Two-Stage Hydraulic Pump for Constant Power Across Pressure
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing hydraulic pumps struggle to maintain a constant power output across varying flow rates and pressures, particularly in single-stage pumps with variable speed mechanisms, which fail to achieve practical differences in flow rates for high flow versus high pressure.
Innovation Solution
A two-stage hydraulic pump assembly driven by a brushless motor assembly, which adjusts speed to maintain constant power output by employing field weakening, and includes a stator and rotor with encapsulated laminations and magnets, along with a radial fan for cooling and a control system for precise operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single-stage pump with variable speed mechanism is used, then the pump can adjust flow rate, but it fails to achieve practical differences in flow rates for high flow versus high pressure operations
Solution Approach 1:
The pump is divided into two distinct stages: a first stage pump and a second stage pump. The first stage pump is configured to provide high flow rates at lower pressures, while the second stage pump provides high pressure at reduced flow rates. This segmentation allows the system to achieve practical and significant flow rate differences between operating modes, resolving the limitation of single-stage variable speed pumps.
2Adaptability or versatility
If mechanical features are used to change piston stroke by varying eccentric cam offset, then variable displacement is achieved, but the system cannot maintain substantially constant power output across varying pressures
Solution Approach 1:
The system employs a variable speed motor assembly that dynamically adjusts its rotational speed based on operating conditions. The motor controller monitors the operational state and modulates motor speed to maintain substantially constant power output across varying pressures, transforming a static mechanical displacement system into a dynamic speed-controlled system.
Solution Approach 2:
The system changes the operational parameters by varying motor speed rather than relying solely on mechanical displacement changes. By adjusting the rotational speed parameter of the motor assembly, the system maintains constant power output (Power = Torque × Speed) as pressure varies, complementing the mechanical variable displacement capability.
3Productivity
If a larger pump assembly is used to achieve equivalent performance, then sufficient flow and pressure are provided, but the pump size increases
Solution Approach 1:
By segmenting the pump into two stages with specialized functions, the system achieves high performance in both high flow and high pressure operations without requiring a single oversized pump. Each stage is optimized for its specific operational range, allowing compact design while maintaining equivalent or superior performance to larger single-stage pumps.
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 achieves a substantially constant power output across varying pressures, improving flow rates and reducing the size of the pump assembly required for equivalent performance compared to larger pumps.
Implementation Method 1
a brushless motor assembly operable to drive the pump assembly, the motor assembly being controlled to operate at a substantially constant power as fluid pressure increases in each stage of the pump assembly
Implementation Method 2
a fan operable to cause air flow through the channels to cool fluid in the reservoir
Implementation Method 3
a shaft connected directly to each of the rotor to the pump member and being operable to transmit power from the rotor to the pump member
Data Source
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.