GB2076127A - Thermostatically controlled mixing valves for hot and cold water - Google Patents

Abstract

The mixing valve controls the mixed temperature by means of a stainless bimetallic thermostatic spiral 146 which acts on a rotary slider 147 to affect the inflow of cold and hot water for the purpose of temperature control. The controlling and shut-off actions occur in a volume control cartridge 104 and in a separate temperature control cartridge 131. The volume control cartridge 104 comprises two packets each consisting of two relatively rotatable ceramic discs 121, 122 and 121', 122'. The cold water and the mixed water are controlled simultaneously by relative rotation of the ceramic discs. Approximately 90% of the housing wall is immersed in cold water. <IMAGE>

Description

SPECIFICATION Improvements in or relating to thermostatically controlled mixing valves for hot and cold water The present invention relates to thermostatically controlled mixing valves for hot and cold water.

It has been discovered that it is advantageous not only to have as effective as possible a separation between the temperature and volume control actions of such valves, but also that compact units which may also be easily installed and disassembled should be incorporated for both control modes. The conventional lifting valves moreover have frequently proved to have disadvantages for controlling the volume.

The invention consists in a thermostatically controlled mixing valve for hot and cold water, wherein separate units are incorporated for controlling the temperature and the delivery volume in the form of at least one cartridge, said cartridge or cartridges being insertable and removable separately into and from a housing, the control operation affecting the cold water supply as well as the hot water supply or the delivery volume of mixed water being performed in either instance by means of a packet of ceramic discs which are rotatable with respect to each other and provided with perforations.

These pairs of discs which, as known per se, act as valves which operate precisely and are hardly affected by attrition, enable appliances to be made which may be adjusted precisely and whose failure rate is satisfactory. In this connection, it was found to be particularly advantageous to lead the cold water into the housing containing the two co-axial units close to its wall, and to install all the internal elements of the appliance which convey hot water and possibly also mixed water in largely totally enclosing manner, so that heating of the mixing assembly housing from the hot water supply side is prevented.

In order that the invention may be more clearly understood, reference will now be made to the accompanying drawings, which show certain embodiments thereof in axial section and in which: Figure 1 shows a mixing valve comprising temperature and volume control units combined into a single cartridge, Figure 2 shows a valve comprising control units which are situated in two separate but interconnected cartridges, and Figure 3 shows a valve comprising two separate unconnected cartridges for the control units.

Referring now to the drawings, the structure of the thermostatic mixing valve according to Figure 1 will now be described.

An assembly housing 1 which may be of tubular construction to simplify manufacture, is connected to cold and hot water lines via connecting pipes 2 and 3. The complete mixing and controlling element is inserted as a compact cartridge into the assembly housing 1 and is secured by means of a retaining screw 49. The cartridge is almost wholly immersed in cold water, which prevents heating of the assembly housing from the side of the hot water connector.

The volume control operation is performed by means of a handle 4 shown at the right of the drawing, acting on a rotary element 5 via splines.

The rotary elements 5 simultaneously acts as the carrying element for the cold water control unit as a whole.

The essential feature of the mixing assembly consists in two packets of ceramic discs or plates 6 and 7 utilised for volume control instead of the conventional valve seats. The control action is performed by radial rotation (through say 900) of the discs with respect to each other. In view of the very compact form of construction, the complete internal element undergoes co-rotation during the volume control operation. The rotary displacement is transmitted from the rotary element 5 to the ceramic disc 7 via a cogged ring 8 or the like, which also exerts an initial stress on the unit as a whole by virtue of a coil spring 9. The ceramic discs may be set to the correct position during initial assembly, by virtue of this initial stress.A metal sleeve which simultaneously acts as an outer race for a smoothly running ball bearing system 11 as well as for receiving the ceramic disc 6, acts as an outer casing 10. The ceramic disc 6 which forms part of the actual closure packet, is set at a precise position with respect to the mating disc 7 by means of two balls 12, in the outer casing 10.

