WO2023007367A1

WO2023007367A1 - Gas safety valve for heat generators

Info

Publication number: WO2023007367A1
Application number: PCT/IB2022/056882
Authority: WO
Inventors: Vanni Gallocchio; Felice DI GESO; Giuseppe Veronese
Original assignee: Vanni Gallocchio; Di Geso Felice; Giuseppe Veronese
Priority date: 2021-07-30
Filing date: 2022-07-26
Publication date: 2023-02-02
Also published as: IT202100020447A1

Abstract

The improved gas safety valve with the function of feeding a burner by mixing the air sucked in by a variable flow fan with the fuel gas in the right proportion, through the modulation of the gas flow through an anchor electromagnet and a linear operator, driven by a stepper motor, made reversible by elastic elements. The device also guarantees the possibility of electrically intercepting the gas flow by means of two dosing elements in series, independent of each other, as required by current legislation.

Description

GAS SAFETY VALVE FOR HEAT GENERATORS

DESCRIPTION

The present invention has as its object an improved gas safety valve that has the function of feeding a burner by mixing the air sucked in by a variable flow fan with a combustible gas in the right proportion.

The valve, according to the invention, must also guarantee the possibility of intercepting, in case of anomalies, the flow of gas with at least two devices as required by current regulations. Heat generators with gas burners are known where the combustion air is forcibly blown to the burner by means of a fan. Blown air heat generators of this type include a combustion chamber, a gas burner in that combustion chamber, gas supply ducts to the burner, an oxidising air supply system, where that air supply system includes at least one fan that forcibly transports the combustion air to the burner and a mixer for the realization of the gas-air combustion mixture.

Heat generators of this type also include safety devices designed to prevent or interrupt the supply of gas in case of reaching the pre-established operating parameters, extinguishing the flame or in case of malfunction of the fan. These known safety devices, represented in fig.l, by current legislation include at least two shutters (1 and 2), electrically equipped, suitable for occluding individually and totally, through the springs (3 and 4), the gas supply duct and which is opened by electrically supplying the coils (5 and 6) only when there are the safety conditions provided for example during ignition or with a lit flame detected by a special device.

The safety system of the known type described above does not allow to partialize the flow rate of the gas used in the burner, and therefore if necessary this function is normally delegated to a third element (7), called modulator, which, controlled by an electromechanical actuator (8), modulates the gas passage section by correlating it to the air flow rate of the fan, which by varying the rotation speed optimizes the stoichiometric combustion ratio The US patent 2009/111065 A1 (TOMPKINS GENE [US] 30-04-2009, can be considered representative of the previous technique.

The problem that is proposed to solve with the present invention is to simplify and reduce the number of components and to facilitate the industrialization of the product.

The purposes of the present invention are:

- Reduce from 3 to 2 the number of operators to achieve the required functions.

- Use a low-cost, low-power anchor maintenance electromagnet.

- Realize the modulation and closure of the gas flow with two interception elements by operating a single operator.

- Possibility to vary also the section of passage of the air flow using the same operator.

- do not require, under normal operating conditions, the movement of the electromagnet to anchor, because the closure with two interceptions is guaranteed by the other operator.

- minimize the number of components for gas regulation and interception that are easy to manufacture.

Further use electrical components with low electrical consumption such as anchor electromagnets and stepper motors without permanent magnets. These and other direct and complementary purposes are achieved with an improved safety valve to be used in gas heat generators.

The state of the art is illustrated in Figure 1.

The improved safety valve with the characteristics referred to in the claims, is mounted in a heat generator and is illustrated as an indication but not limited to, in the attached drawing tables containing the following figures 2, 3 and 4.

Fig. 2 shows schematically the gas heat generator with improved safety valve (V) in the rest conditions (OFF) i.e. without power supply of the operating elements.

The generator shall comprise at least one gas burner (9) housed in that combustion chamber (10), one line (11) of combustion air supply, one line (12) of fuel gas supply, one line (13) of supply of the air/gas mixture to that burner (9), one fan (14), one heat exchanger (15) and one chimney (16) of flue gas evacuation.

The generator shall include at least one safety valve (V) which is also capable of controlling the gas flow rate used by that burner (9).

The safety valve (V) includes a generally metal gas-tight casing called body (17) which has a gas duct (12) in which a shutter is inserted (19), joined by a stem (20), with an iron-magnetic anchor (21) which is held in contact pushed by the spring (22) with a fixed core (23) of an anchor holding electromagnet. On the face of the shutter (19), opposite the cusp seat (24), acts a spring (34) that with its force brings the shutter (19) to the seat (24) of the sliding sleeve (25) for any position called sleeve (25) can assume and totally intercepts the gas, this corresponds to the first element of safety seal of the combustible gas. A gasket (26) housed on the body (17) allows the gas-tight sliding of the sleeve (25) with respect to the body (17).

The sliding sleeve (25) is coaxial and integral with the blind piston (27) which can then slide in turn with respect to the body (17).

The second gas safety seal takes place between the blind piston (27) and the body (17) and is obtained through the gasket (28) housed on the body (17). On the blind piston (27) is obtained an annular front hollow communicating through a calibrated hole (29) with the outer surface of said blind piston. On the extension (30) of the blind piston (27) are obtained the first rack (31), the second rack (32) and the feedback (33) for the spring (22). The second rack (32) is engaged with gears (35,36,37,38,) in turn engaged with a pinion (39) mounted and solidary on the rotor shaft (40) of a stepper motor (41). The spring (22) has one end in contact with the wall (42) of the body (17) and with the other end exerts a force on the support (33) of the extension (30) by sliding the whole system: extension (30), blind piston (27), sleeve (25) shutter (19), stem (20) until it brings the iron-magnetic anchor (21) in contact on the core (23), winning the force of the spring (34), friction and force due to rotor magnetism, when built with permanent magnets, multiplied by the strong reduction ratio due to the gear train (35, 36, 37, 38). To eliminate the force due to the magnetism of the rotor it is preferable to use a stepper motor without permanent magnets.

