Two-Stage Hydraulic Pump for Constant Power Across Pressure Ranges
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Solution Overview
Problem
Existing hydraulic pumps struggle to maintain constant power output across varying flow rates and pressures, particularly in single-stage pumps with variable speed mechanisms, and two-piston pumps with mechanical displacement adjustments are inefficient.
Innovation Solution
A two-stage hydraulic pump assembly driven by a brushless motor, which adjusts speed to maintain constant power through field weakening, combined with a variable displacement mechanism using a common shaft for both stages, and includes a cooling system with a radial fan to manage temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a single-stage pump with variable speed mechanism is used, then power output can be adjusted, but constant power output across varying flow rates and pressures cannot be achieved
Solution Approach 1:
The pump is divided into two independent stages: a first stage piston pump and a second stage piston pump. Each stage can operate independently to deliver fluid at different pressure levels, allowing the system to maintain constant power output across a wider range of flow rates and pressures than a single-stage pump could achieve.
2Adaptability or versatility
If mechanical features are used to change piston stroke, then displacement can be varied, but the system becomes complex
Solution Approach 1:
The pump employs variable displacement mechanisms in both stages that allow dynamic adjustment of piston stroke length. The first stage piston has a variable stroke length that can be adjusted independently, and the second stage piston also has variable displacement capability. This dynamic adjustment enables the pump to adapt to different flow and pressure requirements without requiring complex mechanical transmission systems.
3Power
If a two-stage pump assembly is used, then constant power output can be achieved, but the pump size increases
Solution Approach 1:
The two-stage pump assembly integrates both piston pumps into a single compact unit with shared components. The first stage piston pump and second stage piston pump are coupled together, allowing them to operate in sequence. This merging of functions into a unified assembly achieves constant power output capability while minimizing the overall pump size compared to using separate pumps or a larger single-stage design.
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 pump achieves a substantially constant power output across a wide range of pressures and flow rates, improving efficiency and performance while reducing the size and complexity of the pump assembly.
Implementation Method 1
a brushless motor assembly operable to drive the pump assembly
Implementation Method 2
a fan operable to cause air flow through the channels to cool fluid in the reservoir
Data Source
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AI summary
A pump may generally include a frame including a reservoir. The reservoir stores a hydraulic fluid. The pump may also include a motor assembly supported by the frame and a pump assembly operably driven by the motor assembly. The pump assembly is in fluid communication with the reservoir and configured to dispense the hydraulic fluid out of the frame. The pump assembly includes a first piston and a second piston, wherein the first piston dispenses hydraulic fluid out of the frame between a first pressure and a second pressure greater than the first pressure, and the second piston dispenses hydraulic fluid out of the frame between the first pressure and a third pressure, the third pressure being greater than the second pressure.