WO2018215887A1

WO2018215887A1 - Burner comprising a detecting sensor for a flame and method of modification of a burner

Info

Publication number: WO2018215887A1
Application number: PCT/IB2018/053420
Authority: WO
Inventors: Bruno Giordano; Nicola Francesco RENOFFIO
Original assignee: Idea S.P.A.
Priority date: 2017-05-22
Filing date: 2018-05-16
Publication date: 2018-11-29
Also published as: EP3612768B1; EP3612768A1; IT201700055306A1

Abstract

A burner (100) comprising a sensor (1) for detecting a flame (2) comprising a sensitive element (3) of the flame (2) comprising a phototransistor or photodiode in use facing the flame (2) to receive an electromagnetic wave emitted by the flame (2) and an interface electric circuit (6) connected between the sensitive element (3) and an output (5) of the circuit configured for converting the detecting signal (4) generated by the sensitive element (3) into a flame signal (2) suitable for being received by a control system (103) of the burner (100).

Description

"Burner comprising a detecting sensor for a flame and method of modification of a burner"

*******

Technical Field

The present invention relates to a burner comprising a sensor for detecting a flame for a control system of the burner, and a method for transforming said burner with a sensor for detecting a flame of a photo- resistance type into a burner having a sensor for detecting a flame of a photo-transistor or photodiode type.

In particular the present invention is used in gas-fired or oil-fired burners or with other fuels not expressly indicated herein.

Purely by way of example, a possible use of the burner according to the present invention is in the field of boilers for domestic heating or for industrial applications.

Prior art

In particular, the present invention relates to the field of flame detecting sensors for a control system of a burner in which the control system is preconfigured to receive in input at least:

a preset first range of voltage and/or current corresponding to a status of absence or loss of the flame; and

and at least a second preset range of voltage and/or current, different to the first and corresponding to a status of presence of the flame.

In the prior art, a common control system of combustion of a burner comprises:

an on-off and intercepting device (preferably a valve) which adjusts the fuel supply flow;

- supply means for supplying a comburent acting towards the burner for providing the comburent to the burner;

a sensor for detecting a flame associated, in use, to the burner and positioned at the flame position; a control unit or control system operatively connected to the on-off and modulating device, to the supply means of the comburent and to the sensor for detecting the flame so as to control supply of fuel and comburent as a function of the detecting of the flame.

The comburent supply means preferably comprises a fan infeeding air. In other words, the comburent preferably comprises air, but might include any other type of comburent different to air.

In particular it should be noted that the task of the control unit is mainly that of guaranteeing a "non-toxic" combustion so as not to generate exhausted gases (mainly carbon monoxide) damaging to the health of individuals and also to generate a correct combustion as a function of the power required.

Therefore, during the functioning of the burner the flame signal is measured (using the sensor) and compared with a predefined threshold value (using the control unit) so as to control the combustion.

With reference to the sensor for detecting the flame, at present there exist different types on the market. For example a first type is based on a photo-resistance as a sensitive element which constitutes a member that varies the resistivity thereof as a function of the quantity of light that strikes it.

However, the prior art has numerous drawbacks substantially linked to the fact that at present its production is being wound down as it has a large volume and dimensions, is difficult to build, it generates much waste during manufacturing and requires a careful selection which is carried out directly in the factory or during testing.

Therefore a need is emerging to replace the photoresistors with other types of sensors that enable detection of the quality of the flame.

However, different types of burners and control systems currently exists on the market and are also installed, calibrated on the basis of the voltage and/or current values generated by the photoresistors and which are not suited to functioning with other types of sensors. Object of the present invention

In this situation, the object of the present invention is to realise a burner which obviates the above-mentioned drawbacks.

An object of the present invention is to realise a burner with a sensor for detecting a flame which is able to generate output signals which adapt to the control systems originally configured to operate with the photoresistors.

The above-indicated objects are substantially attained by a burner with a sensor for detecting a flame and by a method for transforming said burner according to what is described in the appended claims.

Brief description of the figures

Further characteristics and advantages of the present invention will more greatly emerge from the detailed description of a preferred but not exclusive embodiment of a burner illustrated in the appended drawings, in which:

- figure 1 illustrates a burner having a control system in which a detecting sensor according to the present invention has been inserted;

- figure 2 is a circuit diagram of a first type of sensor according to the present invention;

- figure 3 is a circuit diagram of a second type of sensor according to the present invention;

- figure 4 is a transparent lateral view of the first type of sensor;

- figure 5 is a transparent lateral view of the second type of sensor;

- figures 6 and 7 illustrate two steps of inclusion of the sensor according to the present invention, in a casing; and

- figure 8 illustrates a table of comparison of the values of the flame signal obtained with the sensor according to the present invention.

