WO1993002308A1

WO1993002308A1 - Tempering valve

Info

Publication number: WO1993002308A1
Application number: PCT/AU1992/000349
Authority: WO
Inventors: Peter John Carter; Jeffrey Wayne Carl; Lionel Allan Gaskell
Original assignee: Gsa Industries (Aust.) Pty. Ltd.
Priority date: 1991-07-15
Filing date: 1992-07-14
Publication date: 1993-02-04

Abstract

A tempering valve for use in hot water supply systems, having a mixing chamber (5) arranged to mix water received from a cold water supply (2) and a hot water supply (3), and an outlet (4) through which the mixed water is discharged. The valve has a thermostatically controlled closure member (7) which is movable between two valve seats (19 and 20). Passage of cold water to the mixing chamber (5) is at least inhibited when the closure member (7) engages one seat (19), and passage of hot water to the mixing chamber (5) is prevented when the closure member (7) engages the other seat (20). Between those two positions, the closure member (7) proportionally controls flow to the mixing chamber (5). Fail safe means becomes operational in the event of failure of the thermostat (8), and that means may open a secondary flow passage (30) for cold water, or it may include a device, such as a coil operated disc valve (149) (Figures 7-9) which functions to shut-off escape of water through the valve outlet (104). Flow inducing means, such as a venturi (140, 142) (Fig. 6) may be incorporated to induce flow from the hot water supply (103) if that supply is at a pressure below the cold water supply (102).

Description

"TEMPERING VALVE" This invention relates to tempering valves as used in hot water supply systems to provide some measure of control over the temperature of the water at the supply outlet.

Tempering valves have a mixing chamber which is connected to both hot and cold water supplies and have a thermostat device which controls the introduction of cold water to that chamber. An outlet of the chamber is connected to a tap or other draw-off point. If the hot water reaching the valve has a temperature below a predetermined level, the thermostat device is inoperative and the valve does not permit cold water to enter the mixing chamber. The temperature of the water at the draw-off point is therefore the same as that of the hot water at the tempering valve, except for heat loss as may occur between the draw-off point and that valve. If however, the temperature of the hot water is above the predetermined level when it reaches the valve, the thermostat device functions to open the cold water supply port so that mixing cold and hot water occurs within the valve. The water then supplied to the draw-off point has a temperature less than that of the hot water entering the valve. Satisfactory operation of such valves can be dependent on continuance of the supply of cold water to the valve. If that cold water supply fails for one reason or another, hot water may continue to flow through the mixing chamber to the outlet and thereby present a dangerous situation. That arises because such valves commonly rely on opening of the mixing chamber to cold water flow as the response to detection of a high temperature in that chamber, and because of that reliance such valves fail to completely shut-off the hot water flow under high temperature conditions.

Australian Patents 560930, 555203 and 572299, each discloses a tempering valve in which there is a continuous and unrestricted flow of hot water into the mixing chamber, and a valve member is operable to control only the quantity of cold water entering that chamber. In the event of at least a partial failure of the cold water supply, the temperature of the water flowing from the mixing chamber by way of the outlet, may not have been tempered or cooled to a safe temperature.

European Patent Application 235472 and German Utility Patent 7142759, each discloses a tempering valve in which there is a thermostatically controlled valve member which regulates the quantity of both hot and cold water entering the mixing chamber. Neither valve however, provides for positive isolation of the hot water inlet from the mixing chamber. As a result, a quantity of hot water is able to by-pass the valve member and flow through the mixing chamber to the outlet in conditions where the cold water flow has ceased. A dangerous situation therefore arises in the event of failure of the cold water supply.

Furthermore, the thermostat device for tempering valves generally includes a tubular body containing a temperature responsive medium which expands with increased temperature, and a push rod which responds to expansion and contraction of that medium and projects out of one end of the tubular body. Such devices are known to fail because of leakage of the medium through a faulty seal or fracture of the tubular body, for example. That can have disasterous consequences in a tempering valve because the cold water inlet will then be cut off from the mixing chamber and water discharged at the associated service outlet will be at maximum temperature. It has been proposed to meet the foregoing problem by arranging the valve so that cold water continues to flow through the outlet in spite of failure of the thermostat. Such a valve forms the subject of Australian Patent 560930. That solution may not be satisfactory under all circumstances because it still permits the hot water flow through the valve outlet.

