GB2231939A - Servo-controlled switching valve particularly for heating systems with sanitary water production - Google Patents

Abstract

A servo-controlled switching valve, particularly for heating systems with sanitary water production, comprises a valve body internally defining a membrane chamber divided into an active compartment (6) and a compensation compartment (14) by a flexible membrane (35), three interconnected ports including the first intake port (18) intended to be connected to a sanitary water production system (46), a second intake port (20) intended to be connected to the return duct (20a) of a heating system (48, 49) and a third outlet port (19) intended to feed a recirculation pump (47). The valve further comprises a cutoff system (39, 40) arranged between the intake ports (18, 20) and the outlet port (19), controlled by the membrane, an electromagnetic control device (24-26) with a movable core (26) acting as an opening and closure element for selectively connecting the active compartment (6) to the compensation compartment (14) or the compensation compartment (14) to the outlet port (19), as well as means (36, 44) for opening and closing an electric circuit which is external to the valve. <IMAGE>

Description

SERVO-CONTROLLED SWITCHING VALVE PARTICULARLY FOR HEATING SYSTEM WITH SANITARY WATER PRODUCTION The present invention relates to a servo-controlled switching valve particularly for heating systems with sanitary water production.

In heating systems which besides producing heating warm water also produce sanitary warm water by means of an appropriate automatic device, it is necessary to install a switching valve in order to switch, for example upon an actuation arriving from external control means, the flow of the primary circuit of the system according to the requirements either through the automatic device for producing sanitary warm water, such as for example a boiler, secondary boilers and the like, or towards the proper heating systems.

As is known, complicated valve assemblies are currently used; though they are satisfactory from some points of view, they have considerable disadvantages, such as that of using electric motors to switch the flow of water and of being therefore very expensive. Said valve assemblies furthermore have response times in the range of ten seconds or more after the electric activation command, due to the intrinsic mechanical inertia of the electric motors employed. Such reaction times must be considered unacceptable, since the production of sanitary warm water must be immediate when requested by the user.

The aim of the present invention is to provide a servocontrolled switching valve particularly for heating systems with sanitary water production, which is conceived so as to drastically reduce the time required to respond to the switching activation command from approximately ten seconds to a few seconds.

A further object of the present invention is to provide a servo-controlled switching valve which is conceived so as to have no outward dynamic seal, i.e. so as to have all the movable flow control components arranged inside the valve body, to the full advantage of a perfect seal even after very long operating periods.

Another object of the present invention is to provide a valve of the above specified kind which is very precise, sensitive and reliable.

Not least object of the present invention is to provide a servo-controlled switching valve which is relatively easy to manufacture at competitive costs.

This aim, these objects and others which will become apparent hereinafter are achieved by a servo-controlled switching valve, particularly for heating systems with sanitary water production, comprising a valve body defining, in its interior, a membrane chamber which is divided into an active compartment and a compensation compartment by a flexible membrane; three interconnected ports including a first intake port intended to be connected to a sanitary water production apparatus, a second intake port intended to be connected to a return duct of a heating system, and a third outlet port intended to feed a recirculation pump; and a cutoff system, arranged between said intake ports and said outlet port and controlled by said membrane, characterized by a control device including an electromagnet with a movable core acting as an opening and closure element to provide a selective connection either between the active compartment and the compensation compartment or between the compensation compartment and the outlet port, as well as means for opening and closing an electric circuit arranged externally to said valve.

Further characteristics and advantages of the present invention will become apparent from the following detailed description, made with reference to the accompanying drawings, which are provided only by way of non-limitative example and wherein: figure 1 is a front elevation view of the servocontrolled switching valve according to the invention; figure 2 is a plan view of the valve of figure 1; figure 3 is a transverse sectional view taken along line III-III of figure 1; figure 4 is a middle vertical sectional view of the valve, taken along line IV-IV of figure 2; figure 5 is a sectional view, similar to figure 4, illustrating the valve in a different operating condition as well as the connections of the valve in a heating system; and figure 6 is a partial view, similar to figure 5, illustrating a different embodiment.

