IT201800006079A1 - Safety system for a gas appliance for water heating - Google Patents

Description

Safety system for a gas appliance for water heating

DESCRIPTION

The present invention refers to a safety system for a gas appliance for heating water, to a gas appliance including this safety system and to a method for controlling the aforementioned gas appliance.

The invention finds particular, although not exclusive, application in the field of the construction and use of gas heating devices, i.e. heating devices using a gas burner. Preferably, the invention finds application in water heating systems, such as, for example, the water heater.

In this field of application there are known devices for heating water provided with a gas burner for heating the water contained in a tank and at least two temperature sensors designed to generate a respective signal representative of the temperature measured by them. water contained in this tank.

Typically, these devices are equipped with a control system including a digital logic for controlling the ignition / shutdown of the gas burner based on the temperature detected by one of the aforementioned sensors. The temperature detected by the second sensor is instead used by the digital logic to verify the correctness of the temperature measured by the first sensor, ie to check the correct operation of the heating device.

A limit of this solution can be identified in an excessive, or in any case not negligible, energy consumption of the control system to ascertain the correct functioning of the heating device.

The purpose of the present invention is to provide a safety system for a gas appliance for heating water, a gas appliance including this safety system and a method for controlling the aforementioned gas appliance structurally and functionally conceived to exceed the limit indicated above with reference to the known solutions. This object is achieved by means of a safety system for a gas appliance for heating water, a gas appliance comprising such a safety system and a method for controlling the aforementioned gas appliance made in accordance with the respective independent claims attached hereto. to this 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 water heating appliance comprises a first and a second sensor adapted to generate respectively a first and a second signal representative of a temperature of the water contained in a tank. the gas appliance.

The first and second sensors are preferably temperature sensors.

According to a first aspect of the invention, the first and second signals are analog electrical signals, preferably in voltage.

According to an aspect of the invention, the first and second sensors are placed inside the tank, preferably in an intermediate area of the same. Preferably, the first and second sensors are positioned so as to measure the temperature of the same part of the water contained in the tank. The first sensor can be adjacent to the second sensor.

The gas appliance includes, in addition to the tank to contain water, a first gas burner to heat the water contained within this tank.

According to one aspect of the invention, the gas appliance can be identified with a water heater. The gas appliance may include a first valve designed to allow / intercept a flow of gas to the first gas burner. The gas appliance may include a first actuator designed to operate the first valve in opening and closing when it is respectively energized and not energized.

According to an aspect of the invention, the safety system comprises an (electrical) power supply circuit to energize the first actuator of the first valve. The first actuator is connected to the power supply circuit.

According to an aspect of the invention, the power supply circuit is connected to an electric power generator adapted to energize this power supply circuit. The electricity generator is preferably a thermoelectric generator, for example it is a thermopile or thermocouple.

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

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

According to an aspect of the invention, the first actuator is energized by a voltage related to the voltage generated by the electricity generator through the power supply circuit.

According to a second embodiment of the invention, the gas appliance comprises a second gas burner and a second actuator designed to operate in opening and closing a second valve of the gas appliance when it is respectively energized and not energized.

The second valve is designed to allow a flow of gas to pass / intercept to the second gas burner and, preferably, to the first gas burner.

In particular, the second valve is designed to allow a flow of gas to pass / intercept to the second gas burner and, in cascade, to the first gas burner.

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

According to an aspect of the invention, the second actuator is connected to the aforementioned power supply circuit and is preferably energized by the electricity 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 instead 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 respectively represent a main valve and a main burner of the gas appliance while the second valve and the second gas burner respectively represent a pilot valve and a pilot burner of the gas appliance. The pilot burner is designed to ignite the main burner by means of its pilot flame.

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

It is evident that in the embodiment of the invention in which the gas appliance is provided with the first and second burners, the closing / opening of the power supply circuit through the switch device determines the energization / non-energization of both the first and the second burner. second actuator.

According to one aspect of the invention, the security system comprises a digital processing unit operatively connected to the first and / or second sensor. The digital processing unit is configured to compare a set-point value representative of a preset temperature with the first or second signal.

The digital processing unit can be a microcontroller.

In addition, or alternatively, the digital processing unit may include an ASIC (Application Specific Integrated Circuit) integrated circuit and possibly additional digital logic to operate according to the invention.

According to an aspect of the invention, the digital processing unit is powered by an electricity generator through a relative electrical circuit that connects the digital processing unit to this electricity generator. Such an electric power generator can be a thermoelectric generator or a battery.