The valve according to Australian Patent 56958S attempts to meet the last mentioned problem by providing fail safe means which, in addition to opening the cole water inlet, closes or partially closes either the valve outlet or the hot water inlet. There remains a difficulty however, in circumstances where the thermostat is operating satisfactorily, but the cold water flow is stopped or substantially reduced because of another kind of failure. Under those circumstances, the hot water flow is not curbed and a dangerous situation exists.

Another problem with tempering valves arises because of differences in the supply pressure of the hot and cold water respectively. Where there is a common source for both the hot and cold water, the two streams are supplied to a mixing chamber at substantially the same pressure. In some circumstances however, and particularly in establishments such as hospitals having a large number of service outlets, the cold water and the hot water are often supplied from different sources. In those circumstances, it often happens that the hot and cold water supplies have substantially differing pressures. Typically the cold water has a higher pressure than the hot water. Because of that difference in supply pressure, it can happen that the high pressure flow dominates to the extent that it hinders or prevents flow from the low pressure supply into the mixing chamber.

It is an object of the present invention to provide a tempering valve of the aforementioned kind which has a safety response to at least partial failure of the cold water flow at the valve inlet. It is a further object of the invention in a preferred form, to provide such a valve which also has a safety response to failure of the thermostat. Yet another object of the invention in a preferred form, is to provide such a valve which provides for proportional control of both the hot water and cold water flows so as to thereby achieve more accurate control of the predetermined temperature for the outlet flow. Still another object of the invention in a preferred form is to provide a tempering valve which ensures adequate mixing of hot and cold water received from respective supplies operating at different pressure.

In accordance with the present invention there is provided a tempering valve including, a hollow body, a mixing chamber within said body, a hot water inlet and a cold water inlet for said chamber, an outlet for said chamber, flow control means within said body and having a closure member and two valve seats, each of which is associated with a respective one of said inlets, said control means being operable to adopt either of two primary flow conditions, in each of which there is engagement between said closure member and a respective one of said seats, and a thermostat which is responsive to changes in the temperature of the water within said chamber so as to cause said operation of the control means, wherein said closure member and valve seat engagement at least inhibits communication between said chamber and said cold water inlet in one said primary flow condition which is adopted as a consequence of decrease in said temperature, and prevents communication between said hot water inlet and said chamber in the other said primary flow condition which is adopted as a consequence of increase in said temperature.

The two primary flow conditions are not necessarily the only flow conditions which can exist. In practical embodiments of the invention it would usually be the case that the flow control means passes through a plurality of intermediate flow conditions when influenced by the thermostat to move away from one primary flow condition to the other. The arrangement is preferably such that such movement has a proportional control effect on flow from each of the two inlets. That is, as the control means traverses in one direction through the intermediate flow conditions, there will be a progressive increase in restriction to flow from, say the cold water inlet, and a corresponding progressive decrease in restriction to flow from the hot water inlet. If the control means traverses in the opposite direction, the hot water flow will be subjected to progressively increasing restriction, and the cold water flow will be subjected to progressively decreasing restriction.

It is preferred that the control means is arranged such that the valve seats are stationary and the closure member moves between two operative positions in each of which the closure member engages a respective one of the two seats. The closure member may be in the form of a hollow cylinder, in which event cold water flowing to the mixing chamber may pass axially through the cylinder.

Flow inducing means may be provided to assist balanced flow from the two inlets in the event that the cold water supply, for example, is at a higher pressure than the hot water supply. Such flow inducing means may include a venturi-like arrangement provided within the cold water flow path and which communicates with the hot water inlet to induce flow from that inlet. Such communication between the hot water inlet and the venturi will of course depend upon absence of engagement between the closure member and the valve seat which is associated with the hot water inlet.

It is preferred to provide fail-safe means which comes into operation in the event of failure of the thermostat. That fail-safe means may include a secondary flow passage for cold water which opens in response to failure of the thermostat and is not affected by- engagement of the closure member with either valve seat. Alternatively, the fail-safe means may include a heat responsive shut-off device which operates to close the outlet from the mixing chamber in the event that water emerging from that chamber has a temperature above a predetermined temperature.

The invention will be hereinafter described in greater detail by reference to the attached drawings of example embodiments of the invention. The particularity of those drawings is not to be understood as superseding the generality of the preceding description.

Figure 1 is a cross-sectional view of one particular valve incorporating an emodiment of the invention.

Figure 2 is a diagrammatic view of part of the valve shown in Figure 1, in which the valve is conditioned to allow both hot and cold water flow to the mixing chamber.

