NZ243394A - Valve rotor, for a mixing valve, having a venturi type mixing chamber and a seal surrounding an opening on rotor periphery - Google Patents

Description

243394 PATENTS FORM NO S Fee No. 4: $260.00 PATENTS ACT 1953 COMPLETE SPECIFICATION After Provisional Hfi: 243394 Dated: 30th June 1992 A MIXING VALVE ROTOR We Relf Distributors 1989 Limited, a New Zealand company of 38A Aliens Road, East Tamaki, Auckland, New Zealand hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: r rv ^ '3j^J / </ 24 ■5P This invention relates to a valve rotor for a mixing valve.

For convenience only the invention will be predominantly described with reference to a valve rotor for a domestic type mixing valve suitable for the mixing of hot and cold water flows of different pressure, for domestic showers, 5 baths, etc, however it is to be understood that it is not to be limited as such. Moreover, because the invention may have many other applications, the prior art and possible applications of the invention discussed below are given by way of example only.

Conventional types of domestic mixing valves use a control rotor inside a 10 valve body, the arrangement and configuration being such that rotation of the rotor within a bore of the valve body opens and closes ports in the valve body. These ports are generally connected to respective hot and cold water supplies of different pressure, and are generally arranged so that the ratio of their respective amounts of opening varies with rotation of the rotor. Hence the 15 mixing ratio of the respective flows may be controlled.

For situations where the hot water supply pressure is much lower than the cold water supply pressure, the valve may incorporate a mixing chamber, designed so that a venturi effect may be produced, wherein the energy of high pressure flow through a nozzle into the mixing chamber is used to draw flow 20 from the low pressure side through the mixing valve, thereby improving the flow rate of the lower pressure flow.

In order to obtain the maximum venturi effect, the higher pressure flow must be prevented from entering the mixing chamber except by way of the nozzle. This generally requires that the tolerances between the rotor and bore of the 25 valve body must be kept small. A consequent problem with the design of such valves is that if the gap is too small, the valve may fail to operate due to 2 243394 seizing of the rotor in the valve body as a result of expansion of the rotor, solid particles in the flow, or the build up of deposits on the adjacent surfaces. Alternatively, if the gap is too large, leakage from the high pressure side to the low pressure side, by-passing the venturi nozzle may occur with a consequent reduction in the venturi effect and loss of mixing control. It is thus necessary for a compromise in the fit of the rotor in the bore which avoids seizing of the rotor and yet ensures a minimum venturi bypass and loss of mixing control.

It is an object of the present invention to address the foregoing problems, or at least to provide the public with a useful choice.

Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.

According to one aspect of the present invention there is provided a valve rotor for a mixing valve which is operated by rotation of the rotor inside a bore formed in a valve body of said mixing valve, said valve rotor having; (i) a mixing chamber formed therein which is communicated with an opening in an end portion of said rotor, and has at least two inlet passages leading thereto from respective first and second openings in outer surfaces of said rotor, said inlet passages being directed into said mixing chamber such that a higher pressure flow through one of said inlet passages causes a reduction in pressure in said mixing chamber which acts to draw in a lower pressure flow through the other of said passages, and (ii) first means for accommodating a first seal element for sealing around a periphery of said first opening when said rotor is fitted in the bore of said mixing valve. 0 20 According to another aspect of the present invention there is provided a valve rotor for a mixing valve substantially as described above wherein said valve rotor further comprises a first seal element fitted in said first accommodating means, said first seal element having a seal passage formed therein for providing a means of communication between a first port in the bore of said mixing valve and said first opening.

According to yet another aspect of the present invention there is provided a valve rotor substantially as described above wherein said rotor further comprises a second means for accommodating a second seal element for sealing between a portion of said rotor and a face of said bore, when said valve rotor is fitted in the bore of said mixing valve.

According to another aspect of the present invention there is provided a method of minimizing bypass leakage in a venturi effect mixing valve which is operated by rotation of a rotor which has two or more flow inlets communicated with a mixing chamber formed therein, said method comprising the step of installing a seal element on said rotor, which seals a passage communicating between one of said flow inlets and said mixing chamber, from a pressure flow from another of said flow inlets.