The rack (31) is also moved by the same operator and is engaged with a gear sector (43) that rotates on the fulcrum (44) and is in solidarity with the bulkhead (45) of appropriate shape and surface to be partialized or close the section of the duct (46). Therefore, each position of the rack (31) corresponds to a position of the bulkhead (45) and consequently a corresponding section of passage of the duct (46) and when the gas route is closed the airway is also closed and heat dispersions due to the natural convection draft of the chimney are avoided.

Fig. 3 represents the same gas heat generator with improved safety valve (V), under the conditions of minimum gas flow.

In these conditions the anchor electromagnet is powered and keeps the anchor (21), the stem (20) and the shutter (19) stationary despite the cusp seat (24), moved by the linear operator, moves away opening the gas route of the first safety interceptor described above.

Under these conditions the gas passes only through the hole (29) of the minimum that is downstream of the sealing front generated by the blind piston (27) and the gasket (28).

The air supply section (11) is also partialized by the bulkhead (45), and the fan to supply the amount of combustion air corresponding to the minimum amount of gas will have a higher rotational speed than it would have if there were no bulkhead. This avoids the instability typical of the fan when operating at low rotational speed.

Fig. 4 represents the same gas heat generator with improved safety valve (V) in the conditions of maximum flow, where the linear operator has positioned the blind piston (27) beyond the gasket (28) opening the gas flow to the maximum and simultaneously opening the bulkhead (45) that frees the air passage section.

Placing the deflector (47) at the gas outlet between the piston (27) and the gasket (28) increases the depression in the gas outlet area due to the Venturi effect, it follows that at the same gas supply pressure a greater pressure difference and therefore a greater flow rate will be available, allowing to reduce both the gas passage sections and the connecting pipes.

In addition, the air having a higher speed creates a greater turbulence in the gas outlet area, which favors the homogeneous mixing between combustible gas and oxidizer for better combustion.

With such a structured valve if the electromagnet is not yet electrically powered, the cusp seat (24) from the shutter (19) always remains closed for any position of the linear operator.

Therefore, with reference to the above description and the attached tables, the following claims are expressed.

Claims

1. Improved gas safety valve (V) for blown air heat generators comprising a forced duct (46) upstream of a fan (14), called gas safety valve (V) is characterised by being positioned close to the air inlet of the fan and comprising at least one gas control actuator assembly (19-

21,25,27,30) passing through the intake air flow, this actuator assembly also includes an anchor electromagnet (23) or attraction electromagnet and preferably a linear element (25,27,30) driven by a stepper motor (41), called actuator group, which can be made reversible by an elastic device (22), in the absence of power supply keeps the magnetic circuit of the anchor electromagnet closed (23) by closing two safety shutters (19,24) and (27,28) in series on the gas route, in which, when the stepper motor is powered by electromechanical or electronic logic, called linear actuator (25,27,30) opens and modulates the flow of gas and eventually air.

2. Valve (V) as per claim 1, characterized by the fact that part of the actuator group (30,31,32,33) is external to the gas circuit, moves transversely to the air flow in suction of the fan (11) and drives the control elements (27) and gas closure (19,28), without the need of gas sealing elements.

3. Valve (V), as per claims 1 and 2, characterized by the fact that the gas sealing seat (24), intercepted by the anchor electromagnet (19,20,21,23,34), is mobile and is moved by the linear actuator (25,30,31,32,33).

4. Valve (V) as per claims 1,2,3, characterized by the fact that with the linear operator (31) in addition to varying the section of passage of the gas route also varies the section of passage of the air duct (46) through the damper (45).

5. Valve (V), as per claims 1,2, 3, 4, characterized by the fact that the actuator (30,32) moved by the stepper motor, with or without permanent magnets, (40,41), has as mechanical elements of linearization of movement more than a tooth gear (35,36,37,39) and a rack (32) suitable to be reversible, even with a high reduction ratio.

6. Valve (V) as per previous claims, characterized by the fact that, with electromagnet (23) powered and linear actuator (25,30,31,32,33) in a suitable position, the gas passage section is determined by a calibrated hole (29) or a calibrated groove.

7. Valve (V) as per previous claims characterized by the fact that when the valve is with partialized or idle gas flow, the air duct (46) is also partialized by a damper (45) so as to require the fan (14) a higher and therefore more stable rotational speed to provide the optimal combustion air to the burner (9).

8. Valve (V), as per previous claims, characterized by the fact of including a deflector (47) positioned in the air supply line (11), upstream of the gas outlet (28), capable of locally increasing the depression with a consequent increase in the available gas flow rate.

9. Valve (V), as per previous claims, characterized by the fact that the gas closure takes place by the sliding of this cylindrical regulation and closing element (27) inside a gasket (28), with self-cleaning dirty scraper function of the sealing elements.

10. Valve (V), as per one or more of the previous claims, characterized by the fact that said damper (45) of partialization of the air duct (46) is operated by the same operator who regulates and closes the gas.

11. Valve (V), as per previous claims characterized by the fact that said damper (45) of closure and partialization of the air duct (46) with appliance in OFF reduces the losses of thermal energy due to the natural draft of the chimney (16).