon fiber reinforced PEEK and silicon carbide ceramics to manufacture pump bodies and friction pairs. However, the elastic modulus of these materials is much lower than that of metals. When the single-stage pressure difference exceeds 10MPa, significant elastic deformation occurs, resulting in a cubic increase in the fitting clearance. The volumetric efficiency plummets to below 60%, and even seal failure and pump body cracking occur. Moreover, the amount of deformation increases non-linearly with the pressure difference, which cannot be completely solved through process optimization.

[0011] Existing ultra-high pressure solutions suffer from multiple leakage points, large pressure fluctuations, and extremely high maintenance costs, failing to meet the requirements of miniaturization, high reliability, and long lifespan in laboratory applications. For space-constrained scenarios such as automotive and wind power installations, existing hydraulic power sources generally suffer from excessive size, weight, and excessive vibration and noise. For ultra-high pressure applications, existing solutions suffer from low integration, short lifespan, and high cost, failing to meet the need for universal applicability across all scenarios.

[0012] In summary, existing multi-pressure hydraulic systems generally suffer from common industry problems such as low integration, large size, low energy efficiency, limited lifespan, poor high-pressure scalability, redundant temperature control systems, and lack of universal adaptability. A new technical solution is urgently needed to address these pain points. Summary of the Invention

[0013] 1. Technical problems to be solved

[0014] The purpose of this invention is to overcome the aforementioned deficiencies of the prior art and provide a single-unit, multi-pump, staged pressure boosting hydraulic power source. It achieves functional division and balanced pressure boosting of multiple pumps using a simplified architecture with a single motor, enabling decoupled oil supply at multiple pressure levels under a single power source and reducing redundant system components. Through three core structures adapted to different scenario requirements, it strictly controls the single-stage pressure difference to ≤7MPa, fundamentally solving the core failure problems of cavitation in metal pumps and elastic deformation in non-metal pumps, achieving synchronized lifespan across the entire system. It integrates a nested reducer and a closed-loop cooling and lubrication system, achieving extreme compactness and high reliability. It supports modular parallel and series expansion, covering requirements from micro-scale to 1MW+ ultra-high power and from 0.3MPa to 120MPa+ across the entire pressure range.

[0015] 2. Terminology Definitions

[0016] To avoid ambiguity in terminology throughout the document, the following naming conventions are used consistently:

[0017] • Single-motor multi-pump step-by-step pressure boosting hydraulic power source: This is the general name of the present invention, referring to all the technical solutions defined in claim 1, and covering all hydraulic power sources based on the core architecture of "single motor coaxial multi-pump + hydraulic circuit series step-by-step pressure boosting";

[0018] • Through-shaft multi-pump dual-speed hydraulic power source: refers to the first preferred embodiment of claim 2, namely the architecture of "through-shaft single motor with clutch and multi-pump + nested reducer low-pressure pump", which is mainly used in scenarios that require both high-pressure intermittent output and low-pressure continuous output at the same time;

[0019] • Main motor self-supplying integrated hydraulic power source: refers to the second preferred embodiment of claim 3, namely the architecture of "high-power main motor through shaft direct drive of multiple pump groups, while realizing its own bearing lubrication and stator cooling", which is mainly used in continuous operation scenarios such as high-power industrial motors and turbine machinery;

[0020] • Symmetrical boosting hydraulic power source: refers to the third preferred embodiment of claim 4, namely the "through-shaft single motor with symmetrical configuration of multiple pumps at both ends" architecture, which is mainly used in ultra-high pressure series boosting scenarios;

[0021] • Pre-pressurization unit: refers to the through-shaft multi-pump dual-speed hydraulic power source used as the first stage of the series boost system, responsible for providing initial pre-pressurization and unified cooling and lubrication for the entire system.

[0022] 3. Technical Solution

[0023] To achieve the above objectives, the present invention adopts the following technical solution: a single-machine multi-pump progressive pressure hydraulic source, comprising a single motor and at least two hydraulic pumps; all hydraulic pumps are rigidly connected in series coaxially along the output shaft of the single motor; at least two of the hydraulic pumps are connected in series along the hydraulic circuit to form a progressive pressure structure, wherein the oil inlet of the subsequent hydraulic pump is connected to the oil outlet of the previous hydraulic pump.

[0024] Technical Solution 1 – Through-shaft Multi-pump Dual-speed Hydraulic Source: The first preferred embodiment of this invention adopts a “through-shaft single motor with a normally disconnected clutch at one end + multiple high-pressure pumps in series, and a single two-stage planetary reducer + low-pressure pump at the other end”. The system employs a series configuration, where the first end of the through-shaft single motor is connected to at least one coaxially connected hydraulic pump via a normally disconnected clutch, and the second end of the through-shaft is connected to a low-pressure pump via a fixed-ratio two-stage planetary reducer. The low-pressure pump output has three branches: a low-pressure output circuit, a pre-pressurization circuit, and a closed-loop cooling and lubrication circuit. The housing of the two-stage planetary reducer is integrally formed with the end cover of the single motor, and the two-stage planetary gear train is completely nested within the inner cavity of the single motor rotor, without occupying additional axial space, achieving a transmission efficiency ≥95%. The pre-pressurization circuit is pressurized step-by-step by the high-pressure pump, finally reaching the pressure required by the system design before being directed to the high-pressure load. The low-pressure output circuit is directed to the low-pressure load. All circuits converge into a constant-temperature oil tank, where the oil tank completes temperature control before entering the next cycle. A bidirectional thrust bearing is provided between the clutch and the first hydraulic pump to withstand the superimposed axial force of multiple hydraulic pumps.

[0025] Technical Solution 2 – Integrated Hydraulic Power Source with Self-Supplying Oil for Main Motor: The second preferred embodiment of this invention adopts a series layout of "high-power industrial main motor with through-shaft direct drive and multiple pump groups". The main motor itself is the sole power source of the system, and its output shaft is a through-shaft. The first end of the through-shaft is rigidly connected in series with at least two hydraulic pump groups, and the second end of the through-shaft is directly connected to an external mechanical load to output power. The oil outlet of the first-stage low-pressure, high-displacement pump of the hydraulic pump group is divided into two paths: one path is connected to the stator cooling channel of the main motor to provide low-pressure cooling oil; the other path is connected to the suction port of the subsequent high-pressure pump to provide positive pressure pre-pressurization. After the subsequent high-pressure pumps pressurize step by step, the high-pressure output end is connected to the hydrostatic sliding bearing oil supply chamber of the main motor itself to provide high-pressure lubricating oil. This architecture has no clutch or reducer, the transmission chain is extremely simple, and the oil supply is naturally synchronized with the start and stop of the main motor, eliminating the risk of bearing dry friction from a physical perspective, and is suitable for high-power continuous operation conditions.

[0026] Technical Solution 3 – Symmetrical Pressure-Boosting Hydraulic Source: The third preferred embodiment of this invention adopts a series layout of "multiple pumps symmetrically configured at both ends of a single through-shaft motor." Equal and symmetrically configured hydraulic pumps are rigidly connected coaxially at both ends of the through-shaft, achieving overall dynamic balance and optimized torsional vibration characteristics. All hydraulic pumps are connected in series along the hydraulic circuit, forming a step-by-step pressure-boosting structure. This architecture has no clutch or reducer, is extremely simple in structure, has excellent dynamic balance performance, and can achieve arbitrary ultra-high pressure output through series hydraulic circuit connection.

[0027] Technical Solution 4 – Modular Parallel Expansion Solution: Two or more sets of through-shaft multi-pump dual-speed hydraulic sources and main motor self-supply integrated hydraulic sources adopt a standardized modular parallel layout. The high-pressure output port and low-pressure output port of each hydraulic source are connected in parallel and summarized, sharing a centralized common constant temperature oil tank to achieve high-power continuous output. The failure of a single set does not affect the operation of the system.

[0028] Technical Solution 5 – Series Hydraulic Circuit Expansion Solution: A set of pre-pressurization units and at least one set of symmetrical boosting hydraulic sources are arranged in series hydraulic circuits. The high-pressure output port of the first set of hydraulic sources is connected to the oil suction port of the first hydraulic pump of the second set of hydraulic sources to achieve higher pressure output, reaching ultra-high pressure of over 100MPa.

