Gas burner safety circuit and method of its operation

Abstract

An electronic safety circuit (1) for controlling a gas supply (G) to a gas burner (2), comprising an electrically operable safety valve (3) for maintaining or stopping the gas supply (G) to the gas burner (2); a thermocouple (4) for receiving heat from the gas burner (2); a first and second semiconductor switch (5, 6). The safety valve (3) is connected to the thermocouple (4), and the first and second semiconductor switch (5, 6) are arranged in series and connected between the thermocouple (4) and the safety valve (3). A control circuit (7) is connected with the first and second semiconductor switch (5, 6) and configured to receive an input signal (S) based on which the control circuit (7) switches the first and second semiconductor switch (5, 6) to a closed state, or switch the first and / or the second semiconductor switch (5, 6) to an open state.

Description

[0001] Gas burner safety circuit and method

[0002] Field of the invention

[0003] The present invention relates to a gas burner safety circuit, in particular to an electronic safety circuit for controlling gas supply to a gas burner.

[0004] Background

[0005] Dutch patent publication NL 2004917 C2 discloses a device for electrically controlled turning off of a gas flame of a gas hob. The device comprises a solenoid valve for opening and turning off a gas supply to the gas hob, a thermocouple to provide a current to the solenoid valve; a switch for switching off the current to the solenoid valve resulting in the solenoid valve being forced into a closed position and thereby turning off the supply of gas, wherein the switch comprises a semiconductor transistor, and a control unit for controlling the switch. In an embodiment, the control unit may comprise a timer, which can be set by a user. If the time set in the timer expires, the gas flame will be turned off.

[0006] The device of the type described above provides the ability to turn off the gas hob by way of a switch, comprising a semiconductor transistor, disrupting current through the solenoid valve and as such stopping the supply of gas. However, the device relies upon fault free operation of the semiconductor transistor to disrupt the current through the solenoid valve. Therefore, should the semiconductor transistor malfunction, then no disruption of the current occurs and the gas burner may not switch off as required.

[0007] Summary

[0008] The present invention seeks to provide an improved electronic safety circuit for controlling gas supply to a gas burner that solves at least in part the problems mentioned above. The electronic safety circuit provides increased robustness and less sensitivity to malfunctioning of electronic components, such that operating the gas burner is reliable and complies with household safety standards.

[0009] According to the present invention, the electronic safety circuit of the type mentioned above comprises an electrically operable safety valve for maintaining or stopping gas supply to a gas burner; a thermocouple for receiving heat from the gas burner when active; and a first semiconductor switch and a second semiconductor switch.

[0010] The safety valve is connected to the thermocouple, and the first semiconductor switch and the second semiconductor switch are arranged in series and connected between the thermocouple and the safety valve. Further, the control circuit is in connection with the first semiconductor switch and the second semiconductor switch, wherein the control circuit is configured to receive an input signal based on which the control circuit is configured to: switch the first semiconductor switch and the second semiconductor switch to a closed state in which a current is allowed to flow through the safety valve for maintaining the gas supply to the gas burner, or switch the first semiconductor switch and / or the second semiconductor switch to an open state in which the current is blocked from flowing through the safety valve for stopping the gas supply to the gas burner, wherein the electronic safety circuit further comprises a signal generator circuit and wherein the control circuit comprises a signal detector circuit in connection with the signal generator circuit, wherein the signal generator circuit is configured to provide the input signal (S) as a dynamic input signal (Sd) or a static input signal (Ss) to the signal detector circuit, wherein the signal detector circuit allows the control circuit to switch the first semiconductor switch and the second semiconductor switch to the closed state when the signal detector circuit receives the dynamic input signal Sd; and switch the first semiconductor switch and / or the second semiconductor switch to the open state when the signal detector circuit receives the static input signal Ss.

[0011] According to the present invention, the series arrangement of the first and second semiconductor switch adds redundancy to the electronic safety circuit in that the first and second semiconductor switch must both be switchable to the closed state for maintaining the gas supply. Should the first or the second semiconductor switch fail to switch to the closed state, then a fault is present in the electronic safety circuit and the gas burner cannot be activated. In case the first and the second semiconductor switch are both in the closed state, then at least one of the first and second semiconductor switch must be switchable to the open state for blocking the current to deactivate the gas burner. Since it will be unlikely that both the first and second semiconductor switch are malfunctioning, the electrical safety circuit will still be able to deactivate the gas burner.

[0012] Short description of drawings

[0013] The present invention will be discussed in more detail below, with reference to the attached drawings, in which

[0014] Figure 1 shows an electronic safety circuit according to an embodiment of the present invention;

[0015] Figure 2 shows an electronic safety circuit according to another embodiment of the present invention.

[0016] Detailed description of embodiments

[0017] Figure 1 schematically depicts an electronic safety circuit 1 according to an embodiment of the present invention. The electronic safety circuit 1 as shown comprises an electrically operable safety valve 3 for connection to a gas burner 2. The gas burner 2 can be activated and provide a flame V when the safety valve 3 is open and gas supply G is allowed to pass through the safety valve 3. When the safety valve 3 is closed, the gas supply G is disrupted or stopped, thereby deactivating the gas burner 2.

