Mixing Chamber Inlet Geometry for Pump Cavitation Suppression
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Solution Overview
Problem
Hydraulic pumps, such as hydraulic vane pumps, are prone to cavitation at high rotation speeds, leading to potential damage and noise, especially when the minimum inlet pressure is lower than the vapor pressure of the conveyed medium.
Innovation Solution
A mixing chamber with a charging inlet designed as a confuser, constriction, and diffuser, where the diffuser has a single side surface inclined at an angle relative to the longitudinal axis, is used to increase the cavitation rotation speed and improve pump charging by optimizing the flow energy distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pump rotation speed is increased to meet high oil demand at low motor speeds, then oil supply to transmission is improved, but cavitation risk increases
Solution Approach 1:
The patent applies preliminary action by introducing a charging flow before the main suction flow enters the pump. This charging flow pre-pressurizes the fluid in the mixing chamber, raising the inlet pressure above vapor pressure before the fluid reaches the pump inlet. By preparing the fluid in advance with sufficient pressure and kinetic energy, the system prevents cavitation from occurring during high-speed pump operation while maintaining high productivity
2Productivity
If excess fluid is fed back into the pump to improve oil supply, then transmission consumer supply is improved, but pump rotation speed increases leading to cavitation
Solution Approach 1:
The patent introduces a mixing chamber as an intermediary component between the pump outlet and inlet. This mixing chamber receives both the suction flow and the charging flow (excess fluid from pump outlet), mixes them together, and delivers the combined flow to the pump inlet. The mixing chamber acts as a mediator that allows the excess fluid to be utilized productively while preventing cavitation through proper flow mixing and pressure equalization
3Stress or pressure
If minimum inlet pressure is lower than vapor pressure of conveyed medium, then pump can operate at lower pressures, but cavitation occurs causing damage and noise
Solution Approach 1:
The patent applies parameter changes by modifying the pressure parameter of the fluid before it enters the pump. The charging flow increases the kinetic energy and pressure of the suction flow in the mixing chamber, changing the pressure parameter from below vapor pressure to above vapor pressure. This parameter change prevents cavitation while allowing the pump to maintain its operating pressure characteristics
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 reduces cavitation by increasing the cavitation rotation speed and improving the guiding of the charging stream, thereby reducing kinetic energy loss and enhancing the efficiency of the fluid pump.
Implementation Method 1
the charging inlet comprises at least a first fluid-guiding section (24) designed as a confuser, a second fluid-guiding section (25) designed as a constriction and a third fluid-guiding section (26) designed as a diffuser
Implementation Method 2
the diffuser is formed by a single side surface (27) inclined by an angle (W) relative to a longitudinal axis (L) of the inside space (20)
Data Source
AI summary
A mixing chamber for generating a pump charge in a fluid pump has an inner wall defining an inside space. A suction inlet is configured to be connected to a fluid source from which it draws a fluid. A charging inlet is configured to admit a fluid stream into the inside space and thereby to generate the pump charge. An outlet from the inside space is configured to let the fluid in the inside space out of the mixing chamber. The charging inlet includes a first fluid-guiding section configured as a confuser, a second fluid-guiding section in the form of a constriction, and a third fluid-guiding section configured as a diffuser. The constriction is located between the confuser and the diffuser and has the smallest diameter within the charging inlet. The diffuser is formed by an inclined side surface.