GB2173344A - Fluid supply device including fluid pressure operated switch - Google Patents

Abstract

A flow operated switch comprises a chamber 1 having a fluid inlet 2 connected to a fluid supply line 6 and a fluid outlet 4 located downstream of the inlet relative to the direction of flow of fluid and a piston 8 at least part of which is made of a magnetic material, and which is located within the chamber 1. A force being applied by a spring 13 to the piston 8 which urges it towards one end of the chamber 1 and, magnetically affected switch contacts are located adjacent the chamber. The piston 8 may move between an OFF position wherein the fluid outlet 4 is closed by the piston 8 to an ON position when the fluid outlet 4 is open, said piston 8 being shaped so that there is no restriction of the flow of fluid through the chamber 1 when the piston 8 is in the ON position; movement of the piston 8 between the OFF and ON positions causing the consequent operation of the magnetically affected switch contacts. <IMAGE>

Description

SPECIFICATION Fluid supply device including fluid pressure operated switch The present invention. relates to fluid supply devices incorporating fluid pressure operated switches, and it is particularly, though not exclusively, concerned with water supply devices for use with powered shower systems.

In many fluid supply systems it is desirable to include electrically operated devices, for example electric pumps, which are switched on and off by changes in the fluid pressure in the fluid supply system. However, in many cases it is desirable to keep the fluid in a fluid supply device separate from any electrical components in a switch, particularly when the fluid in question is water.

A previously proposed switch of such a type is described in GB 1 604 247, said switch comprising a hexagonal float located within a circular water pipe. A portion of circular cross section and reduced diameter is provided at the upstream end of the float, this portion seating in a portion of the pipe which has a similarly reduced diameter. The float is provided with a magnet which causes actuation of an associated reed switch when the water pressure is turned on. However, this construction suffers from the disadvantage that even in the open position the bore of the pipe is restricted by the float causing a restriction in flow. Also the float can become jammed by any solid matter which becomes stuck between the float and the pipe and so efficient operation of the switch is prevented.

It is an object of the present invention to provide a flow switch which does not suffer from these problems.

A particular application of such a switch would be in the water supply system for an electrically pumped shower.

Many household showers are located in upper stories of a building close to the water tank which is usually located in the roof space above the uppermost storey. Consequently, the head of water available at the shower does not provide a sufficiently high water pressure in the water supply system for the shower for adequate operation of the shower.

In order to overcome this problem, electrically powered pumps are often installed in the water supply system for a shower in order to boost the water pressure. In such a system, it is desirable that the electric pump begins to operate as soon as a valve connecting the shower to the water supply system is opened.

It is particularly desirable that the electric pump is actuated by the water flow from the water supply as soon as the valve is opened.

However, the problem often occurs that the water flow in the water supply is low for the reasons stated above.

It is an object of the second aspect of the present invention to obviate or mitigate the above mentioned problems and provide a fluid supply device incorporating an electric pump, which is actuated by fluid flow in a fluid supply line.

According to the present invention there is provided a flow operated switch which comprises a chamber having a fluid inlet connected to a fluid supply line and a fluid outlet located downstream of the inlet relative to the direction of flow of fluid, a piston at least part of which is made of a magnetic material, and which is located within the chamber, a force being applied to the piston which urges the same towards one end of the chamber and, a magnetically affected switch located adjacent the chamber, wherein said piston may move between an OFF position when the fluid outlet is closed by the piston and an ON position when the fluid outlet is open, said piston being shaped so that there is no restriction of the flow of fluid through the chamber when the piston is in the ON position; movement of the piston between the OFF and ON positions causing the consequent operation of the magnetically affected switch.

Said force can be provided by a compression spring or gravity.

The magnetic material is typically, but not exclusively, a non-rusting material such as a ceramic. Alternatively a non-rusting magnet may be mounted on the piston, or a rusting magnet may be provided with a protective cover.

In a particularly preferred embodiment, the inlet and outlet are of the same diameter, the inlet being provided in an end wall of the chamber and the outlet being provided in a side wall of the chamoer such that the direction of flow of fluid is turned through substantially 90". In this preferred case the piston is provided with a transfer passage of constant cross section which curves substantially through 90" such that in the ON position of the piston the positions of the ends of the transfer passage coincide with the positions of the inlet and outlet respectively, the cross sectional areas of the inlet, outlet and transfer passage all being substantially the same.

According to a second aspect of the present invention there is provided a fluid supply device including a flow operated switch which comprises a chamber having a fluid inlet connected to a fluid supply line and a fluid outlet located downstream of the inlet relative to the direction of flow of fluid, a piston at least part of which is made of a magnetic material, and which is located within the chamber, a force being applied to the piston which urges the same towards one end of the chamber, a magnetically affected switch located adjacent the chamber, a valve in the fluid supply line upstream of the fluid inlet and a pump in the fluid supply line, said pump being controlled by the magnetically affected switch; wherein said piston may move between an OFF position when the fluid outlet is closed by the piston and an ON position when the fluid outlet is open, said piston being shaped so that there is no restriction of the flow of fluid through the chamber when the piston is in the ON position; the opening of the valve causing movement of the piston against the effect of said force due to pressure in the fluid supply line, between the OFF and ON positions and the consequent operation of the magnetically affected switch which effects the operation of the pump and causes an increase in the fluid flow in the fluid supply line, said increase maintaining the piston in the ON position; and closure of the valve preventing pressure being applied to the piston and allowing the piston to return to the OFF position under the influence of said force.

