Coolant Pump for electric motors description/claims

The invention relates to a fluid-cooled electric motor having an internal cooling circuit through flown by a rotary-motor cooling pump.

Large electric motors require cooling units for dissipating heat. Both gases and fluid media are utilized as cooling mediums. Since convection is usually not sufficient for the dissipation of power, ventilators or pumps are used for generating flow.

Often it is the electric motor that drives these components. The impeller or pump wheel is directly connected to the shaft of the motor. If rotation speeds other than the nominal shaft rotation speed are required, solutions having an intermediary transmission or clutches are used. With pumps that have to be utilized in explosive environments, these components must additionally meet the EX protection requirements (prevention of sparks). Commonly, such components are produced in small quantities only, and are very expensive. Thus, they have a substantial influence on the costs of the entire assembly. Due to the rigid coupling using the shaft of the motor, the cooling medium is circulated even if there is no need for cooling. This reduces the performance efficiency of the machine.

It is therefore an object of the invention to improve the drive of the cooling circuit of an electric motor in such a manner that a construction that is easy to make is produced, that enables easy installation, that makes it possible to adjust the cooling power so it is tailored to the individual need, and particularly that makes measures for EX protection unnecessary.

This object is attained according to the invention in that the cooling pump has a shaft separate from the electric-motor shaft and is partially or completely within the housing of the electric motor.

A wet-rotor pump, produced in large quantities, is installed into the electric motor. In this manner, significant cost reductions can be achieved, and the pump can be operated independently of the rotation speed of the shaft. This means that the medium is circulated only, if cooling is required. With the use of a pump with variable rotation speed, the cooling output can be adjusted according to need. With the installation of the pump in the motor, additional measures for EX protection are not necessary, or can be done at a significantly reduced expense as opposed to externally operated assemblies.

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Coolant Pump