[0018] The electronic safety circuit 1 further comprises a thermocouple 4 for receiving heat from the gas burner 2 when active. As is known to the skilled person in the art, the thermocouple 4 is arranged to produce a voltage across its positive P and negative N leads dependent on temperature, wherein the voltage is representative of a temperature.

[0019] As further depicted, the electronic safety circuit 1 comprises a first semiconductor switch 5 and a second semiconductor switch 6. In an exemplary embodiment, the first semiconductor switch 5 and the second semiconductor switch 6 may each be a MOSFET semiconductor switch.

[0020] From the electrical topology shown in Figure 1 , the safety valve 3 is connected, i.e. electrically connected, to the thermocouple 4, and wherein the first semiconductor switch 5 and the second semiconductor switch 6 are arranged in series and connected between the thermocouple 4 and the safety valve 3. This electrical topology provides for a safety loop, i.e. an electrical safety loop, allowing for a current 8 to flow through the safety valve 3, the thermocouple 4 and the series arrangement of the first semiconductor switch 5 and the second semiconductor switch 6. The current 8 is provided by the thermocouple 4 when it receives heat from an active gas burner 2.

[0021] There is further provided a control circuit 7 which is in connection (see arrows 5a, 6a) with the first semiconductor switch 5 and the second semiconductor switch 6, wherein the control circuit 7 is configured to receive an input signal S based on which the behaviour of the first semiconductor switch 5 and the second semiconductor switch 6 can be controlled. In particular, based on the input signal S, the control circuit 7 is configured to switch the first semiconductor switch 5 and the second semiconductor switch 6 to a closed state in which a current 8 is allowed to flow through the safety valve 3 for maintaining the gas supply G to the gas burner 2, or switch the first semiconductor switch 5 and / or the second semiconductor switch 6 to an open state in which the current 8 is blocked from flowing through the safety valve 3 for stopping the gas supply G to the gas burner 2.

[0022] It is noted that when the first and second semiconductor switch 5, 6 are switched to the closed state, then the first and second semiconductor switch 5, 6 are considered electrically conductive and allow for the current 8 to exist. Conversely, when the first and / or second semiconductor switch 5, 6 are in the open state, then the first and / or the second semiconductor switch 5, 6 are considered non-conductive and as such the current 8 cannot exist.

[0023] It is further noted that the safety valve 3 is of the type “normally closed”, i.e. in absence of the current 8, the safety valve 3 is closed and blocks the gas supply G. In an exemplary embodiment the safety valve 3 may be solenoid valve, e.g. a spring loaded solenoid valve, wherein a spring element of the solenoid valve biases the valve to a closed position.

[0024] According to the invention, the series arrangement of the first and second semiconductor switch 5, 6 adds redundancy to the electronic safety circuit 1 in that the first and second semiconductor switches 5, 6 must operate as intended. In particular, the current 8 for maintaining the safety valve 3 open can only be established when both the first and second semiconductor switches 5, 6 can be switched to the closed state (i.e. electrically conductive). Should at least one of the first and second semiconductor switches 5, 6 malfunction, and not be switchable to the closed state, then the current 8 cannot exist as result of which the safety valve 3 is closed. In turn the gas burner 2 cannot be active and this would indicate a fault in the electronic safety circuit 1. Furthermore, let both the first and the second semiconductor switches 5, 6 be in the closed state and let a current 8 be established that maintains the safety valve 3 open for gas supply G toward the gas burner 2. In case the input signal S instructs the control circuit 7 to switch the first semiconductor switch 5 to the open state, then this should disrupt the current 8 and block the gas supply G. However, the first semiconductor switch 5 may fail to switch to the open state. Subsequently, the control circuit 7 may then switch the second semiconductor switch 6 to the open state for blocking the current 8 and as such block the gas supply G. Due to the redundancy it will be unlikely that the second semiconductor switch 6 malfunctions as well, so that the gas burner 2 can still be deactivated reliably.

[0025] Likewise, in case the input signal S instructs the control circuit 7 to switch the second semiconductor switch 6 to the open state, then this should disrupt the current 8 and block the gas supply G. However, the second semiconductor switch 6 may fail to switch to the open state. Subsequently, the control circuit 7 may then switch the first semiconductor switch 5 to the open state for blocking the current 8 and as such block the gas supply G. Due to the redundancy it will be unlikely that the first semiconductor switch 5 malfunctions as well, so that the gas burner 2 can still be deactivated reliably.

[0026] In an embodiment, the control circuit 7 may be configured to switch, e.g. simultaneously, the first semiconductor switch 5 and the second semiconductor switch 6 to an open state in which the current 8 is blocked, thereby closing the safety valve 3 and thus stopping the gas supply G to the gas burner 2. As indicated above, it will be unlikely that both the first and second semiconductor switches 5, 6 malfunction, and so the current 8 will most likely be blocked by the open state of at least one of the two semiconductor switches 5, 6.

