HEATING APPARATUS COMPRISING COMBUSTIBLE GAS BURNER

Abstract

A combustible gas heating apparatus includes: a main burner arranged in a combustion chamber of the apparatus, a pilot burner for generating a pilot flame for igniting it, a valve group comprising a main valve arranged on a main duct, and a pilot valve arranged thereon, upstream of the main valve, for supplying gas to the pilot burner, a system for controlling gas to the main and pilot burners, including an electronic control unit operatively associated with the main and pilot valves, a thermal safety device actuable in the presence of inflammable vapors near the apparatus, to safely extinguish the main burner when a predetermined temperature threshold has been exceeded, the pilot burner configured as a continuous pilot burner having a permanent flame, the pilot and main valves being electrically-operated valves, an auxiliary buffer battery configured to power the electronic control.

Claims

1. Combustible gas heating apparatus, for heating water, comprising: a main burner (2) arranged in a combustion chamber (3) of the apparatus, a pilot burner (4) suitable for generating a pilot flame for igniting the main burner (2), a valve group (5) comprising a main valve (6) arranged on a main duct (7) for supplying the combustible gas to the main burner (2), and a pilot valve (8) arranged on said main duct (7), upstream of said main valve (6), for supplying gas to the pilot burner (4), a pilot duct (9) branching off from a portion (7a) of the main duct (7) between said pilot and main valves (8, 6) in order to feed the gas to the pilot burner (4), a system for controlling the supply of gas to said burners, including an electronic control unit (10) that is operatively associated with said main and pilot valves (6, 8), a thermal safety device (12) which can be activated in the presence of inflammable vapours in the vicinity of the apparatus and configured to safely extinguish the main burner (2) when a predetermined temperature threshold in the combustion chamber (3) has been exceeded, said pilot burner (4) configured as a continuous pilot burner having a permanent flame, the pilot valve (8) and the main valve (6) being electrically-operated valves, an auxiliary buffer battery (18) being intended to power said electronic control unit (10) if there is a temporary absence of a mains power supply, such that at least said pilot valve (8) is powered and operated, by means of said control unit (10), in order to ensure that the pilot flame in the pilot burner (4) is maintained during the absence of a mains power supply.

2. The heating apparatus according to claim 1, wherein said control unit (10) is designed to supply power to, and also operate, the main valve (6) during a temporary absence of a mains power supply, after the control unit (10) has been supplied with power by said auxiliary buffer battery (18).

3. The heating apparatus according to claim 1, wherein said thermal safety device (12) comprises an interception element (13) designed to selectively intercept the flow of air that is suitable for igniting the flame in the main burner (2) if the temperature detected in the combustion chamber (3) exceeds the predetermined temperature threshold, thus safely extinguishing the main burner (2).

4. The heating apparatus according to claim 1, wherein said thermal safety device (12) comprises a mechanical thermostat (14) that can change state if the temperature in the combustion chamber (3) exceeds the predetermined temperature threshold, said control unit (10) being designed to recognize when said mechanical thermostat (14) has changed state in order to intervene in the form of a command to safely extinguish the main burner (2).

5. The heating apparatus according to claim 1, wherein said control unit (10) is supplied with power from the mains supply and is designed to send electric command signals to the pilot and main valves (8, 6) in order to open/close the passage of gas through said valves.

6. The heating apparatus according to claim 1, wherein said control unit (10) is operatively associated with a first ON button (10), by means of which said unit (10) is activated, determining the start of the procedure for igniting the pilot burner (4), an OFF button (20), by means of which the user can interrupt the power supply to the control unit (10) and subsequently command the pilot and main valves to close, and a dial (21) for regulating the temperature, by means of which the user can set the desired temperature and subsequently ignite the main burner (2) or not.

7. The heating apparatus according to claim 1, further comprising a device (15) for damping down the flame, which comprises a fireproof grid.

