A THERMOSTATIC MIXING VALVE

Abstract: A thermostatic mixing valve to be used for supplying to hydraulic and sanitary appliances, from supply pipings of hot and cold water, water having a pre-established temperature, which may be controlled within certain limits, comprising a body (11, 12) provided with inlet openings (30) for hot water, inlet openings (31) for cold water, and an outlet opening (33) for mixed water and, inside said body, a temperature sensitive member (24) which, by acting against the action of a spring (32), causes the displacement of a slider (26) which may travel between two shoulders (28, 29) located one in the intake region for hot water and the other in the intake region for cold water, in order to throttle in a different and opposite way the inlet openings (30, 31) offered to the hot water and respectively to the cold water, which waters, inside the valve body, after having been mixed together, lap the temperature sensitive member (24), wherein the inlet openings (30) located in the intake region for hot water have a passage section clearly different from, and preferably greater than, the passage section of the inlet openings (31) located in the intake region for cold water.

Description: DESCRIPTION A THERMOSTATIC MIXING VALVE The present invention has for its object a thermo- static mixing valve of the type used for supplying to hy¬ draulic and sanitary appliances, from supply pipings of hot and cold water, water having a pre-established temperature, which possibly may be controlled within certain limits. Some thermostatic valves of the type taken into ac¬ count here are known, which comprise a body provided with inlet openings in an intake region for hot water, inlet openings in an intake region for cold water, an outlet opening for mixed water and, inside said body, a tempera- ture sensitive member which, by acting against the action of a spring, causes the displacement of a slider which may travel between two shoulders located the one in the intake region for hot water and the other in the intake region for cold water, in order to throttle in a different and oppo- site way the inlet openings offered to the hot water and respectively to the cold water, which waters, inside the valve body, after having been mixed together, lap the tem¬ perature sensitive member. This way, thanks to a suitable sizing of the different parts, it may be obtained that the hot water and the cold water, which enter the valve body and mix together therein, produce mixed water having the wanted temperature. These valves have a heavy drawback, consisting in that the delay with which the valve intervenes for modifying the passage sections offered to the incoming water when the temperature of the mixed water changes, even if it is lit¬ tle, in some specific conditions may give rise to an over- control, and consequently to further regulations in the op¬ posite sense, whereby oscillations of the valve take place. Another drawback consists in that, at the start of the delivery, when the control action of the still cold temper- ature sensitive member has not yet started, the valve al¬ lows excessive intake of hot water and only a reduced in¬ take of cold water, whereby mixed water having an exces¬ sively high temperature is delivered. This gives rise to very disagreable consequences, particularly when the valve controls the temperature of water forwarded to a shower. This drawback may also be repeated in the further operation, in case that casual sudden differences of pres¬ sure between the supply pipings take place. One of the objects of this invention is to find a rem¬ edy, at least in a great measure, for these drawbacks, by embodying a valve having a reduced tendency to the oscilla¬ tion, and which moreover, preferably, in the absence of a control delivers water at a moderate temperature, and in- tervenes more rapidly against the increases in temperature than against the reductions in temperature. The first object is attained, according to the inven¬ tion, in that the inlet openings located in the intake re¬ gion for hot water have a passage section clearly different from the passage section of the inlet openings located in the intake region for cold water. The ratio between the passage section of the larger inlet openings and the passage section of the smaller inlet openings is at least 1.5, preferably 2.5 and more prefer- ably 3.5 or more. Thanks to this feature, which makes the valve accord¬ ing to the invention different from the known valves, wherein said inlet openings have substantially equal pas¬ sage sections, the slider assumes an asymmetric position and, when it is displaced, it acts with a proportionally different effect on the two incoming water flows. Due to the consequent asymmetry of the valve behaviour, the ten¬ dency to the oscillation of the valve is effectively op¬ posed. Preferably, moreover, the inlet openings located in the intake region for hot water have a passage section clearly greater than the passage section of the inlet open¬ ings located in the intake region for cold water. Thanks to this feature, the asymmetry in the valve be¬ haviour consists in that, being equal the supply pressures and the temperature of the delivered water, the valve slider is compelled to locate more near the position in which it throttles the hot water passage, than it could happen in a known valve, in order to compensate for the throttling suffered by the cold water due to the lesser section of the corresponding passage openings. For this reason the valve is in the condition of responding to an increase in the delivered water temperature, more rapidly than to a reduction therein, when, for example, a sudden modification takes place in the pressure of the supply pip- ings. This is of advantage in that a temporary reduction in the temperature of the delivered water is less disagre¬ able than a temporary increase in said tempera¬ ture. Moreover, this advantageous condition is verified, in particular, at the delivery start, thus preventing the initial delivery of excessively hot water. Preferably the valve includes means for modifying the rest position of the slider driven by the temperature sen¬ sitive member, and this allows regulating, within certain limits, the temperature of the delivered mixed water. These and other features, objects and advantages of the present invention will appear more clearly from the following description of an embodiment, having the non-lim¬ itative character of an example, which is diagrammatically shown in the appended drawings, wherein: Fig. 1 shows the cross section of a manifold intended to receive a thermostatic valve, with a valve according to the invention mounted therein and shown in external view; Fig. 2 shows in external view and on a larger scale the sole thermostatic valve of Figure 1; and Fig. 3 shows a cross section thereof, taken along line III-III of Figure 2. The manifold shown in Figure 1 comprises a body 1 wherein there is embodied an inlet connection 2 for hot wa¬ ter, communicating with a passage 4 ending in an annular chamber 6 which defines an intake region for hot wa- ter. Manifold 1 further comprises an inlet connection 3 for cold water, communicating with a passage 5 ending in an annular chamber 7 which defines an intake region for cold water. Moreover the