Plunger Water Pump with Independent High and Low Pressure Cavities
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Solution Overview
Problem
Existing water hydraulic pumps face challenges in achieving high volumetric efficiency and power-to-weight ratio under ultra-high-pressure conditions, with issues such as frictional abrasion, limited pressure capacity, and complexity due to the use of lubricant oil, especially in deep-sea environments.
Innovation Solution
A fully water-lubricated plunger type water pump design featuring a pump body with independent high-pressure, low-pressure, and lubrication cavities, utilizing a flat valve assembly and a plunger-shoe assembly with a supporting valve assembly for fluid communication and lubrication, along with a swash plate and connecting rod mechanism to reduce lateral forces and enhance fluid support, and incorporating polymeric wear-resistant materials and damping structures to minimize abrasion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a mineral oil lubricated structure with separated oil and water cavities is used for high-pressure water hydraulic pumps, then the pressure range can reach 55 MPa∼275 MPa, but the rotation speed is limited to 100 rev/min∼500 rev/min, the volume becomes bulky, and the power-to-weight ratio decreases
Solution Approach 1:
The invention extracts and eliminates the mineral oil lubrication system from the water hydraulic pump, removing the oil cavity, oil seals, and related components. This extraction enables the pump to achieve full water lubrication, allowing operation at higher rotation speeds (1000-3000 rev/min) without the limitations imposed by oil seal heating and degradation, while maintaining ultra-high pressure capabilities (55-275 MPa).
Solution Approach 2:
The invention uses water under pressure as both the hydraulic working medium and the lubricant. By utilizing the hydraulic properties of water itself to provide lubrication at the friction couplings (plunger-cylinder, valve-piston, and bearing surfaces), the system eliminates the need for separate oil lubrication systems, enabling higher rotation speeds and improved power-to-weight ratio while maintaining ultra-high pressure operation.
2Volume of moving object
If the rotation speed is increased to decrease the volume of the pump, then the volume and power-to-weight ratio improve, but the seal between water cavity and lubricant oil cavity would be overheated and fail, especially under high-pressure conditions
Solution Approach 1:
The invention removes the oil-water seal interface entirely by eliminating the mineral oil lubrication system. Without separate oil and water cavities, there are no seals subject to overheating from relative motion between different fluid chambers. The pump operates with full water lubrication, allowing higher rotation speeds that reduce pump volume while maintaining seal reliability through the absence of the problematic seal interface.
3Reliability
If lubricant oil is used for lubrication, then the friction couplings are protected, but oil pollution occurs and an additional pressure compensation device is required for deep sea environments, making the structure complex
Solution Approach 1:
The invention makes the water hydraulic system self-sufficient by using the water working medium itself to lubricate all friction couplings. The water serves dual purposes: as the hydraulic fluid for power transmission and as the lubricant for friction surfaces. This self-service approach eliminates the need for external mineral oil lubrication systems and pressure compensation devices, reducing structural complexity while maintaining reliable friction coupling protection, especially in deep sea environments.
4Device complexity
If a plate valve is used for flow distribution, then the pump structure is compact and maintenance is easy, but the maximum working pressure is limited to 16 MPa and the valve plate is sensitive to pollutants
Solution Approach 1:
The invention replaces the delicate plate valve with a more robust spherical valve design that can withstand ultra-high pressures (55-275 MPa). The spherical valve with its simple geometry and strong sealing capability is designed to be more tolerant of contaminants and higher pressures, accepting slightly increased maintenance requirements as a trade-off for achieving the necessary pressure capability and poll resistance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design achieves high volumetric efficiency and power-to-weight ratio, reduces frictional abrasion, simplifies maintenance, and eliminates the need for lubricant oil, making the pump more environmentally friendly and suitable for deep-sea applications without additional pressure compensation devices.
Implementation Method 1
full water lubrication of the friction couplings
Implementation Method 2
damping structures to minimize abrasion
Data Source
Figure 1~2a
Figure 2b~3
Figure 4~5
AI summary
A plunger water pump comprises a chamber, a rotating main shaft (1) and a plunger distributing unit. The plunger distributing unit comprises a distributing valve assembly (13), a plunger-shoe assembly (23) and a support valve assembly. The chamber is separated into a high pressure chamber (16) and a low pressure chamber (19) being mutually independent by the plunger-shoe assembly (23). The high pressure chamber (16) fluidly communicates with the distributing valve assembly (13), and the low pressure chamber (19) fluidly communicates with the support valve assembly. The plunger-shoe assembly (23) is driven to reciprocate by the rotating main shaft (1), thereby urging the distributing valve assembly (13) to cooperate with the support valve assembly, making the distributing valve assembly (13) to intake and discharge water through the water pump inlet (51) and outlet (50), and at the same time making the support valve assembly to provide fluid lubrication for the rotating unit. The high pressure water discharged from the superhigh pressure pump is independent of the low pressure water for hydrostatic pressure supporting and lubricating, which ensures the volumetric efficiency of the water pump in the superhigh pressure condition and the fluid support and lubrication of the friction pairs in the high velocity and overload condition, and prolongs the service life of the water pump.