[0027] From the above observation it can be concluded that the electronic safety circuit 1 comprising the series arrangement of the first and semiconductor switches 5, 6 provides redundancy to ensure that the safety valve 3 only allows gas supply G to the gas burner 2 when both the first and second semiconductor switches 5, 6 are switchable to the closed state for allowing the current 8 to exist. In case the gas supply G to the gas burner 2 should be stopped, then at least one of the first semiconductor switch 5 and the second semiconductor switch 6 must be switchable to the open state for blocking the current 8, thereby closing the safety valve 3.

[0028] Note that the redundancy incorporated into the electronic safety circuit 1 can be further increased in an embodiment (not shown) wherein the electronic safety circuit 1 comprises a series arrangement of three or more semiconductor switches connected to the control circuit 7 and between the thermocouple 4 and the safety valve 3. Each semiconductor switch in this series arrangement must be switchable to the closed state to allow for the current 8 through the safety valve 3. Should at least one of the three or more semiconductor switches fail to switch to the closed state, the gas burner 2 cannot be activated. In the event that the gas burner 2 is to be deactivated, then at least one semiconductor switch of the three or more semiconductor switches must be switchable to the open state to block or disrupt the current 8.

[0029] The electronic safety circuit 1 of the present invention thus provides two main ways for safe operation of the gas burner 2. First, the thermocouple 4 provides protection based on the presence of heat coming from an active gas burner 2. When no heat is received by the thermocouple 4, then the current 8 will not be provided by the thermocouple 4 and so the safety valve 3 is closed and stops the gas supply G.

[0030] Second, the series arrangement of the first and second semiconductor switches 5, 6 provides a way to disrupt the current 8 when the thermocouple 4 is subjected to heat coming from an active gas burner 2. By providing an appropriate input signal S it is possible to switch the first and / or second semiconductor switch 5, 6 to the open state for disrupting the current 8.

[0031] Therefore, when the first and second semiconductor switches 5, 6 are in the closed state, thus electrically conductive, then the current 8 can be established as the thermocouple 4 is able to operate in usual manner when the gas burner 2 is active and the thermocouple 4 receives heat therefrom. On the other hand, when the input signal S signals to the control circuit 7 to switch the first and / or the second semiconductor switch 5, 6 to the open state, then the current 8 cannot exist anymore as the thermocouple 4 is electrically disconnected from the safety valve 3, thereby causing the safety valve 3 to close.

[0032] Figure 1 shows an embodiment wherein the electronic safety circuit 1 further comprises a signal generator circuit 9 and wherein the control circuit 7 comprises a signal detector circuit 10, wherein the signal detector circuit 10 is in connection with the signal generator circuit 9. The signal generator circuit 9 is configured to provide the input signal S as a dynamic input signal Sd or a static input signal Ss to the signal detector circuit 10. The signal detector circuit 10 in turn allows or enables the control circuit 7 to switch the first semiconductor switch 5 and the second semiconductor switch 6 to the closed state when the signal detector circuit 10 receives the dynamic input signal Sd, and switch the first semiconductor switch 5 and / or the second semiconductor switch 6 to the open state when the signal detector circuit 10 receives the static input signal Ss.

[0033] In this embodiment the dynamic input signal Sd allows the control circuit 7 to maintain the first semiconductor switch 5 and the second semiconductor switch 6 in the closed state, hence allowing for the current 8 provided by the thermocouple 4 when the gas burner 2 is active. When receiving the static input signal Ss, the control circuit 7 switches the first and / or the second semiconductor switch 5, 6 to the open state, thereby disrupting the current 8.

[0034] In a group of embodiments, the dynamic signal Sd can be any signal that oscillates in some way, such as a sinusoidal wave signal, square wave signal, pulse width modulated signal etc. The static signal Ss, as the term such suggests, may be any non-changing signal, e.g. a zero signal, a constant high signal, a constant low signal.

[0035] In an exemplary embodiment, the dynamic input signal Sd may be a dynamic voltage input signal Sd and the static input signal Ss may be a constant voltage input signal. In this embodiment the signal detector circuit 10 is configured to detect the dynamic voltage input signal Sd and allows the control circuit 7 to switch or maintain the first semiconductor switch 5 and the second semiconductor switch 6 in the closed state. The signal detector circuit 10 is further configured to detect the constant voltage input signal Ss for switching or maintaining the first semiconductor switch 5 and / or the second semiconductor switch 6 in the open state. In exemplary embodiments, the dynamic voltage input signal Sd may be a sinusoidal voltage signal, square wave voltage signal, pulse width modulated voltage signal etc.. The static voltage input signal Ss may be a zero voltage signal, or constant high voltage signal or constant low voltage signal.

[0036] In a further embodiment it is conceivable that the signal generator circuit 9 is configured to provide a plurality of static signals Ss to the signal detector circuit 10 for allowing the control circuit 7 to switch or maintain the first semiconductor switch 5 and / or the second semiconductor switch 6 in the open state. Wherein the plurality of static signals Ss may be used to convey different instructions on how to switch the first semiconductor switch 5 and / or the second semiconductor switch 6 to the open state.