8. The heating apparatus according to claim 1, further comprising a water tank (13c) intended to be heated by said apparatus, and a water temperature sensor (13d) in an electronic water thermostat, which is designed to compare the water temperature set by the user with the actual temperature detected by the sensor (13d).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Additional features and advantages of the invention will become clearer from the following detailed description of a preferred embodiment thereof, which is illustrated by way of non-limiting example, with reference to the only attached FIGURE, which is a schematic view of the main parts of a heating apparatus formed in accordance with the invention.

PREFERRED EMBODIMENTS OF THE INVENTION

[0021] With reference to the cited FIGURE, 1 denotes an example of a heating apparatus as a whole, comprising a gas burner, which is only depicted schematically and is formed in accordance with the present invention.

[0022] Said apparatus can be designed as a sanitary water heater or a heater for water intended to be circulated in a plant for heating environments.

[0023] The apparatus 1 comprises a main burner 2 arranged in a combustion chamber 3, on which burner a main flame is generated, a pilot burner 4, which is suitable for generating a pilot flame in order to ignite the main burner 2, and a valve group 5.

[0024] The valve group 5 comprises a main valve 6, which is arranged on a main duct 7 of the valve group, for supplying the combustible gas to the main burner 2, and a pilot valve 8, which is arranged on the duct 7 upstream of the main valve, for supplying the gas to the pilot burner. 9 denotes a pilot duct, which branches off from a portion 7a of the main duct 7 that is situated between the pilot valve 8 and the main valve 6 and is suitable for feeding the gas to the pilot burner 4.

[0025] The main valve 6 and the pilot valve 8 are suitably formed as electrically operated valves, that is electric valves provided with respective actuators that are active on the corresponding shutters of the valves, which actuators are energised by supply signals that are carried through respective electrical supply circuits 6a, 8a. In the FIGURE, circuits 6a, 8a and other electrical connection paths to and from the circuit board are depicted by a dot-dashed line.

[0026] The supply signals originate from an electronic control unit 10, which is formed as a circuit board and is operatively associated with said valves in order to enable the passage of gas through the corresponding valve seats. Said control unit is part of a control system of the apparatus, which is designed to control the supply of gas to the pilot and main burners.

[0027] The control unit 10 is supplied with power by means of a connection to the mains, marked as 11, which is suitable for supplying an alternating voltage having a preset frequency, for example.

[0028] 12 denotes a thermal safety device as a whole, which can be activated when inflammable vapours are present in the vicinity of the apparatus, said device being designed to activate the safe switch-off of the main burner 2 and the pilot burner 4 when a predetermined threshold temperature is exceeded in the combustion chamber.

[0029] In one embodiment, the thermal safety device 12 comprises an interception component 13 that is intended for selectively intercepting the flow of air entering the combustion chamber 3 and is suitable for igniting the flame of the main burner. The interception component 13 acts on an opening 13a, through which the flow of air enters the combustion chamber, and can be activated, for example, by the fusion of a fusible element (not shown) that acts as means for stopping the operating stroke of the interception component, said component being subjected to resilient preload, for example.

[0030] If the threshold temperature mentioned above is exceeded, the stop means fuses, thereby enabling the closing stroke of the interception component.

[0031] 13b denotes a duct for evacuating fumes from the combustion chamber, which, in order for efficient heat exchange, is designed to extend inside a tank 13c for water intended to be heated by means of the heating apparatus.

[0032] 13d marks a temperature sensor (arranged in the tank for detecting the temperature of the water) of an electronic water thermostat, which sensor is operatively associated with the control unit 10 and is designed to compare the temperature of the water set by the user with the actual temperature detected by the sensor.

[0033] In one embodiment, the thermal safety device 12 can comprise a mechanical thermostat, marked as 14 in the FIGURE, which is arranged in a suitable position in the combustion chamber and is operatively connected to the control unit 10. The thermostat 14 can change state if the temperature in the combustion chamber exceeds the preset threshold temperature, and the control unit is designed to identify that the thermostat 14 has changed state, intervening with a command to safely extinguish the main burner as a result.

