DESCRIPTION

Technical field

The present invention relates to a safety system for a gas apparatus for heating water, a gas apparatus comprising such a safety system and a method for controlling the above-mentioned gas apparatus.

Technological background

The invention is used particularly though not exclusively in the field of producing and using devices for heating gas, that is to say, devices for heating by means of a gas burner. In a preferable manner, the invention is used in installations for heating water, such as, for example, boilers.

In this field of use, there are known devices for heating water which are provided with a gas burner for heating the water contained in a tank and at least two temperature sensors which are provided to generate a respective signal which represents the temperature measured by it in respect of the water contained in this tank.

Typically, these devices are provided with a control system which comprises a digital logic unit for controlling the lighting/shutdown of the gas burner on the basis of the temperature detected by one of the above-mentioned sensors. The temperature detected by the second sensor is instead used by the digital logic unit to carry out a check of the correctness of the temperature measured by the first sensor, that is to say, in order to control the correct operation of the heating device.

A limitation of this solution may be defined as an energy consumption which is excessive, or not negligible, of the control system for establishing the correct operation of the heating device.

Summary of invention

An object of the present invention is to provide a safety system for a gas apparatus for heating water, a gas apparatus comprising such a safety system and a method for controlling the above-mentioned gas apparatus which is structurally and operatively configured to overcome at least one above-indicated limitation with reference to the known solutions.

This object is achieved by means of a safety system for a gas apparatus for heating water, a gas apparatus comprising such a safety system and a method for controlling the above-mentioned gas apparatus which are achieved in accordance with the respective independent claims which are appended to the present description.

Preferred features of the invention are defined in the dependent claims. According to a first aspect of the invention, a safety system for a gas apparatus for heating water comprises a first sensor and a second sensor suitable for generating a first signal and a second signal, respectively, which represent a temperature of the water contained in a tank of the gas apparatus.

The first sensor and the second sensor are preferably temperature sensors. According to a first aspect of the invention, the first and second signals are analogue electrical signals, preferably in terms of voltage.

According to an aspect of the invention, the first sensor and the second sensor are arranged inside the tank, preferably in an intermediate zone thereof. Preferably, the first sensor and the second sensor are positioned so as to measure the temperature of the same portion of the water contained in the tank. The first sensor may be adjacent to the second sensor.

The gas apparatus comprises, in addition to the tank for containing water, a first gas burner for heating the water which is contained inside that tank. According to an aspect of the invention, the gas apparatus may be identified as a boiler.

The gas apparatus may comprise a first valve which is arranged to allow to pass/intercept a flow of gas towards the first gas burner. The gas apparatus may comprise a first actuator which is arranged to actuate so as to open and close the first valve when it is energized and non-energized, respectively.

According to an aspect of the invention, the safety system comprises a(n) (electrical) supply circuit for energizing the first actuator of the first valve. The first actuator is connected to the supply circuit.

According to an aspect of the invention, the supply circuit is connected to an electrical energy generator which is capable of energizing this supply circuit. The electrical energy generator is preferably a thermoelectric generator, for example, it is a thermopile or thermocouple.

According to an aspect of the invention, the thermoelectric generator is associated with a gas burner, the generated flame of which energizes the thermoelectric generator.

According to a first embodiment of the invention, the thermoelectric generator may be associated with the generated flame of the first gas burner.

According to an aspect of the invention, the first actuator is energized by a voltage which is correlated with the voltage generated by the electrical energy generator via the supply circuit.

According to a second embodiment of the invention, the gas apparatus comprises a second gas burner and a second actuator which is provided to actuate so as to open and close a second valve of the gas apparatus when it is energized and non-energized, respectively.

The second valve is arranged to allow to pass/intercept a flow of gas towards the second gas burner and, preferably, towards the first gas burner. In particular, the second valve is arranged to allow to pass/intercept a flow of gas towards the second gas burner and, in a cascading manner, towards the first gas burner.

Preferably, the second valve is positioned upstream of the first valve with respect to the direction of flow of the gas flow.

According to an aspect of the invention, the second actuator is connected to the above-mentioned supply circuit and is preferably energized by means of the electrical energy generator, in particular the thermoelectric generator, which energizes the first actuator. In this case, this thermoelectric generator is preferably associated with the second gas burner in place of the first gas burner so as to be energized by the flame generated by the second gas burner.

Preferably, the first valve and the first gas burner represent a main valve and a main burner, respectively, of the gas apparatus while the second valve and the second gas burner represent a pilot valve and a pilot burner of the gas apparatus, respectively. The pilot burner is intended to light the main burner by means of the relevant pilot flame.