[0037] As further depicted in Figure 1 , there is shown an embodiment wherein the control circuit 7 further comprises a drive circuit 12 in connection with the signal detector circuit 10, the first semiconductor switch 5 and the second semiconductor switch 6. The drive circuit 12 is then configured to switch the first semiconductor switch 5 and the second semiconductor switch 6 to the closed state when the signal detector circuit 10 receives the dynamic input signal Sd; switch the first semiconductor switch 5 and / or the second semiconductor switch 6 to the open state when the signal detector circuit 10 receives the static input signal Ss.

[0038] In this embodiment the drive circuit 12 is configured to drive the first and second semiconductor switches 5, 6 to the open state or the closed state. For example, in case the first semiconductor switch 5 and the second semiconductor switch 6 are both chosen as MOSFET semiconductor switches, then the drive circuit 12 may be configured as a MOSFET gate driver for driving the gates of the first and second semiconductor switches 5, 6.

[0039] In the embodiment shown in Figure 1 , the drive circuit 12 may be separated from the signal detector circuit 10, so that the drive circuit 12 is arranged between the signal detector circuit 10 and the first and second semiconductor switches 5, 6. The main function of the drive circuit 12 is to switch or maintain the first and second semiconductor switches 5, 6 in the closed state or the open state. Further, the signal detector circuit 10 is then configured to maintain the drive circuit 12 active in driving the first and second semiconductor switches 5, 6 to the closed state as long as the dynamic input signal Sd is received by the signal detector circuit 10, and maintain the drive circuit 12 inactive and as such switch the first and / or second semiconductor switches 5, 6 to the open state as long as the static input signal Ss is received by the signal detector circuit 10.

[0040] Therefore, in an embodiment wherein the drive circuit 12 is configured as a MOSFET gate driver, and as long as the signal detector circuit 10 receives the dynamic input signal Sd, the drive circuit 12 continuous driving the gate voltages of the first and second semiconductor switches 5, 6 for maintaining the closed state thereof. As long as the signal detector circuit 10 receives the static input signal Ss, the drive circuit 12 stops driving the gate voltages of the first and / or second semiconductor switches 5, 6 and as such the first and / or second semiconductor switches 5, 6 are maintained in the open state.

[0041] Figure 2 shows an exemplary embodiment of an electronic safety circuit 1 wherein the signal detector circuit 10 comprises a first detector circuit part 10a and a second detector circuit part 10b each of which is configured to receive the input signal S, in particular the dynamic input signal Sd and the static input signal Ss. The first detector circuit part 10a allows the control circuit 7 to switch the first semiconductor switch 5 to the closed and open state when the first detector circuit part 10a receives the dynamic input signal Sd and the static input signal Ss, respectively. The second detector circuit part 10b allows the control unit 7 to switch the second semiconductor switch 6 to the closed and open state when the second detector circuit part 10b receives the dynamic input signal Sd and static input signal Ss, respectively. Note that in Figure 2 there is shown an exemplary embodiment wherein the first and second semiconductor switches 5, 6 are depicted as MOSFET switches 5, 6, e.g. n-channel MOSFET switches.

[0042] The first detector circuit part 10a and the second detector circuit part 10b enable redundancy such that safety is increased. For example, should the first or the second detector circuit part 10a, 10b fail to detect or properly process the static input signal Ss, then the first or the second semiconductor switch 5, 6 may not switch to the open state. However, the probability that both the first and the second detector circuit parts 10a, 10b fail simultaneously is considerably lower. So regardless which of the first detector circuit part 10a or the second detector circuit part 10b fails to operate as intended, the control circuit 7 will still be able to switch the first or second semiconductor switch 5, 6 to the open state for disrupting the current 8 and thus stop the gas supply G.

[0043] In Figure 2 it is further shown that in an embodiment the first detector circuit part 10a and the second detector circuit part 10b are arranged in parallel. That is, the first detector circuit part 10a and the second detector circuit part 10b may operate independently from one another to avoid interference and maximise the probability that at least one of the first and second detector circuit parts 10a, 10b operates as intended.

[0044] In similar fashion, as shown in Figure 2, a further embodiment is conceivable wherein the drive circuit 12 comprises a first drive circuit part 12a in connection with the first detector circuit part 10a and the first semiconductor switch 5, and a second drive circuit part 12b in connection with the second detector circuit part 10b and the second semiconductor switch 6. The first drive circuit part 12a is configured to switch the first semiconductor switch 5 to the closed or open state based on the dynamic input signal Sd or static input signal Ss, respectively, received by the first detector circuit part 10a. The second drive circuit part 12b is configured to switch the second semiconductor switch 6 to the closed or open state based on the dynamic input signal Sd or static input signal Ss, respectively, received by the second detector circuit part 10b.

[0045] Like the first and second detector circuit parts 10a, 10b, the first drive circuit part 12a and the second drive circuit part 12b provide redundancy and increased safety of the electronic safety circuit 1 . For example, at least one of the first and second drive circuit parts 12a, 12b needs to operate as intended for driving the first or the second semiconductor switch 5, 6 to the open state for blocking the current 8. It will be highly unlikely that both the first and second drive circuit parts 12a, 12b would not operate as intended, so that deactivating the gas burner 2 becomes robust and more resistant to failure of the electronic safety circuit 1 .

