WO1990012351A1

WO1990012351A1 - Fluid mixer device

Info

Publication number: WO1990012351A1
Application number: PCT/GB1990/000509
Authority: WO
Inventors: William Reid
Original assignee: The Horne Engineering Co. Ltd.
Priority date: 1989-04-05
Filing date: 1990-04-05
Publication date: 1990-10-18
Also published as: ZA902638B; AU5416390A; GB8907640D0

Abstract

A mixer device in the form of a thermostatic mixing tap (1) comprises a discharge tap part (3) and a mixing valve unit (2) attached to the tap part (3). The valve unit (2) includes a thermostatic mixer device (40) receiving relatively hot and cold fluids (water) via inlet ducts (14, 15) and supplying blended water to the tap part (3) to serve as warm water at the desired temperature. The flow of water via the inlet ducts (14, 15) is controlled by a rotary-disc valve device (16) actuated by a control handle (35/35A) of the tap part. The valve device (16) may permit a cold water flow to the tap part (3) by-passing the mixer device (40). The tap (1) substantially avoids the risk of entrapment of warm water at tap closure thereby minimising legionella bacteria growth, and the valve device (16) avoids the need for separate one-way valves for the mixer device.

Description

Fluid Mixer Device

Description

The present invention elates to a fluid mixer device for fitting to fluid discharge apparatus, and more especially to a thermostatic mixing tap.

Warm water for supply to domestic wash basins, showers and other draw-offs at a safe and comfortable temperature for washing, especially without the risk of scalding is provided by mixing relatively hot and cold water at a suitable fluid mixing (or blending) device and this device may comprise a simple manual tap device but in many instances it is preferred that the device is in the form of a thermostatic mixing valve to provide precise temperature control. In large establishments, such as hospitals, colleges and hotels, a considerable number of wash basins may be provided at one or more toilet areas and for economic reasons it has been the practice to supply warm (blended) water to these basins from a large common mixing valve via pipework which will be of considerable length where the wash basin (or shower) are remote from the mixing valve. When there is no draw-off at the wash basins etc this pipework represents a dead leg ie the water therein remains static and entrapped as there is no recirculation present in this pipework. It is normal to supply warm water at a temperature of about 43°C but for the second described prior art above this is now regarded as unsatisfactory as the lengthy supply pipework gives rise to a definite possibility of legionella bacteria growth due to the dwell time of the warm water in this pipework especially as the temperature of the static entrapped water can fall to a level at which legionella growth is most likely. This problem can be substantially avoided by installing an individual mixing valve at each wash basin, but this of course leads to a system which overall is constructionally more complex and hence more costly. In this connection, it is operationally necessary in the case of presently known thermostatic mixers for one-way valves to be present at the hot and cold supply ducts of each mixer to mitigate against fluid back-flows in the associated pipework, and this considerably increases costs.

It is a major object of the present invention to provide a fluid mixing device which can be fitted to fluid discharge apparatus whereby the combination constitutes a convenient warm water supply unit preferably in the form of a thermostatic mixing tap to limit the temperature of the fluid discharge to a set maximum.

According to the present invention there is provided a thermostatic mixing valve unit for fitting to a fluid discharge device whereby the discharge device delivers fluid supplied by the valve unit; supply ducts for the supply of relatively hot and cold fluids to said mixer and an outlet for blended fluid from said mixer; and setta,ble valve means for c controlling the flow of said hot and cold fluids to the mixer via said supply ducts, said valve means being adapted for coupling to an actuator member of a draw-off control of a fluid discharge device.

Preferably the coupling means are provided to couple the, valve means to said actuator member and are located in said blended fluid outlet.

Preferably the actuator member comprises a valve spindle and preferably the valve means comprises a rotary disc valve. The disc valve can comprise a disc assembly including a ported rotary disc mounted on an appropriately ported stationary disc, the rotary disc being coupled to a rotary actuator disc adapted for connection to the actuator member. temperature setting means are provided for the mixer located oppositely to the blended fluid outlet. Preferably the valve means are settable for the delivery of a flow of fluid to the outlet by-passing the mixer in particular this fluid flow can comprise a cold water flow.

The present invention is also a fluid supply apparatus comprising the above thermostatic mixing valve unit in combination with a fluid discharge device.

According to another aspect of the present invention there is provided thermostatic fluid mixer- device apparatus for supplying temperature blended fluid comprising a thermostatic fluid mixer from which temperature blended fluid is discharged, supply ducting for the supply of relatively hot and cold fluids to said mixer, a settable rotary-disc valve for controlling the flow of said hot and cold fluids to the mixer via said supply ducts whereby the temperature of the discharged blended fluid is controlled, an actuator for rotating the rotary-disc valve to set the valve, and a discharge outlet for the discharge of temperature blended fluid from the apparatus.