[0029] Dynamic balancing and torsional vibration optimization design principles:

[0030] • Dynamic balancing optimization: All rotating components undergo individual weight reduction and correction. After the entire machine is assembled, the overall dynamic balancing test and correction are completed to eliminate lateral vibration caused by mass eccentricity. The overall dynamic balancing accuracy reaches G2.5 level in industrial continuous operation scenarios and G0.4 level in high-end precision scenarios.

[0031] • Torsional vibration optimization: For through-shaft multi-pump dual-speed hydraulic power sources and main motor self-supply integrated hydraulic power sources, lightweight materials are used to manufacture the pump set side to minimize the rotational inertia of the cantilever side; by optimizing the cantilever length of the pump set and matching the shaft system stiffness, the critical speed of the shaft system is kept away from the ±15% range of the rated working speed to avoid high-speed resonance.

[0032] • For symmetrical boost hydraulic power sources, the hydraulic pumps at both ends of the through shaft use the exact same model, material and processing technology to ensure that the weight and moment of inertia are completely symmetrical, while achieving optimal dynamic balance and torsional vibration characteristics.

[0033] Oil circuit design principle: The low-pressure pump outlet is divided into three paths: the first path is the low-pressure oil supply output port, continuously outputting low-pressure oil to supply low-pressure loads and cooling / lubrication needs; the second path is connected to the oil inlet of the first hydraulic pump, providing the first stage of positive pressure pre-pressurization; the third path is a closed-loop cooling / lubrication circuit, flowing sequentially through the stator cooling channel of the through-shaft single motor, the lubrication chambers of all transmission mechanisms, and the friction pair chamber of the clutch, finally returning to the constant-temperature oil tank, where the system temperature is uniformly controlled. Multiple hydraulic pumps are connected in series through the oil circuit, with the outlet of the last hydraulic pump connected to the inlet of the high-pressure accumulator. The outlet of the high-pressure accumulator is the high-pressure oil supply output port; the high-pressure accumulator is a core component for enabling the intermittent operation of the high-pressure pump group, maintaining system pressure by storing high-pressure oil, so that the high-pressure pump group only operates briefly during pressurization and remains completely stationary at other times.

[0034] The pump outlets of each stage of the step-up pressure architecture can independently draw oil of the corresponding pressure level to supply loads with different pressure requirements, realizing centralized oil supply with high and low pressure decoupling, without the need to configure independent drive motors and pump sets for different pressure levels.

[0035] General design principles for pre-boost and speed matching:

[0036] 1. Based on the optimal design principle for long service life of hydraulic pump friction pairs, the rated pressure difference between the inlet and outlet of each stage of high-pressure hydraulic pump is ≤7MPa, and the rated speed of the low-pressure pump is ≤3500rpm. This pressure difference is lower than the critical pressure difference for cavitation under normal hydraulic oil operating conditions, while the elastic deformation of non-metallic / composite material pumps is controlled within the micrometer level.

[0037] 2. Adopting a "coaxial + multi-pump series staged pressurization" architecture, it achieves long-life operation at any high pressure level with only one reducer required. The low-pressure pump pre-pressurization pressure is 0.3-0.8MPa, and the pressurization pressure of each stage of the hydraulic pump is evenly distributed at 7MPa.

[0038] 3. The high-pressure pump for intermittent operation adopts a small displacement, high-speed design, which significantly extends its calendar life by leveraging its intermittent operation characteristics; the pump set for continuous operation adopts a medium-speed design, matching the rated speed of the main motor. The high-pressure pump has a cumulative working life of ≥50,000 hours, the low-pressure pump has a cumulative working life of ≥30,000 hours, and the whole machine can achieve a 100,000-hour calendar maintenance-free operation.

[0039] Preferably, the through-shaft single motor adopts an ultra-high power density high-speed permanent magnet synchronous motor, equipped with an alloy steel through-shaft, with a designed power density ≥5kW / kg. The motor volume is only 1 / 4 of that of a traditional low-speed motor of the same power. Combined with a nested two-stage planetary reducer, the overall volume is reduced by more than 80% compared to the traditional three-motor, three-pump solution of the same power. The hydraulic power source can be fully integrated into the standard bearing and the vehicle wheel-side system. Preferably, for high salt spray and strong corrosion conditions such as offshore wind power, all hydraulic components are made of salt spray corrosion resistant materials, with a nickel-phosphorus alloy plating layer thickness ≥25μm. The system is equipped with dual pressure protection. The high-pressure accumulator is equipped with a safety valve and a rupture disc. The safety valve opening pressure is 1.1 times the rated pressure, and the rupture disc burst pressure is 1.2 times the rated pressure. Under low temperature conditions, the constant temperature oil tank can automatically start electric heating, preheating to above 5°C before the system can be started.

[0040] 4. Single-stage differential pressure threshold verification test

[0041] To verify the technical effectiveness and critical characteristics of the 7MPa differential pressure threshold, this invention conducted performance comparison tests under different single-stage differential pressures using industry-standard No. 46 anti-wear hydraulic oil and a pump body distribution pair made of carbon fiber reinforced PEEK material, under the same rotational speed, oil temperature, and oil viscosity conditions. The test results are as follows:

[0042] (1) Comparison of cavitation intensity

[0043] Using the cavitation erosion rate of the metal friction pair surface as the evaluation index, the relative cavitation intensity under different single-stage pressure differences was tested (with 7 MPa as the baseline value 1), where the oil suction side pressure was gauge pressure (the baseline was standard atmospheric pressure 0.1 MPa).

[0044] 5MPa 0.3MPa 0.4MPa 0.2 No obvious cavitation, no changes on the metal surface 7MPa 0.1MPa 0.2MPa 1.0 Slight cavitation, far below the material fatigue limit, with no cumulative damage. 9MPa -0.03MPa 0.07MPa 8.7 Significant cavitation was observed, with numerous microbubbles precipitating from the oil, and pitting corrosion buds appearing on the metal surface. 12MPa -0.07MPa 0.03MPa 65.3 Severe cavitation, high-frequency vibration and impact, rapid erosion of metal surfaces

[0045] Experimental conclusions: The air separation pressure of No. 46 anti-wear hydraulic oil at room temperature is approximately 0.03~0.08 MPa (absolute pressure). When the single-stage pressure difference is controlled within 7 MPa, the absolute pressure on the oil suction side is always higher than the air separation pressure, and the cavitation intensity is negligible. When the pressure difference exceeds 9 MPa, the pressure on the oil suction side approaches or falls below the air separation pressure, and the cavitation intensity increases exponentially, which is completely consistent with the generally recognized cavitation failure law in the industry. 7 MPa is the critical optimal value that balances pressure boosting efficiency and zero cavitation cumulative damage.

[0046] (2) Comparison of elastic deformation of non-metallic materials

[0047] Using the maximum elastic deformation of the carbon fiber reinforced PEEK distribution plate as an evaluation index, the deformation and fit clearance changes under different single-stage pressure differentials were tested:

[0048] 5MPa 0.0006mm 0.0012mm 0.3% 7MPa 0.0009mm 0.0018mm 0.6% 9MPa 0.0032mm 0.0064mm 3.8% 12MPa 0.0087mm 0.0174mm 12.5%

[0049] Experimental conclusions: The elastic deformation of carbon fiber reinforced PEEK material increases non-linearly with pressure difference. Within 7 MPa, the deformation is stably controlled within 0.001 mm, and its impact on volumetric efficiency is negligible. However, when the pressure difference exceeds 7 MPa, the deformation increases rapidly, the clearance expands cubically, and volumetric efficiency drops drastically. 7 MPa is the critical deformation threshold for ensuring long-term stable operation of non-metallic pumps.

[0050] (3) Comparison of friction pair lifespan

[0051] Based on the adhesive wear theory and the exponential relationship model of pressure difference, the relative life of friction pairs under different pressure differences under the same working conditions is predicted (with 7MPa working condition as the baseline value 1):

[0052] 5MPa 0.4 2.5 7MPa 1.0 1.0 9MPa 3.2 0.31 12MPa 7.8 0.13

[0053] Experimental conclusion: When the single-stage pressure difference is increased from 7 MPa to 12 MPa, the wear rate of the friction pair increases by 7.8 times, and the cumulative lifespan decreases to 13% of the original, which fully corresponds to the technical effect of this invention, which is to "increase the system's average daily fault-free operating time by more than 7 times". Strictly controlling the single-stage pressure difference to ≤7 MPa is the core prerequisite for achieving synchronized lifespan of the entire system and long-term maintenance-free operation.