Figure 3 is a viev: similar to Figure 2 but showing the valve conditioned to close off hot water flow to the mixing chamber.

Figure 4 is a view similar to Figure 3 but showing the valve conditioned to close off cold water flow to the mixing chamber.

Figure 5 is a view similar to Figure 2 but showing the valve conditioned to allow cold water flow as a result of failure of the thermostat.

Figure 6 is a cross-sectional view of another valve incorporating a further embodiment of the invention.

Figure 7 is a cross-sectional view of a shut-off device which is usable with the valve of Figure 6 or any other valve incorporating an embodiment of the invention.

Figure 8 is a cross-sectional view taken along line VIII-VIII of Figure 7.

Figure 9 is a cross-sectional view taken along line IX-IX of Figure 7.

The valve shown in Figure 1 includes a hollow body 1 having a cold water inlet 2, a hot water inlet 3 and an outlet 4. The outlet 4 communicates with a mixing chamber 5, and communication between that chamber 5 and each of the inlets 2 and 3 is subject to the influence of thermostatically operated flow control means. In the construction shown, that control means includes a closure member 7 which is mounted within the valve body 1 for relative movement. A thermostat 8 is connected to the member 7 and is operable to move that member 7 as hereinafter described.

In the particular arrangement shown, the closure member 7 is of cylindrical tubular form and is secured to an end portion 9 of the body 10 of the thermostat 8 so as not to be movable relative to that body 10. The member 7 may be secured to the body 10 by cooperation between an external screw thread on the end portion 9 and an internal screw thread formed on an internal transverse wall 11 of the member 7. Obviously, other types of securing means could be adopted. Bore portions 12 and 13 on respective opposite sides of the wall 11 communicate by way of holes 14 formed through the wall 11. The wall 11 may be formed integrally with the cylindrical body 15 of the member 7, or it^' may be formed separately and secured to that body 15 in any appropriate manner so as to be held against relative movement. The thermostat 8 is of known construction and operates in a known manner. A rod 16 slidably mounted within the body 10 projects from one end of that body and an internal spring (not shown) urges that rod 16 into a retracted condition. A temperature responsive medium contained within the body 10 expands with rising temperature and thereby urges the rod 16 further out of the body 10 against the influence of the internal spring.

In the arrangement shown, the thermostat body 10 is arranged substantially coaxial with the valve outlet 4 so that the end portion 17 containing the temperature responsive medium is exposed to water emerging from the mixing chamber 5. Other arrangements are clearly possible. Also in the arrangement shown, the thermostat body 10 is mounted so as to be axially movable relative to the valve body 1. For that purpose, the thermostat body 10 may be slidably mounted in a fixed transverse wall 18 of the valve body 1 as shown. The connected closure member 7 is located between two valve seats 19 and 20 which form part of the flow control means, and the thermostat body 10 is urged towards the uppermost seat 19 by a coil compression spring 21 acting between the two walls 11 and 18. Again, other arrangements are clearly possible.

The valve seat 19 is shown formed by an inner end face of a cap member 22, but it could be formed in other ways, and is engagable by an upper end 23 of the closure member 7 as shown in Figures 1, 4 and 5. The lower seat 20 is shown formed by a surface of the valve body 1, but may be formed in other ways, and is engagable by the lower end 24 of the member 7.

Hot and cold water chambers 25 and 26 resepectively are formed within the valve body 1, and are separated by a fixed internal wall 27 of that body. The closure member 7 is slidably mounted within an opening formed through the wall 27, and any suitable sealing means may be provided between that opening and the member 7. Communication between the chambers 25 and 26 is therefore only possible through the interior of the member 7, and is subject to the member 7 being clear of both valve seats 19 and 20 as shown in Figure 2.

The primary path for cold water flow to the mixing chamber 5 includes a gap 28 (the orifice) between the seat

19 and the control member end 23, as shown in Figures 2 and 3. A secondary flow path is provided as part of fail safe means, and in the arrangement shown that path includes interconnected passages 29 and 30 formed in the cap member 22. A valve seat 31 is provided within the passage 30 as best seen in Figure 5, and a closure member 32 mounted on the terminal end of the thermostat rod 16 is engagable with that seat 31 so as to close the secondary flow path (Figures 2, 3 and 4). It will be appreciated that it is not essential to have a separately formed closure member 32, since the terminal end of the rod 16 could function as a closure member.

