GB2063565A

GB2063565A - Switch device responsive to fluid flow

Info

Publication number: GB2063565A
Application number: GB7939860A
Authority: GB
Original assignee: Kohler Mira Ltd
Current assignee: Kohler Mira Ltd
Priority date: 1979-11-17
Filing date: 1979-11-17
Publication date: 1981-06-03
Also published as: GB2063565B

Abstract

A reed contact unit 3 is carried on the outside of a body 2 through which fluid flows from an inlet to an outlet 25 with an intermediate chamber 7 in which a flow responsive member 5 is displaceable by fluid flow. The member 5 includes a thimble portion 12 with a closed crown 13 extending into the inlet port 8, and ports 14 in the side wall of the thimble portion are uncovered on displacement from a land 19 in the inlet to permit full flow from the inlet through the ports 14 and into the chamber 7. On such displacement a magnet 6 carried on a sleeve portion 16 of the flow responsive member 5 is brought into close proximity to the reed contact unit 3 to actuate its contacts. <IMAGE>

Description

SPECIFICATION Switch device responsive to fluid flow Description: This invention relates to a switch device responsive to fluid flow, in particular a switch device for use with a fluid flow line, such as a water supply pipe.

The switch device of this invention has special application for controlling the operation of a booster pump in a water supply line to a shower o. similar ablutionary appliance so that when the control for the appliance is turned on, the initial flow pressure actuates the switch device that is connected by suitable means to the booster pump which is thereby switched on. Conversely, when the appliance is turned off, the water flow decreases or ceases and the reduction in flow actuates the switch device again whereby the booster pump is switched off.

It is already known to provide switch devices in which a flow responsive member in a fluid flow line is arranged to move under changes in hydraulic pressure or flow rates, and such movement trips or actuates a switch.

However, such prior switch devices are unsatisfactory in many respects for the special application in an ablutionary appliance.

It is an object of this invention to provide a switch device which comprises a flow responsive member in the fluid flow line but which has an improved construction and arrangement to give advantages that include fast response to initial changes in fluid flow and low impedance to full fluid flow past the flow responsive member. Such advantages and other merits of this invention are described later herein.

According to this invention we provide a switch device responsive to fluid flow comprising a hollow body having an inlet leading to a chamber and an outlet leading from the chamber, a flow responsive member within the chamber and carrying a magnet element, a reed switch mounted on the outside of the body aligned with the chamber and arranged for actuation by the magnet element when in adjacent proximity, the flow responsive member having a hollow thimble portion with a closed crown facing into the inlet and with the side wall of the thimble portion being arranged to engage a land in the inlet for cooperation with ports in the side wall, the flow responsive member being arranged for displacement between the inlet and the outlet by fluid flow through the body whereby, on initial flow the fluid acts on the thimble portion which moves away from the inlet land to the chamber and the magnet element is carried to a position adjacent the reed switch to actuate same, and on such movement the ports of the thimble portion are displaced relative to the land permitting full flow from the inlet through the ports and into the chamber to the outlet.

It will be appreciated that whilst fluid flow continues, the flow responsive member is maintained displaced away from the inlet and the reed switch is also maintained in the actuated (or "on") position whilst the magnet element is in close proximity. When the flow decreases, such as by shutting off the fluid supply to the inlet, the flow responsive member will not be supported by the fluid flow acting on the thimble portion, and it will move towards the inlet carrying the magnet element away from the reed switch whereby it will be de-actuated to the "off" position.

The arrangement for the electrical connection to the reed switch can be of any suitable type responsive to actuation and de-actuation of the reed switch.

With the invented switch device, the flow responsive member with the thimble portion provides for a fast response to fluid flow as the crown of the thimble portion extends into the inlet and provides a substantial area on which the fluid pressure can act. In this regard, the flow responsive element can respond to very low pressures such as are encountered in ablutionary systems.

Preferably, there is a seating within the chamber which lies adjacent the inlet, and the flow responsive member includes an abutment adapted to engage such seating to limit the extent of the thimble portion within the inlet.