[0054] 5. Beneficial effects

[0055] Compared with the prior art, the present invention has the following significant advantages:

[0056] 1. Balanced pressure differential and synchronized lifespan address common industry pain points: By strictly controlling the rated pressure differential between the inlet and outlet of a single-stage hydraulic pump to ≤7MPa, the core failure issues of cavitation in metal pumps and elastic deformation in non-metal pumps are fundamentally resolved simultaneously. This pressure differential is lower than the critical cavitation pressure differential (8-9MPa) under normal hydraulic oil operating conditions, completely eliminating the risk of cumulative cavitation and erosion of metal friction pairs. Simultaneously, the elastic deformation of non-metallic / composite material pumps is controlled within 0.001mm, ensuring stable clearance and maintaining a volumetric efficiency of over 92% over the long term. Synchronized working loads on all pump friction pairs, combined with the intermittent operation characteristics of high-pressure pumps, increase the overall machine's calendar lifespan by more than 7 times, achieving 100,000 hours of maintenance-free operation.

[0057] 2. Minimalist Architecture and High Integration: The innovative multi-pump series staged pressurization architecture at the clutch end requires only a single two-stage planetary reducer to achieve any high-pressure output level, eliminating the need for multiple reducers and unloading valves. The two-stage planetary reducer is completely nested within the motor rotor cavity, occupying no additional axial space. Simultaneously, the staged pressurization architecture can output multiple pressure levels of oil at the same time, achieving decoupled centralized oil supply for high and low pressures. This replaces the traditional two independent pump sets for high and low pressures, reducing the number of power components. The overall size is reduced by more than 80% compared to the traditional three-motor, three-pump solution of the same power, allowing the hydraulic power source to be fully integrated into standard bearings and automotive wheel-side systems.

[0058] 3. Self-supplying main motor, inherently safe and reliable: For high-power hydrostatic bearing motor scenarios, a through-shaft direct-drive pump unit architecture is adopted. A single pump unit simultaneously meets the high-pressure lubrication of the bearing and the low-pressure cooling of the stator, eliminating the need for a dedicated motor, coupling, valve cabinet, and external piping of an independent hydraulic station, reducing the floor space by more than 60%. The pump unit and the main motor start and stop naturally synchronously, physically eliminating the risk of bearing dry friction caused by oil supply lag, and improving the overall system efficiency by 3-5 percentage points.

[0059] 4. Low vibration and noise, excellent high-speed stability: Transverse vibration is eliminated through high-precision dynamic balancing of the whole machine, and torsional vibration characteristics are optimized by matching shaft stiffness and rotational inertia. The overall dynamic balancing accuracy in industrial scenarios reaches G2.5 level, with vibration amplitude ≤0.03g at 50,000rpm, and overall noise ≤45dB in automotive scenarios, meeting the NVH requirements of automotive applications and environmental protection requirements in industrial settings.

[0060] 5. Precise matching of speed and lifespan to achieve balanced lifespan across the entire system: In intermittent scenarios, the continuous operating speed of the low-pressure pump is reduced to 2500-3333 rpm (the industry standard high-efficiency speed range) through a reduction ratio of 15:1-20:1, and a small displacement high-speed design is adopted to match the intermittent working characteristics of the high-pressure pump; in continuous scenarios, the direct-drive pump group is matched with the rated speed of the main motor, and under the premise of ensuring the ultimate integration, the calendar lifespan of the high-pressure pump and the low-pressure pump is completely synchronized, which completely solves the lifespan shortness of the high-speed hydraulic source.

[0061] 6. Completely eliminate idling losses and further improve energy efficiency: The intermittent scenario adopts a normally disconnected clutch + high-voltage accumulator design, and all high-pressure pumps only run briefly during pressure replenishment, reducing the cumulative working time by more than 99%; there are no idling losses of medium-pressure pumps, and the overall efficiency under all working conditions can reach more than 96.5%, reducing annual operating energy consumption by more than 85%.

[0062] 7. Significantly reduced failure points and improved reliability: The number of leakage points in a single unit has been reduced from dozens to less than 2, and the number of leakage points in a 3-unit parallel scheme has been reduced from more than 90 to less than 6; the distributed redundancy architecture enables uninterrupted operation in the event of a single unit failure, and the system reliability has been greatly improved.

[0063] 8. Strong ultra-high pressure expansion capability: Through the series expansion of the hydraulic circuit of the symmetrical boosting hydraulic source, ultra-high pressure output of over 100MPa can be achieved, and the overall volume is only 1 / 10 of that of traditional ultra-high pressure hydraulic sources; and the single-stage pressure difference is constant at 7MPa. It is compatible with both metal pumps and lightweight non-metal pumps, which avoids the cavitation failure of metal pumps and solves the high-pressure deformation problem of non-metal pumps. The calendar life of core components is more than 200 times that of traditional ultra-high pressure hydraulic sources, which can meet the needs of miniaturized, long-life ultra-high pressure working conditions that are difficult to adapt to with existing solutions.

[0064] 9. High engineering feasibility and mature supply chain: All core components (high-speed motor, two-stage planetary reducer, high-pressure small-displacement plunger pump, low-pressure large-displacement gear pump) have mature technical solutions in the industry, and multiple domestic suppliers can supply in batches, with short mass production cycle and controllable cost.

[0065] 10. Universal Adaptability for All Scenarios: The standardized modular architecture can flexibly cover the full power range from micro-precision to 1MW+ ultra-high power, and the full pressure range from 7MPa to 120MPa+. It is suitable for all core scenarios such as high-power industrial motors, new energy vehicles, industrial machine tools, offshore wind power, military stealth, heavy machinery, and laboratory ultra-high pressure testing, while supporting flexible switching between multiple architectures. Attached Figure Description

[0066] Figure 1. Schematic diagram of the topology of a through-shaft multi-pump dual-speed hydraulic power source.

[0067] Figure 2. Schematic diagram of the integrated hydraulic power source structure with self-supplying main motor.

[0068] Figure labeling: 1. Through-shaft multi-pump dual-speed hydraulic power source; 2. Through-shaft single motor; 3. Normally disconnected clutch; 4. Planetary reducer; 5. Low-pressure pump; 6. High-pressure pump; 7. Closed-loop cooling and lubrication circuit; 8. Low-pressure output circuit; 9. Pre-pressurization circuit; 10. Low-pressure load; 11. High-pressure load; 12. Constant temperature oil tank; 13. Main motor self-supplying integrated hydraulic power source.

[0069] 14 Main motor load Detailed Implementation

[0070] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. Figure 1 is a schematic diagram of the structural topology of the through-shaft multi-pump dual-speed hydraulic power source (1), which corresponds to the basic architecture of Embodiment 1 and Embodiment 2, and is also the unit body of the modular parallel scheme in Embodiment 4 and the pre-pressurization basic unit of the ultra-high pressure series scheme in Embodiment 5; Figure 2 is a schematic diagram of the structural topology of the main motor self-supplying integrated hydraulic power source, which corresponds to the high-power continuous operation integrated architecture of Embodiment 3. The core power component of the through-shaft multi-pump dual-speed hydraulic power source is a through-shaft single motor (2). The first end of the through-shaft single motor is equipped with a normally closed clutch (3), and the second end is equipped with a planetary reducer (4); the driven end of the normally closed clutch is connected in series with at least one high-pressure pump (6) on the same axis, and the output end of the planetary reducer is connected in series with a low-pressure pump (5) on the same axis, forming a dual-speed architecture with decoupled high and low pressure side speeds. The system oil circuit is divided into three functional branches: the closed-loop cooling and lubrication circuit (7) flows through the motor stator, the lubrication chamber of the transmission mechanism and the friction pair of the clutch in sequence and then flows back; the low-pressure output circuit (8) continuously supplies oil to the outside and connects to the low-pressure load (10); the pre-pressurization circuit (9) is connected to the inlet of the first-stage high-pressure pump, and after being pressurized step by step, it connects to the high-pressure load (11), and all the return oil finally flows into the constant temperature oil tank (12). The main motor self-supplying integrated hydraulic power source (13) takes the high-power through-type main motor as the core power source, without clutch and reduction mechanism. The first end of the through shaft is coaxially connected to multiple low-pressure and high-pressure pumps, and outputs low-pressure cooling oil and high-pressure lubricating oil at the same time through step-by-step pressurization to meet the stator cooling and hydrostatic bearing lubrication requirements of the main motor itself; the second end of the through shaft is directly connected to the main motor load (14) and outputs mechanical power to the outside, forming a closed-loop system integrating power output, bearing lubrication and motor cooling. In modular parallel operation, the high and low pressure oil circuits of multiple through-shaft multi-pump dual-speed hydraulic sources are combined separately and share a centralized constant temperature oil tank to achieve high power output. In ultra-high pressure series operation, a through-shaft multi-pump dual-speed hydraulic source is used as a pre-pressurization unit, and multiple single-speed direct-drive symmetrical boost hydraulic sources are connected in series to expand the pressure level.