In the particular arrangement shown in Figure 1, an inner portion 33 of the cap member 22 is axially movable relative to the valve body 1, and a hand engagable knob 34 is operable to adjust the axial position of that portion 33. Such adjustment enables variation of the temperature at which the closure member end 24 engages the valve seat 20 and thereby closes off hot water flow. In an example arrangement, the aforementioned temperature is adjustable within the range 20°C to 99°C, and preferably is adjusted to operate within the range 30 C to 55°C. The invention is also applicable to valves not having such an adjustment facility. _:

The particular arrangement shown also includes a one-way flow facility 35 between the hot water inlet 3 and the hot water chamber 25. Such a facility need not be provided in all valves to which the invention is applicable.

A valve as described is preset to close hot water flow to the mixing chamber 5 at temperatures above s predetermined temperature, and that condition of the valve is shown in Figure 3. That predetermined temperature will be referred to as the predetermined chamber temperature so as to be distinguished from another predetermined temperature. The Figure 3 condition arises because the thermostat 8 responds to rising temperature in the chamber

5 by causing increased projection of the rod 16 from the body 10. Upward movement of the rod 16 beyond the position shown in Figures 2, 3 and 4, is prevented by engagement between the closure member 32 and the valve seat 31. Consequently, increased projection of the rod 16 can only be accommodated by downward movement of the thermostat body 10 against the action of the spring 21. Such movement progressively increases cold water flow to the mixing chamber 5 by increasing the gap 28 (Figures 2 and 3) between the closure member end 23 and the valve seat 19. That is, the restriction to flow of cold water to the chamber 5 is progressively reduced. At the same time the restriction to hot water flow to the chamber 5 is progressively increased by the progressive closing of the gap between the valve seat 20 and the closure member end 24.

In the valve condition shown in Figure 2, there is flow of both cold water and hot water to the mixing chamber 5. The mixed water escapes from the chamber 5 to the outlet 4 by way of openings 36 formed through the wall 18. If the temperature of the water flowing over the thermostat end portion 17 continues to rise, the condition shown in Figure 3 may be adopted and cold water only will enter the chamber 5.

It will be appreciated that the Figure 3 condition will be adopted in circumstances where there is a reduction in, or complete loss of, cold water flow through the inlet 2. That is a unique and valuable safety feature of the valve according to the present invention. The security of the isolation of the hot water inlet under the Figure 3 condition could be enhanced by provision of an appropriate seal between the member 7 and the seat 20. By way of example, the seat 20 could be formed of a resilient material, or a resilient seating element could be carried by the member 7 so as to engage the seat 20.

Projection of the rod 16 from the thermostat body 10 reduces with falling temperature, and that is reflected in upward movement of the body 10 under the influence of the spring 21. If the temperature continues to fall, the condition shown in Figure 4 may be achieved, at which there is no cold water flow to the mixing chamber 5, and there is minimum interference to hot water flow. That is, the separation between the closure member 7 and the valve seat 20 is at a maximum.

It will be appreciated from the foregoing that the flow control means, which in the arrangement shown constitutes the member 7 and the seats 19 and 20, is able to adopt either of two primary flow conditions, or any of a variety of intermediate flow conditions. A primary flow condition exists when the member 7 engages either of the seats 19 or 20, and in each of those conditions there is maximum restriction to communication between the chamber 5 and one of the inlets 2 and 3, and minimum restriction to communication between the chamber 5 and the other of the inlets 2 and 3.

Intermediate flow conditions exist when the member 7 is not engaging either of the seats 19 and 20, for example as shown in Figure 2. The control means will traverse various intermediate flow conditions as the member 7 moves towards either of the valve seats 19 and 20. In the course of such traversing movement, there will be proportional control of the flow of hot and cold water to the chamber 5 because of the progressive increase in the restriction to one such flow at one end of the member 7 , and a corresponding decrease in restriction to the other flow at the other end of the member 7.

In the event of failure of the thermostat 8, the rod 16 will retract into the body 10 under the influence of the internal spring. At a certain stage in that retraction the closure member 7 engages the valve seat 19, after which further upward movement of the thermostat body

10 is not possible. Thus, as the rod 16 continues to move downwards, the closure member 32 is disengaged from the valve seat 31 and cold water is then able to flow from the chamber 26 through passages 29 and 30 into the bore 12,

13, and from there to the mixing chamber 5. Cold water therefore flows relatively unimpeded to the mixing chamber

5, and as a consequence ensures that the flow through the outlet 4 is at a relatively low temperature.