Preferably said discharge outlet has a coupling means for the attachment thereto of an outlet pipe.

Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings wherein;

Fig l shows a cross-sectional elevation of a thermostastic mixing tap embodying the present invention, specifically through section C-C in Fig 4d;

Fig 1A shows a detail of the disc valve of Fig 1 to a larger scale;

Fig 2 shows a similar elevation of a portion of the tap but through section D-D in Fig 4b;

Fig 3 shows schematically in cross-sectional representation a thermostatic cartridge unit as an example of one form of fluid mixer suitable for use in the tap;

Figs 4a - 4d represent view on section B-B of Fig 2 showing the fluid control disc valve of the tap, and showing various settings of the disc valve;

Fig 5 shows a similar view to that of Fig 1 but with a different form of fluid discharge device enabling horizontal location of the tap;

Fig 6 snows yet a further form of fluid discharge device;

Fig 7 shows a partially sectioned plan view of a water supply apparatus including a fluid mixer-discharge according to the present invention;

Fig 8 shows a front elevation of the apparatus in Fig 7;

Fig 9 shows a part side view in cross-section of a modified disc arrangement for the disc valve; and

Fig 10 shows, ion plan view, of further modification to the disc arrangement.

Referring to Figs 1 - 4a/d of the drawings, a thermostatic luid mixing unit 2 is coupled to a fluid discharge device 3 by means of a nut 4 to form a thermostatic mixing tap 1. More specifically the nut 4 is threaded to a threaded inlet pipe 5 of the device 3 while the unit 2 includes a casing 6 having a threaded head 7 screwed to the nut 4, and the device 3 is secured to a mounting fixture 8 eg a basin or wall, by means of a clamping nut 9 on the threaded pipe 5.

A housing 10 for a thermostatic mixer unit 11 (shown in Fig 3 but not in Fig 1) is screwed into the outer end of the casing 6, while relatively hot and cold fluids (water) are supplied to the casing via inlet conduits 12, 13 (Fig 2) respectively. The hot and cold fluids are delivered to the thermostatic unit 11 via internal ducts 14, 15 respectively and a rotary disc control valve 16 controls the flow of water from the conduits 12, 13 to the respective ducts 14, 15. The unit 2 includes an outer conduit 17 for blended water from the unit 11, a central bore 17A in the disc valve 16 defining a portion of this outlet conduit 17, and the outlet 17 feeds to the inlet pipe 5 of the device 3 which includes a discharge 18 for the blended water on a spout 19.

Considering the rotary disc valve 16 in greater detail, this valve 16 comprises a stack of discs (Figs 1, 1A) defined by a top actuator disc 20, a moving disc 21 and a bottom fixed disc 22, the disc stack 20-22 resting on a compression disc 23 mounted on a shoulder 6A in the casing 6 while the stack is held in place by the casing head 7 bearing on a thrust washer 24. The disc 21 is coupled to the actuator disc 20 by lugs 25 to rotate therewith while the discs 22, 23 are held fixed by anchor dowels 26, 27. The moving disc 21 includes appropriately positioned transfer ducts 28, 29 for transfer of water from the conduits 12, 13 to the ducts 14, 15 when the disc 21 is correctly set, discs 22, 23 including apertures 30, 31 to permit this water flow, and the discs 20, 21 include further ports 32, 33 for the passage of cold water from conduit 13 to the outlet 17 by-passing the unit 11 (see Fig 2) .

For setting of the valve 16 the actuator disc 20 is coupled to a valve spindle 34 of the draw-off control of the device 3, and to this end the disc 20 includes a tubular head 20A which is splined to the inner end of the spindle 34. The other end of the spindle 34 is splined to a tap knob 35 including actuating handle 35A. The tubular head 20A carries apertures 36 for through- passage of blended water.

The thermostatic mixer unit 11 can take any convenient form. Fig 3 shows a possible general arrangement for the thermostatic unit 11, the mixing unit of Fig 3 being in accordance with that described and claimed in the applicants UK patent 2096274. The valve unit 11 of Fig 3 is of cartridge form and the unit 11 includes a sleeve 37 fitted in a head part 10A of the housing 10, an annular valve member 38 concentric with the sleeve 37 and carrying a stirrup 39 which is held in contact with thermostat 40 by means of springs 42 and 42a. The thermostat 40 is urged against a temperature control screw 41 at the outer end of the housing 10 by means of a compression spring 42. The valve member 38 is positioned by the thermostat 40 relative to valve seatings defined by the head part 10A and a lower wall 10B of the housing 10 to regulate the relative quantities of hot and cold water flowing into the unit via ports 43 and 44 respectively. The interior of the sleeve 37 defines an outlet passage for blended water while the hot water and cold water flows inwardly (as shown by the arrows) in an annular passage between the valve member 38 and the sleeve 37 to ultimately reverse and flow, in a mixed condition, over the thermostat 40 whence the mixed flow passes to the outlet passage.