Conveniently, tne chamber is integrally formed with the body of the pump.

In the accompanying drawings: Fig. 1 is a diagrammatic cross-section of a switch according to one aspect of the present invention, Fig. 2 is a sectional side-view of a pump incorporating a flow switch according to the present invention, and Fig. 3 is an end view of Fig. 2 on arrow A sectioned along the line X-X with parts omitted for clarity.

Referring to Fig. 1, a cylinder generally indicated by numeral 1 made of a suitable material for the application, in this case a plastic which does not attract scale from the water has an inlet port 2 of located in the central portion of the lower end3 of the cylinder 1, and an outlet port 4 located in a side wall 5 of the cylinder 1. Inlet and outlet pipes 6 and 7 are attached to the inlet and outlet ports 2 and 4 respectively. A piston 8 made of a material which is capable of being magnetised or a material on which is mounted a magnet which will not be affected by the fluid surrounding it is slidingly mounted within the cylinder 1, the side 9 of the piston 8 sealingly engaging the side wall 5 so that no fluid leaks into the space above the piston 8.A bore 10 is provided in the upper part of the piston 8, said bore 10 extending axially from the central portion of the upper end 11 of the piston 8.

One end 12 of a compression spring 13 is located within the bore 10 and the other end 14 of the compression spring 13 is urged against the central portion of the inside surface of the upper end 15 of the cylinder 1 and restrained from radial movement by means of a locating ring 16 attached to the central portion of the inside surface of the upper end 15. The compression spring 13 urges the piston 8 towards the lower end 3 of the cylinder 1.

A transfer passage 17 is provided in the lower part of the piston 8, said passage 17 having an upstream opening 18 on the central portion of the lower end 19 of the piston 8 and a downstream opening 20 in the side 9 of the piston 8; the diameter of the transfer passage 17 being the same as the diameter of the inlet and outlet ports 2 and 4 which in turn have the same diameter as the inlet and outlet pipes 6 and 7. The inlet port 2 and the upstream opening 18 are always in alignment.

The piston 8 is so positioned that movement towards the upper end 15 of the cylinder 1 causes the downstream opening 20 to be brought into alignment with the outlet port 4.

A bleed passage 21 is provided between the bore 10 and the side ofthe piston 8 near the outlet port 4 to allow the removal of any fluid which has seeped into the space above the piston 8.

The reed switch is located near the top part of the cylinder (not shown) and a valve (not shown) and an electric pump (also not shown) which is connected to its power supply via the reed switch is located in the inlet pipe 6 upstream of the inlet port 2. In the present case, the "off" position is encountered and there is no fluid pressure in the inlet pipe 6 due to the valve being closed. In this position, the piston 8 is urged at the bottom of the cylinder 1 by the compression spring 13 so that the reed switch is not affected by the magnetic influence of the piston 8 and the pump is not connected to the power supply.

The downstream opening 20 is imnediately below the outlet port 4 and does not overlap any part of it so that there is no- communication between the inlet pipe 6 and the outlet pipe 7. On opening the valve, the normal pressure in the fluid supply system forces the piston 8 upwards until the magnetic field of the piston affects the reed switch and causes power to be supplied to the pump. The pump increases the pressure in the system and so forces the piston 8 to its uppermost position when the downstream opening 20 and the outlet port 4 are in alignement. This is the "on" position. The switch will remain in the "on' position with the minimal restriction to flow until the valve is closed. The pressure is then removed from the piston 8 which moves downwardly under the influence of the compression spring 13 disconnecting the power supply from the pump and closing the outlet port 4.

This type of supply device has the advantage that it is very sensitive and can be actuated by the low pressure found in the fluid supply system when the pump is not working.

The configuration of the- piston serves to prevent any leakage even when the valve is closed and the pump is not working.

Referring now to Figs. 2 and 3, the parts corresponding to those described in relation to Figure 1 are given the same numbers in the 100 series.

The pump shown in Figs. 2 and 3 is a double pump having a cold water part C con nected to a cold water supply and a hot water part H connected to a hot water supply, a central motor 130 driving both parts C, H simultaneously. Each part C, H comprises a housing 131 having a water inlet 132 therein.

An impeller 133 is located within the housing on a drive shaft 134 which is driven by the motor 130. A float which is located above the outlet 135 of said pump, the cylinder 101 being formed integrally with the nousing 131.

The piston 108 is located with the cylinder 101 and has raised portions 136, 137 on the bottom surface thereof. These portions 136,137 prevent the bottom surface of the piston 108 from contacting the base of the cylinder 101 and forming a seal such that water cannot act on the base of the piston.