It will be apparent from the foregoing description that a valve according to the invention has the advantage of having fail safe operation in the event of either failure in the cold water supply to the valve, or failure of the valve thermostat. That dual fail safe characteristic is achieved in a relatively simple and effective manner. The particular valve described has the further advantage that it provides effective proportional control of both the hot and cold water flows to the mixing chamber so that the temperature of the water emerging from the valve is more accurately controlled. That is achieved by movement of the closure member of the flow control means between two opposed and spaced valve seats such that flow past one seat is increased as flow past the other is decreased.

In an example variation of the valve particularly described and shown in the accompanying drawings, the closure member 32 may be biased away from the valve seat 31 by suitable means, such as a compression spring, instead of relying on cold water pressure to cause disengagement of the member 32 from the seat 31.

The valve shown in Figure 6 is constructed in essentially the same manner as the valve previously described in relation to Figures 1 to 5, and operates in essentially the same manner, but incorporates some different aspects as hereinafter described. In the description of the Figure 6 valve which follows, components of that valve which correspond in general form and function to components of the Figures 1 to 5 valve, will be given like reference numerals except that they will be in the number series 100 to 199.

One feature of the Figure 6 valve which is not present in the valve of Figures 1 to 5, is flow inducing means as hereinafter described. Flow inducing means of the same or similar form could be incorporated in the valve of Figures 1 to 5 if desired. Another feature is adoption of a form of fail-safe response to cope with thermostat failure, which differs from that described in connection with the valve of Figures 1 to 5.

In the particular valve shown in Figure 6, flow inducing means is provided within the mixing chamber 105 and is operative to promote flow of hot water into that chamber. In the particular arrangement shown, the flow inducing means is formed by a venturi, but other forms of flow inducing means could be adopted. It is preferred, as shown, that the venturi is created, at least in part, by aspects of configuration of the closure member 107 and an element 140 which forms the valve seat 120 and defines at least part of the mixing chamber 105.

In the arrangement shown, the inner surface 141 of a lower part 142 of the closure member 107, slopes inwardly and downwardly in the manner of the frustum of a cone so that the internal cross-sectional size of the member 107 reduces along the part 142 to the lower end 124. It is prefered that the surface 141 is inclined at an angle of about 8° to the longitudinal axis of the closure member, but other angles could be adopted.

The inner surface 143 of the element 140 slopes in the opposite direction to that of the surface 141, and in the arrangement shown the sloping surface 143 extends the full length of the element 140. It is preferred that the surface 143 slopes at an angle of about 9° to the longitudinal axis of the element 140, but again a different angle could be adopted. The surfaces 141 and

143 combine to form a venturi-like configuration as shown, but it is to be appreciated that such a configuration could be formed in other ways.

When the member 107 is separated from the valve seat 120 as shown in Figure 6, the hot water inlet 103 communicates with the mixing chamber 105 through the gap

144 formed between the seat 120 and the member end 124. As a result, hot water enters the mixing chamber 105 at the narrowest point of the venturi. Thus, the pressure energy of the cold water flowing through the chamber 105 is converted into kinetic energy at the point of introduction of the hot water to the chamber 105, and that enables hot water supplied at a substantially lower pressure than the cold water supply to be drawn into the chamber 105 to mix with the cold water. For example, it is not unusual for the ratio of hot water pressure to cold water pressure to be 1:10.

The closure member 107 is moveable backwards and forwards between the valve seats 119 and 120 as in the previously described embodiment. That movement is controlled by the thermostat 108, and for that purpose the upper end of the thermostat push rod 116 needs to abut against the body 101, or a component connected thereto. In the arrangement shown in Figure 6, the push rod 116 abuts against a piston 145 which is slidable axially in the bore 146 of the cap member 122 and is biased by suitable means into engagement with the push rod 116. As shown, the biasing means may comprise a coil spring 147 acting under compression between the piston 145 and a member 148 attached to the valve body 101. The piston 145 thereby maintains downward pressure on the push rod 116. It is to be appreciated however, that the configuration of the components surrounding the spring 147 is such as to prevent the piston 145 moving away from the push rod 116, when the thermostat 108 operates to increase the projected length of the push rod 116. Thus, the principle function of the spring 147 is to cause the push rod 116 to be retracted into the thermostat body 110 as speedily as possible when a temperature reduction takes place. The spring 147 also encourages the temperature responsive medium of the thermostat 108 to operate reproducibly by returning to its initial condition after undergoing a cycle of heating and cooling. It is to be appreciated that the spring 121 will dominate over the spring 147.

