GB2265207A

GB2265207A - Flow-controlled control switch,particularly for pri mary circuits in heating systems

Info

Publication number: GB2265207A
Application number: GB9305403A
Authority: GB
Inventors: Michele Rossignoli; Valter Falavegna; Avito Falavegna
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-03-18
Filing date: 1993-03-16
Publication date: 1993-09-22
Anticipated expiration: 2013-03-16
Also published as: ITVR920022A0; IT1257410B; NL194482B; GB2265207B; NL194482C; NL9300483A; ITVR920022A1; GB9305403D0

Abstract

A flow-controlled valve and switch has a valve body made of two mutually sealingly connected parts (2, 3); a valve element (4), which is movably fitted within the valve body and can throttle, in a controlled manner, the flow of fluid which passes through the valve body; a return spring (5) for the valve element (4); a valve element motion transmission lever (6) which extends through a wall of the valve body, where it is pivoted, so as to affect the valve element (4) and be actuated thereby; a seal such as an O-ring (7) between the lever and the valve body wall; and a microswitch (8) located outside the valve body and actuatable by the transmission lever (6). Extensive flow (in the direction of arrow A) opens the valve and actuates the switch. The device is particularly suited for use in heating circuits, where it prevents heating until there is sufficient flow. <IMAGE>

Description

FLOW-CONTROTTwD CONTROL SWITCH, PARTICULARLY FOR PRIMARY CIRCUITS IN HEATING SYSTEMS The present invention relates to a flow-controlled control switch, particularly suitable for circuits for controlling the circulation of water in primary circuits.

As is known, the current trend in contemporary design of boilers for heating systems and for sanitary hot water production systems is to use heat exchangers (of the gaswater type) which use volumes of fluid which are very small, for example less than one liter, but are heated with a very large addition of heat, for example 20,000-25,000 kcal/h.

With such a power/volume ratio, it is imperative to avoid that sudden localized temperature increases occur in the fluid, since this would make the water boil. When the burner is running, it is therefore indispensable to keep the water heated in the exchanger circulating, at least with a minimum flow-rate which is correlated to the power of the burner being used.

The aim of the present invention is to provide a flowcontrolled control switch which can ensure total shutdown of the burner and thus the halting of the addition of heat to the water to be heated in a primary system of a heating system if the system, for any reason, is unable to ensure adequate circulation in the exchanger, in order to avoid damaging the exchanger irreparably and also to prevent the pipes from bursting. Circumstances which can lead to situations of this kind can occur, for example, due to a total lack or shortage of water in the system, due to the halting of the circulation of the water of the system following a malfunction of the circulation pump, clogging of the pipes, or also due to an excessive load loss of the system, or due to the excessive forming of steam in the pipes, for example following the failure of the control thermostats to intervene.

Another object of the present invention is to provide a flow-controlled switch which is highly sensitive and is capable of ensuring the re-ignition of the burner only if a flow of water sufficient to ensure the correct operation of the system has been established in the exchanger.

Another object of the present invention is to provide a flow-controlled switch which is highly efficient and reliable and can be manufactured at competitive costs.

This aim, these objects and others which will become apparent hereinafter are achieved by a flow-controlled control switch, particularly for primary circuits in heating systems, which comprises: a valve body made of two parts which are mutually sealingly connected; a valve element movably fitted within the valve body and for throttling, in a controlled manner, the flow of fluid which passes through the valve body; elastic return means for the valve element; a valve element motion transmission lever extending through a wall of the valve body, where it is pivoted, so as to affect the valve element and be actuated thereby; means for providing a seal between the lever and the valve body wall; and control means located outside the valve body and being actuated by the transmission lever.

Further details and advantages of the present invention will become apparent from the following detailed description of two preferred but not exclusive practical embodiments of a flow-controlled control switch, given with reference to the accompanying drawings, wherein: figure 1 is a front elevation view of a flow-controlled switch according to the invention, with some parts removed; figure 2 is a plan view of the flow-controlled switch of figure 1; figure 3 is a sectional view taken along the plane III III of figure 1; and figure 4 is a sectional view, similar to the view of figure 3, but related to another embodiment.

In the various figures, identical or similar parts or components have been designated by the same reference numerals.

Initially with reference to figures 1 to 3, the reference numeral 1 generally designates a flow-controlled control switch comprising: a valve body constituted by two parts 2 and 3; a valve element 4, fitted within the valve body so that it can move along the axis X-X of the valve body; a helical compression spring 5 for loading the valve element; a transmission lever 6 which extends through the wall of the part 3 and has an end located inside the valve body, whereby to affect the valve element 4; a gasket 7 for providing a seal between the lever and the part 3; and a microswitch 8 which is located outside the valve body and can be affected by the other end of the lever 6.

More precisely, the parts 2 and 3 can be partially screwed together with a sealing gasket 9 interposed; once they have been screwed together, they define a through passage which is coaxial to the axis X-X. Externally, the parts 2 and 3 each have a threaded end, respectively 10 and 11, for the insertion in, or coupling to, a supply pipe for a heat exchanger. The direction of the flow is indicated by the arrow A in figure 3, i.e. from the part 3 toward the part 2. The part 3 internally delimits a cavity 12 which has a frustum-shaped side wall which widens toward the part 2 and is affected by an intermediate circular groove 13.

The stem 14 of the valve element 4 advantageously has a triangular transverse cross-section (in order to minimize the risk of clogging and jamming) and is slidably mounted within a sleeve 15 which is coaxial to the axis X-X and is supported by a spider 16 accommodated within a circular recess 17 inside the part 2. The head of the valve element, designated by the reference numeral 18, is mushroom-shaped, with a conical outer surface, and is suitable to abut against a first end of the helical spring 5. The spring 5 is arranged around the stem 14 and has a second end inserted into the sleeve 15, so that the head of the valve element is elastically pushed toward the groove 13. In this position, the head 18 engages the transmission lever 6 and keeps it actuated, as shown in figure 3.However, the extension of the spring 5 is such as to never push the head 18 so that it abuts against the edge of the groove 13, so as to leave a minimal annular interspace for the flow of water between the head 18 and the internal wall of the chamber 12.