According to an aspect of the invention, the safety system comprises a switch device which is arranged in the supply circuit in order to close/open this supply circuit so as to energize/not to energize the first actuator.

It is evident that, in the embodiment of the invention in which the gas apparatus is provided with the first burner and second burner, the closure/opening of the supply circuit via the switch device brings about the energization/non-energization both of the first actuator and of the second actuator.

According to an aspect of the invention, the safety system comprises a digital processing unit which is operatively connected to the first and/or second sensor.

The digital processing unit is configured to compare a set-point value which represents a preselected temperature with the first or second signal.

The digital processing unit may be a microcontroller.

Additionally or alternatively, the digital processing unit may comprise an integrated circuit ASIC (Application-Specific Integrated Circuit) and optionally an additional digital logic unit in order to operate according to the invention.

According to an aspect of the invention, the digital processing unit is supplied by an electrical energy generator via a relevant electrical circuit which connects the digital processing unit to the electrical energy generator. This electrical energy generator may be a thermoelectric generator or a battery.

This thermoelectric generator is associated with a gas burner, the generated flame of which energizes the thermoelectric generator. Preferably, this thermoelectric generator is the same one which energizes the supply circuit of the safety system.

According to an aspect of the invention, the digital processing unit is operatively connected to the first and/or second actuator, in particular it is connected to the supply circuit of the above-mentioned actuators (for example, via the above-mentioned switch device or by means of a second switch device) and is configured to actuate the first and/or second actuator on the basis of a comparison between the set-point value and the first (or second) signal, preferably on the basis of a difference between the above- mentioned signals.

In particular, the digital processing unit is configured to actuate the first actuator in order to allow to pass or intercept a flow of gas towards the gas burner and/or the second actuator in order to allow to pass or intercept a flow of gas towards the second gas burner and preferably towards the first gas burner on the basis of a comparison between the set-point value and the first (or second) signal.

By way of example, the first actuator is actuated so as to open by the digital processing unit if the difference between the set-point value and the first (or second) signal is less than or equal to a predefined threshold while the digital processing unit actuates so as to close the first actuator if this difference is greater than the above-mentioned threshold.

According to an aspect of the invention, the safety system comprises a control device which is operatively connected to the switch device, to the first sensor and to the second sensor.

According to an aspect of the invention, the control device may be supplied by an electrical energy generator via a relevant electrical circuit which connects the control device to this electrical energy generator. This electrical energy generator may be a thermoelectric generator or a battery. This thermoelectric generator is associated with a gas burner, the generated flame of which energizes the thermoelectric generator. Preferably, this thermoelectric generator is the same one which energizes the supply circuit of the safety system and/or the digital processing unit.

The control device may comprise the digital processing unit.

The control device comprises an analogue comparator which is operatively connected to the first sensor and second sensor in order to compare the first signal with the second signal.

According to an aspect of the invention, the control device is configured to generate a control signal for controlling so as to open/close the switch device on the basis of the comparison between the first signal and the second signal which is carried out by the analogue comparator.

In other words, the control device is configured for controlling so as to open/close the switch device by means of a control signal which is generated on the basis of a comparison between the first signal and the second signal.

The control signal may be a digital signal, preferably with two levels of voltage.

The comparison between the signals which are generated by the two sensors is therefore carried out by an analogue comparator without the involvement of the digital processing unit, with a resultant saving in terms of electrical energy consumption. In fact, in the event that the digital processing unit has to compare the first signal with the second signal so that the control device generates the control signal, these analogue signals have to be subjected to an analogue/digital conversion upstream of the comparison which inevitably requires greater use of electrical energy with respect to the analogue comparison according to the invention.

The use of an analogue comparator does not therefore require additional processing steps for the signals which are generated by the first sensor and the second sensor, thereby reducing the absorption of energy required by the control device for generating the control signal.

This feature is found to be particularly advantageous if the electrical energy generator which energizes the supply circuit and the digital processing unit is a thermoelectric generator.

According to an aspect of the invention, the analogue comparator is operatively connected to the switch device and is capable of generating the control signal for controlling so as to open/close the switch device on the basis of the comparison between the first signal and the second signal.

In this manner, the analogue comparator directly controls the closure of the first valve and therefore the shutdown of the first burner without using additional electronic components.

According to an aspect of the invention, the analogue comparator is capable of generating the control signal for controlling so as to open the switch device if the difference between the first signal and the second signal is greater than a predefined value and for controlling so as to close the switch device if the difference between the first signal and the second signal is less than or equal to the above-mentioned predefined value.