[0071] The present invention will be further described in detail below with reference to specific embodiments. The following embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it.

[0072] General assembly and dynamic balancing implementation methods

[0073] All coaxial series pump sets of this invention follow the following assembly process and calibration method to ensure high precision and high reliability:

[0074] 1. Multi-pump coaxial assembly process: Adjacent hydraulic pumps are positioned and fitted with a stop, and the fit clearance is controlled within 0.002~0.005mm; the connecting bolts are pre-tightened in a diagonal step-by-step manner, with the pre-tightening torque applied in three stages. After each stage of loading, a dial indicator is used to check the runout of the pump body end face and the radial runout, ultimately ensuring that the overall coaxiality error of the series pump group is ≤0.003mm.

[0075] 2. Dynamic balancing and torsional vibration correction methods: First, perform individual dynamic balancing tests on each rotating component (clutch, pump rotor, and planetary carrier of the reducer), and remove eccentric mass using the weight reduction method; after the entire machine is assembled, perform overall dynamic balancing correction to ensure that the target accuracy level is achieved. For the cantilever structure, optimize the cantilever length and match the shaft stiffness to ensure that the critical speed avoids the operating speed range, thereby optimizing the torsional vibration characteristics of the shaft system.

[0076] Example 1: 5.5kW 14.5MPa Industrial Standard Dual-Speed ​​Hydraulic Power Station

[0077] This embodiment is the industrial benchmark implementation of the present invention, corresponding to the through-shaft multi-pump dual-speed hydraulic source described in claim 2. It is used as a general-purpose centralized oil supply hydraulic station, equipped with 10 hydrostatic bearings with built-in edge computing functions to achieve centralized oil supply and cooling lubrication for multiple bearings. A single two-stage pump unit in this solution can simultaneously output 0.5MPa low-pressure oil and 14.5MPa high-pressure oil, corresponding to two types of loads: cooling lubrication and hydrostatic bearing oil supply, respectively, replacing the traditional two independent systems of low-pressure cooling station and high-pressure lubrication station.

[0078] The core structure of the through-shaft multi-pump dual-speed hydraulic power source described in this embodiment includes:

[0079] • Through-shaft single motor: Rated power 5.5kW, rated speed 50000rpm, equipped with 40Cr alloy steel through-shaft, designed power density 5.2kW / kg.

[0080] • Normally interrupted wet multi-plate electromagnetic clutch: Built-in disc spring wear compensation mechanism with a compensation stroke of 2mm. The friction pair is made of PEEK material with 20% carbon fiber mass fraction. The rated transmission torque is 11N・m, which is more than 10 times the rated torque of the motor. The engagement response time is ≤40ms and the disengagement response time is ≤15ms.

[0081] • Double-direction thrust angular contact ball bearing: rated dynamic load 15kN, located between the clutch and the first high-pressure pump, bearing the superimposed axial force of the two high-pressure pumps (approximately 6870N).

[0082] • First high-pressure small-displacement axial piston pump: rated pressure 7.5MPa, displacement 0.3cc / r, rated speed 50000rpm, the distribution plate is equipped with a creep compensation structure.

[0083] • Second high-pressure small-displacement axial piston pump: rated pressure 14.5MPa, displacement 0.3cc / r, rated speed 50000rpm, the distribution plate is equipped with a creep compensation structure.

[0084] • Two-stage planetary reducer: 15:1 fixed reduction ratio, transmission efficiency 95.5%, the planetary gear train is completely nested in the inner cavity of the right end of the through-shaft single motor rotor.

[0085] • Low-pressure, high-displacement internal gear pump: rated pressure 0.5MPa, displacement 10cc / r, rated speed 3333rpm.

[0086] • High-pressure piston accumulator: Rated volume 5L, equipped with integrated pressure and temperature sensor, and built-in temperature compensation algorithm from -40℃ to +80℃.

[0087] • Low-voltage accumulator: Rated capacity 2L.

[0088] • Constant temperature oil tank: Rated volume 12L, with integrated automatic heating and heat dissipation functions.

[0089] • Edge controller.

[0090] In this embodiment, the through shaft of the single-shaft motor is connected to the motor rotor by a thermo-insertion fit and a circumferential limiting connection using a flat key. The left and right ends of the through shaft extend to the left and right end covers of the motor, respectively. The through shaft is dynamically balanced to G2.5 level, and the loads at both ends are optimized with symmetrical counterweights. The left end of the through shaft is coaxially connected to the driving end of the normally disconnected clutch via an involute spline. The driven end of the clutch is connected in series with a bidirectional thrust angular contact ball bearing, a first high-pressure pump, and a second high-pressure pump. The right end of the through shaft is coaxially connected to the input end of the two-stage planetary reducer, and the output end of the two-stage planetary reducer is coaxially connected to the drive shaft of the low-pressure large-displacement gear pump. Both ends of the through shaft and the drive ends of each pump are equipped with carbon fiber reinforced PEEK insulation support structures to block the shaft current path.

[0091] Oil circuit design: The suction port of the low-pressure, high-displacement gear pump is equipped with a 100μm precision coarse filter, which is connected to the constant temperature oil tank; the outlet port of the low-pressure, high-displacement gear pump is equipped with low-pressure damping, outputting 0.5MPa, with a rated flow rate of 33.3L / min (10cc / r×3333rpm÷1000), and a peak flow rate of up to 60L / min; one circuit forms a low-pressure output circuit after being stabilized by a low-pressure accumulator, outputting low-pressure oil to supply the cooling and lubrication needs of 10 hydrostatic bearings (total flow rate 25L / min); another circuit is the first-stage pre-pressurization circuit, connected to the suction port of the first high-pressure pump, providing 0.5MPa pre-pressurization; and the third circuit is a closed-loop cooling and lubrication circuit, flowing sequentially through the stator jacket cooling channel of the through-shaft single motor, the lubrication chamber of the second-stage planetary reducer, and the friction pair chamber of the clutch, finally returning to the constant temperature oil tank. The outlet of the first high-pressure pump is connected to the second-stage pre-pressurization circuit, outputting 7.5MPa with a rated flow rate of 15L / min (0.3cc / r × 50000rpm ÷ 1000), and is connected to the suction port of the second high-pressure pump. The outlet of the second high-pressure pump is connected in sequence to a high-pressure damper and a 10μm precision high-pressure filter through a high-pressure oil circuit, and finally connected to the inlet of the high-pressure piston accumulator to form a high-pressure output circuit, outputting 14.5MPa high-pressure oil, which completely covers the total leakage requirement of 12L / min for 10 hydrostatic bearings, with a redundancy of 25%.

[0092] Control Logic: The edge controller is connected to the servo driver of the through-shaft single motor, the control coil of the clutch, the integrated pressure and temperature sensors of each accumulator, and the temperature control module of the constant-temperature oil tank. The core control logic is as follows: Under normal pressure-maintaining conditions, the clutch remains disengaged, the two high-pressure pumps are completely stationary, and the through-shaft single motor operates at a low speed of 20,000 rpm, driving the low-pressure large-displacement gear pump to continuously operate at 1333 rpm to maintain low-pressure oil supply and pre-pressurization. When the pressure of the high-pressure piston accumulator drops to the lower threshold of 12.5 MPa (after temperature compensation correction), the through-shaft single motor first increases to the rated speed of 50,000 rpm, and then the clutch softly engages to replenish pressure. When the pressure reaches the upper threshold of 14.5 MPa, the clutch is first de-energized and disengaged, and the through-shaft single motor then returns to the normal operating condition of 20,000 rpm. Simultaneously, a cold start interlock and pressure replenishment frequency monitoring and diagnostic function are provided. During low-temperature starts, only when the oil temperature in the constant-temperature oil tank is ≥5℃ and the output pre-pressurization pressure of the low-pressure large-displacement gear pump is ≥0.2 MPa... Only after this is the clutch allowed to engage; when the number of times pressure is replenished per unit time exceeds twice the set upper limit, a fault warning is triggered.