The lever 6 is preferably constituted by a rod having a circular cross-section, which is accommodated in a transverse hole 20 provided in an expansion 21 of the part 3. Advantageously, the hole 20 has three diameters which increase from the inside outwards. The internal portion, which has the smallest diameter, delimits an opening which is larger than the rod 6, so that there is considerable play between the rod and the hole. The intermediate portion acts as seat for the gasket 7, which is shaped like an O-ring and also acts as fulcrum for the lever 6. The external portion instead accommodates an internally flared ring 22 which acts as stop element for the O-ring 7 and can be kept in position by an annular stop element 23 which is accommodated within a recess provided in a protective casing 24.Said casing is fixed to the expansion 21 by means of one or more screws 25 and accommodates the microswitch 8, which can be accessed by removing a cover 26.

The lever 6 thus has an arm arranged inside the cavity 12, is pivoted on the O-ring 7 and enters the casing 24 with its other arm. The microswitch 8 is provided with two contacts 27 and 28, between which an electric circuit can be closed and opened by means of a movable arm 29 loaded by a spring 30 and actuatable by the lever 6 directly or by interposing a button 31.

The electric circuit which is connected to the contacts 27 and 28 is typically the circuit for supplying electric power for the ignition of the burner of a heating system.

The operation of the above described flow-controlled switch is as follows.

Before leaving the part 2, the water supplied to the part 3 passes through the interspace or slit between the head 18 of the valve element and the edge of the groove 13, until the flow reaches a minimum rate, which is the one required for the safe operation of the exchanger, for example 400-500 l/h. The reaching of this minimum flow-rate value is ensured by the setting or calibration of the spring 5.

Once this threshold value has been exceeded, the thrust applied to the head 18 of the valve element by virtue of the flow-rate increase overcomes the force of the spring 5, so that the valve element is moved axially toward the part 2 and, by virtue of the frustum-shaped configuration of the chamber 12, the flow through the valve is consequently increased considerably. As a consequence of its own movement, the valve element 4 disengages the lever 6, which performs a slight oscillation about its own fulcrum and moves for example to a position which is normal to the axis X-X, in turn releasing the button 31 of the microswitch 8.

Said microswitch can switch and close the electric circuit between the contacts 27 and 28, thereby allowing the ignition of the burner of the system.

It can be seen that the mushroom-head shape of the head of the valve element 4 in combination with the frustumshaped configuration of the chamber 12 allows to keep load losses to a minimum. Furthermore, the triangular or polygonal shape of the cross-section of the stem 14 of the valve element is used to keep friction within the sleeve 15 at a very low value.

Figure 4 illustrates an embodiment constituted by a flow-controlled control switch for sanitary water circuits.

The structure is substantially similar to the one of the embodiment shown in figures 1 to 3, except for the shape of the chamber 12, which is substantially cylindrical and has two diameters. The head 18 of the valve element delimits a small annular interspace together with the smaller-diameter portion of the chamber, so as to ensure the transit of a minimum flow, above which the lever 6 and the microswitch 8 activate all the devices meant to produce sanitary water in a boiler designed to provide not only hot water on a primary circuit for heating radiators but also sanitary water on an appropriate sanitary-water circuit.

As can be seen, in both embodiments the lever 6 oscillates only about its fulcrum, but is not preset to perform axial movements, so that in theory there is no wear of the O-ring which acts as fulcrum and is thus capable of ensuring a durable perfect seal in any position of the lever 6.

If required, the parts 2 and 3 and the ring 22 can be made of brass, whereas all the other components, except for the spring 5, may be made of plastic material.

In the practical execution of the invention, the materials employed, as well as the shape and dimensions, may be any according to the requirements.

Claims

1. Flow-controlled control switch, particularly for primary circuits in heating systems, comprising: a valve body made of two parts which are mutually sealingly connected; a valve element which is movably fitted within the valve body for throttling, in a controlled manner, the flow of fluid which passes through the valve body; elastic return means for the valve element; a valve element motion transmission lever extending through a wall of the valve body, where it is pivoted, so as to affect the valve element and be actuated thereby; means for providing a seal between the lever and the valve body wall; and control means located outside the valve body and being actuated by the transmission lever.

2. Flow-controlled switch according to claim 1, characterized in that said lever is pivoted on said means for providing a seal between the lever and the wall of the valve body.

3. Flow-controlled switch according to claim 2, characterized in that said sealing means comprise an O-ring.

4. Flow-controlled switch according to any one of the preceding claims, characterized in that said valve element comprises a stem with a polygonal cross-section, which is slidably fitted in a supporting sleeve, and a head whose surface arranged facing the flow is substantially conical.

5. Flow-controlled switch according to claim 4, characterized in that said valve body delimits an internal chamber for accommodating the head of the valve element, said chamber expanding in the direction of the flow.

6. Flow-controlled switch according to claim 5, characterized in that said internal chamber is substantially frustum-shaped.

7. Flow-controlled switch according to claim 5, characterized in that said internal chamber has multiple diameters.

8. Flow-controlled switch according to any one of the preceding claims, characterized in that said control means comprise a switch, which is supported by the valve body and has a button which can be actuated by the transmission lever.

9. Flow-controlled control switch, particularly for primary circuits of heating systems, substantially as described above with reference to the accompanying drawings and as shown therein.