GB2081521A - A.C. energised gas pumping device - Google Patents

Abstract

An alternating current energised gas pumping system has a drive system comprising an electromagnet (20-23) energised from an AC mains supply (24) and a movable magnetic element (17) mechanically coupled by a pivoted lever (15) to drive a gas pump (10). Means such as a threaded rod (25) are provided for adjusting the relative magnetic coupling between the magnet and the driving magnetic element (17) of the pump, e.g. by moving the electromagnet with respect to the magnetic element or by adjusting the position of a magnetic screen between the electromagnet and the element. This enables the gas flow from the pump to be adjusted by a simple mechanical adjustment. <IMAGE>

Description

SPECIFICATION Alternating current energised gas pumping devices This invention relates to alternating current energised gas pumping devices.

It is well known to use alternating current energised diaphragm type pumps as aerators for aquaria. It is the usual practice to use an electromagnet energised from an alternating current mains supply to attract and repel alternate half cycles, a permanent magnet which is mechanically coupled to a diaphragm of a diaphragm-type gas pump. Such pumps are normally constructed to have a fixed displacement. To obtain an adjustable air flow, an electronic control may be provided for adjusting the electrical power input to the system or alternatively an adjustable air bleed may be used.

It is an object of the present invention to provide improved means for effecting an adjustment of the gas flow from such a pump.

According to the present invention, an alternating current energised gas pumping device has a drive system comprising an electromagnet adapted to be energised from an alternating current supply and a movable magnetic element associated with the electromagnet and mechanically coupled to drive a gas pump and means are provided for adjusting the relative magnetic coupling between the magnet and the driving magnetic element of the pump.

In one simple form the means for adjusting the magnetic coupling may comprise means for changing the relative physical positions of the electromagnet and the driving magnetic element.

The movable magnetic element may be a ferromagnetic armature and, in this case, threaded adjusting means may be provided for moving the magnetic element towards and away from the electromagnet. The armature in such an arrangement is attracted towards the electromagnet against a resilient return force, conveniently provided by the diaphragm if a diaphragm-type pump is used. The armature thus vibrates. The adjustment is of the mean position of the armature.

Alternatively the movable magnetic element may be a permanent magnet movable across the face of the electromagnet. In this case, the means for adjusting the magnetic coupling may comprise a movable magnetic shunt element arranged to control a shunt flux path diverting magnetic flux away from the magnetic element. A screw adjustment may be provided to control the position of the shunt.

In another construction having a permanent magnet movable across the face of the electromagnet, the adjusting means comprise threaded adjusting means arranged for altering the mean position of the permanent magnet with respect to the electromagnet in the direction of the vibrating motion.

The following is a description of three embodiments of the invention, reference being made to the accompanying drawings in which Figures 1, 2 and 3 are diagrammatic sectional views illustrating respectively the three different embodiments.

Referring to Fig. 1, there is shown diagrammatically a gas-type diaphragm pump 10 having a diaphragm 11 forming part of the wall of a chamber 1 2 having a flap-type inlet valve 1 3 and a flap-type outlet valve 14. Vibration of the diaphragm is effected by means of a lever arm 15 which at one end is pivoted at 1 6 and at the other end is fixed to an elongate permanent magnet 1 7 having poles N, S which normally lie across but spaced from poles 20, 21 on the yoke 22 of an electromagnet 1 8 having a winding 23 with leads 24 for connection to a 50 or 60 Hz alternating current mains supply. The length of the permanent magnet 1 7 is less than the spacing between the poles 20, 21.

It will be seen that, on alternate half cycles of the mains supply, the pole N of the permanent magnet 1 7 is alternately attracted to and repelled from the pole 20 of the electromagnet 1 8. During these alternate half cycles pole S is alternately repelled from and attracted to the other pole 21 of the electromagnet and thus the permanent magnet 1 7 is caused to vibrate mechanically across the face of the electromagnet thereby alternately compressing and pulling out the diaphragm 11 of the diaphragm pump 10.

In the arrangement of Fig. 1, the magnetic coupling between the electromagnet 18 and the permanent magnet 1 7 is adjusted by means of an adjusting screw 25 which engages a captive nut 26 on the electromagnet thereby enabling the electromagnet to be displaced in the axial direction of the permanent magnet. As the screw 25 is rotated, the electromagnet 1 8 is gradually moved further away from the symmetrical position with respect to the poles N, S of the permanent magnet 17, so reducing the driving power applied to the pump 10.