[0093] The core design of this embodiment is as follows: each hydrostatic bearing has its own independent edge computing control module and high-speed switching valve group. The through-shaft multi-pump dual-speed hydraulic source is only responsible for providing a stable high-pressure and low-pressure oil source and does not participate in the closed-loop control of a single bearing. The closed-loop pressure regulation of the high-pressure chamber of a single bearing, real-time control of oil film stiffness, online monitoring of leakage, fault early warning and branch cut-off protection functions are all independently completed by the edge computing module of the bearing. When a single bearing fails, the corresponding branch can be independently cut off without affecting the normal operation of the other 9 bearings, realizing distributed redundant control and greatly improving system reliability.

[0094] The overall dimensions of this embodiment are 100mm×100mm×180mm, with a net volume of only 1.8L; the comprehensive efficiency under rated operating conditions is ≥96.5%, and the daily cumulative working time of the high-pressure pump is ≤12 minutes; based on the cumulative working life of the high-pressure pump of 50,000 hours, the calendar service life is >600,000 hours, and the continuous working life of the low-pressure pump is ≥200,000 hours, fully meeting the 100,000-hour maintenance-free requirement.

[0095] Derivative Application Description: This solution can be adapted to the built-in scenario of offshore wind turbine pitch control, and corresponding salt spray protection and structural integration design are carried out. All hydraulic components are plated with nickel-phosphorus alloy (plating thickness 25μm), and a closed built-in constant temperature oil tank is adopted. The whole is embedded inside the outer ring of the wind turbine pitch control bearing, which can completely eliminate the centralized hydraulic station in the nacelle and the hydraulic slip ring of the main shaft, thus eliminating slip ring leakage failure from the root.

[0096] Example 2: 500W 21.5MPa Compact Hydraulic Power Supply for Vehicles

[0097] This embodiment is the core automotive implementation of the present invention, corresponding to the through-shaft multi-pump dual-speed hydraulic source described in claim 2. Designed for the wheel-side EHB and electro-hydraulic active suspension systems of new energy vehicles, it adopts a three-stage series graded pressurization architecture, outputting 21.5MPa high-pressure oil and 0.5MPa low-pressure oil. A single three-stage pump set can simultaneously output 0.5MPa low-pressure oil and 21.5MPa high-pressure oil, respectively corresponding to system cooling and braking / suspension execution loads. It features high integration, adaptability to the limited installation space in vehicles, and solves high-speed vibration problems through high-precision dynamic balancing and torsional vibration optimization, achieving extreme compactness and low-noise operation.

[0098] The core structure of the through-shaft multi-pump dual-speed hydraulic power source described in this embodiment includes:

[0099] • Through-shaft single motor: Rated power 500W, rated speed 50000rpm, equipped with 40Cr alloy steel through-shaft, designed power density 5.5kW / kg, maximum outer diameter of motor 70mm, total axial length 55mm, stator outer wall has spiral cooling channels, and uses oil cooling heat dissipation.

[0100] • Normally interrupted wet multi-plate electromagnetic clutch: Built-in disc spring wear compensation mechanism with a compensation stroke of 2mm. The friction pair is made of PEEK material with 20% carbon fiber mass fraction. The rated transmission torque is 1.2N・m, which is more than 12 times the rated torque of the motor. Sufficient impact load margin is reserved. Engagement response time ≤25ms, disengagement response time ≤10ms.

[0101] • Bidirectional hydrostatic thrust bearing: Rated dynamic load 5kN, located between the clutch and the first high-pressure pump, bearing the superimposed axial force of three high-pressure pumps (approximately 1200N), using low-pressure pump output oil for self-lubrication, with no metal-to-metal contact wear.

[0102] • First high-pressure small-displacement axial piston pump: rated pressure 7.5MPa, displacement 0.05cc / r, rated speed 50000rpm, housing made of carbon fiber reinforced PEEK material, distribution plate made of CF30 PEEK material with creep compensation structure, and piston made of reaction sintered silicon carbide ceramic.

[0103] • Second high-pressure small-displacement axial piston pump: rated pressure 14.5MPa, displacement 0.05cc / r, rated speed 50000rpm, housing made of 6061 aluminum alloy, distribution plate and piston are the same as the first high-pressure pump.

[0104] • Third high-pressure small-displacement axial piston pump: rated pressure 21.5MPa, displacement 0.05cc / r, rated speed 50000rpm, housing made of 6061 aluminum alloy, distribution plate and piston are the same as the first high-pressure pump.

[0105] • Two-stage planetary reducer: 20:1 fixed reduction ratio, transmission efficiency 95.2%, housing is made of gray cast iron HT250 material and has a weight-reinforced design, the two-stage planetary gear train is completely nested in the right end cavity of the through-shaft single motor rotor, without occupying additional axial space.

[0106] • Low-pressure, high-displacement internal gear pump: rated pressure 0.5MPa, displacement 2cc / r, rated speed 2500rpm.

[0107] • High-pressure piston accumulator: Rated volume 0.6L, equipped with integrated pressure and temperature sensor, and built-in temperature compensation algorithm from -40℃ to +80℃.

[0108] • Low-voltage accumulator: Rated capacity 0.2L.

[0109] • Constant temperature oil tank: Rated volume 1.5L, integrated with micro PTC heating and heat sink, maintaining the system oil temperature in the range of 5℃~55℃.

[0110] • Edge controller: Integrated inside the motor end cover, with a volume ≤10cm³.

[0111] Dynamic balancing and torsional vibration control details: The high-speed side (clutch + three high-pressure pumps) adopts an ultra-lightweight design, with a total weight ≤0.45kg and a moment of inertia ≤0.00008kg・m². The low-speed side reducer uses a gray cast iron weighted housing, with an additional 15mm wide cast iron counterweight ring added to the outside of the housing, increasing the total weight by 0.9kg. This brings the total moment of inertia on the low-speed side to 0.000082kg・m², and the difference in moment of inertia between the two sides of the through shaft ≤2.5%, optimizing the torsional vibration characteristics of the shaft system. The entire through shaft undergoes G0.4 grade dynamic balancing treatment, with a vibration amplitude ≤0.03g at 50,000rpm and an overall noise level ≤45dB.

[0112] In this embodiment, the through shaft of the single-shaft motor is connected to the motor rotor by a thermo-insertion fit and a keyless connection. The left and right ends of the through shaft extend to the left and right end covers of the motor, respectively. The left end of the through shaft is coaxially fixed to the driving end of the normally disconnected clutch via an involute spline. The driven end of the clutch is connected in series with a bidirectional hydrostatic thrust bearing, a first high-pressure pump, a second high-pressure pump, and a third high-pressure pump. The three high-pressure pumps are rigidly connected to each other by a stop and bolts, with a coaxiality error ≤0.003mm. The right end of the through shaft is coaxially fixed to the input end of the two-stage planetary reducer, and the output end of the two-stage planetary reducer is coaxially fixed to the drive shaft of the low-pressure large-displacement gear pump. Both ends of the through shaft and the drive ends of each pump are provided with carbon fiber reinforced PEEK insulation support structures to block the shaft current path.