[0046] Figure 2 shows an exemplary embodiment wherein the first and second semiconductor switches 5, 6 are each n-channel MOSFET switches 5, 6, of which the corresponding drains 5D, 6D, sources 5S, 6S, and gates 5G, 6G are clearly indicated. The first driver circuit part 12a is configured to drive the gate 5G of the first semiconductor switch 5, and the second driver circuit part 12b is configured to drive the gate 6G of the second semiconductor switch 6.

[0047] As further depicted, in an advantageous embodiment the first drive circuit part 12a and the second drive circuit part 12b are arranged in parallel. The first driver circuit part 12a and the second drive circuit part 12b may operate independently from one another to maximise the probability that at least one of the first and second drive circuit parts 12a, 12b operates as intended for switching the first or the second semiconductor 5, 6 to the open state.

[0048] The exemplary embodiment in Figure 2 shows that both the first and second semiconductor switches 5, 6 may be operated in parallel and independently from one another by virtue of the first and second detector circuit parts 10a, 10b and the first and second drive circuit parts 12a, 12b. By operating the first and second conductor switches 5, 6 independently provides redundancy as it will be unlikely that both the first and second semiconductor switches 5, 6 exhibit faults, or that the first and second detector circuit parts 10a, 10b and the first and second drive circuit parts 12a, 12b are malfunctioning. Consequently, the electric safety circuit 1 becomes more robust to faults and the gas supply G can be maintained or stopped in safe manner based on the input signal S, such as the dynamic input signal Sd and static input signal Ss mentioned earlier.

[0049] The input signal S based on which the control circuit 7 maintains the first semiconductor switch 5 and the second semiconductor switch 6 in a closed state or open state can be provided in advantageous ways for increasing safety when operating the gas burner 2.

[0050] For example, Figure 1 shows an embodiment wherein the signal generator circuit 9 may comprise a timer circuit 11 configured to set an adjustable time interval after which the signal generator circuit 9 changes the dynamic input signal Sd to the static signal Ss. In this embodiment the timer circuit 11 allows a user of the gas burner 2 to specify a required time interval after which the gas burner 2 should be deactivated or turned off. In particular, in practice the gas burner 2 is activated and the signal generator circuit 9 provides the dynamic input signal Sd to the signal detector circuit 10 enabling the control circuit 7 to switch and maintain the first semiconductor switch 5 and the second semiconductor switch 6 in the closed state. In this closed state, the current 8 can be provided by the thermocouple 4 and maintains the safety valve 3 open for gas supply G to the gas burner 2. In this way the thermocouple 4 operates as usual and receives heat from the gas burner 2. When the gas burner 2 is in use, the user may specify a time interval after which the signal generator circuit 9 changes the dynamic input signal Sd to the static input signal Ss. When the time interval expires, the signal detector circuit 10 detects the static input signal Ss which causes the control circuit 7 to switch and maintain the first semiconductor switch 5 and / or the second semiconductor switch 6 in the open state, thereby blocking the current 8 and forcing the safety valve 3 to close.

[0051] In an exemplary embodiment, the signal generator circuit 9 or timer circuit 11 may comprise one or more manual controls 11a for adjusting the time interval to be set by the timer circuit 11 for changing the dynamic input signal Sd to the static signal Ss. In a further embodiment, the signal generator circuit 9 may be configured for wireless or remote adjustment of the time interval.

[0052] From Figure 2 it can be seen that the electric safety circuit 1 may comprise a single conductor CB connecting the signal generator circuit 9 and the signal detector circuit 10, wherein the signal generator circuit 9 is configured to provide the dynamic input signal Sd and the static input signal Ss as at least a class B signal carried by the single conductor CB. In an advantageous embodiment the signal generator circuit 9 is configured to provide the dynamic input signal Sd and the static input signal Ss as at least a class C signal carried by the single conductor CB.

[0053] Further details on class B and C specifications can be found in, for example, standard EN IEC 60730-1 :2022, which applies to the inherent safety of automatic electrical controls for household equipment and similar use.

[0054] In a further embodiment, the dynamic input signal Sd and the static input signal Ss carried by the single conductor CB are provided to both the first and second detector circuit parts 10a, 10b as shown in Figure 2. That is, the parallel arrangement defined by the first detector circuit part 10a and the first drive circuit part 12a, and the second detector circuit part 10b and the second drive circuit part 12b, is operated based on the same dynamic input signal Sd and the static input signal Ss carried by the single conductor CB.

[0055] In a further aspect, the present invention relates to a method of controlling gas supply G to a gas burner 2, wherein the method provides improved reliability and safety when controlling the gas supply G. The method comprises the step of providing a gas burner 2 and an electronic safety circuit 1 according to the present invention, wherein the gas burner 2 is connected to the safety valve 3 and wherein the thermocouple 4 is arranged in proximity of the gas burner 2 to receive heat therefrom when the gas burner 2 is active.

[0056] To allow for the gas supply G to the gas burner 2, the method comprises the step of providing a first input signal to the control circuit 7 for switching the first semiconductor switch 5 and the second semiconductor switch 6 to the closed state for allowing the thermocouple 4 to provide the current 8 through the safety valve 3, thereby maintaining the safety valve 3 open.