manifold 1 has a chamber 8 from which starts a delivery connection for mixed water. Chamber 8 thus defines an outlet region for mixed wa¬ ter. Communicating with this chamber 8 there is a seat 10 suitable for receiving the installation of a thermostatic valve. The said hot water intake region 6 and cold water intake region 7 open in said seat 10 intended to receive the thermostatic valve. This exemplary manifold is shown because its structure may aid in explaining the installation and the operation of the termostatic valve, but it should be understood that the manifold is not a part of this invention, that it has been shown only as a clarifying example, and that its structure could also be anyway different from the shown one. The thermostatic valve comprises a body formed by two parts 11 and 12 mutually connected in any known way, for example by means of a threaded connection 13. The body part 11 is provided with seats for two ring packings 14 and 15 located in such a way that, when the valve is inserted in the corresponding manifold, they separate the hot water intake region 6 from the outlet region 8 and from the cold water intake region 7. On its turn, the body part 12 is provided with a seat for a ring packing 16 which, when the valve is inserted in the corresponding manifold, separates from the outer ambient the cold water intake region 7. Moreover, the body part 12 has any known means, such as for example a threading 17, for fixing the valve within the corresponding manifold. In the body part 12 there is seali gly mounted, rotat- able but not axially displaceable, a ring member 18 which protrudes outside the valve body in order to provide a cou¬ pling means 19 for a control handle (not shown). The ring member 18 is internally threaded at 20, and by means of this threading it is coupled with a piston 21, mounted within the body part 12 such as to be allowed to displace axially but not to rotate. This way, by operating from outside a rotation of the ring member 18, an axial dis¬ placement of the piston 21 is obtained. In this piston 21 there is housed a safety spring 22, against which rests a projection 23 of a temperature sensitive member 24. The shown sensitive member 24 if of a kind which is formed by a cylinder-piston assembly containing a special wax having a high thermal expansion coefficient. Such sensitive members are usually employed in the concerned applications; however it should be understood that also different kinds of sensi¬ tive members could be used in the valve according to the invention. To the sensitive member 24 is connected, for example screwed, a tubular projection 25 of a slider 26, which is axially displaceable within the body part 11 wherein it seals by means of a ring packing 27. A spring 32 pushes the slider 26, and along with it the sensitive member 24, towards and against piston 21. Therefore, when the sensi- tive member 24 expands under the action of an increase in temperature, it displaces the slider 26 against the action of spring 32, by increasing its distance from the piston 21. The spring 22 aims to receive possible excessive forces applied to this system, thus preventing its detreri- oration. The slider 26 cooperates, by means of its end portions, with a shoulder 28 located in the hot water in¬ take region, as well as with a shoulder 29 located in the cold water intake region 29, whereby an axial displacement of the slider 26 causes opposite modifications of the pas- sage sections offered, respectively, to the hot and cold water, between the slider 26 and the shoulders 28, respec- tively 29. To said variable passage sections the water arrives through openings, which in this case have the shape of slits, formed in the valve body 11. More precisely, the hot water enters the valve through slits 30, and the cold water enters through slits 31. As it may be observed in the Figures, the passage sections of these slits 30 and 31 are very different, and more precisely, in this preferred embodiment, the slits 31 for cold water passage are very reduced with respect to the slits 30 for hot water pas¬ sage. In the shown example, the ratio between the passage section of the slits 30 for hot water inlet and the passage section of the slits 31 for cold water inlet is more than 4. However, in some cases, the results aimed by the inven- tion may be obtained even by more reduced ratios. The operation of the valve is as follows. At rest, the slider 26 takes a position which depends from the regu¬ lation entered by means of the rotation of the ring member 19 and the corresponding axial displacement of the piston 21 and, along with it, of the sensitive member 24 and the slider 26. In any case, this position is operatively more close to the shoulder 29, because at rest the sensitive member still is cold and therefore it aims to offer the maximum passage to the hot water. However, because the cold water always suffers a throttle due to the more re¬ duced passage section of the openings 31 with respect to the passage section of the openings 30, the position of the slider 26 should in any case be more close to the shoulder 28 than it should be in case the inlet openings were equal the one another, as according to the known art. Therefore, already at start of the operation, the delivery of exces¬ sively hot water is prevented. Thereafter, the stated asymmetry of the slider position, due to the different ex¬ tension of the inlet openings, causes the valve to inter- vene more rapidly for correcting casual increases in tem¬ perature, than for correcting reductions in temperature. because the slider 26 is already relatively more close to the shoulder 28, with which it should cooperate in order to throttle the inlet of hot water. It is important to observe that the stated asymmetry in the behaviour of the valve, due to the different width of the inlet apertures for hot and cold water, operates in the sense of highly attenuating any tendency of the valve to oscillate. Of course, in this connection, the same ef¬ fect could be obtained by the different extension of the inlet openings, even if, contrary to what has been stated as preferred, the inlet openings for hot water have an ex¬ tension substantially more reduced than the extension of the inlet openings for cold water. Therefore, when only the oscillations of the valve are to be prevented, and a protection against possible increases in temperature is not required, the invention may also be embodied in this latter form, opposite with respect to the described and shown ex¬ ample. The device for controlling the temperature, comprising the ring member 18 and the piston 21, may be omitted when a control of the temperature of the delivered mixed water by the user is not required, or it may have the character of a regulation device, to be set initially and not provided with any control member offered to the user. As already said, also other types of temperature sen¬ sitive members, different from the member 24, could be used, and moreover both the push spring 32 and the safety spring 22 could be located in a different manner. Different modifications, in addition to those stated, and any replacement by technically equivalent means, may be introduced in the embodiment of the valve, without depart¬ ing from the field of the invention and the scope of this Patent.