The valve shown in Figure 6 is provided with means for adjusting the temperature above which hot water flow into the chamber 105 is prevented. That means includes the member 148, which is in the form of a screw threaded spindle which cooperatively engages with a threaded bore formed in the cap member 122. The lower end of the spindle 148 abuts against the piston 145 so that rotation of the spindle 148 relative to the member 122 is operative to change the rest position of the piston 145, which is the position shown in Figure 6 Such movement therefore effects adjustment of the temperature at which the closure member 107 closes off hot water flow and thereby also affects the temperature of the outlet flow. It is preferred that the outlet flow temperature is adjustable at least in the range of 30° to 55°C.

In the particular arrangement shown in Figure 6, a one way flow valve is located inboard of each of the inlets 102 and 103. Such one way flow valves need not be provided in all constructions to which the invention is applicable. One way flow valves as shown are of known construction and function in a known manner, and their purpose is to prevent cross-contamination of either of the two water supplies.

The valve as shown in Figure 6 may include fail-safe means located downstream of the mixing chamber 105. One such means which is shown in Figures 7 to 9 includes a shut-off device 149 having a tubular body 150 which can be attached to the threaded part 151 of the valve body 101 adjacent the outlet 104. The device 149 as shown in

Fiugres 7 to 9, includes a pair of superimposed relatively rotatable plates or discs 152 and 153 which extend across the bore 154 through the device. The two discs 152 and

153 are arranged in face to face relationship, and each has a plurality of apertures. The apertures 154 of the disc 152 must be in at least partial registry with the apertures 155 of the disc 153 in order for water to be able to escape from the outlet 104 through the device 149.

Heat responsive means in the form of a coil 156 of suitable material is preferably arranged to control the relative rotational positions of the discs 152 and 153.

In the preferred arrangement shown, opposite ends of the coil 156 are attached to the disc 152 and the disc 153 respectively, so that a tendency of one end of the coil 156 to move relative to the other will result in relative rotation of the two discs 152 and 153. By way of example, such a tendency might result from the overall length of the coil 156 changing in response to changes in the temperature of the water in contact with the coil 156.

In the particular arrangement shown, the coil 156 responds to increase in the temperature of its surroundings towards a predetermined upper limit, to increase its length and thereby effect relative rotation between the discs 152 and 153 such as to move the apertures 154 and 155 out of registry. By way of example the upper limit temperature may be 61°C, or thereabouts. Any suitable means may be adopted to prevent relative rotation of the discs 152 and 153 beyond the position at which flow through the apertures 154 and 155 is prevented. Relative rotation of the discs 152 and 153 is reversible in the sense that cooling of the water temperature to below the predetermined temperature will cause the coil 156 to contract and thereby move the discs 152 and 153 to bring the apertures 154 and 155 into at least partial registry.

In use, a valve as described in relation to Figures 6 to 9 may be preset to close hot water flow to the mixing chamber 105 at a predetermined temperature in the range of 30°C to 55°C. If the temperature of water in the outlet 104 rises above that predetermined temperature (e.g., because of failure of the thermostat 108), the coil 156, will respond to the increasing temperature of the water flowing through the device 149 so as to be automatically actuated closing off flow through the outlet 4.

It will be apparent from the foregoing description that a valve as described in relation to Figures 6 to 9, has substantial advantages over similar prior valves. The valve is capable of satisfactorily mixing hot and cold water delivered from supplies having substantially different supply pressures. The particular valve described has the further advantage of having fail safe operation should the outlet flow temperature rise above a predetermined upper limit, for any reason whatsoever. Various alterations, modifications and/or additions may be introduced into the constructions and arrangements of parts previously described without departing from the spirit or ambit of the invention.

Claims

CLAIMS :

1. A tempering valve including, a hollow body, a mixing chamber within said body, a hot water inlet and a cold water inlet for said chamber, an outlet for said chamber, flow control means within said body and having a closure member and two valve seats, each of which is associated with a respective one of said inlets, said control means being operable to adopt either of two primary flow conditions, in each of which there is engagement between said closure member and a respective one of said seats, and a thermostat which is responsive to changes in the temperature of the water within said chamber so as to cause said operation of the control means, wherein said closure member and valve seat engagement at least inhibits communication between said chamber and said cold water inlet in one said primary flow condition which is adopted as a consequence of decrease in said temperature below a pre-determined chamber temperature, and prevents communication between said hot water inlet and said chamber in the other said primary flow condition which is adopted as a consequence of increase in said temperature above said predetermined temperature.

