GB2227549A

GB2227549A - A mixing unit

Info

Publication number: GB2227549A
Application number: GB8820435A
Authority: GB
Inventors: Robin Nyhof; James Alexander Bruce
Original assignee: Methven & Co Ltd G
Current assignee: Methven & Co Ltd G
Priority date: 1987-03-26
Filing date: 1988-08-30
Publication date: 1990-08-01
Anticipated expiration: 2008-08-30
Also published as: AU8780091A; AU1376288A; GB2227549B; GB8820435D0

Abstract

A unit for mixing a first and a second fluid which are at different pressures, provides for the fluid at the lower pressure a first flow path means (4, 6) having a larger cross sectional area than a second flow path means (5, 7) provided for the fluid at the higher pressure, said first and second flow path means directing said fluids to a mixing region (14). The mixing unit includes respective control means (13, 13') which control the flow of said first and second fluids through the separate flow path means into the mixing region 14. The mixing unit also includes elements (13) locked to handles (12) by compressing O-rings therebetween, and a spout (39) mounted in a securing unit (41), for swivelling in use, by a sealing O-ring (47A) located in a groove (44) and an O-ring (47B) located in a groove of greater circumference than that of groove (44) and engaging in a groove in the inner surface of the securing unit. <IMAGE>

Description

A MIXING UNIT The present invention relates to improvements in and relating to mixing units.

The invention will be described hereinafter with respect to mixing units for mixing hot and cold water prior to the discharge of the mixed water at a desired temperature from a spout or other discharge outlet associated with the mixing unit.

It is, however, to be appreciated that the description of the invention hereinafter is given merely by way of example and it will be apparent to those skilled in the engineering field that the present invention could find application wherever the mixing of fluids of unequal pressures is required.

In the past the mixing of hot and cold water to provide mixed water at a desired temperature has been faced with a number of problems including having to deal with cold water at various pressures but inevitably at a pressure substantially higher than that of the hct water with which it is to be mixed.

In some countries older houses frenuently have a 12 foot head for their hot water systems whila .viewer style houses frequently have a 25 foot head for the. hot water systems.

This means that the hot water will generally be at a pressure of around 5 to llpsi.

In contrast, most cold water supplied -n such countries is generally at a pressure of between 50 and llOpsi. This means that in trying to mix hot and cold water the cold water will tend co push the hot water back up its pipeline so that instead of a mixture of water at a desired temperature being achieved, largely cold water will be discharged.

It is therefore an object of the present invention to provide a mixing unit which in one use thereof is suitable for the efficient mixing of hot and cold water and which overcomes or at least obviates the above identified problem.

Further objects and advantages of this invention will become apparent from the following description.

According to one aspect of the present invention there is provided a method of mixing a first and a second fluid which are at different pressures, said method including providing for the fluid at the lower pressure a first flow path means having a larger cross sectional area than a second flow path means provided for the fluid at the higher pressure, said first and second flow path means directing said fluids to a mixing means.

According to a further aspect of the present invention there is provided a mixing unit for carrying out the above method.

According to yet a further aspect of the present invention there is provided a mixing unit for mixing first and second fluids which are at different pressures, said mixing unit including respective control means which control the flow of said first and second fluids through separate flow path means into a mixing means, tne flow path control means for the fluid at a lower pressure having a cross sectional area which is larger than that cross sectional area of the flow path control means for said fluid of higher pressure.

According to yet another aspect of the present invention some of the parts of the mixing unit are located together by a method for locking together a pair of engageable members which are axially movable relative to each other and to provide for engagement therebetween, said method including: providing a first of said members with an "0" ring (as herein defined) and causing said "O" ring to reduce its thickness to between 25% and 50% of its original thickness resulting in engagement of said "O" ring with a second of said members to provide a locking effect between said first and second members.

In the plumbing trade the term "O$ ring includes all types of annular members of resilient or at least partially resilient materials such as nitrile rubber and are used for the purpose of providing a fluid tight seal within a cavity in which a threaded screw or bolt is secured.

According to yet another aspect of the present invention there is provided a method of mounting together a spout assembly and a mixing unit so that the spout assembly is rotatable relative to the unit but is constrained from axial movement relative thereto, said method comprising: (i) providing said spout assembly with first and second circumferential grooves, the second groove having a greater circumference than the first groove; (ii) providing first and second annular resilient members each of a circumference that is comrn..ensurate with engagement on the circumference of said first groove; (iii) fitting said first resilient member into said first groove and positioning said unit over said spout assembly so that an inner surface of said unit engages with and slides over said first resilient member to expose said second groove;; (iv) expanding said second resilient member to fit said second resilient member into said second groove; (v) providing a recess portion on said inner surface of said unit and sliding said unit so that said expanded second resilient member is engaged within said recess; and whereby said spout assembly is constrained from axial movement relative to said unit but is rotatable relative thereto.