Detailed description of one or more preferred embodiments of the present invention

With reference to figure 1 , a burner 100 is schematically illustrated, applied to a boiler or an industrial application and connected to a control system. The burner 100 comprises:

- a conduit 101 for supply of a fuel;

- a conduit 102 for supply of a comburent;

- a control system 103 operatively connected to the conduits 101 , 102 for supply of the fuel and the comburent for regulating a respective flow rate thereof.

Note that the flow rate of the fuel is regulated by a valve 104 interposed along the relative conduit and connected to the control system 103. The flow rate of the comburent is regulated by increasing/reducing the revolutions of a fan 105 or by regulating the opening of an access mouth of the air. Therefore the fan 105 or the opening of the mouth is connected to the control system 103.

Further, the control system 103 has a housing 106 and an input for connecting a sensor 1 for detecting a flame 2, so that the sensor 1 is facing and arranged at the flame 2.

Note that the sensor 1 for detecting the flame 2 is configurable between a condition of disconnection from the control system 103 in which it is separated therefrom and a condition of connection in which it is inserted in a suitable housing 106 and is electrically connected to the electrical input of the control system 103 so as to send a flame signal 2 from the electric circuit of the sensor 1 to the control system 103. The control system 103 is configured so as to regulate the flow rate of fuel and/or comburent according to the levels of voltage and/or current received by and contained in said flame signal 2.

As mentioned in the foregoing, the aim of the present invention is to operate with already pre-configured control systems (for other types of sensor 1 ) so as to receive in input at least a preset first range of voltage and/or current corresponding to a status of absence or loss of the flame 2 and at least a second preset range of voltage and/or current, different to the first and corresponding to a status of presence of the flame 2.

Note that the sensor 1 according to the present invention is configured to detect various values so as also to evaluate the quality of the flame 2. According to the present invention, a sensor 1 for detecting the flame 2 comprises a sensitive element 3 (figures 4 and 5) of the flame 2 comprising a phototransistor or photodiode in use facing the flame 2 in order to receive an electromagnetic wave (preferably luminous) emitted by the flame 2.

A type of phototransistor or photodiode is advantageously normally configured to select a particular wavelength of the light that is to be detected.

Further, the sensitive element 3 is configured to generate a detecting signal 4 having a voltage and/or current that is variable as a function of the electromagnetic wave emitted by the flame 2 and corresponding at least to a status of absence of the flame 2 or presence of the flame 2.

Further, the sensor 1 comprises an interface electric circuit 6 (figures 2 and 3) connected between the sensitive element 3 and an output 5 of the circuit configured for converting the detecting signal 4 generated by the sensitive element 3 into a flame signal 2.

The electric circuit 6 advantageously enables converting each value of the signal generated by the sensitive element 3 with a corresponding voltage/current level that the control system 103 is predisposed to receive. The flame signal 2 (generated downstream of the electric circuit 6) has a first voltage and/or current level that falls within the first preset range of voltage and/or current of the control system 103 when the electromagnetic wave emitted by the flame 2 corresponds to the status of absence or loss of the flame 2.

Further, the flame signal 2 has a second level of voltage and/or current that falls within the second preset range of voltage and/or current, when the electromagnetic wave emitted by the flame 2 corresponds to the status of presence of the flame 2.

Figure 8 illustrates an example of this correspondence in which the item "voltage level (Vdc) [1 ]" corresponds to the values of the range that the control system 103 accepts in input to signal a determined status of the flame 2, while the item "voltage at the sensor heads 1 (Vdc) [3]" corresponds to the voltage levels that the sensor 1 generates for corresponding statuses of the flame 2.

In order to carry out this adaptation or conversion of the signals, the electric circuit 6 comprises an amplification step 7 configured for amplifying the detecting signal 4 generated by the phototransistor or photodiode. In fact, these generate a detecting signal 4 having a very low bandwidth (micro-amperes or micro-volts) and it is therefore necessary to perform an amplification.

In this regard, in the figures two types of electric circuit are represented. A first type (figure 2) in which the electric circuit 6 is of a digital type so as to adapt to a control system 103 of the burner 100 of electronic type. In this case the amplification step 7 is preferably realised by means of a "mirror current" configuration which is followed in cascade by a protection step 8 (using a resistance) which lastly is followed by a stabilisation step 9 of the voltage (voltage control).

A second type of circuit (figure 3) is of analogue type so as to adapt to a control system 103 of the burner 100 of an electromechanical type. In this case, a current control is carried out. There is preferably a first amplification stage 7 which is followed by a translation section 10 of the detecting signal 4 comprising at least an inner transistor polarised by the electric current.

In both types of circuit, the flame signal 2 is generated in output 5 to the sensor 1 at respective clamps which are in use connected to the input of the control system 103 of the burner 100.