This thermoelectric generator is associated with a gas burner whose flame generated energizes the thermoelectric generator. Preferably, this thermoelectric generator is the same that energizes the power 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 power supply circuit of the aforementioned actuators (for example through the aforementioned switching device or by means of a second switching device ), and is configured to operate 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 aforementioned signals.

By way of example, the first actuator is opened 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 operates the first actuator to close if this difference is greater than the aforementioned threshold.

According to an aspect of the invention, the safety system comprises a control device 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 can be powered by an electric power generator through a relative electric circuit that connects the control device to this electric power generator. Such an electric power generator can be a thermoelectric generator or a battery.

This thermoelectric generator is associated with a gas burner whose flame generated energizes the thermoelectric generator. Preferably, this thermoelectric generator is the same that energizes the power supply circuit of the security system and / or the digital processing unit. The control device may include the digital processing unit.

The control device comprises an analog comparator operatively connected to the first and second sensors for comparing the first signal with the second signal.

According to an aspect of the invention, the control device is configured to generate a control signal to command the switch device to open / close on the basis of the comparison between the first and second signals made by the analog comparator.

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

The control signal can be a digital signal, preferably at two voltage levels.

The comparison between the signals generated by the two sensors is therefore carried out by an analog comparator without the involvement of the digital processing unit, resulting in savings in terms of electricity consumption. In fact, in the hypothesis that the digital processing unit must compare the first signal with the second signal in order for the control device to generate the control signal, these analog signals must be subjected to an analog / digital conversion upstream of the comparison which inevitably requires a greater use of electrical energy than the analogue comparison according to the invention.

The use of an analog comparator therefore does not require further processing stages of the signals generated by the first and second sensor, thus reducing the energy absorption required by the control device for the generation of the control signal.

This feature is particularly advantageous if the electricity generator that energizes the power supply circuit and the digital processing unit is a thermoelectric generator. According to an aspect of the invention, the analog comparator is operatively connected to the switch device and is able to generate the control signal to command the switch device to open / close on the basis of the comparison between the first and second signals.

In this way, the analog comparator directly commands the closure of the first valve and therefore the shutdown of the first burner without the aid of additional electronic components.

According to an aspect of the invention, the analog comparator is adapted to generate the control signal to command the switch device to open if the difference between the first signal and the second signal is greater than a predefined value and to command the switch device to close. if the difference between the first signal and the second signal is less than or equal to the aforementioned predefined value.

According to one aspect of the invention, the aforementioned default value is less than or equal to 0.5 mV. Preferably, this predefined value is between 0.2mV and 0.5mV.

According to an aspect of the invention, the control device comprises the aforementioned digital processing unit.

According to an aspect of the invention, the analog comparator is operationally connected to the digital processing unit and is able to generate an output signal based on the comparison between the first and second signals.

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

The first value can be equal to 0 V (first voltage level) and the second value can 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 able to generate the control signal to command the switch device to close when the output signal assumes the first value and to command the opening of the switch device. switch device when the output signal assumes the second value.

This feature allows you to control the switch device by means of the digital processing unit, while maintaining the burden of comparing the first and second signals with the analog comparator.

According to an aspect of the invention, the analog comparator is able to generate 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 analog comparator, on the other hand, is able to generate 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 aforementioned predefined value.

According to one aspect of the invention, the aforementioned default value is less than or equal to 0.5 mV. Preferably, this predefined value is between 0.2mV and 0.5mV.

According to an aspect of the invention, the safety system comprises a signaling device operatively connected to the control device, and / or to the digital processing unit, and arranged to generate a warning signal on the basis of the value assumed by the output signal. generated by the analog comparator.

The warning signal can be a sound and / or light signal so as to communicate to a user of the security system the outcome of the comparison between the first and second signals generated by the respective sensors. By way of example, the signaling device comprises a buzzer and / or one or more LED devices.

The signaling device may therefore not emit any sound / light signal, or may emit a first light signal, if the output signal assumes the first value and may emit a sound signal and / or a second light signal different from the first (for example in terms of number of LED devices lit and / or color emitted) if the output signal assumes the second value. According to one aspect of the invention, the gas appliance can comprise the safety system provided with at least one of the features described above or a combination of two or more of the features described above. In addition, the gas appliance may include the thermoelectric generator, preferably a thermopile, to energize the power supply circuit and / or the digital processing unit.