According to yet a further aspect of the present invention there is provided a mounting assembly for mounting a spout assembly rotatably relative to a mixing unit but constrained from axial movement relative thereto, said assembly comprising: (i) said spout assembly having a pair of spaced apart circumferential grooves, the second groove being of larger circumference than the first groove; (ii) providing a pair or resilient annular members each of a circumference commensurate with the circumference of said first groove;; (iii) providing said mixing unit with an internal surface adapted to be slidable over one of said resilient members when accommodated within said first groove, said inner surface of said mixing unit further being provided with a recess adapted to accommodate therein the other of said resilient members after it has been expanded and accommodated within said second groove.

Further aspects of this invention which should be considered in all its novel aspects will become apparent from the following descriptions which are given by way of example of embodiments.of the invention. The embodiments will now be described with reference to the accompanying drawings wherein: Figure 1: shows a cross-sectional view through a mixing unit according to an example of the first aspect of the invention; Figure 2(a); (b) & (c): show side and two end views respectively of ceramic disc control valves for hot (a) & BR< (b) and cold (c) water and as used in the example shown in Figure 1; Figure 3: shows a plan view partly sectioned of part of a hot/cold water mixer unit of the type shown in Figures 1 and 2; Figure.4: shows a spout assembly and mixer unit, partly sectioned, similar to the mixer unit shown in Figure 1; Figure 5: shows in larger scale and in part cross-section a spout nut for use sn t embodiment shown in Figure 4; and Figure 6: shows a more detalltd view of the bottom end portion of the spout assembly of Figure 4.

The following examples of the .'n'ention will be described with reference to mixing hot and cold water supplies in which the cold water is at a higher pressure than the cold water supply. It is however to be appreciated that with minor modifications the invention can be adapted to mix other fluids.

In Figures 1 and 2 is one example of a first aspect of the invention which is referenced generally by arrow 1 and is shown having a body section 2 provided with an inlet 3 divided into a separate inlet 4 for a hot water'flow and a separate inlet 5 for the cold water flow. The respective flows then pass, as indicated by the arrows, to control valves which in the example shown are ceramic disc assemblies 6 and 7. These assemblies 6 and 7 in known manner can, as shown particularly in Figures 2, comprise a substantially cylindrical body 8 mounted within which is a fixed ceramic disc 9 which is rotatable relative thereto.

The body 8 has mounted therein behind the disc 9 a further rotatable ceramic disc 10. The rotation of the disc 10 is controlled by a spindle 11 connected with a handle 12 by a handle lever 13. The disc 9 is shown in Figures 2(b) hot water and 2(c) cold water as having in known manner, a pair of quadrant shaped apertures 29 therethrough which when aligned or partially aligned with apertures 30 in disc 10 will allow the flow of water therethrough and hence through apertures 28 provided in the side wall of the body 8. When the assembly 6 or 7 is required to cut-off the flow of water the moveable disc 10 will of course have its solid face blocking off the apertures 29 in disc 9 and simultaneously will have its side surfaces blocking off the apertures 28 in the body 8.Thus, a desired volume of hot or cold water can pass through the respective outlet paths in to a common discharge region indicated by reference arrow 14 which in use can be connected in suitable manner to any suitable discharge outlet such as a spout.

The cold water flow into the region 14 is shown being substantially vertical and via a jet 16 provided in a flow regulator 15. In contrast the flow of hot water is shown being substantially transverse so that an enhanced mixing of the two flows is achieved. A Venturi effect resulting from the relative directions of flow of the hot and cold water is also considered to be important to this enhanced mixing.

In accordance with the present invention the diameter DH (Figure 2(b)) which is at the left hand side of Figure 1 is shown being appreciably larger than the diameter DC which is at the right hand side of Figure 1. Thus, a commensurately larger volume of relatively low pressure hot water is able to flow through the control valve 8 on the left hand side of the mixing unit than the volume of cold water at substantially higher pressure through the right hand control valve 7. In one example of the present invention the diameter DH for the hot water flow is 20mm while the diameter DC for the cold water flow is 15mm. It has been found that such a ratio of diameters provides for adequate compensation for normal differences in fluid pressures as outlined below.In particular, a 20mm diameter for the hot water at 6psi has been found to enable a flow of 10.4 litres per minute compared with hot water flows of about 7.5 to 9 litres per minute commonly available in hot water units operating at 6psi available at present.

