Variable Flow External Rotor Hydraulic Machine
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Solution Overview
Problem
Variable flow internal gear pumps are inefficient when unloaded, while external gear pumps do not suffer from this issue, and there is a need for an external gear pump that can vary flow independently of speed, combining the advantages of variable flow with external gear pump architecture.
Innovation Solution
A variable flow external rotor hydraulic machine with a rotor set where at least one rotor axis is movable relative to the other to vary leakage flow, allowing for independent control of net flow and outlet pressure, featuring a housing and a carrier that supports the movable rotor, and a linear or hydraulic actuator to adjust the rotor position, with a control valve system for closed-loop control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If variable flow internal gear pump is used, then flow rate can be varied, but efficiency deteriorates at low flow rates
Solution Approach 1:
The patent applies the dynamics principle by making the rotor axis movable rather than fixed. The rotor axis can move dynamically to adjust the clearance between rotors, thereby varying the flow rate. This dynamic adjustment allows the pump to maintain efficient operation across different flow conditions, resolving the contradiction between flow variation capability and efficiency at low flow rates.
Solution Approach 2:
The patent changes the physical parameter of rotor axis position to control flow rate. By moving the rotor axis to different positions, the clearance between rotors is adjusted, which directly changes the leakage flow and net flow rate. This parameter change enables the pump to achieve variable flow operation while maintaining efficiency.
2Loss of energy
If external gear pump is used, then efficiency is maintained at all flows, but flow rate cannot be varied independently of speed
Solution Approach 1:
The patent makes the rotor axis movable to enable independent flow control. By dynamically adjusting the rotor axis position, the pump can vary the flow rate independently of the drive shaft speed. This dynamic mechanism allows the external gear pump architecture to achieve variable flow capability while maintaining its efficiency advantages.
Solution Approach 2:
The patent segments the rotor assembly into movable and fixed components. The movable rotor axis is supported by a carrier that can be actuated independently, allowing the flow control function to be separated from the drive mechanism. This segmentation enables independent flow rate adjustment without affecting the efficient external gear pump operation.
3Adaptability or versatility
If movable rotor axis is implemented, then flow rate can be varied, but device complexity increases
Solution Approach 1:
The carrier mechanism serves multiple functions: it supports the movable rotor axis, provides a sealing surface for the rotor, and acts as an actuator mounting platform. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity while achieving flow rate variation.
Solution Approach 2:
The system uses the working fluid pressure itself to actuate the carrier and adjust the rotor axis position. The pressure differential across the carrier creates the force needed to move the rotor axis, eliminating the need for separate actuation mechanisms. This self-service approach minimizes additional complexity.
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
Enables efficient and robust variable flow operation independent of speed, maintaining consistent system oil pressure and reducing inefficiencies at low flow rates, applicable to both pumps and motors.
Implementation Method 1
a carrier movable relative to the housing; in which the movable rotor is mounted on the carrier... varying the output of the hydraulic machine by moving one or both of the first and second rotor axes relative to the other
Data Source
AI summary
A variable flow external rotor hydraulic machine (10, 10′) has an inlet (26, 26′) an outlet (28, 28′), a rotor set having a first rotor (58, 58′) mounted for rotation about a first rotor axis and a second rotor (68, 68′) mounted for rotation about a second rotor axis, the machine being configured as either a pump or a motor, in which at least one of the first and second rotor axes is movable relative to the other to vary a leakage flow between the rotors.