GB2366851A

GB2366851A - Fluid flow control device

Info

Publication number: GB2366851A
Application number: GB0022562A
Authority: GB
Inventors: Patrick Riley
Original assignee: DAHLL Ltd
Current assignee: DAHLL Ltd
Priority date: 2000-09-14
Filing date: 2000-09-14
Publication date: 2002-03-20
Also published as: GB0022562D0

Abstract

The invention is for the equalising of input flow pressures to a hot and cold water mixer unit, such as for a shower, bath or sink, and allows flow adjustment without isolating from the supply. Hot or cold, or both, inlets may have the device. The device 1 has a body 2 having an inlet 3 and an outlet 4 and a spindle 20 mounted in a carrier 16. Spindle 20 is preferably threaded and co-axial with the carrier 16, and the inlet 3, and recessed O-rings 25 and 26 may be included between the pieces. Preferably, adjustment of the spindle 20 is allowed through aperture 19 in the carrier 16 using a screwdriver in head 24. Carrier 16 may be threadingly received in the body 2 and removable using the aperture 19 which is preferably hexagonal to allow the use of an Allen key. The body may have a non-return valve 6 and a filter 13, held in place by circlips 12 and 15. The inlet 3 and outlet 4 may be at 90 degrees to each other.

Description

<Desc/Clms Page number 1> Hot/Cold Water Mixer Unit Description The present invention relates to a water mixer unit primarily of the type used in showers for mixing water of two different temperatures before delivering it to a shower head. The invention is also applicable to mixer taps often used to control a supply of hot and cold water to a bath or sink.

It is known that when a water mixer unit is used, it is important to ensure that the pressure/flow rate of the separate hot and cold water supplies to the unit are balanced with each other. If, for example, the cold water is supplied to the mixing chamber at a higher pressure and greater flow rate than the hot water, the cold water will dominate the hot water and the temperature of the mixed water delivered to the outlet will be too low.

The problem is more apparent in a shower installation where a thermostatic mixing valve is used, as this type of valve delivers water at a constant temperature. Therefore, if there is less hot water due to a pressure/flow rate difference between the separate hot and- cold water supplies to the mixing chamber, the valve will reduce the flow of cold water to match that of the hot. In some cases, where the pressure/flow rate difference is significant, complete shut down of the valve will result.

At present, to overcome the problems mentioned above, a number of colour coded washers each having a different orifice diameter to enable a fitter to balance the hot and cold water supply pressure/flow rate may be provided. The fitter selects a washer with a particular orifice diameter depending on the water pressure/flow rate and mounts it in the cold and/or hot water inlet flow path to alter the pressure/flow rate of the hot and/or cold water flowing into the mixing chamber through the orifice. By positioning one washer in the hot or cold water inlet, or a combination of two washers in both the hot and cold water inlet respectively, the hot and cold water inlet supply pressures and flow rates to the mixing chamber can be balanced or made substantially equal. As an alternative to the washers, discs

formed from wire mesh may be used instead. The pressure/flow of water through the disc is then altered to an extent that depends on the tightness of the mesh. There are a number of disadvantages with the above described solution. Firstly, it is desirable to be able to balance the pressures/flow rate after the mixer unit has been fully installed and water flow to the mixing chamber initiated. It is clearly not possible to do this with the existing mixer unit as it must be isolated from the hot and/or cold water supply to enable it to be partially disassembled with a view to gaining access to the hot and/or cold water inlet flow path to locate a disc therein. Additionally, it is not possible to finely control the hot and cold water inlet pressure/flow rate and thereby balance it accurately when washers or discs are used For example, a disc with the most appropriate orifice diameter may not be available or supplied with the fitting. It is also possible that a fitter may balance the inlet pressures/flow rates by reducing the inlet pressure/flow rate of both the hot and the cold water by too much, thereby effecting the quality of water flow to the user. Finally, a fitter may not select the correct disc for the application or, in some cases, may not fit any at all.