It is to be appreciated that the ratio DH to DC can be adjusted so as to allow for commensurately different pressures of fluids required to flow therethrough.

It will also be appreciated that the present invention can find application in any desired mixing of fluids of any different pressures.

Seals 27, suitably of nitrile rubber or the like, are shown provided throughout the mixing unit so as to ensure that leakage of fluid from the desired flow paths is avoided.

Various techniques have been used in the past in order to achieve a locking effect between a pair of engageable members such as a screw or bolt threaded into a threaded hole or nut. Such techniques have the desired result of restraining the disengagement of the members due to vibration or axial forces imposed thereon.

It has now been discovered however that a locking effect can be achieved simply by the use of an 11011 ring on one of the members which "O" ring is compressed to such an extent that it lockingly engages with the second of the members to provide a locking linkage between the members.

At present "0" rings have been used for their sealing effect and can, for example, have a normal thickness of 1.7mm which after compression to form a seal would usually be reduced by not more than about .2mum i.e. about 11%.

However, it has now been discovered that by increasing the compression of an "0" ring to between 25% and 50%, preferably between 35% and 45%, the material of the "O" ring, suitably nitrile rubber, will flow into a locking engagement with adjacent surfaces of the members. For example into any cavities or recessess available to receive such material and thereby create a locking effect between the members In Figure 3 of the accompanying drawings, an example is illustrated where such a locking effect is provided between a handle lever 13 and a handle 12 connected with a spindle 31 which on rotation by movement of the handle lever 13 and handle 12 controls a control valve seach as a ceramic disc assembly 6 contained within valve body 1.This assembly 6 controls the volume of hot or cold water which is mixed into a total volume of water to provide mixed water of a desired temperature to be discharged from outlet 3?, A further handle lever 1 3 is also shown mounted on the other side of the body 1 for the control of the other of the hot or cold water volumes.

To avoid disengagement of the handle lever 13 from the handle 12 it is necessary to prevent or at least restrain the disengagement of the threaded shaft 33 of the handle lever 13 from the threaded bore 34 in which it is secured. It is to be appreciated that over many years of use involving vigorous movements of the handle lever 13 there is a danger that such disengagement could occur.

To restrain such disengagement the present invention provides an "0" ring 35 beneath a head 36 of the handle lever 13. The length of the threaded shaft 33 ting such that before the head 36 of the lever 13 engages the body 37 a compression of the normal width of the "O" ring 35 of between 25% and 50% can be achieved, prefereably within the range of 35% to 45%. It has been found that with such compression of the "0" ring 35 the material of the "0" ring 35 will flow outwardly and will take on the contours of the formation of the adjacent threaded bore 34 providing a locking effect between the shaft 33 and the bore 34.

It has been found that such compression of the "0" ring does not unduly affect its capability of providing a fluid-tight seal, although in the example such sealing effect is not required. However, in other instances where the sealing effect as well as a locking effect of an "O" ring is necessary or desirable then both effects can be achieved by the compression of the "0" ring as above described.

It is further envisaged that a groove, recess, aperture or the like can be especially provided to receive the material of the "0" ring as it is compressed and which it is believed will enhance the locking effect achievable.

A recess for this purpose can thus be provided at the top of the bore 33 in the figure 3.

To connect the handle 12 with the spindle 31 a screw 38, suitably having a head to be engaged by an Allan key, is shown screwed into the bottom of the bore 34 to have its end engage with the spindle 31. Again a compressed "O" ring can be provided for the screw 38 to lock it into the bore 34.

As indicated above, the present invention also seeks to provide a rotatable mounting for joining together at least of two of the members of a multi-member assembly, for example a spout assembly to a mixing unit in which those members are constrained from axial movement relative to one another. Such a mounting arrangement is required in the mounting of a spout assembly on a plumbing water mixing unit and this enables the spout assembly to be swivelled or rotated to a desired positiop relative to a sink or workbench but wherein lifting of the spout assembly out of the mixing unit is constrained.

This aspect of the present invention will thus be described by way of example with reference to the above mentioned specific mounting arrangement.

Referring to Figures 4 to 5 of the accompanying drawings a spout 39 with a nozzle 40 at its upper end is shown mounted by means of a spout nut 41 to a body 2 of a mixing unit referenced generally by arrow 1.