With reference to the above figures, a servo-controlled switching valve according to the invention comprises four main components, i.e. a shell or flange 1, a flange 2 associable with the flange 1, a hollow body 3 which can be connected to the flange 2, and an electromagnet housing 4 which can be connected to the flange 2.

The first flanae 1 can be made for examPle of plastic

material, such as polytetrafluoroethylene (Teflon), has a I' shell-like shape and is provided, on one side, with a central extension 5, for example cylindrical, and defines, on the other side, a central cavity 6 facing the flange 2 and intended to define an active compartment of the valve.

The lateral wall of the cavity 6 defines a duct 7 including an outer threaded portion 7a and an inner non-threaded portion 7b. A much smaller diameter duct 8 leads into the portion 7b to provide a fluid connection as will be explained hereinafter.

The second flange 2, which can also be made of plastic material such as polytetrafluoroethylene (Teflon) , is centrally provided, in its lower part, with a body or tang 9 which extends axially with respect to said flange and is for example cylindrical. Said tang is internally traversed by an axial hole 12, and is provided, on its outer surface, with annular seats 10 intended to accommodate at least one O-ring 11. The duct 12 furthermore defines, at its outer end portion, an annular seat 13 intended to accommodate a sealing gasket 15 and a retention ring 15a for said gasket.

Furthermore, on the side directed towards the flange 1, the flange 2 defines an axial cavity 14, intended to form a compensation compartment, and a small-diameter duct 16, the function whereof is explained hereinafter, leads into said cavity.

The hollow body 3 is made of metal, such as brass, and comprises four ports 17, 18, 19 and 20. The first port 17 is intended to sealingly accommodate the tang 9 of the flange 2. The port 18 extends laterally from the body 3, for example at 900 with respect to the port 17, and is externally or internally threaded so that it can be coupled to a feed duct 18a (fig. 5). Perpendicular to the lower wall of the port 18, the hollow body defines a shoulder 41, forming an abutment for a plate 39.

The port 19 is defined laterally on the body 3, for example at 900 with respect to the port 18, and protrudes outwards from said body transversely with respect to the port 17. The outer end of the port 19 is at least partially threaded so that it can be removably coupled to an outlet duct 19a. The port 19 is internally designed for the discharge of fluid (water) from the hollow body 3, and is made in the shape of a Venturi tube (figure 3). The fourth port 20 extends axially to the port 17. The outer surface of the end portion of port 20 may be threaded so as to allow removable coupling to a feed duct 20a. A neck 21 is defined inside the port 20, and a frustum-shaped spring 22 is fixed therein; the other end of said spring abuts against a plate 40 the function whereof will be explained hereinafter.

A wing 23 furthermore extends transversely from the hollow body 3, at the port 19, and defines a duct 23a, intended to connect the ports 19 and 20 to the inside of the housing 4.

The housing 4, which is for example cylindrical and made of plastic material such as polytetrafluoroethylene (Teflon), is intended to accommodate a hollow electromagnet 24 connected to external power supply and control means through contacts 25, a movable core 26, for example cylindrical and covered with plastic material, movably mounted inside the axial cavity 32 of the electromagnet 24, a cylindrical return spring 27 acting between the core 26 and the flange 2, as well as a hollow support 28 extending in the axial cavity 32 and accommodating the core 26, intended to sealingly support and secure the housing 4 to the flange 2 and to the wing 23.

A sealing gasket 29a is fixed at one end of the core 26, for closing the duct 8 in the flange 2 in the position of the core shown in fig. 5, and a sealing gasket 29b is fixed at the other end of said core 26, for closing a duct 30 formed in the support 28 in the position of the core shown in fig. 4, said duct 30 is in turn connected to the duct 23a. A longitudinal channel 31 is furthermore provided in the lateral surface of said core 26 for connecting the end portions of the cavity 32 not occupied by the core 26; the ducts 8 and 16 lead into one of said end portions and the duct 30 leads into the other.