It is an aim of the present invention to overcome or substantially reduce the problems mentioned above.

According to the invention, there is provided a hot and cold water mixer unit for a shower or tap having a chamber and a regulator through which water flows from a supply into the chamber to be mixed with water of a different temperature supplied thereto from another source, the regulator having means to adjust the pressure/flow rate of the water flowing through the regulator into the chamber to balance it with the pressure/flow rate of the water entering the chamber from said other source, said means being operable to adjust the pressure/flow rate without isolating the regulator from the supply.

In a preferred embodiment, the mixer unit includes a pair of regulators to enable the pressure/flow rate of the water entering the chamber from both sources to be

independently adjusted without isolating either regulator from their respective supplies.

Preferably, the or each regulator includes a body having a flow path therethrough for the passage of water from a supply into the chamber and a spindle displaceable into the flow path to constrict it and thereby reduce the pressure/flow rate of the water passing through the regulator into the chamber.

Advantageously, the spindle is threadingly received in a carrier mounted in the body, the spindle and carrier being coaxial.

A seal is conveniently disposed between the spindle and the carrier. The seal is preferably an O-ring and is disposed in a recess in the spindle.

In a preferred embodiment, the spindle has a head accessible through an aperture in the carrier to enable rotation of the spindle via the head when the carrier is mounted in the body.

The head of the spindle is conveniently slotted to receive the blade of a screwdriver. Preferably, the carrier is threadingly received in an aperture in the body.

In a preferred embodiment, the aperture in the carrier is hexagonal to receive the head of an Allen key thereby enabling rotation of the carrier to mount it in, or remove it from, the body.

A seal is conveniently disposed between the carrier and the body. The seal is prefereably disposed in a recess in the carrier.

Preferably, the non-return valve is removable via an aperture in the body when the carrier is removed. The filter is also, preferably, removable via an aperture in the body when the carrier is removed.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: FIGURE 1 is a cross sectional side elevation through the pressure regulator forming part of the mixer unit according to the present invention; FIGURE 2 is an end view of the mixer unit shown in Figure 1 in the direction of arrow X; and Figure 3 is an exploded view of the carrier and spindle separated from the body. Referring now to the drawings, Figures 1 and 2 illustrate a pressure/flow rate regulator 1 forming part of the mixer unit of the invention that has a body 2 with a water supply inlet 3 and outlet 4 through which hot or cold water flows into the mixing chamber of the hot and cold water mixing unit. The unillustrated part of the mixer unit comprising a housing in which the mixing chamber is formed, and of which the pressure/flow rate regulator forms a part of, is conventional and so will not be described further.

It will be appreciated that the mixer unit can have a single pressure/flow rate regulator 1 for the hot or cold inlet. Preferably, however, the mixer unit has two regulators 1, one for the hot and one for the cold water supply inlets to the mixing chamber.

The inlet 3 and outlet 4 are arranged substantially at 90 degrees to each other to form an elbow. A hot or cold water supply pipe (not shown) is inserted into the inlet 3 and coupled thereto using a threaded collar that is received on the thread 5 on the outside of the inlet 3. A non-return valve 6 is disposed within the body 2 in the flow path and comprises a plunger 7 mounted within a casing 8 and carrying a spring 9. When water flows through the inlet 3 in the direction indicated by arrow Y in Figure 1, the pressure of the water overcomes the bias provided by the spring 9 to push the plunger 7 to the left, as shown in Figure 1, and allow water to flow through the non-return valve 6. When water flow ceases, the bias provided by the spring 9 urges the plunger towards the right when viewing it in the direction shown in Figure 1, so that the head 10 of the plunger 7 closes the flow path and prevents any back flow of water through the regulator 1 into the supply pipe. An O-ring seal

7a is provided on the head of the plunger 7 that provides a seal between the plunger 7 and the casing 8 to prevent backflow through the non-return valve 6. The non return valve 6 is mounted in the body 2 against a shoulder 11 and is retained in position by a removable circlip 12.