By way of example only the mixing unit 1 is shown having a hot water control valve 42 and a cold water control valve 43 with a desired volume of cold water passing upwardly through a mixing regulator 15 or mixing with the hot water travelling in the directior indicated by arrow A so that a desired temperature of water passes upwardly through the spout 39.

The spout 39 is, of course, enquired to be rotatable relative to the mixer unit 1 but to be constrained from being lifted or raised outwardly teLeLrom.

Accordingly, the bottom of the spcut assembly 39A as shown particularly in Figure 6 is shown provided with a first groove 44 and spaced therefrom and adjacent a bottom end 39B of the spout 39 a second groove 45 which has a larger circumference than groove 44.

The relationship between the circumferences of the grooves 44 and 45 is such that a resilient annular member, suitably an "0" ring of nitrile rubber or the like, can be accommodated within the groove 44 while the same sized resilient member needs to be expanded so as to be able to be accommodated within the groove 45. In one arrangement the increase in the circumference of the groove 45 relative to the circumference of groove 44 is of the order of 10%. This is the approximate expansion of the "0" ring or the like in order for it to be accommodated within the groove 45.

As shown in Figure 6 the bottom end 39B of the spout assembly 39 can have a chamfered edge 46 to facilitate the rolling thereover of the "0" rings, a pair of the "O" rings 47A and 47B being shown in Figure 4. The internal diameter of the spout nut 42 is such that a sliding fit is achieved over the "0" ring 47A located in the groove 44. The inner surface of the spout nut 41, as shown in Figure 5 has a groove or recess 48 adapted to accosmIodate the expanded "0" ring 47B when located in the groove 45.

The bottom edge of the spout nut 41 is provided with a chamfer 49 to facilitate the passage or the nut 41 past the "0" ring 47B as will now be described.

To achieve the mounting arrangemont shown in Figure 4, the "0" ring 47A is positioned swithin the groove 44 and the spout nut 41 is positioned thereover to expose the groove 45 into which will be positioned the further "0" ring 47B. In achieving this fitment the "O" ring 47B will need to be expanded by a desired amount to be fitted on the larger circumference of the groove 45.

Downward movement of the nut 41 results in the "0" ring 47B being received into the groove or recess 48 in the nut 41. The outer part of the lock nut 41 can have a thread 51 enabling the nut 41 to be screwed into a threaded portion 50 of the body 2 with a fluid-tight seal being achieved by means of a sealing member 51' or the like.

The expanded nO" ring 47B located within the groove or recess 48 provides an axial locking effect between the nut 41 and the spout assembly 39. The result is that the spout assembly 39 can be rotated readily relative to the spout nut 41 and the mixing unit 1 without any force being generated which would tend to unscrew the nut 41 from the body 2.

However resistance to any upward i.e. axial movement of the spout assembly 39 relative to the nut 41 and body 1 is created by the friction between the "0" ring 47B and the recess 48 and 45. It will be appreciated that the "0" rings 47A and 47B are also providing bears, surfaces for the rotation of the spout assembly 39 thus avoiding any metal to metal contact as was experienced in previous mounting arrangements of this type. Furthermore, in that neither the body 2 nor its projecting portion 50 are required to have any aperture to accommodate a pin or screw then the mixing unit 1 is reversible front and back as may be required for any particular situation.

In the event that dis-assembly of the spout assembly 39 and the nut 41 is required then the lock therebetween can be broken if sufficient force is applied resulting in the return of the nut 41 past the bottom "0" ring 47B.

It can thus be seen that in a relatively simple but effective manner a rotatable mounting between a pair of members can be achieved in which axial movement therebetween is resisted and wherein external and unsightly locking fitments are not required.

Where in the aforegoing description reference has been made to specific components or integers of the invention having known equivalents then such equivalents are herein incorporated as if individually set forth.

Although this invention has been described by way of example and with reference to examples thereof it is to be understood that modifications or improvements can be made thereto without departing from the scope or the spirit of the appended claims.

Claims

1. A method of mixing a first and a second fluid which are at different pressures, said method including providing for the fluid at the lower pressure a first flow path means having a larger cross sectional area than a second flow path means provided for the fluid at the higher pressure, said first and second flow path means directing said fluids to a mixing means.

2. A method as claimed in claim 1 substantially as hereinbefore described with reference to Figures 1 and 3 of the accompanying drawing.

3. A mixing unit for carrying out the method of mixing a first and a second fluid which are at different pressures as claimed in claim 1 or claim 2.

