GB2236017A - Fluid movement signalling device - Google Patents

Abstract

A fluid movement signalling device comprises a body 5 having a passage 6 through which fluid can flow and a float 11 mounted in the passage for movement in the direction of fluid flow, float 11 being restrained against angular movement about an axis parallel to the direction of flow through the passage e.g. by ribs (8a, b) on body 5 and fins (12) on the float (Fig 3). The device also comprises a permanent magnet 14 movable with the float and having a magnetic axis 9 transverse to the direction of flow through the passage, and a sensor, such as a reed switch 15, or Hall effect device, responsive to movement of the float/magnet for signalling the presence or absence of fluid flow. Compartment 16 may serve as a junction box or may house circuit boards or other components. Body 5 and float 11 may be acetal resin. The float may be opposed by a spring enabling mounting in any orientation. <IMAGE>

Description

Fluid Movement Signaling Device This invention relates to a fluid movement signalling device.

According to the present invention, there is provided a fluid movement signalling device comprising a body having a passage through which fluid can flow, a float mounted in the passage for movement in the direction of fluid flow through the passage, means restraining the float against angular movement about an axis parallel to the direction of flow through the passage, a permanent magnet movable with the float and having a magnetic axis transverse to the direction of flow through the passage, and a sensor responsive to movement of the magnet, and hence of the float, for signalling the presence or absence of fluid flow through the passage.

Preferably, the sensor is housed in a compartment provided in the body and isolated from the passage.

Conveniently, the sensor is in the form of a reed switch, although alternatively it could be, for example, a Hall Effect device.

Preferably, the permanent magnet is provided in the float.

Conveniently, the float has inner and outer parts and the permanent magnet is supported by the inner part. In this case, the inner and outer parts may be snap-fittable together.

Preferably, the permanent magnet is a bar magnet Preferably, the body has a plurality of angularly spaced ribs which project into the passage and which support the float for movement in the direction of fluid flow through the passage whilst defining channels through which the fluid can flow between the body and the float. In this case, the restraining means may comprise the ribs and parts on the float co-operable with the ribs.

The invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a sectional view of one embodiment of a fluid movement signalling device according to the invention, taken along line I-I of Figure 3, Figure 2 is a sectional view of the device shown in Figure 1, taken along the line II-II of Figure 3, Figure 3 is a sectional view of the device shown in Figures 1 and 2, taken along the line III-III of Figure 1, and Figure 4 is an exploded perspective view of the float of the device shown in Figures 1 to 3.

Referring to the drawings, the device shown therein comprises a body 5 having a central vertical passage 6 and four equi-angularly spaced longitudinally extending ribs 8a, 8k, 9 and 10, projecting into the passage 6. The ribs are so dimensioned that they support a float 11 in a vertical position whilst maintaining free movement of the float up and down. The float has fins 12 which co-operate with the ribs 8a and 8b to restrain the float against angular movement about the longitudinal axis of the passage 6.

At its lower end, the passage 6 has a reduced diameter portion 13 the diameter of which corresponds to the diametrical clearance between the free edges of opposed ribs. The float 11 is arranged so that in the absence of fluid flow through the passage 6 the lower end of the float is disposed in the portion 13 of the passage 6, this position being defined by the length of the float fins 12.

A permanent bar magnet 14 is provided within the float 11 and a sensor in the form of a reed switch 15 is housed in a compartment 16 which is formed in body 5 and which is isolated from the fluid flow. The magnetic axis of the magnet 14 is perpendicular to the axis of the passage 6, and in the absence of fluid flow through the passage 6, the magnet 14 is aligned with the centre of the reed switch 15. The compartment 16 extends into the rib 10 so that the reed switch 15 can be in close proximity with the magnet 14. In the rest position shown, the magnet 14 is aligned with the centre of the reed switch 15 and the reed switch is in an open condition thus interrupting an electrical circuit through the reed switch.

The body 5 has an input port 18 at its lower end and an outlet port 23 at its upper end. When fluid flows through the body 5 in the direction of arrow C there comes a point (determined by the weight of float 11 and the clearance between the float 11 and the reduced diameter portion 13 of the passage 6) when the float rises from its rest position and floats upwards until it comes into contact with a stop bar 17. At this position, the magnet 14 influences only one blade of the reed switch 15 causing the switch contacts to close and complete an electrical circuit.