Figs 4a.-4d show various settings of the disc valve 16 for desired flow conditions. Thus in Fig 4A the disc 21 is set by handle 35A for the tap shut condition where flows from the conduits 12, 13 are blocked. Movement of the handle 35A by an appropriate amount (ie 1/8 turn) places the tap 1 in the cold only flow condition as shown in Fig 2 and Fig 4B, while movement of the handle 35A a further 1/8 turn (Fig 4D) causes a flow of mixed water from the tap 1 ie the transfer ducts 28, 29 communicate the conduits 12, 13 with the ducts 14, 15 respectively. A significant characteristic is that at no intermediate point between the positions shown in Figs 4B and 4D would there be a disconcerting halting of water flow since at all intermediate positions, as examplified by Fig 4c, there would always be an appropriate degree of overlap between the various transfer ducts and ports of the valve 16 to ensure water flow to the outlet 17. Further, the valve 16 in the shut condition precludes transfer of water from one conduit 12, 13 to the other conduit 12, 13 via the thermostat unit 11 so that the valve 16 has a supplementary check valve function to prevent backflows of water in the supply pipelines connected to the conduits 12, 13.

As will be understood the tap 1 shown in Fig 1 is intended for conventional positioning, ie upright, on a ledge of a wash basin.

It will be appreciated of course that the thermostat unit 2 could be used readily with other forms of fluid discharge devices. Thus, Fig 5 shows a discharge device 3 with a differently positioned spout 19 for horizontal orientation of the thermostatic mixing tap l. Fig 6 shows yet a further form of fluid discharge device 3 wherein, in place of the spout 19 of Figs 1 and 5, a mixed water outlet 45 is located on the inlet tube 5 of the device 3: this enables a pipeline receiving blended water from the tap 1 to be located behind the mounting wall 8 and this may be preferred in some situations, for example where the tap 1 is supplying to a shower.

Thus the present invention provided a compact thermostatic mixing tap which can be convenient to operate and be relatively inexpensive. By using the present tap at individual water draw-offs eg at wash basins, it is possible to mitigate against the disadvantages of extra cost and complexity of a water distruction system which uses individual mixers at draw- offs. The present tap can be very conveniently used in pre-assembled toilet units for installation in buildings.

The cold water for the thermostatic unit 2 can be at ambient temperatures and taken from a cold water storage tank (not shown) . However it would be possible to use for the cold water, water taken from a hot water supply and cooled in a heat exchanger, as is described and claimed in the applicants UK Patent 2099559.

The tap l can be made of any suitable materials ie metal or plastics (where appropriate) and the discs of the valve 16 may be of ceramic material. Modifications are of course possible. For example the valve 16 could be of a different type from that shown.

Another advantage of the tap 1 is the the control screw 41 setting the temperature of the blended water is located at the outer end of the tap so that normally the screw 41 would be relatively inaccessible behind the wall 8. Consequently unauthorised tampering with the screw 41 would be prevented or impeded. Essentially the desired blended water temperature would be set at installation of the tap, but may of course be further adjusted from time to time.

In the embodiment shown in Figs 7 and 8, a fluid mixer-discharge 50 supplied temperature blended water to a water outlet pipework 51 having an outlet previously but in this case the cover 7A of the unit 2 carries the outlet 45 for the temperature blended water, and the unit 2 is connected by means of nut 4 to an actuator assembly 52 for the disc valve 16 of the unit 2 rather than to a tap (3) as in the Figs 1 - 5 embodiments. The actujator assembly 52 includes a spindle (not shown) coupled to the actuator disc 20 of valve 16 for example in the manner described previously, and again a knob 35 carrying operating handle 35A is fitted to the spindle. The water outlet pipework 51 comprises an outlet pipe 53 having one end fitted to the water outlet 45 and the other end coupled to an elbow 54 from which a discharge pipe 55 extends, the discharge pipe 55 passing through partition wall 8 so that the discharge 51A is externally located. The pipe 55 is held on the partition wall 8 by means of a ring 56 and a clamping but 57.

In the modification shown in Fig 9, instead of having the transfer ducts 28, 29 int he form of recess in the rotary disc 21, these ducts 28, 29 are formed in Fig 9 by elongate, open sided, slots in the disc 21, the inner end of each slot being closed by the actuator disc 20 which is placed in satisfactory sealing engagement with the disc 2 assisted by plastics holding rivet 40. This alternative formation of the ducts 28, 29 should be easier to produce and should also cause the disc 21 to be structurally more satisfactory.

