Pumps – Electrical or getter type – Electromagnetic
Patent
1989-02-02
1991-08-27
Smith, Leonard E.
Pumps
Electrical or getter type
Electromagnetic
310 11, H02K 4406
Patent
active
050429698
DESCRIPTION:
BRIEF SUMMARY
The invention refers to a pump or a control valve for molten metal.
The transport of molten metal from one location to another for various purposes, particularly for casting purposes, has always been a dangerous operation which has been difficult to control.
PRINCIPLES OF KNOWN PUMPS
There are a number of different types of pumps apart from the purely mechanical devices to obtain sufficient pressure to produce movement in molten metal. The straightforward mechanical pumps such as centrifugal pumps have certain limitations due to temperature problems, the durability of the materials in the pump, blockages etc. Using compressed air, pressurized gas or vacuum all require special designs with obvious drawbacks.
Some metal pumps on the market utilize electrical phenomena. These are based on the known phenomenon that when a current carrying conductor crosses a magnetic flux the conductor is subjected to a mechanical force. This principle is used for pumps where a direct current is led through the metal by means of conducting electrodes, which are in contact with the metal. The magnetic flux which crosses the field of current through the metal is created by either a permanent or a DC magnet. The problem with this type of pump is the restricted lifetime of the electrodes and the insulation surrounding them. Another problem is the corrosion of the electrodes which causes impurities in the metal.
The same basic principle could be applied from an asynchronous motor to molten metal pumps. Here, the molten matter is subjected to a travelling magnetic field from a linear wound motor in a duct of refractory material. This is a relatively complex electrical design and great care has to be taken with the refractory material so as to reduce the air space as much as possible.
PURPOSE OF THE INVENTION
The overall objective of the invention is to design a pump or control valve which is simpler and cheaper to produce and operate than known pumps. A more specific aim is to design a pump which satisfies the following conditions: rise in pressure, must be produced by means of a straightforward static coil carrying alternating current (usually at mains frequency) the molten metal.
PRINCIPLE OF THE INVENTION
Based on the above, a pump/control valve could be designed in accordance with the characterizing part of claim of patent 1. Other advantageous features are indicated in the subsidiary claims.
For the sake of simplicity, the principle of the invention will be explained with reference to the pump function. The control valve function is achieved by mounting the pump against the direction of flow.
Another simplification in explaining the means of operation is that reference is made to a cylindrical design of the pump. This is not an absolute necessity should a square or polygonal cross section be preferable for any reason.
A device in accordance with the invention will solve many problems encountered whilst handling molten metal.
As this pump can be fully-regulated from zero to the maximum lifting height it is designed for, it can be advantageously used for: casting for example casting)
The pump can be used to replace the lifting or tipping units which are widely used to obtain adequate head and flow control.
A pump designed for a small pressure rise, but large flow volumes could be used for: of alloy or for the addition of fibres etc.
When used as a control valve for molten metal the pump in the present invention could be located so that a counterpressure to gravitational forces is formed during tapping. As a control valve, this design will allow most of the functions mentioned for the pump to be carried out, however the dimensions could be somewhat less exacting.
EXAMPLE
The illustrations show in FIG. 1 a longitudinal axial section through the central part of a pump designed in accordance with the invention,
FIG. 2A an equivalent longitudinal axial section through an alternative design of the pump in FIG. 1, whilst
FIG. 2B shows a cross section along line A-B in FIG. 2A.
FIG. 3 shows counterwindings in accordance with
REFERENCES:
patent: 2929326 (1960-03-01), Ingels
patent: 3706399 (1972-12-01), Sundberg
R. Panholzer, "Electromagnetic Pumps", Feb. 1963, in Electrical Engineering, pp. 128-135.
Scheuermann David W.
Smith Leonard E.
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