A wire mesh filter 13 is also mounted in the body 2 against a second shoulder 14. The filter is also retained in position using a circlip 15. The filter 13 is spaced from the non-return valve 6 to allow the end of the plunger 7 to protrude from the non- return valve 6 when flow through the inlet 3 into the body 2 is initiated.

It will be appreciated that both the filter 13 and non-return valve 6 are optional components as they are not essential to enable the pressure of the water entering the mixing chamber to be controlled. They are, however, preferable, as the filter removes any foreign bodies from the supply and the non-return valve prevents cross bleeding of the cold water supply into the hot and vice versa.

The body 2 has a threaded open end opposite the inlet 3 and coaxial therewith in which a carrier 16 is received. The carrier 16 has an external thread 17 that rotatably engages with the thread in the open end of the body 2 to mount the carrier 16 in the body 2. The carrier 16 is tubular with a internally threaded portion 18 for approximately half the length of the carrier 16 extending from the end 16a received in the body 2. The opposite visible end 16b of the carrier 16 has an aperture 19 therein which is hexagonal in shape to receive the head of an Allen key (not shown) which is used to mount the carrier 16 in the body 2 and tighten it in position therein or remove it from the body 2 for reasons that will become apparent hereinafter.

A spindle 20 is received within the carrier 16 and has a threaded end portion 21 that threadingly engages with the internal thread 18 of the carrier 16. The opposite end 22 of the spindle 20 has a slotted head 24 that is accessible through the hexagonal aperture 19 to enable the blade of a screwdriver (not shown) to be used to rotate the spindle 20 within the carrier 16 to retract it into the carrier 16 when rotated in an anticlockwise direction, or so that part of it protrudes out of the carrier 16 into the flow path in the body 2 when rotated in a clockwise direction. A rubber O-ring

oil seal 25 is disposed in a recess in the outer surface of the spindle 20 near the head 24 to prevent egress of water from between the spindle 20 and the carrier 16. Similarly, a second rubber O-ring seal 26 is disposed between the outer surface of the carrier 16 and the body 2 to prevent the egress of water from between the carrier 16 and the body 2.

Operation of the above described regulator 1 will now be described. Once the regulator 1 has been fitted and the water supply connected to the inlet 3 with the carrier 16 and spindle 20 in position in the body 2, the fitter can insert the blade of a screwdriver into the slotted head 24 of the spindle 20 to rotate it so that its threaded end portion 21 protrudes further into the flow path in the body 2 thereby constricting the flow and changing the pressure and/or the flow rate of the water passing through the elbow. As can be seen from Figure 1, by rotating the spindle 20 in a clockwise direction, it will move further into the body 1 and thereby reduce the gap between the end of the spindle 20 and the opposite wall of the body 2, indicated by distance A in Figure 1. As the size of the gap A is reduced and the flow and/or pressure is reduced. Therefore if, for example, the pressure/flow rate of the cold water is greater than the pressure/flow rate of the hot, the spindle 20 of the regulator 1 mounted to the cold water supply can be rotated to alter through the regulator 1 and thereby balance the inlet pressures of the cold water with that of the hot as they enter the mixing chamber. It will be appreciated that there is no need to interrupt the supply of water through the regulator 1 during rotation of the spindle 20 to perform the adjustment described above.

As can be seen from the end view of Figure 2, the body is provided with markings 27 to enable the fitter to select a different position for the spindle 20 by lining the slot up with a chosen marking 27. It will be appreciated however, that rotation of the spindle 20 allows fine adjustment of the size of the constriction and allows precise balancing of the pressure/flow rate between the hot and cold water supplied to the mixing chamber.