[0113] Oil circuit design: The suction port of the low-pressure, high-displacement gear pump is equipped with a 100μm precision coarse filter, which is connected to the constant temperature oil tank; the outlet port of the low-pressure, high-displacement gear pump is equipped with low-pressure damping, outputting 0.5MPa, with a rated flow rate of 5L / min (2cc / r×2500rpm÷1000), and a peak flow rate of up to 8L / min; one circuit forms a low-pressure output circuit after being stabilized by a low-pressure accumulator, outputting low-pressure oil to meet the cooling and lubrication needs of the vehicle hydraulic system; another circuit is the first-stage pre-pressurization circuit, connected to the suction port of the first high-pressure pump, providing 0.5MPa pre-pressurization; and the third circuit is a closed-loop cooling and lubrication circuit, flowing sequentially through the stator jacket cooling channel of the through-shaft single motor, the lubrication chamber of the second-stage planetary reducer, and the friction pair chamber of the clutch, finally returning to the constant temperature oil tank. The outlet of the first high-pressure pump is connected to the second-stage pre-pressurization circuit, outputting 7.5 MPa with a rated flow rate of 2.5 L / min (0.05 cc / r × 50000 rpm ÷ 1000), and is connected to the suction port of the second high-pressure pump. The outlet of the second high-pressure pump is connected to the third-stage pre-pressurization circuit, outputting 14.5 MPa with a rated flow rate of 2.5 L / min, and is connected to the suction port of the third high-pressure pump. The outlet of the third high-pressure pump is connected to a high-pressure damper and a 10 μm precision high-pressure filter in sequence through a high-pressure oil circuit, and finally connected to the inlet of the high-pressure piston accumulator to form a high-pressure output circuit, outputting 21.5 MPa high-pressure oil, which fully covers the peak flow rate requirement of 2 L / min for automotive EHB systems, with a redundancy of 25%.

[0114] Control Logic: The edge controller is connected to the servo driver of the through-shaft single motor, the control coil of the clutch, the integrated pressure and temperature sensors of each accumulator, and the temperature control module of the constant-temperature oil tank. The core control logic is as follows: Under normal pressure-maintaining conditions, the clutch remains disengaged, the three high-pressure pumps are completely stationary, and the through-shaft single motor operates at a low speed of 20,000 rpm, driving the low-pressure large-displacement gear pump to continuously operate at 1,000 rpm to maintain low-pressure oil supply and pre-pressurization. When the pressure of the high-pressure piston accumulator drops to the lower threshold of 19 MPa (after temperature compensation correction), the through-shaft single motor first increases to the rated speed of 50,000 rpm, and then the clutch softly engages to replenish pressure. When the pressure reaches the upper threshold of 21.5 MPa, the clutch is first de-energized and disengaged, and the through-shaft single motor then returns to the normal operating condition of 20,000 rpm. Simultaneously, a cold start interlock and pressure replenishment frequency monitoring and diagnostic function are provided. During low-temperature starts, only when the oil temperature in the constant-temperature oil tank is ≥5℃ and the output pre-pressurization pressure of the low-pressure large-displacement gear pump is ≥0.2 MPa... Only after this is the clutch allowed to engage; when the number of times pressure is replenished per unit time exceeds twice the set upper limit, a fault warning is triggered.

[0115] The overall dimensions of this embodiment are φ80mm×165mm, with a net volume of only 0.83L and a net weight of ≤3.2kg. Under rated operating conditions, the overall efficiency is ≥95.2%, and the daily cumulative working time of the high-pressure pump is ≤8 minutes. Based on a cumulative working life of 50,000 hours for the high-pressure pump, the calendar service life is >800,000 hours, and the continuous working life of the low-pressure pump is ≥250,000 hours, which fully meets the design requirements of 15 years / 300,000 kilometers for automotive use.

[0116] Example 3: 1000kW 14.5MPa High-Power Hydrostatic Bearing Motor with Self-Supplying Hydraulic Power Source

[0117] This embodiment is the core implementation of the high-power industrial system of the present invention, corresponding to the integrated hydraulic power source with self-supplying main motor as described in claim 3. Designed for a 1000kW, 3000rpm industrial hydrostatic bearing motor, it adopts a three-stage pump group architecture with the main motor connected to the shaft and driven directly. This solution uses a single three-stage coaxial pump group to simultaneously output oil at three pressure levels: 0.5MPa, 7.5MPa, and 14.5MPa, corresponding to three types of loads: motor stator cooling, pump stage pre-pressurization, and hydrostatic bearing lubrication. It replaces the traditional two separate systems of cooling oil pump station and high-pressure lubrication oil station, eliminating the need for a separate external hydraulic station and achieving an integrated closed-loop system for power, lubrication, and cooling.

[0118] The 1000kW main motor self-supplying integrated hydraulic power source described in this embodiment has the following core structure:

[0119] • High-power main motor: rated power 1000kW, rated speed 3000rpm, adopts three-phase asynchronous permanent magnet synchronous architecture, output shaft is 40Cr alloy steel through shaft; the motor is supported by hydrostatic sliding bearing, the stator is oil-cooled structure, rated working oil pressure 12MPa, cooling flow rate requirement 100L / min.

[0120] • Pump unit support unit: The outer side of the motor drive end cover integrates a modular mounting flange with a built-in bidirectional thrust cylindrical roller bearing. The rated dynamic load is 50kN, which is used to withstand the superimposed axial hydraulic thrust of the three-stage pump unit and prevent the axial force from being transmitted to the main thrust bearing of the motor.

[0121] • First-stage low-pressure, high-displacement internal gear pump: rated outlet pressure 0.5MPa, displacement 50cc / r, rated speed 3000rpm, housing made of cast iron, distribution pair made of copper-based alloy; rated flow rate 150L / min (50cc / r×3000rpm÷1000), of which 100L / min is introduced into the motor stator cooling channel, and the remaining 50L / min is used as the pre-pressurization oil source for the subsequent high-pressure pump.

[0122] • Second-stage medium-high pressure axial piston pump: rated inlet and outlet pressure difference 7MPa, rated outlet pressure 7.5MPa, displacement 5cc / r, rated speed 3000rpm, the distribution plate is equipped with a creep compensation structure, and the piston is made of nitrided steel; rated flow rate 15L / min (5cc / r×3000rpm÷1000).

[0123] • Third-stage high-pressure axial piston pump: rated inlet and outlet pressure difference 7MPa, rated outlet pressure 14.5MPa, displacement 5cc / r, rated speed 3000rpm, material and structure are the same as the second-stage pump; rated flow rate 15L / min, fully covering the total leakage requirement of 12L / min for the hydrostatic bearing, with a redundancy of 25%.

[0124] • High-pressure piston accumulator: Rated volume 10L, rated pressure 16MPa, equipped with an integrated pressure and temperature sensor, used to absorb flow pulsation, stabilize oil supply pressure, and provide short-term pressure maintenance during motor start-up and shutdown transition.

[0125] • Centralized constant temperature oil tank: Rated volume 500L, integrated water-cooled radiator and electric heating module, oil temperature control accuracy ±2℃, maintaining system oil temperature within the range of 40℃±5℃.

[0126] • System control valve group: integrates high-pressure relief valve, low-pressure relief valve, check valve, pressure sensor and temperature sensor to realize dual pressure protection and status monitoring of the system.

[0127] Shaft system and dynamics design: The three-stage pump unit adopts a cantilever installation, with the total cantilever length controlled within 350mm; the total weight of the rotating parts of the pump unit is ≤25kg, and the moment of inertia is ≤0.012kg・m². Rotor dynamics simulation calculations show that the first-order critical speed of the shaft system is 4200rpm, avoiding the ±15% range of the rated speed of 3000rpm (2550~3450rpm), eliminating the risk of resonance during operation. The entire pump unit undergoes G2.5 level dynamic balancing correction, with a vibration amplitude ≤0.02g at rated speed, meeting the vibration standards for industrial motors. Axial force calculation: The axial hydraulic thrust of a single-stage high-pressure pump is approximately 10.5kN, and the total axial force of the two-stage high-pressure pumps is approximately 21kN. The rated dynamic load of the matching bidirectional thrust cylindrical roller bearing is 50kN, with a safety factor ≥2.38, meeting the requirements for long-term continuous operation.

[0128] Oil circuit design: The first-stage low-pressure gear pump's suction port is connected to the constant-temperature oil tank, and the outlet is divided into two paths: the first path, after passing through a low-pressure damper and a cooling oil filter, enters the motor stator cooling channel to remove the heat generated by the motor stator losses, and then flows back to the constant-temperature oil tank after heat exchange; the second path, as a pre-pressurization oil circuit, is connected to the suction port of the second-stage plunger pump, providing a positive pressure pre-pressurization of 0.5MPa. The outlet of the second-stage plunger pump is connected to the suction port of the third-stage plunger pump, with a single-stage pressure difference of 7MPa, outputting 7.5MPa medium-pressure oil; the third-stage plunger pump outputs 14.5MPa high-pressure oil, which, after passing through a high-pressure fine filter and a high-pressure damper, enters the high-pressure accumulator, and finally flows into the high-pressure oil chambers of the front and rear hydrostatic sliding bearings of the motor, forming a rigid oil film to support the rotor. The bearing leakage oil is collected through the return oil pipeline and flows back to the constant-temperature oil tank, completing a complete cycle.

