Fixed Displacement Pump Flow Control via Gear Speed and Ratio Pump
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Solution Overview
Problem
Variable displacement pumps, such as axial piston pumps, are expensive and difficult to maintain in contaminated environments, and are susceptible to fluid cavitation, leading to performance deterioration.
Innovation Solution
A controller system for a fixed displacement pump, comprising a pump speed control gear set, a ratio control pump, and a relief valve, which includes a sun gear, planet carrier, ring gear, and a rotor, allowing for varying flow rates by controlling the rotational speed and fluid egress, thereby mitigating contamination and cavitation issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If variable displacement pumps are used to vary flow rate, then flow rate variation capability is improved, but cost and maintenance difficulty increase
Solution Approach 1:
The system divides the flow control function into two separate components: a fixed displacement pump that handles the main fluid delivery, and a variable displacement pump that handles flow rate adjustment. This segmentation allows each component to be optimized independently, using simpler and more cost-effective fixed displacement technology for the primary function while maintaining flow variability capability.
Solution Approach 2:
The patent combines the output of a fixed displacement pump with a variable displacement pump in parallel configuration. The fixed displacement pump provides the primary fluid flow, while the variable displacement pump adjusts the total flow rate by varying its contribution. This merging approach achieves flow rate variation capability while using simpler, more cost-effective fixed displacement technology for the main pumping function.
2Adaptability or versatility
If variable displacement pumps are used in contaminated environments, then flow rate control is improved, but reliability deteriorates due to contamination and cavitation susceptibility
Solution Approach 1:
The system segments the pumping function to use a fixed displacement pump for the primary fluid delivery task in contaminated environments, which is inherently more reliable and less susceptible to cavitation. The flow rate control is achieved by adjusting the speed of this robust pump rather than using a complex variable displacement mechanism that would be vulnerable to contamination and cavitation damage.
Solution Approach 2:
The patent replaces the mechanical variable displacement mechanism with a speed control approach. Instead of mechanically varying the displacement of a pump (which creates cavitation risks), the system maintains constant displacement but varies the rotational speed of the fixed displacement pump. This substitution eliminates the mechanical complexity and cavitation susceptibility associated with variable displacement designs while maintaining flow rate control capability.
3Reliability
If fixed displacement pump with speed control is used, then reliability in contaminated environments is improved, but device complexity increases due to additional control mechanisms
Solution Approach 1:
The variable displacement pump in the system serves multiple functions: it compensates for flow variations, maintains system pressure, and provides flow rate adjustment capability. By making this component multi-functional, the system achieves reliable operation in contaminated environments without requiring overly complex control mechanisms, as the variable displacement pump handles multiple control tasks simultaneously.
4Measurement precision
If axial piston pumps are used for flow rate variation, then flow control precision is improved, but ease of repair worsens
Solution Approach 1:
The patent employs a variable displacement pump that can be more easily replaced or maintained compared to axial piston pumps. While axial piston pumps offer precise flow control, they are expensive and difficult to maintain in contaminated environments. The chosen variable displacement pump design prioritizes ease of repair and replacement, accepting slightly reduced precision in exchange for significantly improved maintainability and lower cost.
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 system enables efficient and cost-effective variation of flow rates while maintaining pump performance in contaminated environments, reducing maintenance costs and extending the service life of the prime mover, and is more rugged than traditional variable displacement pumps.
Implementation Method 1
The pump speed control gear set includes a sun gear, a planet carrier, and a ring gear. The sun gear is configured to be driven by a prime mover. The planet carrier includes one or more planet gears meshed with the sun gear. The ring gear is meshed with the planet gears and is configured to connect to an input shaft of the fixed displacement pump.
Implementation Method 2
The ratio control pump includes a stationary body, and a rotor coupled to the planet carrier of the pump speed control gear set. The rotor is configured to co-act with the body to pump fluid.
Implementation Method 3
The relief valve is connected to the ratio control pump and configured to restrict fluid egress from the ratio control pump.
Data Source
AI summary
A controller for varying flow rate of a fluid from a fixed displacement pump is provided. The controller includes a pump speed control gear set, a ratio control pump, and a relief valve. The pump speed control gear set includes a sun gear configured to be driven by a prime mover, a planet carrier including one or more planet gears meshed with the sun gear, and a ring gear meshed with the planet gears. The ring gear is configured to connect to an input shaft of the fixed displacement pump. The ratio control pump includes a stationary body, and a rotor coupled to the planet carrier of the pump speed control gear set. The rotor is configured to co-act with the body to pump fluid. The relief valve is connected to the ratio control pump and configured to restrict fluid egress from the ratio control pump.