4. A mixing unit for mixing first and second fluids which are at different pressures, said mixing unit including respective control means which control the flow of said first and second fluids through separate flow path means into a mixing means, the flow path control means for the fluid at a lower pressure having a cross sectional area which is larger than the cross sectional area of the flow path control means for said fluid o higher pressure.

5. A mixing unit as claimed in clair 4 wherein a body section thereof is divided into separate inlets for hot and cold fluid flows which pass respective control valves and wherein the flow path for the hot fluid is greater in cross sectional area than that of the flow path for the cold fluid.

6. A mixing unit as claimed in claim 5 wherein the diameter of the hot fluid flow path is about 20mm and the diameter of the cold fluid flow path is 15mm.

7. A mixing unit as claimed in claim 5 or claim 6 wherein the control valve are ceramic disc assemblies fitted in known manner within the body section.

8. A mixing unit for mixing first and secondfluids which are at different pressures substantially as hereinbefore described with reference to Figures 1 to 3 of the accompanying drawing.

9. A method of mounting together first and second members of a mixing unit as claimed in any one of claims 3 to 8 wherein the the first member is rotatable relative to the second member but is constrained from axial movement relative thereto, said method comprising: (i) providing said first member with first and second circumferential grooves, the second groove having a greater circumference than the first groove; (ii) providing first and second annular resilient members each of a circumference that is commensurate with engagement on the circumference of said first groove; (iii) fitting said first resilient member into said first groove and positioning said second member over said first member so that an inner surface of said second member engages with and slides over said first resilient member to expose said second groove;; (iv) expanding said second resilient member to fit said second resilient member into said second groove; (v) providing a recess portion on said inner surface of said second member and sliding said second member so that said expanded second resilient member is engaged within said recess; and whereby said first member is constrained from axial movement relative to said second member but is rotatable relative thereto.

10. A method as claimed in claim 9 substantially as hereinbefore described with reference to Figures 4 to 6 of the accompanying drawings.

11. A mounting assembly for mounting a first member rotatably relative to a second member of a mixing unit so that the first member is rotatable relative to the second member but is constrained from axial movement relative thereto, said assembly comprising: (i) said first member having a pair of spaced apart circumferential grooves, the second groove being of larger circumference that the first groove; (ii) providing a pair or resilient annular members each of a circumference commensurate with the circumference of said first groove;; (iii) providing said second member with an internal surface adapted to be slidable over one of said resilient members when accommodated within said first groove, said inner surface of said second member further being provided with a recess adapted to accommodate therein the other of said resilient members after it has been expanded and accommodated within said second groove.

12. A mounting assembly as claimed in claim 11 wherein said first member is a spout assembly of a water supply unit and said second member is a lock nut of a water mixing unit.

13. A mounting assembly as claimed in claim 12 wherein the lock nut is engaged in a threaded manner with the mixing unit after the spout member is engaged therewith.

14. A mounting assembly as claimed ii any one.of claims 11 to 13 wherein the circumference of the second groove is about 10% greater than the circumference of the first groove.

15. A mounting assembly for mounting a first member rotatably relative to a second member but constrained from axial movement relative thereto substantially as hereinbefore described with reference to Figures 4 to 6 of the accompanying drawings.

16. A method of locking together a pair of engageable members of a mixing unit as claimed in any one of claims 3 to 8 wherein the members are axially movable relative to each other and to provide for engagement therebetween, said method including: providing a first of said members with an "O" ring (as hereinbefore defined) and compressing said "O" ring to reduce its thickness to between 25% and 50% of its original thickness resulting in engagement of said "O" ring with a second of said members to provide a locking effect between said first and second members.

17. A method as claimed in claim 16 wherein the "0" ring is compressed to between 25 and 50% of its normal thickness.

18. A method as claimed in claim 17 wherein the "O" ring is compressed to between 35 and 45% of its normal thickness.

19. A method of locking together a pair of engageable members of a mixing unit wherein the members are axially movable relative to each other and to provide for engagement therebetween substantially as hereinbefore described with reference to Figure 3 of the accompanying drawings.

20. An assembly of at least first and second members locked together in accordance with the method of claim 16 or claim 19.

21. An assembly as claimed in claim 20 wherein the first member is a handle lever and the second member is a handle of a tap assembly.

22. An assembly of at least first and second members of a mixing unit wherein the members are locked together substantially as hereinbefore described with reference to the Figure 3 of the accompanying drawings.