In any case, the electric circuit 6 is supplied by a supply voltage or current applied to the output 5 of the circuit. In the example of figure 8, it can be observed that a light of 1 nominal Lux corresponds to a voltage at the heads of the sensor 1 of about 3.49 Volts, while a light of 1 .5 Lux corresponds to a voltage at the heads of the sensor 1 of about 3.13 Volts.

The phototransistor or photodiode is preferably of a type that is selective of the wavelength and is configured to generate the detecting signal 4 when the electromagnetic wave has a value comprised between 0 and 3 nominal Lux, but it might be configured differently according to needs. Further, the sensor 1 has an elongated shape according to a direction going from the phototransistor or photodiode to the output 5 of the circuit, so as to be easily able to be inserted according to an insertion direction in a housing 106 of the control system 103 of the burner 100.

As can be seen in figures 4 and 5, two connecting clamps are present at the output 5 which are arranged, with respect to one another, staggered according to the extension direction of the sensor so as to optimise the volumes and with the aim of realising the connection of the clamps with the external cables for connecting to the control system 103 of the burner 100.

On the internal side of the sensor 1 the clamps are connected to respective electronic devices (J6 and J7) of the sensor 1 in which they are also staggered to one another in a similar way to the clamps.

In this way, it is advantageously possible to prevent inversion of the cables connected to the clamps (which define a coupling of the capacitive type) and facilitate the entire assembly in a restricted space.

In figures 6 and 7 it can be seen that the sensor 1 comprises an external casing 1 1 (preferably made of plastic) with the aim of protecting the circuit and the sensitive element 3. The housing 1 1 preferably has a longitudinal extension from an output hole 12 of the sensitive element 3, so that the sensitive element 3 projects out of the casing 1 1 , to a connecting hole 13 from which the contacts of the output 5 of the sensor 1 project, so as to be able to connect them to the control system 103 of the burner 100. The casing 1 1 is advantageously realised in two semi-parts 14 hinged at the part from which the sensitive element 3 projects, and which are closed once the rest of the sensor 1 has been inserted. A complementarily- shaped seat to the sensor 1 is afforded internally of the semi-parts.

The casing 1 1 has a broadening 15 at the part which is electrically connected to the control system 103 of the burner 100.

Note that the housing 1 1 is advantageously complementarily shaped with respect to the housing already present on the control system 103.

A further object of the present invention is a transformation method of the burner 100 described in the foregoing.

In particular, the method follows directly from the above disclosure which is incorporated in its entirety in the following. The method comprises the following operative steps:

selecting the sensitive element 3 for detecting the flame 2 comprising a phototransistor or photodiode configured to receive an electromagnetic wave emitted by the flame 2 and to generate a detecting signal 4 having voltage and/or current that is variable as a function of the electromagnetic wave emitted by the flame 2 and corresponding at least to a status of absence of the flame 2 or of presence of the flame 2;

- making an interface electric circuit 6 connected between the sensitive element 3 and an outlet 5 of the circuit so as to generate a flame signal 2 in output 5 that has a first voltage and/or current level that falls within the first preset range of voltage and/or current of the control system 103 when the electromagnetic wave emitted by the flame 2 corresponds to the status of absence or loss of the flame 2, and in such a way that said flame signal 2 has a second level of voltage and/or current that falls within the second preset range of voltage and/or current, when the electromagnetic wave emitted by the flame 2 corresponds to the status of presence of the flame 2.

Further, the method comprises the step of inserting the sensor 1 internally of the housing and positioning it at the housing 106 of the control system 103 of the burner 100 so as to position the sensitive element at the flame 2, and so as to electrically connect the sensor 1 to the control system 103. The present invention attains the set objects.

In fact, the present invention enables adapting the signals generated by the sensitive elements such as the phototransistor or photodiode to a common control system of a burner preconfigured to operate with photoresistors.

In particular, the interface circuit enables matching the signals generated so as not to have to modify the whole control system and so as to be able to adapt thereto the sensor with a phototransistor or photodiode given equal wavelengths detected corresponding to the different statuses of the flame.

Claims

1. A burner (100) for a boiler or industrial applications, comprising:

a conduit (101 ) for supply of the fuel;

a conduit (102) for supply of a comburent;

5 - a control system (103) operatively connected to the conduits (101 ) (102) for supply of the fuel and the comburent for regulating a respective flow rate thereof; said control system (103) having a housing (106) for a sensor (1 ) for detecting a flame (2); said control system (103) being preconfigured for receiving in input at least a first range of voltage and/or0 current characteristic of a photo-resistance flame sensor and corresponding to a status of absence or loss of the flame (2) and at least a second range of voltage and/or current characteristic of a photo-resistance flame sensor and different from the first and corresponding to a status of presence of the flame (2);

