Pumps – Motor driven – Electric or magnetic motor
Patent
1996-01-16
1997-02-04
Thorpe, Timothy
Pumps
Motor driven
Electric or magnetic motor
310 17, F04B 4304
Patent
active
055991742
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a diaphragm pump with a magnetic actuator.
Magnetic actuators for diaphragm pumps are known and operate by interaction between a magnetic field and electric current flowing in one or more coils or windings. Typically magnetic actuators include an electromagnet incorporating a fixed core and a winding associated with the core, influencing a movable armature also of soft ferromagnetic material. The armature is connected to the diaphragm. It is also known to include one or more permanent magnets mounted on a movable actuator member connected to the diaphragm, with the permanent magnets influenced by an electromagnet. In GB-A-2095766, a single permanent magnet is shown mounted directly on the diaphragm of a diaphragm pump.
Generally, designs known hitherto are intended for low power applications such as aerators for aquariums and little attention has been given to ensuring good magnetic and electrical efficiency.
The present invention provides a diaphragm pump comprising a housing, a diaphragm mounted in the housing for a reciprocating motion in a predetermined direction, the housing and the diaphragm enclosing a pumping chamber so that the diaphragm has inner and outer surfaces relative to the pumping chamber, a permanent magnet assembly secured to the outer surface of the diaphragm for movement therewith, the magnet assembly providing at least a pair of opposed magnetic poles, having all the pole faces of the assembly being adjacent one another and directed away from the outer surface of the diaphragm so as to extend transversely of said predetermined direction of motion of the diaphragm, and an electromagnet assembly having at least a pair of opposite poles located opposite but spaced in said direction of motion from said pole faces of said pair of poles of the permanent magnet assembly.
Preferably, said permanent magnet assembly comprises respective permanent magnets for each of said opposed magnetic poles, one pole of each said permanent magnet providing a respective one of said pole faces directed away from the diaphragm and the other poles of said permanent magnets being directed towards the diaphragm, and at least one soft ferromagnetic back iron member interlinking said other poles of the permanent magnet. With this back iron member, the only effective poles of the complete magnet assembly are those facing away from the diaphragm.
Typically, each of said permanent magnets is formed as a separate piece of magnetisable material. However, it is also possible to form the permanent magnets as separately magnetised parts of a unitary piece of magnetisable material.
Said back iron member can be secured between said permanent magnets and the diaphragm. In preferred arrangements, the thickness of the permanent magnet assembly in said predetermined direction of motion is less than the dimensions of each pole face transverse to said direction.
In a preferred embodiment, the permanent magnet assembly has circular symmetry about an axis in said direction of motion providing one pair of poles comprising an inner central pole and an outer annular pole, and the electromagnet assembly has corresponding circular symmetry.
In another arrangement, the permanent magnet assembly comprises an array of poles of alternating polarity and the electromagnet simply has a corresponding array of alternate poles. Conveniently said arrays are circular.
Conveniently, the electromagnet assembly may comprise a central core element, a single coil wound on said central core element, a star shaped core piece at one end of the central core element having radial arms forming the poles of one polarity in the array, and folded core pieces extending from the other end of the central core element round the coil to lie between the arms of the star shaped core piece and form the poles of the other polarity in the array.
Examples of the present invention will now be described with reference to the accompanying drawings in which:
FIG. 1 is a cross sectional schematic view of a diaphragm pump incorporating a diaphragm
REFERENCES:
patent: 3572980 (1971-03-01), Hollyday
patent: 4533890 (1985-08-01), Patel
patent: 4786240 (1988-11-01), Koroly et al.
patent: 5011380 (1991-04-01), Kovacs
Clark Richard E.
Cook Stephen J.
Huntleigh Technology plc.
McAndrews, Jr. Roland G.
Thorpe Timothy
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