The flanges 1 and 2 are associable simply by placing them mutually adjacent, and can be fixed to one another through adapted retention means, such as screws 33 (figure 2), Allen screws and the like. Coupling of said flanges causes the cavities 6 and 14 to face each other, said cavities remaining, however, separated by a flexible and elastically yielding membrane 35, made for example of pyrene-propylene rubber and peripherally sealingly locked between the flanges 1 and 2. Said membrane 35 is furthermore centrally provided with a vertical element, for example cylindrical, intended to secure a magnet 36.

A plate 37 of plastic material or the like is centrally associated with the membrane 35, on the side thereof facing the chamber 14, and an actuation rod or stem 38 is rigidly and axially associated to said plate and is movably mounted within the axial hole 12 of the flange 2, from which it protrudes into the hollow bod until the port 20. Inside the hollow bod 3, the stem is provided with two further plates 39 and 40, for example made of plastic material or the like, which are sealingly fixed thereto with the interposition of a spacer 42, made for example of plastic material or the like. The plate 39 can abut against the shoulder 41 formed inside the port 18, ahead of the ports 19 and 20, and is intended to control or cut off the flow arriving from the duct 18a when the stem 38 is moved toward the port 20.The plate 40 is arranged inside the port 20, is loaded by the spring 22 which abuts against it with one of its ends and is adapted to control or cut off the flow arriving from the duct 20a.

The extension 5 of the flange 1 externally supports a proximity microswitch or a Reed bulb 44. Said microswitch 44 is normally open and can be controllably closed by the magnet 36, or by another means, to close an external electric circuit, not illustrated, connected to the contacts 45a and 45b.

Figure 5 furthermore schematically indicates the main components of a complete heating system which comprises a circuit for the production of sanitary warm water and one for the water for the system of radiators. Said components are: a boiler 46 or device for producing sanitary warm water, a recirculation pump 47, an exchanger 48, radiators 49 and a feed duct 50.

Figure 6 illustrates a different embodiment of the switching valve according to the invention, in which an axial guiding hole is provided through the extension 5 instead of the magnet 36 and the Reed bulb 44; a control pin 55 is slidably inserted in said extension through a teflon sleeve 56 and a sealing gasket 57. The pin 55 has an end thereof which protrudes into the cavity 6 and supports a flanged head 58 made for example of teflon, and another end which protrudes from the flange 1 and supports a head 59 acting as a stop abutment.

The pin 55 is loaded by a spring 60, which is arranged for example within the cavity 6 and acts between the flanged head 58 and the flange 1 or the sleeve 56.

Along the path of the pin 55 there is the actuation button 61 of a switch 62.

The operation of the above described valve is as follows. The valve is intended to be inserted on the water return circuit; i.e., the pump 47 has its suction side connected to the port 19 which is fed by the port 18 if the sanitary warm water production device or system 46 is active or by the port 20 if the heating system 49 is operating.

The pressure produced by the pump 47 on its own delivery side is sent, through the feed duct 50, to the port 7 of the flange 1, and when the electromagnet 24 is not activated, the core 26, due to the antagonist effect of the spring 27, closes the channel 30 by means of the plug gasket 29b, so that the ducts 8 and 16 are mutually connected; said ducts stabilize or balance the pressure between the active compartment 6 and the compensation compartment 14, allowing the frustum-shaped spring 22 to push the plate 40 to the closed position and the plate 39 to the open position. In this configuration (shown in fig. 4), the port 18 is connected to the port 19 and the flow therefore passes through the warm water production system 46.Furthermore, the magnet 36, as an effect of its own magnetic field, or the pin 55, pushed by plate 37, actuates the proximity microswitch 44 or 62, thus closing the electric circuit which is arranged externally to the valve (not illustrated) and connected thereto through the contacts 45a and 45b.