According to an aspect of the invention, the above-mentioned predefined value is less than or equal to 0.5 mV. Preferably, this predefined value is between 0.2 mV and 0.5 mV.

According to an aspect of the invention, the control device comprises the above-mentioned digital processing unit.

According to an aspect of the invention, the analogue comparator is operatively connected to the digital processing unit and is capable of generating an output signal on the basis of the comparison between the first signal and second signal.

Preferably, the output signal is a digital signal which can take on a first value and a second value, in particular a first voltage value and a second voltage value.

The first value may be equal to 0 V (first voltage level) and the second value may be equal to 5 V (second voltage level).

According to an aspect of the invention, the digital processing unit is operatively connected to the switch device and is capable of generating the control signal for controlling so as to close the switch device when the output signal takes on the first value and for controlling so as to open the switch device when the output signal takes on the second value.

This feature allows control of the switch device by means of the digital processing unit, but maintaining the burden of the comparison between the first signal and second signal with respect to the analogue comparator.

According to an aspect of the invention, the analogue comparator is capable of generating the second value of the output signal if the difference between the first signal and the second signal is greater than a predefined value. The analogue comparator is instead capable of generating the first value of the output signal if the difference between the first signal and the second signal is less than or equal to the above-mentioned predefined value. According to an aspect of the invention, the above-mentioned predefined value is less than or equal to 0.5 mV. Preferably, this predefined value is between 0.2 mV and 0.5 mV.

According to an aspect of the invention, the safety system comprises a signalling device which is operatively connected to the control device and/or to the digital processing unit and is provided to generate a warning signal on the basis of the value which is taken on by the output signal which is generated by the analogue comparator.

The warning signal may be an audible signal and/or illuminated signal so as to communicate to a user of the safety system the result of the comparison between the first signal and the second signal which are generated by the respective sensors. By way of example, the signalling device comprises a buzzer and/or one or more LED devices.

The signalling device may therefore not emit any audible/illuminated signal, or may emit a first illuminated signal, if the output signal takes on the first value and may emit an audible signal and/or a second illuminated signal which is different from the first signal (for example, in terms of number of LED devices illuminated and/or colour emitted) if the output signal takes on the second value.

According to an aspect of the invention, the gas apparatus may comprise the safety system which is provided with at least one of the above- described features or a combination of two or more of the above-described features. Furthermore, the gas apparatus may comprise the thermoelectric generator, preferably a thermopile, in order to energize the supply circuit and/or the digital processing unit.

According to an aspect of the invention, a method for controlling the gas apparatus for heating water comprises:

· generating a first signal which represents a temperature of the water contained in the tank of the gas apparatus by means of the first sensor of the gas apparatus,

• generating a second signal which represents a temperature of the water contained in the tank of the gas apparatus by means of the second sensor of the gas apparatus,

• comparing the first signal with the second signal by means of the analogue comparator of the gas apparatus,

• generating a control signal by means of the control device of the gas apparatus on the basis of the comparison between the first and second signals,

• controlling so as to close/open the switch device of the gas apparatus by means of the control signal so as to energize/not to energize the first actuator of the gas apparatus.

According to an aspect of the invention, the first temperature sensor and the second temperature sensor measure in a continuous or intermittent manner (for example, each minute or more generally in accordance with a pre-established interval) the temperature of the water contained in the tank. According to an aspect of the invention, the comparison between the first signal and the second signal is carried out in a continuous or intermittent manner (for example, each minute or more generally in accordance with a pre-established interval).

Brief description of the drawings

Features and advantages of the invention will be better appreciated from the following detailed description of preferred embodiments thereof which are illustrated by way of non-limiting example with reference to the appended Figures, in which :

• Figure 1 is a schematic view of a gas apparatus according to the invention,

• Figure 2 is a schematic view of a first embodiment of a safety system according to the invention,

• Figure 3 is a schematic view of a second embodiment of a safety system according to the invention.

Description of embodiments of the invention

With reference initially to Figure 1, there is generally designated 100 a gas apparatus for heating water which is constructed according to the present invention.

The gas apparatus 100 comprising a tank 1 for containing water, a first gas burner 2 for heating the water which is contained inside the tank 1, a first valve 3 which is provided to allow to pass/intercept a flow of gas towards the first gas burner 2, a first actuator 4 arranged to actuate so as to open and close the first valve 3 when it is energized and non-energized, respectively, and a safety system according to the invention.

The gas apparatus 100 further comprises a second gas burner 6, a second valve 7 which is provided to allow to pass/intercept a flow of gas towards the first and second gas burners 2, 6 and a second actuator 8 arranged to actuate so as to open and close the second valve 7 when it is energized and non-energized, respectively.