The ring 1 3 acts as a stop for the closure packet 6, 7 and for reception of the O-ring 14 which prevents a flow of cold water at the outside of the ceramic discs. The unit as a whole is shut off by a sealing screw 15 which simultaneously carries joints 1 6 and 1 7 which prevent an outflow of water into the volume control handle of the cold water control unit. The stop ring 1 8 centred on the outer diameter acts to iimit the rotary displacement of the volume control handle. To assure precise positioning, the stop ring is centred in a slot B in the casing tube 10 of the housing. A disc or washer 1 9 acts as a seat for the prestressing spring, as well as a safety stop for the cogged ring 8 or the like.At the left-hand side, the temperature is set at the required temperature by means of a rotary handle 21. The control operation is performed primarily by means of two elements, by virtue of the co-operation of a control spring 23 situated in the rotary handle and of an expansion element 22. The working substance of the expansion element may be Freon (Registered Trade Mark) or a fluid, a bimetallic plate spring packet also being possible for the actuation. The expansion element expands axially upon being heated and generates a particular force which may be adjusted by means of a control spring, that is to say that a control or governing action may be obtained to scale by the opposed action of these two forces.The connection between the two force sources is formed by a connecting rod 24 which actuates a control cyclinder 25, and aperture c and d (bores and slots) are thereby opened or closed in greater or lesser degree depending on adjustment. If the control cylinder 25 is displaced towards the left (direction X), it reduces the aperture c and less hot water flows into a mixing space e, whereas the displacement of the control cylinder in the direction X increases the aperture d and more cold water flows from the jacket a into the mixing space e, the mixing water temperature being reduced as a result. The left-hand side unit, which is equally compact, is primarily carried by the rotary element 26. The inset ring 27 as well as the bonded ring 28, are the closure seats for the temperature control operation.The sealing surfaces have a rubber layer of a thickness of approximately 0.5 mm vulcanised to them.

In order that the governing balance between the rated value spring 23 and the controlling force of the thermostat element 22 may be exposed to minimum disturbance, frictional forces caused by the sealing resistance of the O-ring 50 and the sleeve 51, as well as the forming of scale between element 25 and the carrier 26 should be prevented. To obtain sediment repelling connecting rods 24 and control cylinders 25, they are nickel plated chemically, coated with Tefion (Registered Trade Mark), or made from stainless steel.

The closure packet (ceramic discs) 6, 7 is installed at the hot water control side in similar manner to that of the cold water control side described (at the right in Figure 1). The shape and dimensions of the discs 6,7 are the same as at the cold water side. The rotary element 26 is also journalled in the outer casing 29 via ball bearings 11. A ring 31 is bonded in with a spacing ring 32, to act as a stop for the ceramic discs 6, 7 and to receive a sleeve 30. The cogged ring 8 or the like, the coil spring 9', the disc or washer 19', as well as the safety ring 20', are similar to those at the mating side and have the same functions and dimensions. The closure and control unit as a whole is closed by means of the sealing screw 32.

The joints 16' and 17' have the same dimensions and functions at 1 6 and 1 7. The temperature is controlled at the rear side of the sealing screw 32 by turning the handle 21 which fits on a rotary spindle 33. By rotation of the handle and via the splines on the rotary spindle, a spring locator 34 is thrust against the control spring which in its turn transmits the force to a supporting plate 35. This function also causes displacement of the control cylinder and greater opening of the hot water apertures C, to the effect that the mixed water becomes hotter. Excessive rotation of the temperature control system is prevented by a stop ring 36.A safety stop which prevents complete rotary opening to the hot setting, but may be overridden by means of pressure on a key, is installed in the temperature control handle to prevent scalding and protect children.

To assure easy operation of the temperature control handle or rather of the rotary spindle 33, an anti-friction washer 37 is placed between the rotary spindle 33 and a safety ring 38. To prevent rotary displacement of the spring locator as well as of the stop ring, the two elements are constructed with cogs or cams g and h which slide in grooves of the sealing screw 32. To secure ease of rotation between the connecting rod 24 and the supporting plate 35, the centre of rotation fmay be produced by means of a ball. A high frictional resistance at the point fwould cause poor sliding of the supporting plate 35 in the groove h and the rotary displacement of the inner element would also be impeded. The two units, being the hot and cold water control units, are joined together into a closed cartridge by means of a casing tube 39.

The synchronous rotation of the ceramic discs 7 is transmitted via the connecting tube 40, with a special denticulation. The denticulation is so formed on the connecting tube 40 that any longitudinal expansion may be taken up within the cartridge. To increase torsional stability, fins are situated at the inner side, which at the same time centre the expansion element.

To calibrate the temperature control system, the spring 42 is prestressed in greater or lesser degree by means of an adjusting bolt 41. The calibrating spring simultaneously acts as a protection against overpressure. To simplify the assembling operation, this unit is inserted in the preassembled state, complete with plate 43 and safety ring 44. To prevent outflow of water along the adjusting bolt, use is made of the O-ring 48 which for its part is secured by a press-fit ring 45.

An O-ring 46 is inserted to prevent direct oufflow of cold water into the outlet without flowing through the mixing space.

Outer O-rings 52 have the purpose of sealing and delimiting the cold and hot water inflow passages.

