Hydraulic Tank Segmentation for Foam Prevention
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Solution Overview
Problem
In electrohydraulic vehicle steering systems, the high performance of motor pump units leads to violent mixing of air and hydraulic fluid in small, one-piece tanks, resulting in foam formation and decreased efficiency due to air being sucked into the pump.
Innovation Solution
A fluid container with an equalizing chamber and a return chamber, where the suction port for the pump is located within the return chamber, separating high and low kinetic energy fluid regions to prevent mixing, and using flow restrictors and venting means to maintain air separation and prevent foam formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a small one-piece tank is used to reduce installation space and costs, then the tank size is reduced, but violent mixing of air and hydraulic fluid occurs due to high velocity flows
Solution Approach 1:
The tank is divided into multiple chambers (equalizing chamber, return chamber, suction chamber) with distinct functions. Each chamber handles specific fluid flows separately, preventing the violent mixing that would occur in a single chamber. The return chamber receives high-velocity return flow, the equalizing chamber provides a calm air-fluid interface, and the suction chamber supplies stabilized fluid to the pump.
Solution Approach 2:
Different regions of the tank are designed with different flow characteristics. The return chamber has high-velocity flow suitable for receiving return hydraulic fluid, while the equalizing chamber maintains low velocity to prevent foaming. The suction chamber provides stabilized, foam-free fluid to the pump. Each local region is optimized for its specific function.
2Object-generated harmful factors
If flow guiding elements are used to stabilize inflowing hydraulic fluid, then foaming is reduced, but the device complexity increases
Solution Approach 1:
Instead of adding complex flow guiding elements to a single chamber, the invention segments the tank into multiple chambers, each with simple geometry. The chamber walls themselves define the flow paths, eliminating the need for additional flow guiding components while achieving the same stabilization effect.
3Ease of operation
If the suction port is applied in the equalizing chamber, then fluid supply to the pump is provided, but air bound in foam is sucked into the pump
Solution Approach 1:
The suction port is located in a dedicated suction chamber that is fluidically connected to but separate from the equalizing chamber. This segmentation ensures that the suction port draws from a region where fluid has been stabilized and foam has settled, preventing air ingestion while maintaining reliable fluid supply to the pump.
Solution Approach 2:
The return chamber acts as an intermediary between the equalizing chamber and the suction chamber. It receives high-velocity return flow, stabilizes it, and then allows the stabilized fluid to flow into the suction chamber, which then supplies foam-free fluid to the pump. The intermediary chamber prevents direct interaction between the equalizing chamber and suction port.
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 solution effectively prevents foam formation even at high performance densities by clearly separating high and low kinetic energy fluid regions, ensuring efficient operation of the motor pump unit without mixing air and fluid, thus maintaining system efficiency.
Implementation Method 1
the chambers are delimited from one another by chamber walls which have at least one flow restrictor provided therein which is arranged between the chambers
Implementation Method 2
the return chamber being provided with a suction port for a pump
Data Source
AI summary
A fluid container, in particular a hydraulic tank for a motor pump unit, has an equalizing chamber that is adapted to contain a supply of fluid and air, and at least one return chamber into which a return flow of the fluid can flow, a fluid communication being provided between the return chamber and the equalizing chamber. The return chamber is provided with a suction port for a pump, in particular of the motor pump unit.