[0034] For ease of representation, both the embodiments of the thermal safety device 12, that is comprising the interception component 13 and the thermostat 14, respectively, are shown in the diagram in the attached FIGURE, these, however, being considered to be alternative solutions to one another, and are therefore individually applied to the apparatus in alternative ways.

[0035] The apparatus 1 likewise comprises a device for damping down flames, denoted by 15 and represented only schematically in the FIGURE, which is intended for blocking the propagation of the flame outside the apparatus. In one embodiment, the device 15 comprises a fireproof grid comprising holes that runs around the outside of the combustion chamber. The mesh arrangement of said grid is intended to prevent flames from escaping into the environment when inflammable vapours that are burnt by the flames of the burners of the apparatus are present.

[0036] 16 marks a flame-detection electrode, which is arranged near to the pilot flame and is operatively connected to the control unit 10.

[0037] 17 marks a discharge electrode/flame ignition electrode, which is also arranged near to the pilot burner and is operatively connected to the control unit.

[0038] In one embodiment, the functionalities of the electrodes 16 and 17 can be integrated in a single electrode.

[0039] In accordance with one aspect of the invention, the pilot burner 4 is suitably designed as a continuous pilot burner, that is having a permanent flame, and, in a preferred embodiment, the pilot valve 8 is designed to be supplied with power by means of the control unit 10, from an auxiliary buffer battery 18, which can order the corresponding actuator of the pilot valve to open said pilot valve so as to ensure that the flame of the pilot burner is maintained in the event of a mains blackout, that is in the temporary absence of a power supply from the mains to the pilot valve.

[0040] In other words, the buffer battery 18 is intended for supplying power to the control unit 10 in the temporary absence of a mains power supply, such that the control unit in turn orders the pilot valve to open/close during the temporary absence of a mains power supply.

[0041] In one embodiment of the invention, the buffer battery 18 is designed to also supply power to the main valve 6, in addition to the pilot valve, by means of the control unit so as to ensure the functionality of the apparatus during a temporary absence of a mains power supply.

[0042] With particular reference to the electronic unit 10 for controlling the apparatus, said unit is operatively associated with an ON button, denoted by 19, by means of which the unit is activated, thereby initiating the procedure of igniting the pilot burner, and an OFF button, denoted by 20, by means of which the user can interrupt the supply of power to the control unit 10, consequently commanding the pilot and main valves to close. 21 marks a dial for regulating the temperature, which is only depicted schematically and by means of which the user can select the desired temperature. The dial for regulating the temperature can alternatively function by means of two or more buttons for selecting the temperature and by a series of LEDs or by an LCD screen.

[0043] During operation, the ignition procedure is therefore easy for the user to activate. In fact, starting from a non-operative state of the apparatus, by pressing the ON button, the user activates the circuit board of the control unit and initiates the ignition process.

[0044] Said process provides that the pilot valve 8 (which enables the passage of gas through the pilot burner 4) is opened and provides ignition discharge by means of the igniter electrode 17. Once the pilot flame has been ignited, the control unit 10 is notified that the pilot flame has been ignited by means of the flame sensor 16 (electrode for detecting the flame, which operates by detecting the ionisation current for example).

[0045] The pilot burner 4 can be ignited following a prolonged OFF period (the user completely turns off the application by means of the OFF button), or following the loss of the pilot flame during operation (for example the loss of the flame caused by gusts of wind, by a temporary absence of gas, by a blackout, or following the intervention of the thermal safety device).

[0046] In the event of prolonged OFF periods, the user needs to be present in order to switch on the control board 10 by means of the ON button. It is essential for the user to be present, since otherwise, after long periods of inactivity in which the application is switched off, inflammable vapours may have accumulated that the thermal safety device 12 would not be able to detect.