According to one aspect of the invention, a method for controlling the gas appliance for heating water includes:

• generate a first signal representative of a temperature of the water contained in the tank of the gas appliance through the first sensor of the gas appliance,

• generate a second signal representative of a temperature of the water contained in the tank of the gas appliance by means of the second sensor of the gas appliance,

• compare the first signal with the second signal using the analog comparator of the gas appliance,

• generate a control signal by means of the gas appliance control device based on the comparison between the first and second signal, • command the gas appliance switch device to close / open by means of the control signal so as to energize / do not energize the first actuator of the gas appliance.

According to one aspect of the invention, the first and second temperature sensors measure continuously or intermittently (for example every minute or, more generally, according to a predetermined interval) the temperature of the water contained in the tank.

According to an aspect of the invention, the comparison between the first and the second signal occurs continuously or intermittently (for example every minute or, more generally, according to a predetermined interval).

Characteristics and advantages of the invention will become clearer from the detailed description below of its preferred embodiment examples illustrated, by way of non-limiting example, with reference to the attached figures in which:

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

• Figure 2 is a schematic view of a first embodiment of a security system according to the invention.

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

With initial reference to Figure 1, 100 indicates as a whole a gas appliance for heating water, made in accordance with the present invention.

The gas appliance 100 comprising a tank 1 to contain water, a first gas burner 2 to heat the water contained inside the tank 1, a first valve 3 arranged to allow a flow of gas to pass / intercept towards the first gas burner 2, a first actuator 4 arranged to operate the first valve 3 in opening and closing when it is respectively energized and not energized and a safety system according to the invention.

The gas appliance 100 also comprises a second gas burner 6, a second valve 7 arranged to let pass / intercept a flow of gas towards the first and second gas burners 2,6, and a second actuator 8 arranged to operate the second valve 7 in opening and closing when it is respectively energized and not energized.

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

Figure 2 shows a first embodiment of the security system according to the invention, indicated as a whole with the reference number 200.

The safety system 200 comprises a first and a second sensor 9,10 suitable for generating respectively a first and a second signal representative of a temperature of the water contained in the tank 1. In particular, the first and second sensors 9,10 are temperature sensors configured to generate a respective analog voltage signal.

The safety system 200 also comprises a power supply circuit 11 for energizing the first and second actuators 4,8. The first and second actuators 4,8 are therefore connected to the power supply circuit 11 through 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 generated by this gas burner.

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

The security system 200 also includes a digital processing unit 14 operatively connected to the first sensor 9 and configured to compare a set-point value representative of a preset temperature with the first signal.

In particular, the digital processing unit 14 is a microcontroller powered by the thermoelectric generator 12 through a relative electrical circuit 21 which may include a DC / DC converter.

The digital processing unit 14 is operatively connected to the power supply circuit 11 by means of a second switch device 5 to operate the first and 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 aforementioned signals.

The set-point value can be manually set by a user using a knob 15 or other known input device.

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

The control device 16 may include the digital processing unit 14.

The control device 16 comprises an analog comparator 17 operatively connected to the first and second sensors 9,10 for comparing the first signal with the second signal.

The control device is also configured to generate a control signal 18 to command the switch device 13 to open / close on the basis of the comparison between the first and second signals made by the analog comparator 17.

In particular, the analog comparator 17 is operatively connected to the switch device 13 and is able to generate the control signal 18 to command the switch device 13 to open / close on the basis of the comparison between the first and second signals.

Specifically, the analog comparator 17 is able to generate the control signal 18 to command the switch device 13 to open if the difference between the first signal and the second signal is greater than a predefined value and to command the switch device 13 to close. if the difference between the first signal and the second signal is less than or equal to this predefined value. Preferably, the default value is 0.2mV or 0.5mV.

Figure 3 shows a second embodiment of the security system according to the invention, indicated as a whole with the reference number 200 '.

The characteristics of the security system 200 'in common with those of the security system 200 shown in figure 2 are indicated with the same reference number.

With reference to Figure 3, the analog comparator 17 is operationally connected to the digital processing unit 14 and is able to generate an output signal 19 based on the comparison between the first and second signals.

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 adapted to generate the control signal 18 to command the switch device to close 13 when the output signal 19 assumes a first value and to command the switch device 13 to open when the output signal 19 assumes a second value.

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

Preferably, the default value is 0.2mV or 0.5mV.

The safety system 200 'also comprises a signaling device 20 operatively connected to the digital processing unit 14 and arranged to generate an audible and / or light warning signal on the basis of the value assumed by the output signal 19 generated by the comparator. analog 17. Specifically, the signaling device 20 comprises a buzzer and a plurality of LED devices and does not emit any sound / light signal if the output signal 19 assumes the first value and emits a sound and / or light signal if the signal output 19 assumes the second value.

The invention thus achieves the intended purposes by achieving the aforementioned advantages with respect to known solutions.