[0057] To stop the gas supply G to the gas burner 2, the method comprises the step of providing a second input signal to the control circuit 7 for switching the first semiconductor switch 5 and / or the second semiconductor switch 6 to the open state for blocking the current 8 from flowing through the safety valve 3, as a result of which the safety valve 3 closes.

[0058] Note that the first input signal and the second input signal are different types of the input signal S that can be provided to the control circuit 7 for switching the first semiconductor switch 5 and / or the second semiconductor switch 6 as required. As discussed in light of the electronic safety circuit 1 , the first and second semiconductor switches 5, 6 determine as to whether the current 8 can or cannot be provided to the safety valve 3 by the thermocouple 4. By providing the first input signal to the control circuit 7 allows the thermocouple 4 to provide the current 8 for maintaining the safety valve 3 open and allowing the gas supply G to the gas burner 2. By providing the second input signal to the control circuit 7 blocks the current 8 through the safety valve 3, thereby closing the safety valve 3 and hence stopping the gas supply G.

[0059] In an embodiment, the first input signal is a dynamic input signal Sd and the second input signal is a static input signal Ss. In this embodiment, the dynamic input signal Sd enables the control circuit 7 to switch and maintain the first and the second semiconductor switch 5, 6 in the closed state. The static input signal Ss enables the control circuit 7 to switch and maintain the first and / or the second semiconductor switch 5, 6 in the open state. In an exemplary embodiment, the dynamic input signal Sd is a dynamic voltage input signal and the static input signal Ss is a constant voltage input signal.

[0060] It is important to note that, depending on the application in which the electronic safety circuit 1 is used, the current 8 provided by the thermocouple 4 may not be sufficient or suitable to open the safety valve 3 from its closed position. For example, in case the safety valve 3 is a solenoid valve, then the current 8 provided by the thermocouple 4 is insufficient to generate the magnetic force required for moving the safety valve 3 from its closed position to the open position. However, the current 8 is sufficient to maintain the open position of the safety valve 3. Therefore, in such applications the safety valve 3 may be opened manually or by other means first to allow for the gas supply G and to activate the gas burner 2. Once the gas burner 2 is active, the first and second semiconductor switches 5, 6 are in the closed state by means of a suitable input signal S, e.g. the dynamic input signal Sd, and wherein the thermocouple 4 provides the current 8 to maintain the safety valve 3 in the open position. Deactivating the gas burner 2 can be achieved by disrupting the current 8 as explained in detail above. For example, by means of the timer circuit 11 and the adjustable time interval after which the signal generator circuit 9 changes the dynamic input signal Sd to the static input signal Ss, such that the first and / or the second semiconductor switch 5, 6 switches to the open state.

[0061] In view of the above, the present invention can now be summarised by the following embodiments:

[0062] Embodiment 1 . An electronic safety circuit (1) for controlling a gas supply (G) to a gas burner (2), comprising an electrically operable safety valve (3) configured for maintaining or stopping the gas supply (G) to the gas burner (2); a thermocouple (4) configured for receiving heat from the gas burner (2) when active; and a first semiconductor switch (5) and a second semiconductor switch (6); wherein the safety valve (3) is connected to the thermocouple (4), and wherein the first semiconductor switch (5) and the second semiconductor switch (6) are arranged in series and connected between the thermocouple (4) and the safety valve (3); and further comprising, a control circuit (7) in connection with the first semiconductor switch (5) and the second semiconductor switch (6), and wherein the control circuit (7) is configured to receive an input signal (S) based on which the control circuit (7) is configured to: switch the first semiconductor switch (5) and the second semiconductor switch (6) to a closed state in which a current (8) is allowed to flow through the safety valve (3) for maintaining the gas supply (G) to the gas burner (2), or switch the first semiconductor switch (5) and / or the second semiconductor switch (6) to an open state in which the current (8) is blocked from flowing through the safety valve (3) for stopping the gas supply (G) to the gas burner (2), . wherein the electronic safety circuit (1) further comprises a signal generator circuit (9) and wherein the control circuit (7) comprises a signal detector circuit (10) in connection with the signal generator circuit (9), wherein the signal generator circuit (9) is configured to provide the input signal (S) as a dynamic input signal (Sd) or a static input signal (Ss) to the signal detector circuit (10), wherein the signal detector circuit (10) allows the control circuit (7) to switch the first semiconductor switch (5) and the second semiconductor switch (6) to the closed state when the signal detector circuit (10) receives the dynamic input signal (Sd); and switch the first semiconductor switch (5) and / or the second semiconductor switch (6) to the open state when the signal detector circuit (10) receives the static input signal (Ss).

[0063] Embodiment 2. The electronic safety circuit (1) according to embodiment 1, comprising a single conductor (CB) connecting the signal generator circuit (9) and the signal detector circuit (10), wherein the signal generator circuit (9) is configured to provide the dynamic input signal (Sd) and the static input signal (Ss) as at least a class B signal carried by the single conductor (CB).

[0064] Embodiment 3. The electronic safety circuit (1) according to embodiment 1 or 2, wherein the dynamic input signal (Sd) is a dynamic voltage input signal and the static input signal (Ss) is a constant voltage input signal.