The rotor described above may preferably be of a cylindrical shape and made from a non corrosive material such as brass. However other materials may be suitable. For example, the rotor may be molded from a high density plastic. The rotor may be formed to tolerances that allow a sliding fit in a bore of a mixing valve body, with sufficient clearance to prevent jamming due to expansion, or the build up of deposits and grit etc. The rotor may be provided with suitable means for rotation. For example this may comprise an arm removable attached to the rotor and arranged so as to be movable in a peripheral slot in the valve body. / ''' 4 243394 0 20 The rotor may have provision for O-rings which enable the peripheral slot for the control arm to be sealed, when the rotor is fitted in the bore of the valve body to prevent leakage at the peripheral slot.

The rotor may also have provision for seals for shutting off supply ports in the valve body when the rotor is turned to a shut off position.

The rotor passage in the rotor may pass from an opening at an end portion of the rotor through an interior portion of the rotor to a mixing chamber formed in the body of the rotor. Preferably the rotor passage may pass coaxially through the rotor from one end face thereof, with an opposite end of the rotor passage forming the mixing chamber. The first opening in the outer surface of the rotor may preferably be formed in an outer peripheral surface thereof, and be communicated with the mixing chamber by means of a hole of predetermined size which opens into the mixing chamber. However, the first opening may be provided on any surface of the rotor which moves relative to an inner surface of the mixing valve when the rotor is fitted into the mixing valve. For example, the first opening may be provided in an opposite end of the rotor, with the opposite end formed as a flange which can move adjacent to the bottom end of the bore of the valve body.

The second opening in the outer surface of the rotor may be communicated with the mixing chamber by means of a second passage. This second passage may comprise a hole of a predetermined shape and diameter which acts as a nozzle leading into the mixing chamber. The hole may preferably be drilled coaxially from said opposite end of said rotor. However, the second passage may be of any suitable form which provides communication from an outer surface of the rotor restriction means, into the mixing chamber. 243394 The first seal element may be made of any suitable non-corrosive material which can provided a low friction resilient seal against an inner surface of the bore of the valve body . For example a plastics material such as acetal plastic may be suitable. The accommodating means for the first seal element may comprise a recess formed in the rotor. The size of the recess may be such that the first seal protrudes slightly from the surface of the rotor so as to fit sealingly against an inner surface of the bore when the rotor is inserted therein. The first seal element may have a passage formed therein with an opening in one face which aligns with the first opening of the rotor, and an opening on another face positioned so as to align with an opening in the bore of the valve body. This passage may comprise an elongated passage to accommodate non alignment of the opening in the bore body and the first opening in the rotor. The opening of the passage which communicates with the port in the bore may be of appropriate shape and dimensions to provide suitable regulation of flow through the opening as the rotor is turned in the bore of the valve body.

Higher pressure flow to the rotor may be supplied from a high pressure port in the mixing valve body. This port may preferably be located in the bore of the valve body. However the only requirement in location of this port is that rotation of the rotor relative to the valve body will result in a change in the opening of a passageway between the high pressure port and the second opening in the rotor.

The second seal element may be formed so as to fit into a suitably shaped recess in the rotor body, in a similar manner to that for the first seal element. It is not necessary for the second seal element to completely seal a path from the high pressure port to the second opening. This is because any fluid not sealed by the second seal cannot bypass the second the mixing chamber due to the presence of the first seal elem^n, wiuuu 6 243394 completely seals the only other opening to the mixing chamber. The second seal element may preferably be made of a similar material to that of the first seal element, although different materials may be used as required or desired. For example it may be desirable to use a high 5 temperature resistant material for the first seal element which seals higher temperature flow.

The second seal element may be shaped to provide the necessary metering of the higher pressure flow with rotation of the rotor. In the case of a peripherally mounted second seal, an edge of the seal may be formed so as 10 to lie at an incline to the rotor axis. The opening of the high pressure port may thus be progressively varied as the second seal is moved relative to the high pressure port.

Alternative arrangements and locations of the second seal and the second opening may be possible. For example the second seal may be provided on 15 a bottom portion of the rotor, with the high pressure port provided in the bottom of the bore of the valve body.

Since there is not the same sealing requirements for the second seal, this seal may even be omitted and the rotor itself suitably formed to provide the necessary flow control characteristics, and passage to the second opening.

