Patent ID: 8680729

Claim:
A motor drive, particularly for submersed electric pumps, comprising a jacket closed hermetically by a bottom and by a head in order to form a first hermetic chamber, said first hermetic chamber containing an electric motor that is immersed in a bath of dielectric cooling liquid, said jacket being associated with an enclosure in order to form a second hermetic chamber, said second hermetic chamber containing a power supply and control unit that can be connected to said electric motor, said motor drive comprising a compensation means that balances the variations in volume of said dielectric cooling liquid and generates an overpressure with said first hermetic chamber, said first hermetic chamber being substantially independent of said second hermetic chamber, said compensation means comprising a first elastic bellows member, which is accommodated in a first seat that is formed in said bottom and is arranged between said first hermetic chamber and said second hermetic chamber, said first elastic bellows member being joined to said bottom in order to form at least part of said first hermetic chamber, said bottom engaging axially within said enclosure in order to close said second hermetic chamber hermetically, said first elastic bellows member comprising an elastic return portion that is joined to a deformable supporting portion, said elastic return portion comprising at least one first cylindrical body that is closed at one end by a dome, said deformable supporting portion comprising at least one second cylindrical body that is joined coaxially to said first cylindrical body, a free end of said second cylindrical body being joined to said bottom.