5 - a sensor (1 ) for detecting a flame (2) configurable between a condition of disconnection from the control system (103) and a condition of connection in which it is inserted in said housing (106) and electrically connected to the input of the control system (103) so as to send said flame signal (2) from the electric circuit (6) to the control system (103); said 0 control system (103) being configured so as to regulate the flow rate of fuel and/or comburent according to the levels of voltage and/or current received by said flame signal (2):

characterised in that said sensor (1 ) comprises:

a sensitive element (3) of the flame (2) comprising a phototransistor or 5 photodiode in use facing the flame (2) to receive an electromagnetic wave emitted by the flame (2); said sensitive element (3) being configured for generating a detecting signal (4) having voltage and/or current that is variable as a function of the electromagnetic wave emitted by the flame (2) and corresponding at least to a status of absence of the flame (2) or of o presence of the flame (2) ;

an interface electric circuit (6) connected between the sensitive element (3) and an output (5) of the circuit configured for converting the detecting signal (4) generated by the sensitive element (3) into a flame signal (2) characteristic of a photo-resistance flame sensor; said flame signal (2) having a first voltage and/or current level that falls within the first range of voltage and/or current of the control system (1 03) characteristic of a photo-resistance flame sensor, when the electromagnetic wave emitted by the flame (2) corresponds to the status of absence or loss of the flame (2); said flame signal (2) having a second level of voltage and/or current that falls within the second preset range of voltage and/or current of a photo-resistance flame sensor, when the electromagnetic wave emitted by the flame (2) corresponds to the status of presence of the flame (2).

2. The burner (100) according to claim 1 , characterised in that said electric circuit (6) comprises an initial amplification step (7) configured for amplifying the detecting signal (4) generated by the phototransistor or photodiode.

3. The burner (100) according to any one of the preceding claims, characterised in that said electric circuit (6) is of analogue type so as to adapt to a control system (103) of the burner (100) of electromechanical type.

4. The burner (100) according to claim 3, characterised in that said electric circuit (6) comprises an intermediate step of translating the detecting signal (4) comprising at least an inner transistor polarised by the electric current.

5. The burner (100) according to any one of the preceding claims from 1 to 2, characterised in that said electric circuit (6) is of digital type so as to adapt to a control system (103) of the burner (100) of an electronic type.

6. The burner (100) according to any one of the preceding claims, characterised in that said electric circuit (6) is supplied by a supply voltage or current applied to the output (5) of the circuit.

7. The burner (100) according to any one of the preceding claims, characterised in that the phototransistor or photodiode is of a type that is selective of the wavelength and is configured for generating the detecting signal (4) when the electromagnetic wave has a value comprised between 0 and 5 nominal Lux.

8. The burner (100) according to any one of the preceding claims, characterised in that the sensor (1 ) has an elongated shape from the phototransistor or photodiode to the output (5) of the circuit, according to an insertion direction in a housing (106) of the control system (103) of the burner (100).

9. The burner (100) according to any one of the preceding claims, characterised in that the sensor (1 ) comprises an external casing (1 1 ).

10. A transformation method of a burner (100) comprising a control system (103) having a housing (106) for a sensor (1 ) for detecting a flame (2), wherein said control system (103) is preconfigured for receiving in input at least a first range of voltage and/or current characteristic of a photo-resistance flame sensor and corresponding to a status of absence or loss of the flame (2) and at least a second range of voltage and/or current characteristic of a photo-resistance flame sensor and different from the first and corresponding to a status of presence of the flame (2);

characterised in that it comprises following operating steps:

- disconnecting the sensor for detecting a flame (2) of a photo- resistance type from the housing (106) of the control system (103); - realising a sensor (1 ) for detecting a flame (2) by means of the following operating substeps:

selecting a sensitive element (3) for detecting the flame (2) comprising a phototransistor or photodiode configured for receiving an electromagnetic wave emitted by the flame (2) and for generating a detecting signal (4) having voltage and/or current that is variable as a function of the electromagnetic wave emitted by the flame (2) and corresponding at least to a status of absence of the flame (2) or of presence of the flame

(2); making an interface electric circuit (6) connected between the sensitive element (3) and an outlet (5) of the circuit so as to generate (5) a flame signal (2) in output that has a first voltage and/or current level that falls within the first range of voltage and/or current of the control system (1 03) characteristic of a photo-resistance flame sensor, when the electromagnetic wave emitted by the flame (2) corresponds to the status of absence or loss of the flame (2), and such that said flame signal (2) has a second level of voltage and/or current that falls within the second range of voltage and/or current characteristic of a photo-resistance flame sensor, when the electromagnetic wave emitted by the flame (2) corresponds to the status of presence of the flame (2);

inserting the sensor (1 ) for detecting a flame (2) realised in this way into the housing (106) of the control system (103).