Furthermore, although it is generally envisaged that the lower pressure supply to the mixing chamber would be sealed from the pressure of the higher pressure flow by the first seal between the low pressure port and the mixing chamber, the invention is not limited to this configuration. It may be possible to achieve the same effect in reducing venturi bypass 25 leakage by designing the seal at the high pressure port so that higher pressure fluid was completely contained within a passage between the high pressure port and the second o^eriiiig^ ^of"' the rolor. ' In tliis . »■ * c> \ •, ; ^ c ;>' f ;• ''r' ' i. ;7 VS1^r,„ "3 3 ;' A ' J IQq-i ? I i'i ol ' ;f ;% ,ilJ4 jj , ' <»b<4 ■ ...«// vr.J ;20 ;243394 ;configuration, the first seal element for sealing around a periphery of the first opening, as discussed in the previous aspects of the present invention, ;would be a seal at the high pressure port, with the high pressure opening in the rotor being the first opening. ;Further aspects of the present invention will become apparent from the ensuing description which is given by way of example only and with reference to the accompanying drawings in which: ;Figure 1: is a cross sectional view of a mixing valve with a rotor according to one aspect of the present invention, and ;Figure 2: is a view of the rotor of figure 1 showing a first seal element, ;and; ;Figure 3: is a view of the rotor of figure 2 from an opposite side showing a second seal element. ;With respect to figure 1 of the drawings there is shown a mixing valve generally indicated by arrow 1 comprising a valve body 2 and a rotor 3, said rotor being in accordance with a embodiment of the present invention. The valve body 2 comprises high pressure inlet 4 and low pressure inlet 5 which have respective high pressure and low pressure ports 6 and 7 leading into a cylindrical bore 8 of the valve body 2. ;The rotor 3 is made from brass which has been machined to a predetermined diameter slightly less than the diameter of the bore 8. There is thus sufficient clearance between the rotor 3 and the bore 8 to ensure seizing does not occur due to thermal expansion of the rotor, or due to deposits or grit forming on the rotor and causing jamming. A lower end - ;8 ;•' 7.9 oj ;243394 ;0 20 ;portion of the rotor 3 is suitably machined to accommodate respective high pressure and low pressure annular seals 9 and 10 which seal against the respective high pressure and low pressure ports 6 and 7 when the rotor 3 is aligned in the condition shown in figure 1. The seals 9 and 10 effectively shut off flow from the high pressure and low pressure inlets 4 and 5 into the bore 8 of the valve body 2. ;The rotor 3 is further fitted with O-rings 11 and 12 provided on either side of a lever mounting hole 13. A lever (not shown) which is moveable in a peripheral slot (not shown) machined in the valve body 2, may be threaded into the mounting hole 13, and used for rotating the rotor 3 inside the bore 8 through a predetermined angle. The O-rings 11, 12 provide a seal to prevent fluid from flowing from the bore region of the valve out through the lever slot. ;The rotor 3 further comprises a first passage 20 consisting of a hole drilled along a central axis of the rotor 3 from a top end 21 of the rotor. The bottom end of the first passage 20 terminates at a lower interior region 22 of the rotor 3. ;As shown in figure 2, the rotor 3 further comprises a first opening 23 in an outer surface of the rotor 3 which is connected to the lower region 22 (Fig. 1) of the first passage 20 so that the first passage 20 effectively connects the opening at the top end 21 with the first opening 23. ;The rotor 3, as shown in figure 2 has a machined section generally indicated by arrow 25 defining a recess for accommodating a first seal element 26 (shown fitted). The first seal element 26 is made from an acetal plastic material, and is sized so as to fit snugly in the machined section 25, and protrude a predetermined distance from the peripheral silrface of the rotor 3 so as to provide a sliding seal fit in the bore 8. The first sealelejnent..^ ;/ v o ;9 ;24339 ;26 has a passage 27 formed therein with an opening 28 aligned with the first opening 23 of the rotor 3, and a rectangular opening 29 located so as to align with the low pressure port 7 when the rotor 3 is turned in the bore 8. The passage 27 comprises a channel with bottom and side walls formed in 5 the first seal element 26 and a top wall formed by the surface of the bore 8 when the rotor 3 is fitted therein. The rectangular opening 29 is of a predetermined size and shape to enable correct regulation of flow from the low pressure port 7 through the passage 27, as the rotor 3 is turned in the bore 8. ;10 The first seal element 26 may be easily removed from the machined section 25 for replacement when worn, or to enable a seal element having different shaped passages and flow characteristics to be fitted as required. ;The rotor 3 further comprises second opening 50 at a bottom end portion 51. This second opening 50 is communicated with the lower interior