[0065] Embodiment 4. The electronic safety circuit (1 ) according to any of embodiments 1 to 3, wherein the control circuit (7) further comprises a drive circuit (12) in connection with the signal detector circuit (10), the first semiconductor switch (5) and the second semiconductor switch (6), wherein the drive circuit (12) is configured to: switch the first semiconductor switch (5) and the second semiconductor switch (6) to the closed state when the signal detector circuit (10) receives the dynamic input signal (Sd); switch the first semiconductor switch (5) and / or the second semiconductor switch (6) to the open state when the signal detector circuit (10) receives the static input signal (Sd).

[0066] Embodiment 5. The electronic safety circuit (1) according to any of embodiments 1-4 wherein the signal detector circuit (10) comprises a first detector circuit part (10a) and a second detector circuit part (10b) each of which is configured to receive the dynamic input signal (Sd) and the static input signal (Ss), wherein the first detector circuit part (10a) allows the control circuit (7) to switch the first semiconductor switch (5) to the closed state and open state when the first detector circuit part (10a) receives the dynamic input signal (Sd) and static input signal (Ss) respectively; and wherein the second detector circuit part (10b) allows the control unit (7) to switch the second semiconductor switch (6) to the closed state and open state when the second detector circuit part (10b) receives the dynamic input signal (Sd) and static input signal (Ss) respectively.

[0067] Embodiment 6. The electronic safety circuit (1) according to embodiment 5, wherein the first detector circuit part (10a) and the second detector circuit part (10b) are arranged in parallel.

[0068] Embodiment 7. The electronic safety circuit (1) according to embodiment 5 or 6, wherein the drive circuit (12) comprises a first drive circuit part (12a) in connection with the first detector circuit part (10a) and the first semiconductor switch (5), and a second drive circuit part (12b) in connection with the second detector circuit part (10b) and the second semiconductor switch (6), wherein the first drive circuit part (12a) is configured to switch the first semiconductor switch (5) to the closed state or open state based on the dynamic input signal (Sd) or the static input signal (Ss), respectively, received by the first detector circuit part (10a); and wherein the second drive circuit part (12b) is configured to switch the second semiconductor switch (6) to the closed state or open state based on the dynamic input signal (Sd) or static input signal (Ss), respectively, received by the second detector circuit part (10b).

[0069] Embodiment 8. The electronic safety circuit (1) according to embodiment 7, wherein the first drive circuit part (12a) and the second drive circuit part (12b) are arranged in parallel.

[0070] Embodiment 9. The electronic safety circuit (1) according to any of embodiments 1 to 8, wherein the signal generator circuit (9) comprises a timer circuit (11) configured to set an adjustable time interval after which the signal generator circuit (9) changes the dynamic input signal (Sd) to the static signal (Ss).

[0071] Embodiment 10. A method of controlling a gas supply (G) to a gas burner (2), comprising the steps of providing a gas burner (2) and an electronic safety circuit (1) according to any of embodiments 1-10, wherein the gas burner (2) is connected to the safety valve (3) for receiving the gas supply (G) therefrom, and wherein the thermocouple (4) is arranged in proximity of the gas burner (2) to receive heat therefrom when the gas burner (2) is active; providing a first input signal to the control circuit (7) for switching the first semiconductor switch (5) and the second semiconductor switch (6) to the closed state for allowing the thermocouple (4) to provide the current (8) through the safety valve (3), thereby maintaining the safety valve (3) open; providing a second input signal to the control circuit (7) for switching the first semiconductor switch (5) and / or the second semiconductor switch (6) to the open state for blocking the current (8) from flowing through the safety valve (3), thereby closing the safety valve (3), wherein the first input signal is a dynamic input signal (Sd) and the second input signal is a static input signal (Ss).

[0072] Embodiment 11 . The method of embodiment 10, wherein the dynamic input signal (Sd) is a dynamic voltage input signal and the static signal (Ss) is a constant voltage input signal.

[0073] The present invention has been described above with reference to a number of exemplary embodiments discussed above and as shown in the drawings. Modifications and alternative implementations of some parts or elements are possible, and are included in the scope of protection as defined in the appended claims.