To secure easy operation of the volume control system, and to prevent a flow between the volume and temperature control systems, use is made of double-lipped joints 30. Satisfactory sealing as well as easy displaceability and rotatability are also required in the case of joints 16 and 17.

The ceramic discs are formed from oxide ceramics and the two confronting surfaces are lapped; this degree of surface precision engenders an adhesive force which assures total hermeticity even during a displacement. The adhesive force is so great that an initial stress on the discs by means of a spring or stressing washer would be superfluous. Prestressing elements are fitted however to prevent lifting off in case of back pressure or vacuum effect in the pipes, as well as for ease of assembly. The closing operation is performed by turning one disc with respect to the other through 850, thereby increasing or reducing the cross-section of the passageway. A disc is secured against relative rotation at the external diameter by means of two plastics material balls which fit precisely into a groove. The mating disc is precisely centred and turned by means of the cogged or cam ring 8.

The mixing appliance described, intended to mix cold and hot water to a predetermined mixture temperature, is applicable generally to sanitary ware e.g. for showers and bathrooms. It is readily adaptable to be wall-mounted i.e. it may be connected to any piping system comprising hot and cold pipes. The predetermined mixing temperature may be kept constant, practically without being affected by the supply of mixed water and by the feed pressure, due to a governing system comprising an expansion element and an adjustable control spring. The volume as well as temperature control operations are performed by means of two rotary handles installed externally on a spindle in each case. The volume control operation is not performed in conventional manner by means of two valve seats, but by means of two ceramic discs sliding on each other in each instance.Both water supply systems are turned off separately, so that no internal circulation may take place. Particles of dirt cannot impair the function and it is consequently possible to dispense with filters. The volume control system is wholly separate from the temperature adjustment system. The construction is so arranged that the mixing space is almost wholly surrounded by cold water. The pipe pressure constantly thrusts the rotatable ceramic disc against the stationary mating disc; this assures substantially total sealing, even at the highest pressures. To prevent lifting off however, in the case of a possible vacuum in the feed pipes, an initial stress is assured by means of a spring. Journalling in ball bearings allows of smooth rotatability of the prestressed internal elements.

In the mixing valve shown in Figure 2, the temperature and volume control units are housed in separate cartridges. This mixer controls and governs the mixing temperature by means of a stainless bimetallic thermo-spiral. This spiral acts with a radial force on a slider which affects the inflow of cold and hot water as a function of its setting and of possibly required correction. This spiral assures a rapid, precise and reliable control.

A different thermo-element may evidently also be specified.

The volume control cartridge is a compact unit whose principal supporting element is a housing 4 of plastics material reinforced with glass fibre. It is very simple to install the complete cartridge. The cartridge is inserted into the smooth bore of a housing 101 up to the impingement edge on a volume control cartridge 104. At the same time, two cogs situated on the volume control cartridge, are inserted at the end side into corresponding grooves in the housing. The volume control cartridge is secured against relative rotation and positioned at the same time, in this manner. The cartridge is secured by means of a cap nut which is secured on the housing by means of a screwthread. It is unnecessary to unscrew the handle upon installing and withdrawing the cartridge.All the components of the cartridge are so assembled that they are joined to the latter even when the cartridge is not installed, and do not drop off.

The mixed water flow is controlled via a volume control handle 105. The latter is fitted on the splines of a spindle 1 09 to obtain positioning of the handle. The handle 105 is secured by means of a screw 108 which is screwed at the end into a screw-thread cut into the spindle 109. The screw is covered by means of a covering cap 106 which is secured to the handle by a slight snap-in pressure. This measure primarily offers an improvement in appearance and furthermore also provides protection against unauthorised removal of the handle. The spindle is also turned when the handle 105 is turned.The rotary displacement is limited by a cog or cam located on the spindle 109 which encounters its angular limitation of approximately 1 60--1700 at the impingement edges in the supporting housing 11 3. The stop in the supporting housing 113 may be displaced by means of splines which are in engagement with the volume control cartridge 104. The transmission of force then occurs via an entraining rod 1 23. This entraining rod which is hexagonal (but which may also have splines, two flats, etc.) is inserted into a hexagonal socket of the spindle 109. The joint is glued and thereby secured by means of an adhesive such as that known as "Loctite" (R.T.M.). The entraining rod itself is inserted into a hexagonal socket of an entraining element 119.The entraining element 119 thus also undergoes co-rotation and may pick up a control disc 121 by means of cogs and turn the same on a disc 122 (inlet disc) which is secured against co-rotation in the volume control cartridge.