2. A valve according to claim 1, wherein communication between said chamber and said cold water inlet is at a maximum when said control means adopts said other primary flow condition, and communication between said chamber and said hot water inlet is at a maximum when said control means adopts said one primary flow condition.

3. A valve according to claim 1 or 2, wherein said control means is operable to adopt any of a plurality of intermediate flow conditions in which said closure member does not engage either x>f said valve seats, and a change from one said intermediate flow condition to another results in an increase in a restriction to communication between said chamber and one of said inlets, and simultaneously results in a decrease in a restriction to communication between said chamber and the other said inlet.

4. A valve according to claim 1, wherein said closure member is mounted within said body for movement relative thereto between two operative positions, and said closure member engages a different one of said valve seats in each of said positions.

5. A valve according to claim 4, wherein said thermostat includes two relatively movable parts, and said closure member is connected to one said part so as to be movable thereby between said operative positions.

6. A valve according to claim 4 or 5, wherein movement of said closure member towards either one of said seats results in a progressively increasing restriction to communication between the chamber and the said inlet which is associated with the seat towards which said closure member moves, and simultaneously results in a progressively decreasing restriction to communication between the chamber and the other said inlet.

7. A valve according to any preceding claim, wherein said closure member is generally in the form of a hollow cylinder, opposite ends of which are each engagable with a respective one of said seats, and at least one passage is provided within said cylinder whereby water can flow axially through said cylinder from one of said inlets to said chamber.

8. A valve according to any preceding claim, wherein flow inducing means is operative to induce flow from one of said inlets into said chamber in response to flow from the other said inlet to said chamber.

9. A valve according to claim 8, wherein said flow inducing means is in the form of a venturi.

10. A valve according to claim 9, wherein said venturi is provided in the flow path between said cold water inlet and said chamber, and is operable to induce flow from said hot water inlet.

11. A valve according to claim 9 or 10, wherein said venturi is formed at least in part by said closure member.

12. A valve according to claim 11 when appended to claim

10. wherein at least part of said flow path is through said closure member, and an internal surface of said closure member forms at least part of said venturi.

13. A valve according to any one of claims 9 to 12, wherein said venturi is formed in part by a surface of said chamber.

14. A valve according to any preceding claim, wherein fail safe means is operative to open a secondary flow path in response to failure of said thermostat, whereby communication is effected between said cold water inlet and said chamber, and that communication is not prevented by engagement between the closure member and either of said valve seats.

15. A valve according to claim 14, wherein said fail safe means includes a secondary flow passage formed within said body, and a secondary closure member which is operative to close said secondary flow passage when the thermostat is functional, and to open said secondary flow passage when the thermostat is not functional.

16. A valve according to any one of claims 1 to 13, wherein fail safe means is operative to close said outlet in response to the temperature of water within that outlet exceeding a pre-determined outlet temperature.

17. A valve according to claim 16, wherein said fail safe means includes two relatively movable plates, each of which has at least one aperture therethrough, and temperature responsive means which is operable to influence the position of one said plate relative to the other such that said apertures are at least partially in registry when said outlet water temperature is below the said pre-determined outlet temperature, and are out of registry when said outlet water temperature is above said pre-determined temperature.

18. A valve according to any preceding claim, including means for adjusting said predetermined chamber temperature.

19. A tempering valve including, a hollow body, a mixing chamber within said body, a hot water inlet and a cold water inlet for said chamber, an outlet for said chamber, a thermostat having two relatively movable parts and being operative to cause said relative movement in response to a change in the temperature of the water within said chamber, a closure member attached to one of said thermostat parts so as move therewith between two operative positions, a first valve seat which is engaged by said closure member in one said operative position and is arranged so that said engagement at least inhibits communication between said cold water inlet and said chamber, and a second valve seat which is engaged by said closure member in the other said operative position and is arranged so that said engagement prevents communication between said hot water inlet and said chamber.

20. A tempering valve substantially as herein particularly described with reference to any one of the embodiments shown in the accompanying drawings.