Such seating may comprise a shoulder defining one end of the chamber, and the abutment may comprise a flange or rib on the flow responsive member.

The provision of such abutment and seating permits the flow responsive member to settle to an "off" position and to be located when there is no fluid flow.

Conveniently, such flange or rib also provides a face for locating the magnet element on the flow responsive member so that the distance between the magnet and the reed switch for the "off" position can be maintained constant and predetermined.

The land formed in the inlet is arranged to close the ports in the side wall of the thimble portion when the flow responsive member is in the "off" position so that the thimble portion acts in the manner of a piston which is driven by fluid pressure out of the inlet.

However, the device may include adjacent the land a narrow clearance of seepage gap between the side wall of the thimble portion and the inlet so that a limited degree of seepage may occur without interfering with the requisite response to fluid flow applying pressure to the thimble crown.

Preferably, in the body the inlet, outlet and chamber are aligned and of generally cylindrical shape with the inlet and outlet being adapted for connection in a fluid supply pipe by means of a threaded connection or a gland coupling. Such an arrangement enables the body to be made of dimensions such that the flow path through the inlet and the outlet, and through the ports and the chamber substantially corresponds to the bore of the fluid supply pipe. Thus, the coupling of the invented switch device into an existing fluid supply pipe can be achieved simply and with out introducing a restriction in the flow capacity through the fluid supply pipe.

The body may comprise an assembly of two parts comprising a first part forming the inlet, and a second part forming the chamber and the outlet with each part being adapted for fluid-tight inter-engagement. The first part preferably has a hollow spigot end portion which is inserted in the second part, and the end face of the spigot end portion provides the seating within the chamber. Furthermore, the spigot end portion has an internal bore constituting the land with which the ported side wall of the thimble portion co-opsrates.

This arrangement of a two part body provides simple assembly and disassambly of the device as required, and servicing or replacement of the flow responsive member can be carried out be disconnecting the two body parts.

It is also an advantage that the flow responsive member with the thimble portion has the wall portion that engages the land within the inlet, for the flow responsive member is guided by such engagement on initial displacement relative to the chamber.

Preferably the chamber is formed in the second body part by a counterbore which provides an internal shoulder at the outlet.

This shoulder provides an abutment or limit for engagement by the flow responsive member on maximum displacement within the chamber.

In the preferred construction of the flow responsive member, the thimble portion extends from one side of the flange or rib, and to the other side there extends a hollow sleeve portion on which the magnet element is received being located thereon between the flange or rib and a retainer fitted to the free end of the sleeve portion.

By locating the magnet element on the sleeve portion it is possible to arrange for the magnet to be brought into close proximity with the reed switch mounted on the outside of the body through which the magnetic force acts on the reed switch. The body is preferably made of a material of non-ferromagnetic material such as brass.

The reed switch is mounted on the outside of the body for location at a predetermined distance in the direction of movement of the flow responsive member. Preferably the location comprises a groove extending around the body in which a housing for the reed switch is received for movement around the body so that it can be adjusted relative to the position of minimum magnetic interference if desired.

The reed switch housing can be mounted on the body and secured thereto by a strap which can be loosened to permit of such adjustment during fitting, or the strap can be undone to permit removal of the reed switch for servicing or the like.

Preferably the reed switch is encapsulated in a plastic compound to protect it from damage, and to insulate the switch in the event that it is contacted by water or other conductive fluid.

The reed switch may be connected to a semi-conductor switch and associated electronic components and circuits remote from the reed switch so that the semi-conductor switch is connected to a pump in the fluid supply line.

An exemplary embodiment of this invention will now be described with reference to the accompanying drawings wherein: Figure 1 is a side elevation of a switch device according to this invention; and Figure 2 is a section on A-A shown in Fig.

1.

With reference to the drawings, the switch device comprises a first body part 1, a second body part 2, a reed switch 3 mounted on the first body part and a strap 4 securing the switch thereto, and there is a flow responsive member 5 and magnet element 6 within a chamber 7 in the second body part 2.