An entraining rod 1 23 furthermore extends as far as an entraining element 124 in the volume control cartridge 1 04. This also has a hexagonal socket intended to receive the entraining rod. The entraining element 1 24 is thrust on to the control disc 121' by means of a nut 125 which is screwed on the entraining rod 123, and said disc is thus placed under initial stress together with disc 1 22', to prevent lifting off of the discs. The nut 125 is secured and sealed on the entraining rod 123 by means of an adhesive such as "Loctite" as referred to above. The entraining element 1 24 which picks up the control discs 121' by means of cogs, is thus turned together with the entraining element 119.This has the result that the cold water flow and the mixed water flow are closed or opened at the same time. Two flows of water are thus turned off in the closed position, and therefore no circulation can take place. The cold water should be opened approximately 3 to 40 earlier than the mixed water, so that the gap loss may be balanced reliably and that, on the basis of acoustic considerations, a pressure loss may be obtained above the mixed water packet which reduces noise and also damps noise at the intake of the cold water control packet.

Like the volume control cartridge, the temperature control cartridge also forms a compact unit whose principal supporting element is a plastics material housing 131. The principal purpose of this cartridge consists in spatial delimitation. Among other things, it provides an external delimitation of the large inner mixing space, the housing 101 remains cool and so protects the user against burns. Approximately 90% of the marginal housing area is in contact with the cold water.

The temperature control cartridge may be installed very simply. It is inserted from the left into the smooth bore of the housing 101 until it reaches a shoulder of the temperature control cartridge 1 31. Two cogs are inserted simultaneously at the end side into corresponding grooves of the housing 101 and are thus secured positionally and against relative rotation. The cartridge is held by a cap nut 1 59 which is screwed on the left-hand side outer screw-thread of the housing 101. The connection between the temperature and volume control cartridges is established approximately at the centre of the housing by means of a simple plug and socket joint which is sealed by means of an O-ring 129.

The temperature is present by a temperature control handle 132. The latter carries a temperature scale 133 which, in conjunction with the markings on a marking ring 127, offer the possibility of precise temperature setting to the user of the thermostat.

An anti-scald key 138 is installed in the temperature control handle 132 as a protection against accidentally exceeding the temperature set. If a higher temperature is desirable, for example higher than 380C, this key 138 must be depressed to overcome the impingement edge in the stop 1 53. Upon turning back to a lower temperature than 380C, a spring 1 39 secured on an insert 1 60 pushes the anti-scald key 138 back into its initial position. The impingement for the lowest and highest presettable temperatures equally occurs between the anti-scald key 1 38 and a stop 153 which is positioned on a cover 1 56 by means of splines and may also be calibrated.

The rotary displacement of the temperature control handle 132 is transmitted to the spindle 1 35 via splines. Said spindle is provided with a denticulation which is in engagement with the denticulations of the two gears 140 and 140'.

These gears are housed in the entraining element 141. In the upper part 136 is also located a denticulation in which the gears engage. The two gears 140 and 140' undergo co-rotation when the spindle 135 is turned. Since these gears are then still in engagement only with the denticulation in the upper part, the entraining element 141 as a whole is turned. The size of the gears is so arranged as to establish a transmission ratio of 3 :1. The entraining element 141 is fixedly joined to a transmission rod 143. In turn, the latter is connected via bolts 144 to a receiving element 145 which is housed in a cylindrical part of the temperature control cartridge 1 31. A bimetallic spiral 146 is adhered, soldered or spot-welded to this receiving element. The spiral is equally firmly joined to an inner rotary slider 147. The presetting action may thus be operated.In case of temperature deviation, the spiral may react and turn the rotary slider 147 as warranted by the prevailing situation. The rotary slider 147 has slots milled in it which are then placed in alignment with the inlets in an inlet tube 148 according to the required temperature. The volumetric ratio for the required temperature may be determined in this manner. A clearance loss is unavoidable in a mixing action of this kind. This clearance loss should be kept as low as possible to prevent impairment of the results of the mixing operation.

Another advantage of the mixer consists in that the basis point may be adjusted from the outside without removing the temperature control cartridqe.

The governing and shut-off operations consequently occur in separate cartridges. This separation into cartridges was mandatory because use is made of two identical ceramic disc packets which are practically maintenance-free, for the shut-off operation. To avert circulation and thus also the incorporation of non-return valves, the two ceramic disc packets are so arranged that the cold and mixed water flows are opened and closed in parallel with each other. A prefiltering stage at the connector pipes for cold and hot water is eliminated by virtue of the ceramic discs.

Approximately 90% of the inner marginal areas is in contact with cold water. This practically eliminates the risk of being scalded or burnt on the mixing housing. The planned application of plastics material for the supporting elements of the temperature and volume control cartridges allows of economical rational production of the mixer. Longitudinal expansions and additions of tolerances are balanced by means of a spring. In the absence of cold water, the active component expands and rotates the inner rotary side until the flow of hot water is interrupted. The throughflow of the mixed water does not occur in the housing.