In the embodiment shown, the inlet port 18 has an internal thread and the outlet port 23 has an external thread and both ports 18 and 23 have diameters which are comparable with the diameter of the passage 6.

The compartment 16 is formed on one side of the body 5 and is large enough to serve as a junction box or to house circuit boards or other components, as well as the reed switch 15. The compartment 16 is closed by a cover 21 secured in place by a screw 21.

The ribs 8a and 8b extend into the outlet port 23 and are each provided with a groove 7. These grooves 7 locate and house the stop bar 17. On assembly the stop bar 17 is inserted through the outlet port. The stop bar 17 is U-shaped with barbed ends that hold the bar captive once inserted.

The float 11 is prevented from travelling through the passage 6 by the stop bar 17 positioned across the outlet port.

When the device is in a full-flow condition (as shorn in Figure 2) the float 11 takes up a position against the stop bar 17. In this condition the flow is unimpeded through the portion 13 of the passage 6 flows around the float 11 between the ribs 8a, 8k, 9 and 10 and out through the outlet port 23.

An 'O'-ring seal can be located against a shoulder between portion 19 and the threaded portion of the inlet port 18 and insertion of the '0'-ring seal is facilitated by means of tapered portion 20.

In the embodiment shown the magnet is of square section in a plane normal to its magnetic axis and of rectangular section in a plane parallel its axis.

This ensures that the magnet can only be fitted in a mating hole in the float 11 with its magnetic axis correctly aligned.

The float 11 comprises an inner plug 24 and an outer shell 25. The inner plug 24 has a hole 28 of square cross-section to accommodate the magnet 14 with its axis correctly aligned. The ends of the magnet 14 protrude from the hole 28 and co-operate with the outer shell 25 to ensure that the magnet 14 will always have its magnetic axis at right angles to the fins 12.

The shell 25 and the plug 24 are snap fittable together by a split button end 26 on the plug 24 co-operating with a mating hole 27 in the shell 25.

The body 5 and float 11 are of non-magnetic material, such as acetal resin.

The device can be used to detect liquid movement or to detect gaseous movement such as movement of air in a pneumatic system.

As shown, the reed switch 15 is open when there is no flow and is closed when there is flow.

However, this can be reversed by changing the position of the reed switch or the magnet. Alternatively, the reed switch could have a set of change-over contacts or more than one reed switch could be provided.

Other devices which can sense or are stimulated by a magnetic field can be used in place of the reed switch - for example Hall Effect devices.

In the embodiment shown the float acts against gravity and thus must be vertically mounted with fluid movement upwards. In an alternative arrangement, the float could be opposed by a spring thus enabling it to be mounted in any orientation and increase its operating range.

Claims (10)

1. A fluid movement signalling device comprising a body having a passage through which fluid can flow, a float mounted in the passage for movement in the direction of fluid flow through the passage, means restraining the float against angular movement about an axis parallel to the direction of flow through the passage, a permanent magnet movable with the float and having a magnetic axis transverse to the direction of flow through the passage, and a sensor responsive to movement of the magnet, and hence of the float, for signalling the presence or absence of fluid flow through the passage.

2. A device according to Claim 1, wherein the sensor is housed in a compartment provided in the body and isolated from the passage.

3. A device according to Claim 1 or Claim 2, wherein the sensor is in the form of a reed switch.

4. A device according to any one of the preceding claims, wherein the permanent magnet is provided in the float.

5. A device according to Claim 4, wherein the float has inner and outer parts and the permanent magnet is supported by the inner part.

6. A device as claimed in Claim 5, wherein the inner and outer parts are snap fittable together.

7. A device as claimed in any one of the preceding claims, wherein the permanent magnet is a bar magnet.

8. A device as claimed in any one of the preceding claims, wherein the body has a plurality of angularly spaced ribs which project into the passage and 5 which support the float for movement in the direction of fluid flow through the passage whilst defining channels through which the fluid can flow between the body and the float.

9. A device as claimed in Claim 8, wherein the 10 restraining means comprises the ribs and parts on the float co-operable with the ribs.

10. A fluid movement signalling device substantially as hereinbefore described with reference to the accompanying drawings.