Drive System for a Cleaning Head Disposed in a Tank

Abstract

When, according to the invention, constructing a drive system for rotating the cleaning head in a tank and allowing the system to comprise a hysteresis coupling having two magnetic parts which are present inside the liquid space (4) and outside this, respectively, a completely liquid-tight separation between the housing (2) and the gear (14) may be ensured. The magnetic part (8, 18) of the hysteresis coupling may be formed by electromagnets, and with a displaceable (13) position of the one part relative to the other part (11, 19) the coupling may be adjusted with respect to the transferred torque and / or speed.

Description

THE PRIOR ART[0001]The invention relates to a drive system for rotating a cleaning head in a tank, said drive system comprising a housing having a propeller mounted in a liquid channel to which cleaning liquid is supplied under pressure, as well as a gear which is driven by the propeller, and which is mounted separated from the cleaning liquid in the housing as a safeguard against leakage of cleaning liquid, said gear transferring the rotation produced by the propeller to a reduced rotation of the cleaning head in the tank, wherein the rotation produced by the propeller is transferred to the gear via a magnetic coupling having coupling parts, the one coupling part of which being disposed inside the housing in the liquid channel and the other coupling part of which being disposed outside the housing, and wherein the coupling parts are configured either as mutually parallel discs or as two cylindrical, concentrically mounted discs.[0002]As a safeguard against leakage it is known to se...

AI Technical Summary

Benefits of technology

[0009]Such a hysteresis coupling provides for an unprecedented possibility of ensuring a quite certain torque transfer of the rotating movement also at the start phase for cleaning heads for tanks. It has been found that in spite of the great difference in the speed of rotation at the moment of start between the driving and the driven magnetic parts, the hysteresis coupling is capable of supplying a torque which is sufficiently great to accelerate the driven magnetic part and thereby the gear in terms of speed, if it is dimensioned correctly, that is that it can transfer a torque which is greater than the starting torque. The advantageous properties of the hysteresis coupling include e.g. its ability to transfer an almost constant torque independently of the relative speed between the coupling parts, and the ability of the coupling to operate with a continuous or varying slip, said slip being “soft” and without any detrimental effect on the structure.

Problems solved by technology

This may take place by means of various gaskets and stuffing boxes, but it has been found that these do not always operate reliably, in particular after wear, liquid exposure and ageing.

No gear mechanisms are included in the system, and its speed cannot be adjusted.

In practice, however, it is difficult to make such a magnetic coupling having permanent magnets work in connection with cleaning heads for tanks, especially because of a relatively great starting torque and the high speed of rotation of the driving magnetic part at the moment of start.

The coupling slips in a jerky and shaking manner, because the magnetic forces are interrupted and can then only transfer very small torques.

To this should be added that such a magnetic coupling cannot readily be set to transfer a variable torque or a variable speed.

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