As will be seen the operation of the above described valves taps of the present invention has the sequence: OFF (Fig 4A) to COLD WATER ONLY (Fig 4B) then to TEPID WATER (mixture of cold and blended water) then to WARM WATER (with the temperature controlled by the mixer unit 11 so as to be limited to a safe maximum level, usually 43°C) . In the variation shown in Fig 10, however, the port 33 is dispensed with so that the valve (tap) moves simply from the closed position to the mixed (warm water supply) position (Fig 10) and the is no cold water delivery. The closed position is indicated as position C in Fig 10. Further modifications are of course possible.

It will be observed that in all the described embodiments of the present invention, the discharge device (item 3 in Fig 1) is very close to the mixing unit 11 so reducing the supply duct length to a very minimal level. Consequently very little tepid or warm water can gather in the device when the tap is off, that is there is virtually no dead leg present. Also any entrapped water will be efficiently flushed when the tap is opened. Consequently by means of the present invention the risk of legionella bacteria growth is avoided or minimised in comparison with prior art arrangements. The present invention also ensures that:

1. The temperature of the supply water to taps or basins (or baths) is at a safe and comfortable temperature, usually 43°C.

2. The mixing unit maintains the desired temperature (eg 43°C) , thereby avoiding a scalding risk.

3. The supply temperature can be adjusted to select specific requirements by means of adjuster 41.

4. The adjuster 41 however is concealed to avoid unauthorised tampering.

5. The hot water supply can be at a temperature (eg 60 - 65°C) meeting the rules of health authorities.

Claims

1. A thermostatic mixing valve unit for fitting to a fluid discharge device whereby the discharge device delivers fluid supplied by the valve unit, said mixing valve unit comprising a thermostatic fluid mixer; supply ducts for the supply of relatively hot and cold fluids to said mixer and an outlet for blended fluid from said mixer; and settable valve means for controlling the flow of said hot and cold fluids to the mixer via said supply ducts, said valve means being adapted for coupling to an actuator member of a draw-off control of a fluid discharge device.

2. A valve unit as claimed in claim 1, wherein the coupling means are provided to couple the valve means to said actuator member and are located in said blended fluid outlet.

3. A valve unit as claimed in claim 1 or 2, wherein the actuator member comprises a valve spindle.

4. A valve unit as claimed in any one of the preceding claims, wherein the valve means comprises a rotary disc valve.

5. A valve unit as claimed in claim 4, wherein the disc valve comprises a disc assembly including a ported rotary disc mounted on an appropriately ported stationary disc, the rotary disc being coupled to a rotary actuator disc adapted for connection to the actuator member.

6. A valve unit as claimed in claim 5, wherein said rotary disc includes transfer ports to permit dual flow of relatively hot and cold fluids.

7. A valve unit as claimed in claim 6, wherein said transfer ports comprise elongate slots in the rotary disc, an open outer side of each slot being closed by the rotary actuator disc.

8. A valve unit as claimed in any one of said claims 4 to 7, wherein the disc valve is arranged such that during the application of relative rotary movement for changing the valve setting from a closed setting to a dual hot/cold flow setting uninterrupted fluid discharge from the valve unit exists.

9. A valve unit as claimed in any one of the preceding claims, wherein temperature setting means are provided for the mixer located oppositely to the blended fluid outlet.

10. A valve unit as claimed in any one of the preceding claims, wherein the valve means are settable for the delivery of a flow of fluid to the outlet by¬ passing the mixer, this fluid flow preferably comprising a cold water flow.

11. Fluid supply apparatus comprising a thermostatic mixing valve unit as claimed in any one of the preceding claims in combination with a fluid discharge device.

12. Thermostatic fluid mixer-discharge apparatus for supplying temperature blended fluid comprising a thermostatic fluid mixer from which temperature blended fluid is discharged, supply ducting for the supply of relatively hot and cold fluids to said mixer, a settable rotary-disc valve for controlling the flow of said hot and cold fluids to the mixer via said supply ducts whereby the temperature of the discharged blended fluid is controlled, an actuator for rotating the rotary-disc valve to set the valve, and a discharge outlet for the discharge of temperature blended fluid fro the apparatus.

13. Apparatus as claimed in claim 12, wherein said rotary-disc valve is settable such that cold fluid by¬ passes the mixer to be discharged from the discharge outlet.

14. Apparatus as claimed in claim 12 or 13, wherein said discharge outlet has coupling means for the attachment thereto of an outlet pipe.