Flow-Select

Flow-Select: Discretely adjustable displacement pump

Challenge

Within a hydraulic system, hydrostatic pumps supply the consumers with volume flow. In general, hydrostatic pumps are divided into two groups: Constant displacement pumps with fixed flow rate and variable displacement pumps with adjustable flow rate. Variable displacement pumps make it possible that only the volume flow actually required is provided. This leads to a large reduction of waste. A major disadvantage, however, opposing the use of a variable displacement pump is the high acquisition cost. Variable displacement pumps are significantly more costly than fixed displacement pumps because a complex variable and control system is required. This means that in many applications constant pumps are still used for supply, despite the considerable loss of efficiency.

Solution

The invention is characterized by the fact that it uses several constant displacement pumps connected in parallel. These pumps can be switched on or off individually, thus enabling different volume flow stages to be realized. A novel hydraulic-mechanical control device automatically selects the appropriate volume flow stage so that the flow rate is always optimally adapted to the demand. The constant displacement pumps can be of any type. For example, less expensive gear pumps can also be used. The invention allows simple and cost-effective volume flow adjustment. Thus, a higher efficiency can be achieved compared to a constant displacement pump and the realization would be feasible for a fraction of the price of a conventional variable displacement pump. Such a pump would be well suited for applications where constant displacement pumps are too inefficient and conventional variable displacement pumps are too expensive.

Advantages

• Purely hydraulic-mechanical controller, resulting in a very robust design
• Relatively inexpensive
• Applicable in different system architectures
• Number and size of the stages can be selected according to the application

Status

• Patent pending: Not yet disclosed. No rights against third parties can be derived from the patent application not yet disclosed.
• State of development: The concept has been simulated and a prototype for functional verification is currently being developed.

RWTH Aachen University is looking for partners for patent exploitation AND/OR research partners for development cooperation.

RWTH Technology #2269

Areas of application Fluid technology systems

Key words #Digitalpump #hydraulic-mechanical #Controlling