region 22 15 of the first passage 20 by means of a hole 52 drilled substantially along a central axis of the rotor 3. This hole 52 acts as a nozzle opening into the lower interior region 22 which acts as a mixing chamber. ;Figure 3 is a view of the rotor in figure 2 from an opposite side. Parts in figure 3 identical to those of figure 2 are identified with the same 20 numerals, and description is omitted for brevity. As shown in figure 3, the rotor 3 has a machined section generally indicated by arrow 55 defining a recess for accommodating a second seal element 56 (shown fitted). The second seal element 56 is also made from an acetal plastic material, and is sized so as to fit snugly in the machined section 55, and protrude a 25 predetermined distance from the peripheral surface of the rotor 3 so as to provide a sliding seal fit in the bore 8. The second seal element 56 has an inclined face 57 formed on one side thereof which lies at an incline to the ;10 ;:'J. r j' ;' % ^1/ ;2433 ;axis of the rotor 3 when the second seal element 56 is fitted in the machined section 55. ;The machined section 55 is formed substantially symmetrical to the axis of the rotor 53 to simplify machining procedures, and also to provided positive 5 location of the second seal element 56. With the second seal element 56 fitted in the machined section 55, a passage 58 is formed between the inclined edge 57 and a portion of the rotor 3. This passage 58 provides a flow path for flow from the high pressure port 6 to the second opening 50 when the rotor 3 is fitted in the bore 8. ;10 The angle of the inclined edge 57 with respect to the axis of the rotor 3 is chosen to provide the required metering of flow from the high pressure port 6, as the rotor 3 is turned relative to the high pressure port 6. Since the second seal element 56 may be easily removed from the machined section 55, different shaped seal elements may be fitted to suit different 15 operating pressures and other requirements. The second seal element 56, as with the first seal element 26 may be easily replaced when worn. ;The second seal element 56 as shown in figure 3 does not provide a complete seal of flow from the high pressure port 6 to the second opening 50. However, due to the first seal element 26 and the O-ring 11, there is no 20 other path which the flow from the high pressure port 6 can take. Bypass flow to the mixing chamber at the lower interior region 22 is thus prevented. Hence, all the flow from high pressure port 6 passes into the second opening 50, along the hole 52 where the velocity is increased, and into the lower interior region 22 where it mixes with flow coming from the 25 low pressure port 7 via the passage 27 and first opening 23. Due to the velocity from the hole 52 which acts as a nozzle, pressure in the lower interior region 22 (mixing chamber) is reduced, providing a venturi effect ;11 ;243394 ;0 20 ;which acts to draw the flow from the low pressure port 7 through the first passage 20 and out of the opening at the upper end 21 of the rotor 3. ;We believe the advantages of our invention to be as follows, however it should be appreciated that all such advantages may not be realised on all embodiments of the invention, and the following list if therefore given by way of example only, as being indicative of potential advantages of the present invention. Furthermore, it is not intended that the advantages of the present invention be restricted to those of the list which follows: - ;1. The provision of seal elements in the rotor enables the flow from the inlet ports to be effectively sealed from each other until they are mixed in the mixing chamber. This prevents bypass of the flow to the mixing chamber and ensures the maximum venturi effect is obtained. ;2. Since the seal elements may be easily removed from the rotor, the seal elements may be easily replaced when worn. Furthermore, different shaped seal elements may be used depending on operating requirements for the valve. For example a different incline angle for the inclined edge of the second seal element may be chosen, and the depth of the passage 27 of the first seal element may be changed. Furthermore, different materials may be chosen to suit different operating temperatures and pressures. ;3. The machined sections for the first and second seal elements may be made to the same dimensions, thereby simplifying manufacturing. Alternative shapes of machined sections are also possible. For example, it may be desirable for the machined section to be sufficiently large to enable the first or second seal element" to also incorporate a mixing chamber region ' ;12 ;section. In this case different shapes of mixing chambers and nozzles for the rotor may be easily manufactured. ;4. The design wherein seal elements for metering the flow in a mixing valve are fitted into the rotor, may have advantages for any type of mixing valve where flow is controlled by rotation of a rotor inside a bore. ;Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof as defined in the appended claims. ;T t rj ;>\ ;i' * 243394