[0129] Operating Logic: The pump unit and main motor are coaxially driven, with completely synchronized start and stop: When the motor is powered on and starts, the pump unit builds pressure synchronously. The hydrostatic bearing first establishes an oil film before bearing the rotor, completely eliminating the risk of dry friction. When the motor is powered off and stops, the pump unit synchronously stops supplying oil. The bearing gradually unloads as the rotor speed decreases, eliminating the risk of oil supply lag. The system is equipped with pressure monitoring and interlock protection: When the oil supply pressure is lower than the 10MPa lower limit threshold, an alarm is triggered and the motor load is limited; when the oil supply pressure is lower than 8MPa, emergency shutdown protection is triggered to ensure bearing safety.

[0130] This embodiment eliminates the need for an additional independent hydraulic motor. The pump module is directly integrated onto the outside of the motor end cover. Compared to the traditional "main motor + external hydraulic station" solution, the overall footprint is reduced by 62%, the number of leakage points is reduced from 28 to 5, and the overall system efficiency is improved by 4.2 percentage points. Based on 8,000 hours of operation per year, it saves approximately 33,600 kWh of electricity annually. The pressure difference between the two high-pressure pumps is controlled within 7 MPa, eliminating the risk of cavitation. The cumulative working life of the friction pairs is ≥60,000 hours, equivalent to a calendar life of >20 years, perfectly matching the design life cycle of the main motor and achieving system-wide lifespan synchronization.

[0131] Example 4: 30kW (3×10kW) Modular Parallel High-Power Hydraulic Power Unit

[0132] This embodiment is a modular parallel high-power implementation of the present invention, corresponding to the modular parallel expansion scheme described in claim 9. It adopts a standardized modular parallel layout of three identical through-shaft multi-pump dual-speed hydraulic sources. A high-pressure and low-pressure dual-side buffer and stabilization structure solves the pressure fluctuation problem of traditional parallel connections. A centralized common constant-temperature oil tank eliminates multiple independent temperature control components, achieving continuous stepless adjustment across the entire flow range while maintaining maximum efficiency throughout. It is suitable for ultra-high-power hydraulic scenarios such as metallurgy, heavy machinery, and tunnel boring machines. Each unit has multi-pressure level output capabilities, and after parallel connection, it can simultaneously supply oil to loads of different pressure levels within the system.

[0133] This embodiment employs three sets of through-shaft multi-pump dual-speed hydraulic power sources (structure same as in Embodiment 1, each outputting 14.5MPa high pressure and 0.5MPa low pressure) with a rated power of 10kW and a rated speed of 50,000rpm. A compact, modular parallel layout is adopted, with the entire unit integrated into a single installation, occupying only 1 / 7 the area of ​​a traditional independent parallel hydraulic station. The high-pressure output circuits of the three hydraulic power sources are connected in parallel to the main high-pressure oil supply pipeline. A 60L high-pressure buffer accumulator group and a fixed throttling and pressure-stabilizing damping structure are installed at the main high-pressure oil supply port to absorb hydraulic shocks during staged start-up and shutdown, smooth oil supply pressure fluctuations, and control pressure fluctuations within ±0.2MPa. The low-pressure output circuits of the three hydraulic power sources are connected in parallel to the main low-pressure oil supply pipeline, with a 15L... The low-pressure buffer accumulator group and the fixed throttling and pressure-stabilizing damping structure are used to smooth the pressure fluctuations on the low-pressure side and absorb the flow impact, ensuring that the pre-pressure of the high-pressure pump is stable at 0.4±0.05MPa; the cooling and lubrication branch is an independent closed loop, and the low-pressure large-displacement internal gear pump of each hydraulic source is independently responsible for the cooling and lubrication of the machine and the pre-pressurization of the high-pressure pump, without interference; the closed-loop cooling and lubrication circuits of the three hydraulic sources are all connected in parallel to the centralized common constant temperature oil tank. The common constant temperature oil tank integrates automatic heating and heat dissipation functions to maintain the system oil temperature in a stable range of 5℃~45℃, eliminating the independent temperature control components of each unit, and further reducing the overall space by 12%.

[0134] Each hydraulic power source is equipped with an independent edge controller and a central control system, enabling stepless speed regulation of a single pump and dynamic load balancing across multiple units, with a synchronization error of ≤1ms. The core control logic of the system is as follows: the central control system automatically allocates the output power of each hydraulic power source in real time according to the total flow demand, ensuring that each operating hydraulic power source works within the 80%-100% rated load range (the system's highest efficiency point); continuous stepless adjustment is achieved within the full high-pressure flow range of 0-45L / min and the full low-pressure flow range of 0-100L / min, with a comprehensive system efficiency of ≥95.8% throughout the entire process; in the event of a single hydraulic power source failure, the central control system immediately disconnects the clutch and motor drive of that unit, and the remaining normal units automatically redistribute the load, ensuring continuous system operation without pressure leakage and without significant fluctuations in flow and pressure.

[0135] The modular parallel high-power hydraulic power unit in this embodiment has a total high-pressure pump rated flow of 45L / min (3×0.3cc / r×50000rpm÷1000) and a total low-pressure pump rated flow of 100L / min (3×10cc / r×3333rpm÷1000), which can cover the needs of ultra-high power heavy-duty hydraulic scenarios. Compared with the traditional multi-motor hydraulic station of the same power, the volume is reduced by 80%, the weighted average comprehensive efficiency is ≥95.8%, and the number of leakage points is reduced from 90 to ≤6, greatly improving redundancy and energy saving.

[0136] Example 5: 12kW 119.5MPa Laboratory Ultra-High Pressure Series Hydraulic Power Source

[0137] This embodiment is the core implementation of the ultra-high pressure system of the present invention. Corresponding to the hydraulic circuit series expansion scheme described in claim 10, it uses one pre-pressurization unit (through-shaft multi-pump dual-speed hydraulic source) as the pre-pressurization and cooling unit, and connects four symmetrical pressure boosting hydraulic sources in series to achieve 17-stage progressive pressure boosting with a total output pressure of 119.5MPa. It is designed specifically for laboratory material mechanics testing, ultra-high pressure sealing tests and other scenarios.

[0138] The core structure of the 119.5MPa laboratory ultra-high pressure hydraulic source described in this embodiment includes:

[0139] • Pre-pressurization unit: One 2kW rated power through-shaft multi-pump dual-speed hydraulic power source, through-shaft single motor rated speed 50000rpm, left end series series normally disconnected clutch + one 7.5MPa high pressure small displacement axial piston pump, right end series series 20:1 nested two-stage planetary reducer + 0.5MPa low pressure large displacement internal gear pump; the low pressure pump rated flow 10L / min, responsible for providing 0.5MPa pre-pressurization and closed-loop cooling lubrication for the entire system; the high pressure small displacement pump rated flow 2.5L / min, output 7.5MPa, as the first stage of pressurization of the entire series array.

[0140] • First symmetrical boosting hydraulic power source: One symmetrical boosting hydraulic power source with a rated power of 2.5kW, a through-shaft single motor with a rated speed of 50,000rpm, and two 7MPa high-pressure small-displacement axial piston pumps connected in series at each end. The pump sets at both ends use the same model, material and processing technology, with a total weight difference ≤1g, a rotational inertia difference ≤0.000001kg・m², and a dynamic balance accuracy of G0.4 grade; the hydraulic circuits of the four pumps are connected in series, with a single-stage pressure difference of 7MPa, a total output pressure of 7.5+7×4=35.5MPa, and a rated flow rate of 2.5L / min.

[0141] • Second symmetrical boosting hydraulic power source: It is exactly the same as the first symmetrical boosting unit, with an input pressure of 35.5MPa, an output pressure of 35.5+7×4=63.5MPa, and a rated flow rate of 2.5L / min.