Fig. 2 illustrates another embodiment of aerator for an aquaria. In Fig. 2 a diaphragmtype pump is shown diagrammatically at 30 with the diaphragm 31 and an air outlet 32.

The pump is mounted in a cap member 33 forming an end closure for a housing 34, the cap member having a flange 35 with a thread 36 engaging an external thread 37 on the member 34. The member 34 is cylindrical and houses an electromagnet 38 having a coil 39 around a central pole 40 on a pot-type core 41 having an annular outer pole 42. The central pole is coaxial with the housing. A ferromagnetic armature 43 of disc shape form is mounted on the diaphragm 31 and faces the poles of the electromagnet, being spaced from these poles by a distance which, ignoring the bellows deflection, can be adjusted by rotation of the cap member 33 on the housing 34. The diaphragm 31 provides a resilient return force for the armature 43 which is attracted electromagnetically to the electro magnet.The armature thus vibrates at a fre quency determined by the alternating supply frequency but the magnetic coupling and hence the amplitude of the vibration will de pend on the adjustment of the position of the cap 33 on the housing 34.

In the construction shown in Fig. 3, there is shown an electromagnet comprising a soft iron U-shaped yoke 50 having two poles 51, 52 with a winding 53 around the yoke arm forming the pole 52. This winding is energised from an alternating current supply at terminals 55, 56. A permanent magnet 57 of bar-shaped form extends across the poles of the yoke but spaced therefrom, the length of the magnet being less than the spacing between the poles. This magnet is mounted on a lever arm 60 pivoted at 61 in an arrangement similar to that shown in Fig. 1 and is con nected to a diaphragm 62 of a diaphragmtype gas pump 63 having an outlet 64. The arrangement of Fig. 3, as thus far described, operates in a similar manner to that of Fig. 1, the alternating current causing the permanent magnet to vibrate and hence to drive the pump.In the arangement of Fig. 3, the pump and the electromagnet are fixed relative to one another in a support structure and adjustment of the magnetic coupling between the electro magnet and the permanent magnet is effected by means of a movable soft iron element 66 in the gap between the yoke poles and the permanent magnet, the soft iron element forming a partial shunt for the flux between the poles of the electromagnet. The position of the element 66, which is conveniently an elongate member extending across one pole of the electromagnet in a direction substantially towards the other pole, can be effected by means of a screw 67 carrying a nut 68 on which the element 66 is mounted. The shunt 66 will not effect the drive to the pump when the shunt is fully removed from the gap between the electromagnet and the perma nent magnet. However as it is moved in between the magnet and the electromagnet, the magnetic forces on the permanent magnet -will be reduced and hence the output of the pump will be reduced.

Claims (7)

1. An alternating current energised gas pumping device having a drive system com prising an electromagnet adapted to be ener gised from an alternating current supply and a movable magnetic element associated with the electromagnet and mechanically coupled to drive a gas pump and means for adjusting the relative magnetic coupling between the magnet and the driving magnetic element of the pump.

2. A pumping device as claimed in claim 1 wherein the means for adjusting the relative magnetic coupling comprise means for changing the relative physical positions of the electromagnet and the driving magnetic element.

3. A pumping device as claimed in claim 2 wherein the movable magnetic element is a ferromagnetic armature and wherein the adjusting means comprise threaded adjusting means for moving the magnetic element towards and away from the electromagnet.

4. A pumping device as claimed in claim 3 and having resilient means arranged for moving the armature away from the electromagnet.

5. A pumping device as claimed in claim 2 wherein the movable magnetic element is a; permanent magnet movable across the face of the electromagnet and wherein the adjusting means comprise threaded adjusting means arranged for altering the mean position of the permanent magnet with respect to the electromagnet in the direction in the vibratory motion.

6. A pumping device as claimed in claim 1 wherein the means for adjusting the relative magnetic coupling comprises a movable magnetic shunt element arranged to control a shunt flux path diverting magnetic flux away from the magnetic element.

7. A pumping device substantially as here it before described with reference to Fig. 1 or Fig. 2 or Fig. 3 of the accompanying drawings.