Claims (16)

WHAT WE CLAIM IS;

1. A valve rotor for a mixing valve which is operated by rotation of the rotor inside a bore formed in a valve body of said mixing valve, said valve rotor having; 5 (i) a mixing chamber formed therein which is communicated with an opening in an end portion of said rotor, and has at least two inlet passages leading thereto from respective first and second openings in outer surfaces of said rotor, said inlet passages being directed into said mixing chamber such that a higher pressure flow through one 10 of said inlet passages causes a reduction in pressure in said mixing chamber which acts to draw in a lower pressure flow through the other of said passages, and (ii) first means for accommodating a first seal element for sealing around a periphery of said first opening when said rotor is fitted in 35 the bore of said mixing valve.

2. A valve rotor for a mixing valve as claimed in claim 1 wherein said valve rotor further comprises a first seal element fitted in said first accommodating means, said first seal element having a seal passage formed therein for providing a means of communication between a 20 first port in the bore of said mixing valve and said first opening.

3. A valve rotor for a mixing chamber as claimed in claim 2, wherein said rotor further comprises a second means for accommodating a second seal element for sealing between a portion of said rotor and a face of said bore, when said valve rotor is fitted in the bore of said 25 mixing valve. •v 14 { Uqqj * " '' 1924;' & /.';243394;

4. A valve rotor for a mixing valve as claimed in any one of claims 1 to 3 wherein said rotor is made from a non-corrosive metal.;

5. A valve rotor for a mixing valve as claimed in any one of claims 1 to 3 wherein said rotor is made from a high density plastics material.;5

6. A valve rotor for a mixing valve as claimed in any one of claims 1 to 5 wherein said rotor is provided with an arm for rotation of said rotor, said arm being arranged so as to be moveable in a peripheral slot of the body of said mixing valve when said rotor is fitted in the bore of said mixing valve.;10

7. A valve rotor for a mixing valve as claimed in claim 6 wherein said rotor is provided with grooves for accommodating O-rings whereby said peripheral slot for said control arm may be sealed when said rotor is fitted in the bore of said mixing valve.;

8. A valve rotor for a mixing valve as claimed in any one of claims 1 to 7;15 wherein said rotor has provision for seals for shutting off supply ports in the valve body when said rotor is turned to a shut off position.;

9. A valve rotor for a mixing valve as claimed in any one of claims 1 to 8 wherein said first accommodating means for said first seal element comprises a recess formed in said rotor, the size of said recess being;20 such that said first seal protrudes slightly from the surface of said rotor so as to fit sealingly against an inner surface of said bore when said rotor is inserted therein.;

10. A valve rotor for a mixing valve as claimed in any one of claims 1 to 9;wherein said first seal element is made of an acetal plastics material.;, * /' : , ' ' 15 243394

11. A valve rotor for a mixing valve as claimed in any one of claims 3 to 12 wherein said second seal element comprises an edge formed so as to lie at an incline to the axis of said rotor.

12. A mixing valve fitted with a valve rotor as claimed in any one of 5 claims 1 through 11.

13. A method of minimizing bypass leakage in a venturi effect mixing valve which is operated by rotation of a rotor which has two or more flow inlets communicated with a mixing chamber formed therein, said method comprising the step of installing a seal element on said 10 rotor, which seals a passage communicating between one of said flow inlets and said mixing chamber, from a pressure flow from another of said flow inlets.

14. A valve rotor substantially as described herein with reference to the accompanying drawings.

15 15. A mixing valve substantially as described herein with reference to the accompanying drawings.

16. A method of minimising bypass leakage in a venturi effect mixing valve substantially as described herein with reference to the accompanying drawings. 20 KELF DISTRIBUTORS 1989 LIMITED by its Attorneys ^ ,;'v ^ °CT 1994 $ JAMES & WEI.I.S 16