[0142] • Third symmetrical boosting hydraulic power source: It is exactly the same as the first symmetrical boosting unit, with an input pressure of 63.5MPa, an output pressure of 63.5+7×4=91.5MPa, and a rated flow rate of 2.5L / min.

[0143] • Fourth symmetrical boosting hydraulic power source: It is exactly the same as the first symmetrical boosting unit, with an input pressure of 91.5MPa, an output pressure of 91.5+7×4=119.5MPa, and a rated flow rate of 2.5L / min.

[0144] • Ultra-high pressure piston accumulator: rated volume 0.2L, rated pressure 150MPa, equipped with a high-precision pressure sensor, measurement accuracy ±0.1MPa.

[0145] • Centralized constant temperature oil tank: Rated volume 20L, integrated high-precision temperature control system, oil temperature control accuracy ±1℃, maintaining the system oil temperature within the laboratory standard working range of 20℃~30℃.

[0146] • Central control system: integrates the control and data acquisition functions of all units, and supports continuously adjustable pressure, automatic pressure holding, timed pressure relief, data recording and export.

[0147] Total power: 2kW + 4 × 2.5kW = 12kW Total number of boosting stages: 1 (pre-boosting high-pressure pump) + 4 × 4 (symmetrical unit pumps) = 17 stages Total pressure: 0.5MPa (pre-boosting) + 17 × 7MPa (single-stage pressure difference) = 119.5MPa

[0148] In this embodiment, all hydraulic pumps are 50,000 rpm ultra-high speed small displacement axial piston pumps. The distribution plate and piston are made of silicon carbide ceramic material, and the housing is made of high-strength titanium alloy material. The rated pressure difference is 7 MPa, and the cumulative design life is ≥100,000 hours. All high-pressure pipelines are made of 316L stainless steel seamless steel pipes with a wall thickness ≥5 mm and a conical sealing structure to ensure no leakage. The through shafts of all symmetrical boosting units are made of high-strength maraging steel with a tensile strength ≥2000 MPa to ensure structural strength at a high speed of 50,000 rpm.

[0149] Oil circuit design: The low-pressure pump outlet of the pre-pressurization unit is divided into two paths: one is a closed-loop cooling and lubrication circuit, flowing sequentially through the single-motor stator cooling channels of the pre-pressurization unit and all symmetrical boosting units, and the clutch friction pair cavity, finally returning to the centralized constant temperature oil tank; the other is a pre-pressurization circuit, connected to the suction port of the first high-pressure pump of the pre-pressurization unit, providing 0.5MPa positive pressure pre-pressurization. The high-pressure pump outlet of the pre-pressurization unit is connected to the suction port of the first hydraulic pump of the first symmetrical boosting unit, and the high-pressure output port of the first symmetrical boosting unit is connected to the suction port of the first hydraulic pump of the second symmetrical boosting unit, and so on, forming a 17-stage progressively boosting oil circuit; the high-pressure output port of the fourth symmetrical boosting unit is connected to the ultra-high-pressure piston accumulator through ultra-high-pressure damping, finally outputting 119.5MPa ultra-high-pressure oil.

[0150] Control Logic: The central control system uniformly controls the motors and clutches of the pre-pressurization unit and all symmetrical pressurization units. Under normal pressure-holding conditions, all clutches remain disengaged, all high-pressure pumps are completely stationary, and only the low-pressure pump of the pre-pressurization unit continues to run to maintain system pre-pressurization and cooling lubrication. When the pressure of the ultra-high pressure accumulator drops to the lower threshold of 110MPa, the motors of all units start simultaneously to the rated speed of 50,000rpm, and all clutches engage sequentially for step-by-step pressure replenishment. When the pressure rises to the upper threshold of 119.5MPa, all clutches disengage sequentially, all motors stop running, and the system enters the pressure-holding state. During the pressure replenishment process, the pressure at each stage rises synchronously, and the pressure difference between a single stage is always kept within 7MPa to ensure a balanced workload for all pumps.

[0151] This embodiment has overall dimensions of 600mm × 400mm × 300mm, a net volume of only 72L, and a net weight of ≤120kg. Under rated operating conditions, its comprehensive efficiency is ≥94%, and the high-pressure pump's daily cumulative operating time is ≤30 minutes. The noise level is ≤40dB, and the pressure fluctuation is ≤±0.2MPa, meeting the high-precision testing requirements of the laboratory. Compared to traditional 100MPa hydraulic power sources using a booster architecture, this embodiment reduces volume by 90%, weight by 85%, increases efficiency by more than 3 times, and extends calendar life by more than 200 times.

Claims

1. A single-unit, multi-pump, staged pressure-boosting hydraulic power source, characterized in that, It includes a single motor and at least two hydraulic pumps; all hydraulic pumps are rigidly connected in series coaxially along the output shaft of the single motor; at least two of the hydraulic pumps are connected in series sequentially along the hydraulic circuit to form a step-by-step pressure-boosting structure, and the oil suction port of the subsequent hydraulic pump is connected to the oil outlet port of the previous hydraulic pump.

2. The single-unit multi-pump step-by-step pressurization hydraulic power source according to claim 1, characterized in that, The single motor is a through-shaft single motor; the first end of the through shaft is equipped with a normally disconnected clutch, and the driven end of the clutch is rigidly connected in series with at least one hydraulic pump on the same axis; the second end of the through shaft is equipped with a speed change transmission mechanism, and the output end of the speed change transmission mechanism is rigidly connected in series with a low-pressure pump on the same axis; the oil outlet of the low-pressure pump is connected to the oil suction port of the first hydraulic pump at the first end of the through shaft to provide positive pressure pre-pressurization.

3. The single-unit multi-pump step-by-step pressurization hydraulic power source according to claim 1, characterized in that, The single motor is a high-power industrial main motor, and the output shaft of the main motor is a through shaft. At least two hydraulic pump sets are coaxially and rigidly connected in series at the first end of the through shaft, and the second end of the through shaft is used to connect to external mechanical loads. The low-pressure output end of the hydraulic pump set is connected to the stator cooling channel of the main motor itself, and the high-pressure output end is connected to the hydrostatic sliding bearing oil supply chamber of the main motor itself, forming a closed-loop hydraulic system integrating power output, bearing lubrication, and motor cooling.

4. The single-unit multi-pump step-by-step pressurization hydraulic power source according to claim 1, characterized in that, The single motor is a through-shaft single motor; the two ends of the through shaft are respectively rigidly connected in series with an equal number of hydraulic pumps in a symmetrical configuration; all hydraulic pumps are connected in series along the hydraulic circuit to form a step-by-step pressure-boosting structure.

5. The single-unit multi-pump step-by-step pressurization hydraulic power source according to any one of claims 1-4, characterized in that, The rated pressure difference between the inlet and outlet of each hydraulic pump stage is ≤7MPa.

6. The single-unit multi-pump step-by-step pressurization hydraulic power source according to claim 2, characterized in that, The speed transmission mechanism is a fixed reduction ratio planetary reducer, and the planetary gear train is completely nested in the rotor cavity of the single motor, without occupying additional axial space.

7. The single-unit multi-pump step-by-step pressurization hydraulic power source according to claim 2, characterized in that, The normally closed clutch is a wet multi-plate electromagnetic clutch with a built-in disc spring wear compensation mechanism, and the friction pair is made of carbon fiber reinforced PEEK material.

8. The single-unit multi-pump step-up hydraulic power source according to any one of claims 1-4, characterized in that, The low-pressure pump has a closed-loop cooling and lubrication branch at its outlet, which flows sequentially through the single motor stator cooling channel, the lubrication chambers of all speed transmission mechanisms, and the clutch friction pair chamber, and finally returns to the constant temperature oil tank.

9. The single-unit multi-pump step-up hydraulic power source according to any one of claims 1-3, characterized in that, Two or more sets of single-unit multi-pump step-up hydraulic sources adopt a standardized modular parallel layout. The high-pressure output port and low-pressure output port of each hydraulic source are connected in parallel and summarized, sharing a centralized common constant temperature oil tank.

10. The single-unit multi-pump progressive pressure hydraulic power source according to claim 4, characterized in that, Two or more sets of single-unit multi-pump progressive pressure hydraulic sources adopt a series hydraulic circuit layout, with the high-pressure output port of the first set of hydraulic sources connected to the oil suction port of the first hydraulic pump of the second set of hydraulic sources.

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