The first valve 3 and the first gas burner 2 represent a main valve and a main burner of the gas apparatus 100, respectively, while the second valve 7 and the second gas burner 6 represent a pilot valve and a pilot burner of the gas apparatus 100, respectively.

Figure 2 shows a first embodiment of the safety system according to the invention which is generally designated 200.

The safety system 200 comprises a first and a second sensor 9, 10 which are capable of generating a first and a second signal which represent a temperature of the water contained in the tank 1, respectively. In particular, the first and second sensors 9, 10 are temperature sensors which are configured to generate a respective analogue signal in terms of voltage.

The safety system 200 further comprises a supply circuit 11 for energizing the first actuator and the second actuator 4, 8. The first actuator and the second actuator 4, 8 are therefore connected to the supply circuit 11 via which they are energized by a thermoelectric generator 12, in particular a thermopile. The thermoelectric generator 12 is associated with the second gas burner 6 so as to be energized by the flame which is generated by this gas burner.

The safety system 200 comprises a switch device 13 which is arranged in the supply circuit 11 to close/open the supply circuit 11 so as to energize/not energize the first and the second actuators 4, 8.

The safety system 200 further comprises a digital processing unit 14 which is operatively connected to the first sensor 9 and which is configured to compare a set-point value which represents a preselected temperature with the first signal.

In particular, the digital processing unit 14 is a microcontroller which is supplied by the thermoelectric generator 12 via a relevant electrical circuit 21 which may comprise a DC/DC converter.

The digital processing unit 14 is operatively connected to the supply circuit 11 by means of a second switch device 5 in order to actuate the first and the second actuators 4, 8 on the basis of a comparison between the set- point value and the first signal, preferably on the basis of a difference between the signals mentioned above.

The set-point value may be selected manually by a user by means of a knob 15 or other known input device.

In addition, the safety system 200 comprises a control device 16 which is operatively connected to the switch device 13 and the first and second sensors 9, 10.

The control device 16 may comprise the digital processing unit 14. The control device 16 comprises an analogue comparator 17 which is operatively connected to the first and second sensors 9, 10 in order to compare the first signal with the second signal.

The control device is further configured to generate a control signal 18 for controlling so as to open/close the switch device 13 on the basis of the comparison between the first signal and the second signal carried out by the analogue comparator 17.

In particular, the analogue comparator 17 is operatively connected to the switch device 13 and is capable of generating the control signal 18 for controlling so as to open/close the switch device 13 on the basis of the comparison between the first signal and the second signal.

Specifically, the analogue comparator 17 is capable of generating the control signal 18 for controlling so as to open the switch device 13 if the difference between the first signal and the second signal is greater than a predefined value and for controlling so as to close the switch device 13 if the difference between the first signal and the second signal is less than or equal to this predefined value.

Preferably, the predefined value is equal to 0.2 mV or 0.5 mV.

Figure 3 shows a second embodiment of the safety system according to the invention which is generally designated 200'.

The features of the safety system 200' in common with those of the safety system 200 shown in Figure 2 are indicated with the same reference numeral.

With reference to Figure 3, the analogue comparator 17 is operatively connected to the digital processing unit 14 and is capable of generating an output signal 19 on the basis of the comparison between the first signal and the second signal.

The control device 16 comprises the digital processing unit 14, which is operatively connected to the switch device 13. In addition, the digital processing unit 14 is capable of generating the control signal 18 for controlling so as to close the switch device 13 when the output signal 19 takes on a first value and for controlling so as to open the switch device 13 when the output signal 19 takes on a second value.

In particular, the analogue comparator 17 is capable of generating the second value of the output signal 19 if the difference between the first signal and the second signal is greater than a predefined value while the first value of the output signal 19 is generated by the analogue comparator 17 if the difference between the first signal and the second signal is less than or equal to this predefined value.

Preferably, the predefined value is equal to 0.2 mV or 0.5 mV.

The safety system 200' further comprises a signalling device 20 which is operatively connected to the digital processing unit 14 and which is provided to generate an audible and/or illuminated warning signal on the basis of the value taken on by the output signal 19 which is generated by the analogue comparator 17. Specifically, the signalling device 20 comprises a buzzer and a plurality of LED devices and does not emit any audible/illuminated signal if the output signal 19 takes on the first value, and emits an audible signal and/or illuminated signal if the output signal 19 takes on the second value.

The invention thereby achieves the objects set out, affording the advantages mentioned above with respect to the known solutions.