If the regulator 1 requires maintenance, such as the replacement of the non-return valve 6 and/or filter 13, access can be obtained to them without removing the

regulator 1 or disconnecting it from the inlet pipe or mixing chamber. This is achieved by removing the carrier 16 from the body 2 once the regulator 1 has been isolated from the supply. If the spindle 20 is rotated in a clockwise direction so that its head 24 is recessed within the carrier 16, it is then possible to insert the head of an Allen key in the hexagonal aperture 19 in the end of the carrier 16. Rotation of the Allen key then withdraws the carrier 16 together with the spindle 20 from the body 2. The circlips 12, 15 can then be removed through the aperture in the body 2 once the carrier 16 has been removed as can the filter 13 and the non-retum valve 6 for renewal or cleaning.

In an additional, unillustrated embodiment, the spindle may be used to completely stop the flow of water through the pressure regulator to allow maintenance to the remaining part of the mixing unit without shutting off the water supply elsewhere. This is achieved by providing a seal, such as a rubber O-ring adjacent to the end of the spindle 20 extending into the flow path which, when the spindle is rotated in a clockwise direction, will eventually contact a sealing face on the body 2 thereby closing the flow path and providing a seal between the spindle 20 and the body 2 of the regulator 1.

Many modifications and variations of the invention falling within the terms of the appended claims will be apparent to those skilled in the art and the foregoing description should be regarded as a description of the preferred embodiments only.

Claims

Claims 1. A hot and cold water mixer unit for a shower or tap having a chamber and a regulator through which water flows from a supply into the chamber to be mixed with water of a different temperature supplied thereto from another source, the regulator having means to adjust the pressure/flow rate of the water flowing through the regulator into the chamber to balance it with the pressure/flow rate of the water entering the chamber from said other source, said means being operable to adjust the pressure/flow rate without isolating the regulator from the supply.
2. A mixer unit according to claim 1, including a pair of regulators to enable the pressure/flow rate of the water entering the chamber from both sources to be independently adjusted without isolating either regulator from their respective supplies.
3. A mixer unit according to claim 1 or 2, wherein the or each regulator includes a body having a flow path therethrough for the passage of water from a supply into the chamber and a spindle displaceable into the flow path to constrict it and thereby reduce the pressure/flow rate of the water passing through the regulator into the chamber.
4. A mixer unit according to claim 3, wherein the spindle is threadingly received in a carrier mounted in the body, the spindle and carrier being coaxial.
5. A mixer unit according to claim 4, wherein a seal is disposed between the spindle and the carrier.
6. A mixer unit according to claim 5, wherein the seal is an O-ring disposed in a recess in the spindle.
7. A mixer unit according to any of claims 4 to 6, wherein the spindle has a head accessible through an aperture in the carrier to enable rotation of the spindle via the head when the carrier is mounted in the body.

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8. A mixer unit,according to claim 7, wherein the head has a slot therein to receive the blade of a screwdriver.
9. A mixer unit according to claim 7 or 8, wherein the carrier is threadingly received in an aperture in the body.
10. A mixer unit according to claim 9, wherein the aperture in the carrier is hexagonal to receive the head of an Allen key thereby enabling rotation of the carrier to mount it in, or remove it from, the body.
11. A mixer unit according to claim 9 or 10, wherein a seal is disposed between the carrier and the body.
12. A mixer unit according to claim 11, wherein the seal is disposed in a recess in the carrier.
13. A mixer unit according to any of claims 4 to 12, wherein a non-return valve is mounted in the pressure regulator.
14. A mixer unit according to any of claims 4 to 13, wherein a filter is mounted in the regulator.
15. A mixer unit according to claim 13, wherein the non-return valve is removable via an aperture in the body when the carrier is removed.
16. A mixer unit according to claim 14 or 15, wherein the filter is removable via an aperture in the body when the carrier is removed.
17. A mixer unit according to any preceding claim wherein the body is elbow shaped such that the flow path turns through 90 degrees between the inlet and outlet.

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18. A mixer unit according to any of claims 4 to 17, wherein the carrier and spindle are mounted co-axially with the inlet.
19. A mixer unit substantially as hereinbefore described with reference to the accompanying drawings.