Claims

CLAIMS1 . An electronic safety circuit (1) for controlling a gas supply (G) to a gas burner (2), comprising an electrically operable safety valve (3) configured for maintaining or stopping the gas supply (G) to the gas burner (2); a thermocouple (4) configured for receiving heat from the gas burner (2) when active; and a first semiconductor switch (5) and a second semiconductor switch (6); wherein the safety valve (3) is connected to the thermocouple (4), and wherein the first semiconductor switch (5) and the second semiconductor switch (6) are arranged in series and connected between the thermocouple (4) and the safety valve (3); and further comprising, a control circuit (7) in connection with the first semiconductor switch (5) and the second semiconductor switch (6), and wherein the control circuit (7) is configured to receive an input signal (S) based on which the control circuit (7) is configured to: switch the first semiconductor switch (5) and the second semiconductor switch (6) to a closed state in which a current (8) is allowed to flow through the safety valve (3) for maintaining the gas supply (G) to the gas burner (2), or switch the first semiconductor switch (5) and / or the second semiconductor switch (6) to an open state in which the current (8) is blocked from flowing through the safety valve (3) for stopping the gas supply (G) to the gas burner (2), wherein the electronic safety circuit (1) further comprises a signal generator circuit (9) and wherein the control circuit (7) comprises a signal detector circuit (10) in connection with the signal generator circuit (9), wherein the signal generator circuit (9) is configured to provide the input signal (S) as a dynamic input signal (Sd) or a static input signal (Ss) to the signal detector circuit (10), wherein the signal detector circuit (10) allows the control circuit (7) to switch the first semiconductor switch (5) and the second semiconductor switch (6) to the closed state when the signal detector circuit (10) receives the dynamic input signal (Sd); and switch the first semiconductor switch (5) and / or the second semiconductor switch (6) to the open state when the signal detector circuit (10) receives the static input signal (Ss).

2. The electronic safety circuit (1) according to claim 1 , comprising a single conductor (CB) connecting the signal generator circuit (9) and the signal detector circuit (10), wherein the signal generator circuit (9) is configured to provide the dynamic input signal (Sd) and the static input signal (Ss) as at least a class B signal carried by the single conductor (CB).

3. The electronic safety circuit (1) according to claim 1 or 2, wherein the dynamic input signal (Sd) is a dynamic voltage input signal and the static input signal (Ss) is a constant voltage input signal.

4. The electronic safety circuit (1) according to any of claims 1 to 3, wherein the control circuit (7) further comprises a drive circuit (12) in connection with the signal detector circuit (10), the firstsemiconductor switch (5) and the second semiconductor switch (6), wherein the drive circuit (12) is configured to: switch the first semiconductor switch (5) and the second semiconductor switch (6) to the closed state when the signal detector circuit (10) receives the dynamic input signal (Sd); switch the first semiconductor switch (5) and / or the second semiconductor switch (6) to the open state when the signal detector circuit (10) receives the static input signal (Sd).

5. The electronic safety circuit (1) according to any of claims 1-4 wherein the signal detector circuit (10) comprises a first detector circuit part (10a) and a second detector circuit part (10b) each of which is configured to receive the dynamic input signal (Sd) and the static input signal (Ss), wherein the first detector circuit part (10a) allows the control circuit (7) to switch the first semiconductor switch (5) to the closed state and open state when the first detector circuit part (10a) receives the dynamic input signal (Sd) and static input signal (Ss) respectively; and wherein the second detector circuit part (10b) allows the control unit (7) to switch the second semiconductor switch (6) to the closed state and open state when the second detector circuit part (10b) receives the dynamic input signal (Sd) and static input signal (Ss) respectively.

6. The electronic safety circuit (1) according to claim 5, wherein the first detector circuit part (10a) and the second detector circuit part (10b) are arranged in parallel.

7. The electronic safety circuit (1) according to claim 5 or 6, wherein the drive circuit (12) comprises a first drive circuit part (12a) in connection with the first detector circuit part (10a) and the first semiconductor switch (5), and a second drive circuit part (12b) in connection with the second detector circuit part (10b) and the second semiconductor switch (6), wherein the first drive circuit part (12a) is configured to switch the first semiconductor switch (5) to the closed state or open state based on the dynamic input signal (Sd) or the static input signal (Ss), respectively, received by the first detector circuit part (10a); and wherein the second drive circuit part (12b) is configured to switch the second semiconductor switch (6) to the closed state or open state based on the dynamic input signal (Sd) or static input signal (Ss), respectively, received by the second detector circuit part (10b).

8. The electronic safety circuit (1) according to claim 7, wherein the first drive circuit part (12a) and the second drive circuit part (12b) are arranged in parallel.

9. The electronic safety circuit (1 ) according to any of claims 1 to 8, wherein the signal generator circuit (9) comprises a timer circuit (11) configured to set an adjustable time interval after which the signal generator circuit (9) changes the dynamic input signal (Sd) to the static signal (Ss).

10. A method of controlling a gas supply (G) to a gas burner (2), comprising the steps ofproviding a gas burner (2) and an electronic safety circuit (1) according to any of claims 1-10, wherein the gas burner (2) is connected to the safety valve (3) for receiving the gas supply (G) therefrom, and wherein the thermocouple (4) is arranged in proximity of the gas burner (2) to receive heat therefrom when the gas burner (2) is active; providing a first input signal to the control circuit (7) for switching the first semiconductor switch (5) and the second semiconductor switch (6) to the closed state for allowing the thermocouple (4) to provide the current (8) through the safety valve (3), thereby maintaining the safety valve (3) open; providing a second input signal to the control circuit (7) for switching the first semiconductor switch (5) and / or the second semiconductor switch (6) to the open state for blocking the current (8) from flowing through the safety valve (3), thereby closing the safety valve (3), wherein the first input signal is a dynamic input signal (Sd) and the second input signal is a static input signal (Ss).11 . The method according to claim 10, wherein the dynamic input signal (Sd) is a dynamic voltage input signal and the static signal (Ss) is a constant voltage input signal.

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