The first body part 1 is hollow and generally cylindrical with a threaded spigot end portion 8 received within the second body part 2 and in threaded engagement therewith for fluid-tight connection. The first body part 1 is arranged and adapted for connection to a fluid supply line, such as a water pipe, and has an internal thread for this purpose.

The second body part 2 is hollow and generally cylindrical and has a hollow externally threaded spigot 9 for connection to a fluid supply pipe. The second body part is counterbored to provide the chamber 7 of which one end has a shoulder 10 formed by the bottom of the counterbore, and the other end has a seating 11 formed by the end face of the spigot 8 of the first body part.

The flow responsive member 5 comprises a thimble portion 1 2 having a closed crown end 1 3 which faces into the inlet to the chamber provided by the spigot 8 of the first body part. The side wall of the thimble portion is formed with four axial ribs 1 2a that separate four axial ports 14 through which fluid can flow in use. The flow responsive member includes an external flange 1 5 of which one face seats on the seating 11 and the opposed face locates the magnet element 6 which is of annular dorm. The magnet element 6 is supported on a hollow sleeve portion 1 6 of the flow responsive member which extends from the flange 15, and the magnet element is secured to the sleeve portion by a retainer 1 7.

The internal bore of the spigot portion adja cent the inlet seating 11 provides a land 1 8 for engagement with the side wall of the thimble portion, and the bore is relieved to provide a narrow clearance or gap 1 9 between the side wall of the thimble portion remote from the land. The gap 1 9 facilitates entry of the crown of the thimble portion fully into the spigot portion without interference or jamming, and the gap is also small enough to ensure that the device is sensitive to small flows of fluid.

The reed switch comprises reed contacts 20 in known rnan,1er which are connected to conductors of a lead wire 21. The contacts are enclosed in a housing 22 which is suitably filled with a potting compound (not shown for clarity) for insulation. The housing has a lug 23 at one end engaging in an annular groove 24 formed on the outside of the second body part to locate the housing, and the reed switch assembly is secured to the second body part by the strap 4. The contacts of the reed switch are positioned to lie adjacent the chamber intermediate the the inlet and outlet.

As will be appreciated the reed switch can be removed from the second body part or loosened and turned around the body part.

The switch device is shown in the drawings in the "off" position in which there is no significant fluid flow from the inlet to the outlet. The direction of flow is indicated by the arrow in Fig. 2. A certain amount of seepage can arise through the limited clearance 1 9 between the thimble portion and adjacent the land 18.

When flow commences, for instance by turning on an appliance connected to the fluid supply line, fluid flows through the hollow spigot and acts on the crown end 1 3 of the thimble portion so as to urge the flow responsive member towards the outlet. As the clearance is restricted the effect of any seepage permitted is neglible, and the initial force is applied to the crown to achieve a fast reaction so that the flow responsive member moves into the chamber lifting the flange 1 5 from the seating 11 and the ports 14 clear from the land 1 8. The ports are thus fuily opened or exposed to the fluid flow which can pass over the crown into the chamber and through the ports to the outlet 25. The maximum movement on displacement of the flow responsive member is limited by the shoulder 10 adjacent the outlet 25.

On such displacement by the fluid flow, the magnet element 6 is lifted into close proximity to the read switch 3 so that the reed contacts 20 are caused to close, and whilst the flow continues the magnet element 6 is maintained in such effective proximity.

When the flow decreases or stops, the flow responsive member 5 is no longer supported within the chamber 7 and it will fall to the "off" position shown to settle on the seating 11. On such movement of the magnet element relative to the reed switch contacts, the reed switch is de-actuated.

On displacement, the movement of the flow responsive member is guided both by the flange 1 5 and retainer 1 7 engaging the wall of the chamber and by the side wall of the thimble portion engaging the land. The diameters of the flange 15 and the retainer 1 are slightly larger than the diameter of the magnet 6 so that the surface area in contact with the chamber are small and frictional resistance is minimised. Such guiding ensures that the flow responsive member cannot jam or twist on fast movement relative to the chamber.

In the embodiment just described, the bore of the chamber and the dimensions of the magnet element and the ports in the flow responsive member are such to ensure that the passageway for full fluid flow through the chamber from the inlet to the outlet is substantially the same as the bore of the fluid pipe. The size of the ports and their arrangement can be varied for different applications.