Claims (11)

CLAIMS 1. Safety system for a gas appliance (100) for heating water, said gas appliance comprising a tank (1) to contain water and a first gas burner (2) to heat the water contained inside of said tank (1), said safety system (200,200 ') comprising: • a first sensor (9) suitable for generating a first signal representative of a temperature of the water contained in said tank (1), • a second sensor (10) suitable for generating a second signal representative of a temperature of the water contained in said tank (1), • a power supply circuit (11) to energize a first actuator (4) of a first valve (3) which is arranged to allow a flow of gas to pass / intercept towards said first gas burner (2), said first actuator (4 ) being designed to operate said first valve (3) in opening and closing when it is respectively energized and not energized, • a switch device (13) located in said power supply circuit (11) to close / open said power supply circuit (11) so as to energize / not energize said first actuator (4), • a digital processing unit (14) operatively connected to said first and / or second sensor (9,10) and configured to compare a set-point value representative of a preset temperature with said first or second signal, and • a control device (16) operatively connected to said switching device (13) and to said first and second sensors (9,10), characterized in that said control device (16) comprises an analog comparator (17) operatively connected to said first and second sensors (9,10) to compare said first signal with said second signal and by the fact that said control device (16 ) is configured to generate a control signal (18) to command said switch device (13) to open / close on the basis of the comparison between the first and second signals made by said analog comparator (17). 2. Safety system according to claim 1, wherein said analog comparator (17) is operatively connected to said switch device (13) and is adapted to generate said control signal (18) to command said switch device ( 13) on the basis of said comparison between said first and second signals. 3. Safety system according to claim 2, wherein said analog comparator (17) is adapted to generate said control signal (18) to open said switch device (17) if the difference between the first signal and the second signal is greater than a predefined value and to command said switch device (13) to close if the difference between the first signal and the second signal is less than or equal to said predefined value. Security system according to claim 1, wherein said control device (16) comprises said digital processing unit (14), said analog comparator (17) being operatively connected to said digital processing unit (14) and being able to to generate an output signal (19) on the basis of said comparison between said first and second signals, said digital processing unit (14) being operatively connected to said switching device (13) and being able to generate said control signal (18) ) to command said switch device (13) to close when said output signal (19) assumes a first value and to command said switch device (13) to open when said output signal (19) assumes a second value. Safety system according to claim 4, wherein said analog comparator (17) is adapted to generate said second value of said output signal (19) if the difference between the first and second signals is greater than a predefined value. 6. Safety system according to any one of the preceding claims, in which said first and second signals are analog electrical signals, preferably in voltage. 7. Gas appliance for heating water, said gas appliance (100) comprising a tank (1) to contain water, a first gas burner (2) to heat the water contained inside said tank (1 ), a first valve (3) arranged to allow a flow of gas to pass / intercept towards said first gas burner (2), a first actuator (4) arranged to operate said first valve (3) in opening and closing when it is respectively energized and non-energized and a safety system (200,200 ') according to one of claims 1 to 6. Gas appliance according to claim 7, wherein said gas appliance (100) comprises a thermoelectric generator (12) for energizing said power supply circuit (11) and / or said digital processing unit (14). 9. Gas appliance according to claim 7 or 8, wherein said gas appliance (100) comprises a second gas burner (6), a second valve (7) arranged to allow a flow of gas to pass / intercept towards said second gas burner (6) and, preferably, towards said first gas burner (2), and a second actuator (8) connected to said supply circuit (11) and arranged to operate said second valve (7) in opening and closing ) when it is respectively energized and not energized, said first gas burner (2) being a main burner and said second gas burner (6) being a pilot burner designed to ignite said main burner by means of a relative pilot flame. Gas appliance according to claim 9, wherein said thermoelectric generator (12) is associated with the second burner (6) so as to be energized by the flame generated by said second burner (6). Method for controlling a gas appliance (100) according to one of claims 7 to 10, said method comprising: • generate a first signal representative of a water temperature contained in the tank (1) of the gas appliance (100) by means of the first sensor (9) of the gas appliance (100), • generate a second signal representative of a water temperature contained in the tank (1) of the gas appliance (100) by means of the second sensor (10) of the gas appliance (100), • compare said first signal with said second signal using the analog comparator (17) of the gas appliance (100), • generate a control signal (18) by means of the control device (16) of the gas appliance (100) based on the comparison between said first and second signals, and • command the switch device (13) of the gas appliance (100) to close / open by means of said control signal (18) so as to energize / not energize the first actuator (4) of the gas appliance (100).