Claims: CLAIMS 1 . A thermostatic mixing valve to be used for supply¬ ing to hydraulic and sanitary appliances, from supply pip- ings of hot and cold water, water having a pre-established temperature, which possibly may be controlled within cer¬ tain limits, of the type comprising a body (11,12) having first inlet openings (30) in an intake region (6) for hot water, second inlet openings (31) in an intake region (7) for cold water, at least one outlet opening (33) in an out¬ let region (8) for mixed water and, inside said body (11,12), a temperature sensitive member (24) which, by act¬ ing against the action of a spring (32), causes the dis¬ placement of a slider (26) which may travel between two shoulders (28,29), located the one (28) in the intake re¬ gion (6) for hot water and the other (29) in the intake re¬ gion (7) for cold water, in order to throttle in a differ¬ ent and opposite way the inlet openings (30,31) offered to the hot water and respectively to the cold water, which wa- ters, inside the valve body (11,12), after having been mixed together, lap the temperature sensitive member (24), characterized in that the inlet openings (30) located in the intake region (6) for hot water have a passage section clearly different from the passage section of the inlet openings (31) located in the intake region (7) for cold wa¬ ter. 2 . A thermostatic valve as set forth in Claim 1, characterized in that the ratio between the passage section of the larger inlet openings and the passage section of the smaller inlet openings is at least 1.5. 3 . A thermostatic valve as set forth in Claim 1, characterized in that the ratio between the passage section of the larger inlet openings and the passage section of the smaller inlet openings is at least 2.5. 4 . A thermostatic valve as set forth in Claim 1, characterized in that the ratio between the passage section of the larger inlet openings and the passage section of the smaller inlet openings is at least 3.5. 5 . A thermostatic valve as set forth in Claim 1, characterized in that the inlet openings (30) located in the intake region (6) for hot water have a passage section clearly greater than the passage section of the inlet open- ings (31) located in the intake region (7) for cold water. 6 . A thermostatic valve as set forth in Claim 1, characterized in that said inlet openings (30,31) are em¬ bodied in the form of slits formed in the valve body. 7 . A thermostatic valve as set forth in Claim 1, characterized in that it includes means (18-21) for modify¬ ing the rest position of the slider (26) driven by the tem¬ perature sensitive member (24), thus allowing regulating, within certain limits, the temperature of the delivered mixed water. 8 . A thermostatic valve as set forth in Claim 7, characterized in that said means (18-21) for modifying the position of the slider (26) include a ring member (18), ro- tatable but not axially displaceable with respect to the valve body (11,12), and a piston (21) screwed with respect to said ring member (18) and axially displaceable but not rotatable with respect to the valve body (11,12), said sen- sitive member (24) resting against said piston (21) under action of a pushing spring (32). 9 . A thermostatic valve as set forth in Claim 8, characterized in that said ring member (18) protrudes out- side the valve body (11,12) with means (19) for connecting a control handle. 10 . A thermostatic valve as set forth in Claim 8, characterized in that said sensitive member (24) rests against said piston (21) with the interposition of a safety spring (22). 11 . A thermostatic mixing valve characterized by the peculiarities, arrangements and operation, as they appear from the above specification and annexed drawings, or re¬ placed by their technically equivalent means, taken in their whole, in their various combinations or separately.

Inventors: KNAPP FRANCESCO, KNAPP, FRANCESCO
Applicants: GEVIPI AG, KNAPP FRANCESCO, GEVIPI A.G., KNAPP, FRANCESCO
Application year: 1995
Main classification: G05D23
IPC codes: G05D23