Additionally, the annular magnet element is so mounted on the sleeve portion that it is brought into close proximity to the reed switch contacts both in the radial and axial directions.

It is envisaged that the body of the switch device could be modified as desired for different applications. The chamber and seating could be provided in one body part providing the inlet with another body part providing the outlet and closing the chamber with a spigot portion inserted in the chamber end of the other body part. Alternatively, the body of the switch could comprise a three part assembly with each end having gland or threaded connector.

The flow responsive member is preferably a moulding of plastic, but it could be of nonferromagnetic material such as brass. It could comprise an assembly of two or more parts.

The magnet is formed of a non-corrosive material and may be a high density permanent magnet of which the magnetic field and strength is sufficient to operate the reed switch in use. Various permanent magnet materials could be employed.

Claims

1. A switch device responsive to fluid flow comprising a hollow body having an inlet leading to a chamber and an outlet leading from the chamber, a flow responsive member within the chamber and carrying a magnet element, a reed switch mounted on the outside of the body aligned with the chamber and arranged for actuation by the magnet element when in adjacent proximity, the flow responsive member having a hollow thimble portion with a closed crown facing into the inlet and with the side wall of the thimble portion being arranged to engage a land in the the inlet for co-operation with ports in the side wall, the flow responsive member being arranged for displacement between the inlet and the outlet by fluid flow through the body whereby, on initial flow the fluid acts on the thimble portion which moves away from the inlet land to the chamber and the magnet element is carried to a position adjacent the reed switch to actuate same, and on such movement the ports of the thimble portion are displaced relative to the land permitting full flow from the inlet through the ports and into the chamber to the outlet.

2. A switch device according to claim 1 wherein there is a seating adjacent the inlet for engagement by an abutment on the flow responsive member.

3. A switch device according to claim 2 wherein the abutment comprises a flange or rib on the flow responsive member.

4. A switch device according to claim 3 wherein the magnet element is located on the flow responsive member and engages one face of the rib or flange.

5. A switch device according to any one of the preceding claims wherein adjacent the land there is a seepage gap or clearance between the thimble portion and the inlet.

6. A switch device according to any one of the preceding claims in which the inlet, outlet and the chamber are aligned and of generally cylindrical shape with the inlet and the outlet being adapted for connection in a fluid supply pipe.

7. A switch device according to claim 6 wherein the body comprises an assembly of two parts of which the first part forms the inlet and the second part forms the chamber and the outlet with each part being adapted for fluid-tight inter-engagement.

8. A switch device according to claim 7 wherein the first part has a hollow spigot end portion which is inserted in the second part and the end face of the spigot provides an annular seating within the chamber adjacent the inlet.

9. A switch device according to claim 8 wherein the hollow spigot end portion has an internal bore consituting the land.

10. A switch device according to any one of claims 7, 8 or 9 wherein the second body part is counterbored to provide the chamber and an internal shoulder at the outlet to limit movement of the flow responsive member.

11. A switch device according to any one of claims 4 to 10 wherein the flow responsive member includes a sleeve portion on which the magnet element is received and located.

12. A switch device according to claim 11 wherein the magnet element is annular and is retained on the sleeve portion by a retainer.

1 3. A switch device according to any one of the preceding claims wherein the reed switch is mounted on the outside of the body and located at a predetermined distance in the direction of movement of the flow responsive member.

14. A switch device according to claim 1 3 wherein the body is formed with a groove and a lug on a housing for the reed switch engages the groove and locates the reed switch on the body.

1 5. A switch device according to claim 1 4 wherein the outside of the body is cylindrical and the groove extends aroung the periphery of the body, the reed switch being mounted on the body by an adjustable strap to permit adjustment of the reed switch on the housing and relocation of the lug in the groove at said predetermined distance.

1 6. A switch device according to any one of claims 13, 14 or 1 5 wherein the reed switch has reed contacts and includes a potting compound for insulating the live contacts.

1 7. A switch device substantially as de scribe with reference to the accompanying drawings.