When instead the electromagnet 24 is fed through the contacts 25 by an external electric circuit (not illustrated), it causes the movement of the core 26 from the position indicated in figure 4 to the position indicated in figure 5, opening the duct 30 and closing the duct 8 by means of the plug-shaped gasket 29a. In this case, the pressure exerted by the pump 47 remains confined within the active compartment 6, while the compensation compartment 14 is connected to the duct 30 through the duct 16 in the flange 2 and the duct 31 in the core 26, thus producing a suction and consequently a differential pressure between the active compartment 6 and the compensation compartment 14. As an effect of this phenomenon, the membrane 35 pushes the plate 37 toward flange 2, which plate, through the stem 38, and overcoming the resistance of the spring 22, pushes the plate 39 in the closed position, interrupting the flow through ports 18 and 19, and the plate 40 in the open position, connecting the outlet port 19 to the inlet port 20. In this case the circulation occurs through the heating system 49. Furthermore, due to the movement performed, the magnet 36 or the pin 55 releases the proximity microswitch 44 or 62, thus opening the electric circuit arranged externally to the valve by means of the contacts 45a and 45b. The described configuration is the one illustrated in figures 5 and 6.

The execution of the duct 19 as a Venturi tube allows to mount the servo-controlled switching valve on hydraulic circuits which have load losses close to zero, since the shape of said port facilitates the onset of a differential pressure sufficient for operation in the chamber formed by compartments 6, 14.

In its practical execution, the invention as described above is naturally susceptible to structural and functional modifications without thereby abandoning the scope of the protection of the invention, defined by the content of the following claims.

Claims (9)

1. A servo-controlled switching valve, particularly for heating systems with sanitary water production, comprising a valve body defining, in its interior, a membrane chamber which is divided into an active compartment and a compensation compartment by a flexible membrane; three interconnected ports including a first intake port intended to be connected to a sanitary water production apparatus, a second intake port intended to be connected to a return duct of a heating system, and a third outlet port intended to feed a recirculation pump; and a cutoff system, arranged between said intake ports and said outlet port and controlled by said membrane, characterized by a control device including an electromagnet with a movable core acting as an opening and closure element to provide a selective connection either between the active compartment and the compensation compartment or between the compensation compartment and the outlet port, as well as means for opening and closing an electric circuit arranged externally to said valve.

2. A valve according to claim 1, characterized by a housing seat for said core, said seat defining two end chambers arranged at a respective end of said movable core, said chambers being mutually connected through at least one groove in the movable core; one of said end chambers being connected to said outlet port, the other end chamber being connected to a first duct leading to the active compartment and to a second duct leading to the compensation compartment, said movable core having, at the ends thereof, respective plugs for selectively closing either the connection to the outlet port or the connection to the first duct leading to the active compartment.

3. A valve according to claim 1 or 2, wherein said movable core is elastically biased.

4. A valve according to any preceding claim, wherein said means for opening and closing an electric circuit comprise a proximity switch adapted to act in response to the movements of the membrane inside the membrane chamber.

5. A valve according to claim 4, wherein said switch is a microswitch comprising a Reed bulb and a control magnet mounted on the membrane.

6. A valve according to claim 4, characterized in that said microswitch comprises a switch and an actuation pin which is elastically biased and sealingly slidably mounted in a wall of the membrane chamber along the movement path of said membrane to be actuated thereby.

7. A valve according to any preceding claim, wherein said cutoff system between said inlet and outlet ports comprises a rod connected to said membrane and slidably and sealingly mounted between said membrane chamber and an interconnection region of said ports, a cutoff sector mounted on said rod movable between an open and a closed position to selectively allow or cutoff the flow between said first inlet port and the other two ports, and a locking sector adapted to cutoff the flow between the second inlet port and the other two ports when said cutoff sector is in open position.

8. A valve according to any preceding claim, wherein said outlet port is in the shape of a Venturi tube to create a differential pressure between the active and compensation compartments so as to vary configuration of the membrane.

9. A servo-controlled switching valve, particularly for heating systems with sanitary water production, substantially as herein described with reference to the accompanying drawings.