[0047] The user therefore oversees whether or not inflammable vapours are present.

[0048] The circuit board of the control unit 10 keeps the pilot flame ignited even when no heat is requested (this being the continuous pilot burner).

[0049] This characteristic allows for the thermal safety device 12 to function correctly, which, as a mechanical thermal safety device, only functions if at least the pilot burner 4 remains ignited (so as to burn the inflammable vapours that may have accumulated and by the thermal safety device 12 intervening if the predetermined threshold temperature is exceeded).

[0050] In the event that the mains lacks electric current, for example as a result of a temporary blackout, advantage is taken of the buffer battery 18 that maintains the supply of power to the pilot valve (and possibly the main valve) by means of the circuit board. In the absence of a buffer battery, the circuit board of the control unit would be deenergised and therefore the valves 6 and 8 would close and the pilot and main flames would be extinguished; in the event of an accumulation of inflammable vapours during the period in which there is no electric current, the function of the thermal safety device 12 would not be performed because this device cannot operate when the pilot burner is extinguished. As a result, the subsequent ignition in order to restore the electric current in the mains would result in dangerous situations.

[0051] Furthermore, without the provision of the buffer battery 18, the user would have to switch the apparatus back on by hand in the event of a power failure.

[0052] The situation in which the pilot flame is extinguished as a result of brief periods of no gas, due to gusts of wind or similar events, are managed by the circuit board as normal re-ignitions when there is mains voltage.

[0053] In the case of repeated failed ignitions, said board is moved into a “lockout” state. In these situations, although the function of safe turning off in the presence of inflammable vapours is not activated because there is not a flame, no dangerous conditions arise since the spark of the igniter can ignite the inflammable vapours that may be present, and also a reduced amount of time between the first failed ignition attempt and “lockout” state is selected, for example less than a few minutes, preferably less than three minutes. It should be noted that reignition following a “lockout” state requires the presence of the user (ON button).

[0054] It should be noted that the pilot flame in the apparatus according to the invention is not used to heat any thermoelectric generators and has the sole function of igniting the main burner. Therefore, the pilot burner can be designed to generate a smaller amount of energy. Therefore, less energy will be dissipated during the rest (“standby”) periods where the pilot burner remains ignited anyway.

[0055] If a thermal safety device 12 intervenes (arranged in series with the flow of air that enters the combustion chamber), the circuit board of the control unit does not “directly” notice a possible intervention by the device 12. Therefore, the system is moved to a “lockout” state since it is no longer able to switch on.

[0056] Instead, in the event that a thermal safety device comprising a mechanical thermostat 14 intervenes, the circuit board of the control unit is intended for receiving the signal relating to the state of the thermostat and can respond depending on the logic implemented (for example activating the switch-off of both burners).

[0057] The invention therefore meets the predefined objects, thus achieving the advantages mentioned above with respect to the known solutions.

[0058] The advantages achieved by means of the apparatus formed according to the invention include the fact that the use of a continuous pilot burner ensures that inflammable vapours that may be present near the apparatus are burnt by the pilot flame during the standby periods, thus reducing the risk of explosion and also allowing for the use of thermal safety devices that are inexpensive and have an adequate degree of robustness and reliability. Due to the provision of a buffer battery that is operatively connected at least to the control unit (and the pilot and main valves are also commanded to open/close by means of the control unit as a result), the apparatus is not affected by the problems associated with temporary blackouts of the mains, thereby preventing the user from being left without hot water during the temporary absence of a supply of power from the mains and having to switch the apparatus back on by hand.

[0059] Furthermore, the provision of electrically operated main and pilot valves makes the ignition process more “user friendly” for the user, and also allows for automatic reignition if the pilot burner has been accidentally extinguished. Furthermore, the combination of the features mentioned above in the apparatus according to the invention means that a thermoelectric generator (thermocouple/thermopile), which is known to be subjected to ageing and loss of performance, does not need to be used.