This establishes the advantage that there is no need for a cast housing comprising a cast mixing chamber. The large mixing chamber which allows of adequate circumcirculation of the thermostatic bimetal, is another advantage of the valve.

No more than two dynamic joints in the form of collar seals are present throughout the system.

The combination between ceramic discs acting as a shut-off element and the rotary slider is impervious to sediment and dirt. This fact enhances the functional reliability of the thermostat.

In the case of the third embodiment shown in Figure 3, a cast housing 201 is provided as a housing for the assembly. A cartridge 204 (volume control cartridge) and a cartridge 231 (temperature control cartridge) are inserted in each case from the corresponding extremities of the housing. By contrast to the embodiment hereinabove described, the two cartridges 204, 231 are not pushed close together at their internal extremities. At the extremities of the housing, the two cartridges 204,231 are each secured in the housing by means of two screws inserted through the housing 201 (as shown at s).

Two wall-side inlet pipes 202 and 202' for cold and hot water are each fitted with an anti-noise sleeve 271 of rubber or of plastics material diverging inwards conically and arranged on a supporting sleeve 270. The noise damping action secured by means of the sleeve 271 acting in the manner of a venturi nozzle is enhanced complementarily by the annular cavity 272 left between the sleeves 270 and 271.

In this example too, an insignificantly small part of the housing wail is in direct contact with hot water. A comparatively wide cold water passage 272 is situated in particular behind the front side of the housing 201 (shown at the bottom in Figure 3) facing away from the wall so that a perfect protection is assured against scalds. Moreover, this embodiment corresponds to the embodiment according to Figure 2 in essence, that is to say a first ceramic disc packet 221, 222 intended for cold water control, and a second ceramic disc packet 221 222' intended for mixed water control, are also provided in this case.

Claims (9)

1. A thermostatically controlled mixing valve for hot and cold water, wherein separate units are incorporated for controlling the temperature and the delivery volume in the form of at least one cartridge, said cartridge or cartridges being insertable and removable separately into and from a housing, the control operation affecting the cold water supply as well as the hot water supply or the delivery volume of mixed water being performed in either instance by means of a packet of ceramic discs which are rotatable with respect to each other and provided with perforations.

2. A mixing valve as claimed in claim 1, wherein the two units for controlling the temperature and volume are in the form of a single cartridge and are inserted into a tubular housing open at both extremities, the supply of hot water as well as the supply of cold water to the mixing chamber situated in the central area of the housing and comprising the thermo-element being adjustable in each case by a pair of ceramic discs by means of a rotary handle situated at an extremity of the housing, whereas the temperature control action is performed at the other housing extremity by means of a rotary handle acting on the thermo-element.

3. A mixing valve as claimed in claim 1, wherein the two ceramic disc packets utilised for volume control action, of which one controls the cold water supply and the other the mixed water delivery volume, are situated in a first cartridge inserted into a tubular housing and operable from a housing extremity by means of a rotary handle, whereas the temperature control action is brought about by means of a thermostatic element adjustable from the other side of the housing by means of a rotary handle, which acts on a rotary slider controlling the hot water supply, the rotary slider and the thermostatic element being located in a second cartridge inserted co-axiaily with respect to the first cartridge into the tubular housing.

4. A mixing valve as claimed in claim 1,2 or 3, wherein at least the inner parts of the housing located between the hot and cold water connectors of the housing and conveying hot and/or mixed water, are immersed in cold water during operation.

5. A mixing valve as claimed in claim 1, wherein the two ceramic disc packets are positioned in a first cartridge inserted from one extremity into a cast housing and act to control the cold water and the mixed water, respectively.

the two cartridges being secured in the cast housing by means of radial screws.

6. A mixing valve as claimed in claim 5, wherein a small part only of the housing wall is in contact with hot water, a comparatively wide cold water conveying passage being situated at the front side of the housing facing away from the wall side.

7. A mixing valve as claimed in any of the preceding claims, wherein an anti-noise sleeve of rubber or plastics material which is situated in a supporting sleeve whilst leaving an annular cavity and widens inwards conically is inserted into the inlet connectors of the housing for hot and cold water.

8. A mixing valve substantially as hereinbefore described with reference to Fig. 1 of the accompanying drawings.

9. A mixing valve substantially as hereinbefore described with reference to Fig. 2 of the accompanying drawings.

1 0. A mixing valve substantially as hereinbefore described with reference to Fig. 3 of the accompanying drawings.