By providing a large base area on the piston, a mechanical advantage is obtained when the water pressure is first applied making the switch more responsive to low pressures. Projections 138 and 139 are provided at the top of the cylinder which prevents the piston from contacting the top of the cylinder and forming a seal thereto in a similar way to portions 136, 137 at the bottom of the piston. A vent 140 is provided in the top of the piston connecting the transfer passage 17 to the space above the piston and so allowing any water which is located above the piston to be drawn in to the transfer passage. This also serves as a means for tuning tne response of the switch to water pressure as when the water pressure is very low a small flow of water can escape through the vent and so the piston does not move.However, when the pressure is raised the vent cannot cope with the increased flow of water and the pressure is exerted on the piston causing it to move upwards.

In the embodiment shown in Figs 2 and 3, the parts C, H are totally independent of each other despite being driven by the same motor.

The type of pump shown in the drawing has the advantage when one of the parts C, H is activated the impeller in the other parts can rotate freely without causing an increase in pressure in that part of the system.

It will be appreciated that the embodiments shown in the drawings have the advantage over previously proposed flow switches in that they do not cause any restriction to the flow when they are in the ON position and also are not so susceptible to jamming by debris in the water. Consequently, the present system may be used mutatis mutandis for supplying a liquid having solids suspended therein.

Claims (13)

1. A flow operated switch which comprises a chamber having a fluid inlet connected to a fluid supply line and a fluid outlet located downstream of the inlet relative to the direction of flow of fluid, a piston at least part of which is made of a magnetic material, and which is located within the chamber, a force being applied to the piston which urges the same towards one end of the chamber and, a magnetically affected switch located adjacent the chamber, wherein said piston may move between an OFF position when the fluid outlet is closed by the piston and an ON position when the fluid outlet is open, said piston being shaped so that there is no restriction of the flow of fluid through the chamoer when the piston is in the ON position; movement of the piston between the OFF and ON positions causing the consequent operation of the magnetically affected switch.

2. A switch as claimed in claim 2, wherein the force is applied by means of a spring.

3. A switch as claimed in Claim 1 or 2, wherein the magnetically operable switch is a reed switch.

4. A switch as claimed in any preceding claim, wherein the magentic material is a nonrusting material.

5. A switch as claimed in any preceding claim, wherein the the inlet and outlet are of the same diameter, the inlet being provided in an end wall of the chamber and the outlet being provided in a side wall of the chamber such that the direction of flow of fluid is turned through substantially 90 , the piston being provided with a transfer passage of constant cross section which curves through substantially 90" such that in the ON position of the piston the positions of the ends of the transfer passage coincide with the positions of the inlet and outlet respectively, the cross sectional areas of the inlet, outlet and transfer passage all being substantially the same.

6. A fluid supply device including a flow operated switch which comprises a chamber having a fluid inlet connected to a fluid supply line and a fluid outlet located downstream of the inlet relative to the direction of flow of fluid, a piston at least part of which is made of a magnetic material, and which is located within the chamber, a force being applied to the piston which urges the same towards one end of the chamber, a magnetically affected switch located adjacent the chamber, a valve in the fluid supplyline upstream of the fluid inlet and a pump in the fluid supply line, said pump being controlled by the magnetically affected switch; wherein said piston may move between an OFF position when the fluid outlet is closed by the piston and an ON position when the fluid outlet is open, said piston oe ing shaped so that there is no restriction of the flow of fluid through the chamber when the piston is in the ON position; the opening of the valve causing movement of the piston against the effect of said force due to pres sure in the fluid supply line, between the OFF and ON positions and the consequent oper ation of the magnetically affected switch which effects the operation of the pump and causes an increase in the fluid flow in the fluid supply line, said increase maintaining the piston in the ON position; and closure of the valve preventing pressure being applied to the piston and allowing the piston to return to the OFF position under the influence of said force.

7. A fluid supply device as claimed in claim 6, wherein the force is applied by means of a spring

8. A fluid supply device as claimed in claim 6 or 7, wherein the magnetically operable switch is a reed switch.

9. A device as claimed in any one of claims 6 to 8, wherein the magnetic material is typically a non-rusting material.

10. A device as claimed in any of claims 6-9, wherein the inlet and outlet are of the same diameter, the inlet being provided in an end wall of the chamber and the outlet being provided in a side wall of the chamber such that the direction of flow of fluid is turned through substantially 90 , the piston being provided with a transfer passage of constant cross section which curves through substantially 90" such that in the ON position of the piston the positions of the ends of the transfer passage coincide with the positions of the inlet and outlet respectively, the cross sectional areas of the inlet, outlet and transfer passage all being substantially the same.

11. A device as claimed in any of claims 6-10, wherein the chamber is integrally formed with the body of the pump-.

12. A flow switch as claimed in Claim 5 which is substantially as herein described with reference to the accompanying drawings.

13. A device as claimed in Claim 6 which is substantially as herein described with reference to the accompanying drawings.